LT1 or L98

Well today I had my first problem with the Camaro and i've had it for a month. She wouldn't start for some unknown reason, and suddenly I have a hole in the hose that goes from my Air Intake Hose down to my Headers. So with these two problems i'm coming to the conclusion that my little 305 is about to reach the end of it's life. Well probably not but it gives me an excuse to at least think about an Engine Swap lol. So guys what do you think LT1 the 275hp Legend or the L98 the 230hp Small Block that could. I like the LT1 for it's gas mileage, reliablity and well top end power but I also like the challenge of building up an L98. Let me know what you think I should do and btw money does play a role in this swap. Thanks Guys.

The thing to remember is they're both 350's, the LT1 will cost more up front but probably be easier to mod. The L98 is cheaper up front but will take more to run the same..I've seen LT1's go anywhere from $1500-$2500 w/harness and accessaries, and L98's about half that..but L98's are becoming harder to find while LT1's are plentiful at salvage yards. But you'll need more than just the motor and harness for the LT1...not sure what all..but it'll probably "nickel & dime you"...$$

With the right heads + cam + intake etc for each, BOTH are capable performers...
Owners choice...

L98 would be cheaper to find than an LT1... LT1 is pretty quick stock, but with the money you'd spend on an LT1, you could get the L98, and with whatever left over money you have, you can mod it up to out perform a LT1. all you need to do is change the intake on the L98 to that of, lets say, a mini ram, and you'll be out performing an LT1 any day. L98 are torque monsters down low, but have no top end. LT1's have good top end due to their intake... but like i said before, if you get yourself a HSR or MR intake to replace the stock TPI in a L98, you'll be eating LT1's :D but if you got an LT1, you could always convert it into an LT4... it'll run you almost 3 grand though if im not mistaken.

i foresee another "lt1 vs. l98" debate coming up...:p

I got my LT1 complete with harness and computer for 1250. I bought the rad and fan assembly along with it for not much more. I modified the harness myself and saved the 500+ dollars I would have needed to buy a Painless harness.

You can come out pretty cheap if you so chose. I went ahead and bought a CAI, Slp headers and full exhaust right to begin with.

I am not trying to start a war, but I don't think you could outrun an LT1 with the same money. Unless, you got a really good deal on everything you bought. I hear the L98s fall on there face after about 5200 even with an aftermarket intake setup. I have seen a dyno graph of a stock tpi 350. It made 320 tq and 230 hp at the wheels. The torque drops off pretty quick after its peak. The stock LT1s I have seen begin low AND stay high till the end.

Whatever you chose, at least it will be in a 3rd gen;)

[i]I hear the L98s fall on there face after about 5200 even with an aftermarket intake setup. I have seen a dyno graph of a stock tpi 350. It made 320 tq and 230 hp at the wheels. The torque drops off pretty quick after its peak. The stock LT1s I have seen begin low AND stay high till the end.

Whatever you chose, at least it will be in a 3rd gen;) [/B]




That would be because of the heads. They don't flow real well after 5k rpms. All they need is a good port job and they will flow as well or better than stock LT1 heads. So HSR or MR + ported heads = an L98 that will kill stock or lightly modded LT1's

Uhh.... no. Its the INTAKE that is the problem on L98 engines. The heads are a close second. The aluminum L98 Corvette heads are pretty decent, but the iron ones suck. I dont think anyone is going to get 230 cfm out of an iron L98 head.

As far as the debate goes, you're asking the wrong crowd here. We're pro-TPI, so of course we're going to say go with the TPI engine. Either case is going to cost a lot of money, so pick the one in your budget that you can find easily. L98 engines are getting very hard to find.

Let me be specific here. The TPI setup dies at 4500. The heads die at 5K. So even if you replace the intake now you are limited by the heads. And there is a guy on here that got 248 CFM out of his stock ported iron heads.

If that is true about his heads, I would be REALLY surprised. More power to him!

The aluminum L98 Corvette heads are pretty decent, but the iron ones suck. I dont think anyone is going to get 230 cfm out of an iron L98 head.

Shouldn't be too hard to get well over 230 cfm porting a set of iron L98's. They are not a bad head to begin with.

Car Craft got 15HP more than a set of stock 882's on the dyno in their old 'Junkyard Jewel' series with a set of iron TPI heads. And 882's despite being from the smogger era flow better than the aluminum L98 head.

Intake port Flow @ 28" water:

882: 205 cfm @ .500" (http://www.chevyhiperformance.com/chevyhighperformance/techarticles/p104564_image_large.jpg)

L98 aluminum: 196 cfm @ .500" (http://www.chevyhiperformance.com/chevyhighperformance/techarticles/p104408_image_large.jpg)

Which would be cheaper to port, the Iron or Aluminum L98 heads? Would they flow the same, or would one out flow the other? Cuz i was thinking about porting out my heads till i get some aftermarket ones, but i have access to aluminum L98 heads, and my stock iron heads... i just don't know which one would give me more power if i port 'em

As far as I know, and I could be wrong, the only difference between the aluminum and the iron heads is the materials they were made from.

Same casting, only the aluminum heads are lighter, of course, and probably easier to work with.

Edit: I have heard that iron heads do flow just a bit better than the same aluminum heads but the few extra horsepower is negated by the increased weight.

LT1's, as much as I love them aren't where it's at. There is no market for them, parts are $$$ and there is no real advantage to picking one over the older SBC design.

I say, stick with the traditional sbc (L98), buy some decent AFTERMARKET heads (they are cheap, why bother with L98 aluminum SCRAP), carb it (TPI sucks) and go racin. :)

Have fun!

Everyone's gonna defend their preferences and choices made, which is OK. But just b/c everyone can't get L98 heads to flow, DON'T mean it can't be done..

The LT1 is probably one of the most owner modified smallblocks made, there's just so much, more info and more aftermarket for them than the L98 EVER had...at the right time.

**"So many misconceptions, so little time", as said many times; there are avariety of heads & cams in the L98's evolution.
It's just not good sense to group them all together in general. **

I've seen many of these heads apart and understand where the restrictions are. The bowls have a TON of room for improvement despite their already good performance I've seen an easy 25-30HP increase in just a good bowl-port / valve job on them.

The Vortechs flow slightly better "as cast" but once the TPI heads are ported right, they jump ahead. One drawback are the castings are thin, this doesn't leave a lot of room for runner enlarging. But raising and reshaping the runner entrances and gasket matching parts DOES make a difference.

**I am taking my time with porting my L98 heads,and will try to take pics and get flow numbers, before and after. And I'm consulting some very experienced "head-porters" who've assured me there's BIG gains to be had...(intake too) I'm gonna have less than $250 in my L98 heads, and am shooting for a 30HP increase in just the improved heads. I'm also porting the intake as everyone sees some potential in it too.

BTW my Iron heads don't "suck"...:cool:

There rated as 285/300 HP in the GMPP book, listing of heads. VERY close in almost every way(number wise)to the LT1's...64cc Chambers, 1.94/1.5 valves,straight plugs...I'm going to cc my intake runners this week...The Corvette's list at 163cc, and my iron heads are supposed copies....LT1's are supposed to be 170cc...
The main difference is LT1's are a "swirl" design, the L98's are a "Tumble" design...
These ARE facts, NOT hearsay...look'em up for yourself...

How are my L98 heads a big restriction??????:confused:

Also, the Intake was designed for the Corvette 350, it was simetaniously(sp?) slapped on the LB9 305, the VERY SAME PARTS....only the injectors were downsized to 19lbs from 22lbs...

Max lift flow numbers aren't where it's at, it's the mid range, where the valves spend most of their time...
230cfm is really more than a 350 needs, it would kill some throttle response and low end performance!...Which is why you see alot of smallblock heads promote, 190-210 range...:think:

The LT1 is probably one of the most owner modified smallblocks made, there's just so much, more info and more aftermarket for them than the L98 EVER had...at the right time.

That's not true. SBC has 50 years of history, LT1 has 5 years at most. Don't be fooled by the 2 pages in summit that outline fuel pressure gauges and hotchkiss parts for 4th gens. Third gens have a MUCH LARGER aftermarket, because it is universal.

And regarding heads- the goal is to go fast. Why spend any money modding a stock head or a vortech head, if for the same price (or a little more), a true aftermarket head will outperform it with minimal work?? This is a no brainer. Just look at all the guys on this very forum that dump a ton of money into a motor and can't best 13.50's. In a world where every 4 door grocery getter now has 300hp, what is the point in modding a car to get 285? Sounds like a waste to me.

It's all about combo, and it's all about the heads.

JMO.

Edit: I have heard that iron heads do flow just a bit better than the same aluminum heads but the few extra horsepower is negated by the increased weight.

Thats false. If two heads are identical in every aspect except the metal they are made of, they are going to flow identically. The iron head will insulate better and make slightly more power because of it, but the aluminum head will tolerate more compression due to better ability to disipate heat. Both heads have advantages, the aluminum is just more expensive but lighter and easier to modify/repair.

Originally posted by steve10358
That's not true. SBC has 50 years of history, LT1 has 5 years at most. Don't be fooled by the 2 pages in summit that outline fuel pressure gauges and hotchkiss parts for 4th gens. Third gens have a MUCH LARGER aftermarket, because it is universal.

JMO. LT1 has been around since 92 and has been modded since. True the small block has been around since 55 but the LT1 probably has just as much, if not more, stuff you can do to it.

There are some N/A LT1's in the 9's(388+ CID). Don't know how many tuned ports are there but they came out in 85 so they have a few years on the LT1.

If it were me, I'd swap an LS1 and go from there. But that is expensive!

After that, I'd stick with the old fashioned small block. Many head choices. Use the LT1 intake as a cheaper alternative than modding the TPI. It might cost a little more in the long run but I think you'd be better off.

The LT1's main (so called)advantages are the shorter runner intake and taller port heads, why is spending $1200-$1500 for a motor and extra $500 or so in adapting it and maybe $1000 in labor for someone to install it, a cheaper alternative to buying a HSR or MR + F/R + WP Heads + cam = $1600????:confused:

And as for stock iron heads, mine are rated at 285/300HP STOCK!
(Part#10125377 or casting#14011083)
I'm looking at getting a little over 400HP out of them and putting only $250 in them, very much worth my time, to me...

Because I can, and am willing to port my heads, I won't spend $1,000 for a set of aftermarket heads that will flow the same as mine when ported. I guess I've always been one to want to swim upstream, but I've learned a lot that way...:)

Airflow = HP and heads are where it's at, I know...but I'm not willing to shell out a grand for minimal gains over what I'll have.
When I buy aftermarket heads, they'll be Aluminum, so I can run another point of compression on pump gas, and they'll be supporting more than the 420HP combo I'm building now...:)

You don't see many fast TPI's out there either b/c most want it "fast & easy", they give up on the "Tuned Port" b/c everyone tells them they can't do it with LTR...Guess I'm hard headed there too..:D When I get told "you can't do it", I become more determined to prove them all wrong..;)

And for "the guys in this forum who dump a ton of money and run 13.50's....Combination is EVERYTHING!...That goes way beyond just heads....Buying aftermarket heads will NOT improve this.
If they install a set of 230+CFM race heads, a 240*/ .540" cam, MR and don't address programming, injector sizing, gearing and stall etc....or if the cam doesn't operate in the heads optimal flow range...They won't go faster than 13.50's either! And they will have spent a TON MORE money...
BTW, I know I'll hit high 12's with my combo(ported stock heads), I'm gonna try to stretch it to the mid-low 12's tho..:cool: ...we'll see this spring!:cool:

Go with an LS1 ;)

ls1's are bad ass... but they're really expensive to mod. :( would rather build my own sbc and make it out perform a modded ls1 for way less than what it would cost to buy an ls1 and put the same mods on it

TPI's are known to be better for low speed and mid range power because of the longer air runners. With a modest amount of mod's it could easily keep up with an LT1. It is all a matter of personal preference. LT1's are more technologically advanced and there is a large market for them. TPI's have a huge market and so far have a wider range of user's because of the ease of install into cars of all sorts. Remember that the 1st Gen blocks have been used since 1955 to 1994.

BOZ :cool:

guys I am in no way tring to start a war with this comment but does anyone out there have a stock headed, no nitrous, no superchargered l98 that can run 10's or 11's? And if so how many are there? two or three? With this in mind how can anyone say a modded l98 with stock ported heads,cam, and programming will run with a stock ported heads, cam and programmed lt1? Just looking at the facts. Not trying to start another war here. If anyone has facts to back up the l98 just lets us know. Maybe this coming year we all could get together and have a lt1 vs l98 heads up shootout. And just let the track times speak for themselves. Anyway as long as we are all busting those mustangs that's all that really matters. :D

Originally posted by mako350Z28
Let me be specific here. The TPI setup dies at 4500. The heads die at 5K. So even if you replace the intake now you are limited by the heads. And there is a guy on here that got 248 CFM out of his stock ported iron heads.

I know "The guy" who got 248cfm@ .480" lift out of his stock 083 castings, with larger valves. He was assisted by the owner of Cylinder Head Specialties www.cylinderheadspecialties.com and his heads flow great on the exhaust too (185cfm@.600" EGR port)

He also siamese ported his intake manifold and it pulls HARD up to 6500rpm with STOCK runners now. No track times yet but I'll let you know when he gets his @ss to the track.

He also siamese ported his intake manifold and it pulls HARD up to 6500rpm with STOCK runners now. No track times yet but I'll let you know when he gets his @ss to the track.

I don't see how it can pull hard with stock runners. They are like straws! TPI always fools the butt-o-meter, though. Let us know if you get any numbers next year.

There are some N/A LT1's in the 9's(388+ CID). Don't know how many tuned ports are there but they came out in 85 so they have a few years on the LT1.

TPI SUCKS!!! You can't lump the potential of the 50 year old SBC into the tiny 7 year window that TPI was around. You can't do anything with the TPI that GM had. You'd have to convert a carb intake over to get past that and still have FI. :)

The LT1 intake can help, but you can't get much more than 270-high280's out of it... which doesn't support all that much power for the guys that have more money than me. :)

The real problem is that no one has ever organized a race series that focused on just the F-body. But there are tons of series with SBC's- so that's where the technology curve goes. Look at the Mustangs if you don't believe me. They've got several race series, and you can cheaply get a Stang into the 9's, and it's not just cause of weight! It's really too bad the F-body never saw that... but then again- all of us bickering, undecisive fools helped bring it down too. LOL.

"I like new ones"
"No, I like old ones, new ones suck"
"Well, I don't like the rules"
"They were designed around politics"
bicker bicker, fight fight.


LOL

Merry Christmas!

S.

TPI's suck, LT1's suck...lets all buy Mustangs..:rolleyes: :barf: :no:

You're missing the point.

1. TPI does suck. Pure Garbage. Anyone who says otherwise has never hung out near a flow bench before. I do wish I didn't have reverse flow though... it'd be nice to just throw a set of heads on my T/a.

2. LT1's had some improvements, but still have $ome flaw$ overall- and a very limited aftermarket. Also- what would be the incentive for a hardcore racer to chose our vehicle, aside from personal preference? They're heavy, the intake is trash if you wanna compete in a serious race series, and you need to convert an aftermarket set of heads over to get anywhere, if you don't wanna dump $4000 on the right AFR's.

3. I WISH we had the industry support that the Mustangs get. I'm a realist. It'd be naive to think F-bodies are all there are. Let's all face it- as much as I love the F-body, it's DEAD and we are left in it's wake. :)

There's no way around it.

Keep in mind- I'm not trying to insult anybody, and there are certainly many ways to skin a cat- but there are a lot of misconceptions here. I am trying to argue the fact that a third gen really does have more options, the LT1 and LS1 aren't the end all's to the SBC, and if you wanna get anywhere, scrap the only real weakness... the TPI.

Later.

Do you have flow bench numbers for a TPI??
I do get near a flow bench once and a while...I HAVE seen "ported" stock TPI intakes only give up 12HP to a "SuperRam", is that garbage...if so what is your yardstick to gage it by???(That was w/o adding aftermarket runners or base.)
The SuperRam has a much shorter runner too...:think:

I'm just saying, I think there are a lot of misconceptions too, in the other direction.
I'll agree with you about more options out there for the L98, ofcourse. And NO "All Out Racer" would even choose an LS1, but that's NOT what we're talking about here.
We're talking about a fast daily driver with very streetable manners...I still believe a TPI can accomplish this...
I've already shown you one(TPI) in the 12's, do I have to find one in the 11's, then 10's.???
How fast will make it NOT garbage???

I guess I'll be the only 3rd Gen staying true to it's design, powerplant & all...at least for now...

(I guess next we'll see LT1's in F150's???)

I don't know, maybe it's cause all my friends are in the 8's and 9's, that I think 12's is ho-hum now-a-days. No insult to anybody, I run 12's and am dissapointed.

Sure, TPI cars can run 12's. All it takes is a few bolt-ons, and the right combo. But once you start getting serious, it becomes a major drawback. Show me one NA Stock intake TPI car running -9's, much less 10's or 11's that hasn't been gutted- and I'd be impressed...but you're never gonna find one.

Heck- I've seen a couple LPE 383 C4 Vettes w/ Ported heads and ported stock TPI's that couldn't bust 108-110 in the quarter. Tell me that's not a waste of money... all cause of the bottle neck up top. An NA 383, should at least run low low 12's @ 117.

And even in the long run- it's more about combo than anything. Just cause a near stock TPI motor runs high 12's doesn't truly mean that's a reflection on the intake. Nothing was really done to make the engine draw in that much more air to tax the intake. Start adding real heads, and a cam- and it's all restriction from there.

That's why so many guys run 12's with such a low MPH out of these cars. They make mods to take advantage of the torque, but the cars all nose over in the end. It's just the nature of the beast.

I guess I'll be the only 3rd Gen staying true to it's design, powerplant & all...at least for now...

You're cutting yourself short. Out of the thousands of TPI cars out there, there is no point in keeping to the original anything. These cars will never appreciate. There are two many of them. Not only that- but isn't the goal of all of this to go fast? Why cut power output down for the sake of a TPI fetish? There's no point!

But hey, to each their own. This conversations getting too hostile, and I'm done. A car's just a car.

Originally posted by mako350Z28
That would be because of the heads. They don't flow real well after 5k rpms. All they need is a good port job and they will flow as well or better than stock LT1 heads. So HSR or MR + ported heads = an L98 that will kill stock or lightly modded LT1's So a stock 350 tpi with ported heads and an intake can kill a slightly modded Lt1?

I am not saying my car is fast but I would race somebody quick that said all they had was ported heads and an intake on a stock 350 tpi. I imagine there is somebody out there that is running 12s but how is it going to look after the 1/4.

Now put in a nice cam and a really nice exhaust with all the bolt ons and maybe.

Great post Steve.

I agree that TPI becomes the bottleneck once you change heads/cam/displacement/etc. If you're an all out drag racer, then yes, TPI sucks. But for a street car, TPI rocks. Nice low end torque on the street. It's great! Even if you're a road racer (me in 5 years :) ) the low end torque is great for boosting you out of turns quicker than a similarly equipped LT1/LS1 car.

One problem I saw with your post: The 9 second stock intake car comparison. Why pick the intake when we're comparing engines? I've never seen an LT1 with a wet OPTI run 12's, let alone run. TPI cars can run 12's with wet engine compartments :p

-Rippin

Like I said before, my goal is to have a fast but very streetable, fun car to drive..

Sorry about those Vette's, I guess they didn't learned the right combo...I was pulling @ 101 mph with the meager mods I had..
But this isn't a court decision that now says, "Now no-one in a 383 TPI can top110 mph"...

Who cares about 8's, 9's or even 10's...they're just not streetable...or fun to drive on the street...:p
I'm not trying to "Kenny Bernstein" and I sure don't want a "Trailer Queen", sitting in my garage 90% of the time...

I'd say mid 11's is about the limit of good streetability..and I think I'm in good company in that asessment...
And I believe, that with an aftermarket TPI base and runners, mid 11's can be had...

And my '90 is one of like 1700 made during the 6 month production year in which they held the name "IROC", cut short b/c GM refused to renew its rights and Chrysler quickly jumped on it....

Just for thech's sake I'm gonna take my TPI(&heads) to the flow bench at my local speed shop after Christmas and post the results...I was gonna have it bead-blasted anyways...:thumb:
I'm gonna get cold, hard, facts...we'll see how it goes...

I don't get hostle bro..:) I think debates are essential to cut through all the propaganda BS...
I might get frustrated when people tell me I can't do something and no evidence to prove it...:( not hostile..
But hey, I knew my decision wasn't a popular one; everyone wants to buy/ sell parts, or promote them, or justify why they bought them...human nature...
If there's a will, there's a way...remember..:D

I think things are getting a little clearer now.

For a 12 second street ride, you guys are right. You can make due with TPI. And I'll end it at that. :)

Everybody has different wants and needs, and there are many ways to obtain it. I am still learning, and just wanna have fun with the ride.

Best wishes to all.

Steve :)

Originally posted by 90rocz


Who cares about 8's, 9's or even 10's...they're just not streetable...or fun to drive on the street...:p
I'm not trying to "Kenny Bernstein" and I sure don't want a "Trailer Queen", sitting in my garage 90% of the time...

I'd say mid 11's is about the limit of good streetability..and I think I'm in good company in that asessment...
And I believe, that with an aftermarket TPI base and runners, mid 11's can be had...

And my '90 is one of like 1700 made during the 6 month production year in which they held the name "IROC", cut short b/c GM refused to renew its rights and Chrysler quickly jumped on it....



slightly off topic, and just to push the envelope a bit, I would say all motor, high 10 low 11s would be around the limit to a very streetable daily driver. But with any kind of power adder allowed, anywhere in the 10s (atleast) can be very streetable, for what I consider streetable

The LT1 can breath fairly well, has a stronger aftermarket than some people want to acknowledge, and has been a proven performer in the 9 and 10 sec street car range. anyway, I'm a huge fan of the LT1 (vs the LS1), so while I can come here and back up the benefits of an LT1, I am also quite careful not to step on L98 guys the way the LS1ers try to do to us.

The abilities and drawbacks of both motors is very well known, and there are a ton of options for both. Driver preference is going to play as large of a role as anything. If it was me, I would swap in an LT1, sure, but if it was me I would also love to have an iroc sittin in the driveway to go with my 4th gen. Both can make power, its a matter of how streetable you want it, gas mileage, tuning capability, drag race or roll race or cruiser or daily driver ,etc

Right, I was speaking of mid 11's NA, you're right a Turbo or Supercharger etc would easily subtract another 1/2 sec to 1 sec...
Which I have'nt rulled out yet...down the road.
Yes I know it's "easier" to make more Peak power at a higher rpm with a shorter runner and taller port heads, just means I must go a completely different route than you...
I would'nt kick a 4th Gen outta my driveway either, but My ROC's my Fav and it's not going anywhere soon...:D
I'd also like to round out the stable with a 1st Gen BBC SS Camaro, like my dad's...someday... :bow: :bow:

i love my L98... but i like how the LT1 doesnt die as quick as the L98 does top end wise. thats why im going the extra mile in putting an LT1 to replace my blown L98 instead of looking for another L98 to put in it's place. im going to miss the low end torque you get out of an L98, but i think the top end power from an LT1 will make up for the missing 10 lbs of low end torque lol

if this topic is still goin' around by the time my swap is completed, ill reply and let you guys know how big of a difference i feel going from a slightly modded L98 to a bone stock LT1

EDIT: not gonna do the swap... just gonna rebuild the L98 instead

Don't expect a big difference, least not 'til you start moddin it. I pull LT1's around here all the time, even hung with LS1's 0-60; at least before I tore down my motor to freshen it and change cam and do some headwork. Now I want to see how I'll fair with some "strong", modded LS1's...I've still got a few tricks to use...

No offence ,but you must have some pretty slow ls1's where you come from. My buddies stock 98 with 3:73 gears, exhaust, and hypertech programming run 12.78 so I dont think you could even stay with one in the first 60 feet not to mention 60 mph. Just my thoughts and trying to have a little fun. Like I said lets all get together and get someone to host a lt1, ls1, l98 shootout. One of the rules would be that you would have to drive you car like on a 50 mile run before the race and lets see which motor really is better. But I think we all ready know the answer. I am a lt1 guy but even I know that the ls1 is better. I will take second place I guess. BUt I bet those l98's would finish a strong third. Just some laughs guys not trying to be smart.:D

Ok, L98/LT1/LS1 shootout:

100 mile trip. Pump gas. Maximum of $20,000 invested. Have stock and modified classes.

I honestly think with a limit that high, L98's would be real competitive (not in the stock class). All it takes it money...

-Corey

Originally posted by jonesy91z28
Like I said lets all get together and get someone to host a lt1, ls1, l98 shootout. One of the rules would be that you would have to drive you car like on a 50 mile run before the race and lets see which motor really is better. But I think we all ready know the answer. I am a lt1 guy but even I know that the ls1 is better.

I wouldnt jump to that conclusion. I have no love for the LS1 nor am I impressed

but a shootout sounds cool, too hard to ever make fair, but who plays fair ;)

Well said guys... :)

money can get you a 9 second car... i personaly think if i had the cash, i'd go out and get myself a 2002 ss, and a 427 ci c5-r block to go in the place of the stock ls1. would be kinda raw to own a 4th gen with a c5-r block in it, wouldn't you think? i wouldn't stop there though... i'd go forced induction just to make sure i wouldnt be touched by any other car on the street, lol, but thats only if i won the lotto... if i won the lotto, i think i'd build that camaro without a second thought :D and if i had the money, i think i'd go all out as far as i can on an L98 and on an LT1 just to see which one really is superior, lol

in all honesty, i like the LT1's, but i think you can build an L98 to spank LT1's and it's much more fun to do so :D

Basically what i'm getting from you guys is that after a little money an L98 is gonna be the better choice but what if I swapped the L98 Intake for an LT1 intake that should compromise the top end loss problem shouldn't it?

Originally posted by mako350Z28
As far as I know, and I could be wrong, the only difference between the aluminum and the iron heads is the materials they were made from.

Same casting, only the aluminum heads are lighter, of course, and probably easier to work with.



No, the iron and aluminum L98 heads are completely different. They are not the same casting. The aluminum heads have 58cc combustion chambers while the iron ones are 64cc's. I forget the numbers but the intake port size and shape, as well as the flow numbers, are different too. Also, the iron heads have EGR ports built into the exhaust while the aluminum heads do not.

Originally posted by 94LT1Maro
Basically what i'm getting from you guys is that after a little money an L98 is gonna be the better choice but what if I swapped the L98 Intake for an LT1 intake that should compromise the top end loss problem shouldn't it?


What everyone is getting at is probably that its all about combo and choice. You may get an L98 for cheaper than an LT1, and spend the left over $ on something like a cam and headers, and maybe it will be as fast as an LT1. But then if you had the LT1, you could add that cam or headers to that and be ahead again with matched mods but for a bit more $. You can play that same game with LT1 vs LS1 too until you really work over the motor to get rid of advantages one recieved from the factory and not the other.

As for an LT1 intake on an L98, I know intakes can be converted for different applications but I'm not sure what machining would be involved in that, unless their is an aftermarket alternative available for that already. But they are NOT direct replacements bc of the reverse flow cooling of LT1

Originally posted by 94LT1Maro
Basically what i'm getting from you guys is that after a little money an L98 is gonna be the better choice but what if I swapped the L98 Intake for an LT1 intake that should compromise the top end loss problem shouldn't it? OKay lets just set this straight l98's and lt1's are basically the same animal. An lt1 is just an l98 on crack (reverse cooling) Past the bottom end it doesnt really matter because chances are youre going with an aftermarket intake. Put a tpis mini-ram on an L98 and youll outrun and lt1. The bottom end of the engines is really the same and i think the heads are pretty similar? The main difference is the intake.

Originally posted by Bad AZz Z28
As for an LT1 intake on an L98, I know intakes can be converted for different applications but I'm not sure what machining would be involved in that

All the answers you need: www.lt1intake.com

IMO, given a set budget (gotta buy the car/engine with it), an L98 can be made to stomp an LT1. Because L98's and mods for it are cheaper, you always have more "mod money" when compared to doing an LT1/LS1 buildup.

-Corey

Originally posted by Rippin92RS
All the answers you need: www.lt1intake.com

IMO, given a set budget (gotta buy the car/engine with it), an L98 can be made to stomp an LT1. Because L98's and mods for it are cheaper, you always have more "mod money" when compared to doing an LT1/LS1 buildup.

-Corey

nice. I know I've seen/heard of a converted intake before but never paid much attention.

It really comes down to what people want to build between L98 and LT1 and what deal they can get with one. Unlike that tin foil crap :) , a small block is a small block and can use alot of the same good parts. an L98 with LTx intake, some good SBC heads and a solid bottom end has no reason to not perform very well and be good daily driven.

Here is my 2 cents on the whole L98 vs. LT1 debate:

Stock vs. Stock the LT1 will most likely beat the L98 in every catagory except low end torque. With that being said, there are some things that I think makes the LT1 less desirable:

-Opti-Junk
-Unique heads

Basically, I think what makes the LT1 is the intake. Sure, the heads are better, but they aren't that great and looking down the road at performance mods, you are going to want to get better heads. Cost is always a factor and lets face it, the LT1 is one of the most expensive chevy engines to mod when we are talking hard parts. Not to metion that you need an ignition system to support the mods and the Optispark is quite possibly one of the most sad ignitions I have ever seen.

-on the other side of the coin-

The L98 has a great intake and heads combo if you have a truck that needs to pull stumps. However, there are so many different aftermarket intakes out for these engines you can basically pick and choose one that best matches your driving style.

Either way, when it comes to making more power, it is not going to be cheap. If you are looking for a stock engine that you do not intend to ever produce 400+ HP then I think the LT1 would be my first choice, just be prepaired to deal with all the headaches that come along with swapping in an LT1 as the serpentine assy drive setup that comes on these engines is not directly compatible with a 3rd gen. The Corvette serpentine setup works great but you will still need custom A/C lines and the vette A/C compressor is not cheap if you have to buy one.

For reference, I helped my friend install an LT1 into his 86 T/A about 4 years ago and then later helped him do the HOT-LT4 (heads and cam) conversion on it. http://lt4.cz28.com Impressive for what it is but not how much he had to pay for everything. He still doesn't have the A/C hooked up but it could easily be done.

So let me put all this in perspective:

Your typical LT1 puts out 275 HP, upgrade the exhaust and induction as well as all of the free mods, and you are looking at a solid 300hp. The best stock L98 makes 245hp. Even with the exhaust and induction upgrades as well as free mods I think you are going to be hard pressed even to hit the LT1's stock 275hp. To get to 300hp you are going to need a very agressively ported intake and possibly aftermarket runners. However, IF you get the TPI L98 to 300hp, it is going to be making a lot more torque than an LT1 with the same HP, and is going to be making it a lot earlier.

To get to 400hp with either engine, I think one needs to seriously consider aftermarket heads. Heads for the LT1 are going to be more expensive since not as many companies offer them, on the other hand, I don't think 400 HP is attainable using a stock TPI intake on an L98 even with the best heads so that is additional cost that needs to be considered.

In the end, I think you need to make a choice of what you want for your car. Do you want an engine that makes good high RPM power or one that has torque-on-demand?

Here we go again...
The gains from an LT1 are not just the intake, I don't really think it's a great advantage over the TPI. It was a combination of the intake + taller port aluminum heads + larger cam; but all this didn't really boost torque numbers a great deal, it just moved the peak torque point higher in the rpm range increasing HP slightly.
So, NO "one" part of an LT1 is that superior, period; but the entire combo resulted in maybe a .4 improvement stock for stock...

Combination is everything!, if you build an L98 around a package that the heads will support the cam and intake, you can still be as quick. I'm not trying to mimic an LT1, powerband, rpm etc..I'm building around my TPI...everthing I do will meet it's needs..

There's a pretty good article about Torque vs. HP in the new Hot Rod, the only reason for buying the mag....:think: It explains a little better why an L98 can keep up with an LT1...

Jonesy, maybe the LS1's here are slow, and no offense(and noe taken) but 12's with 3.73 gears, exhaust, Prom..:lol:
Thanx for the comic releif bro...:D
And Ya know what, second place, is just First Loser...:eek: :)

Hey, set a date after March, I'll try to have her back together..:thumb:
But it's gonna take more than 12.70's to own the combo I'm workin on tho...

I've been taking this project slow and deliberate, I could've dumped a slippery converter in and steep gears, cam, and sticky's and be in the 12's right now. But I want this project to be an extremely streetable, reliable, stock appearing, sounding, sleeper that will pull past most all comers with Authority!...
(This is my current, NOT my fastest attempt...)

Yeah Kevin91Z, there are a few differences in the Vette heads from iron, But the basic port/runner designs / flow characteristics are almost copies...Truthfully I'd take the iron over the Vette's anyday..Pro's and con's for Aluminum are well known...

Merry Christmas to all my Bow Tie brothers!..:D

Hey 90irocz I see that you live in ohio. How far up do you live? I live in kentucky. After march when you get you car done you can give me a ring and maybe we can meet at clay city. I dont know if you have heard of this track but I do know alot of people from ohio come down and race there. If you come down I can show you a stock ls1 with 3:73 and exhaust run 12.70's first hand. Also maybe I will have my car ready to go again by then and I can show you a street driven 9 second lt1. hell I will drive it to and from the track that's like 150 mile round trip. Just some thoughts maybe even some laughs. Good luck with the tpi I really would like to see one run good. ;)

Originally posted by jonesy91z28
Hey 90irocz I see that you live in ohio. How far up do you live? I live in kentucky. After march when you get you car done you can give me a ring and maybe we can meet at clay city. I dont know if you have heard of this track but I do know alot of people from ohio come down and race there. If you come down I can show you a stock ls1 with 3:73 and exhaust run 12.70's first hand. Also maybe I will have my car ready to go again by then and I can show you a street driven 9 second lt1. hell I will drive it to and from the track that's like 150 mile round trip. Just some thoughts maybe even some laughs. Good luck with the tpi I really would like to see one run good. ;) 9 seconds eh whats it run consistently? My buddies dad has a C4 corvette with a race block v6 and a rather large turbo that runs consistent 9.7's hes hopeing to have it in the 9.5's by next summer. And those times are on ET streets he could drive it to the track, do a burnout, run the 1/4 in under 10 seconds, and drive home, all without even swapping a tire.

Here we go again:

The opti spark has gotten a bad rep because of the early non vented design. Once it got wet, it died. That changed in 95 with the vented design.

Its a pretty good setup, the best of any small block. Much better than a distributor. It was just in a bad spot right under the water pump.

The LT1 also came with the best rods ever put in a small block. A full point compression over a TPI. Better flowing intake. Better flowing heads. Better computer controls. Better y-pipe. Better transmissions. ETC...

My 96 WS6 ran 13.18@104 with just HPP+, thermostat, K&N, air foil, 4.10 gears, and 1LE driveshaft. Everything else was completely stock including the tires. I then added a HOT cam, 1.6 rockers, new springs, 52mm TB, SLP dual cat headers, RPS turbo clutch, Hurst shifter, Kenny Brown SFC, Hotchkis panhard rod, Racenet LCA's, Nitto Drag Radials, and LT1 Edit. Ran 12.4@111.

Stock heads with all emission crap still intact. Passed IM240 emissions twice. Got 28mpg before the cam and 26mpg after on the highway. Pulled 324rwhp which is about 375 flywheel HP.

My Dad's 95 Comp TA had the exact same mods as mine but he went with the LT4 intake and LT4 heads and cat pipe. He pulled 369rwhp which is about 420 flywheel HP.

Both cars were dynoed right after each other so its a pretty good comparison of what the intake and heads can do on a LT1. FWIW, he ran 12.2@113 and he was a couple hundred pounds heavier than mine.

The LT1 is just as easy to mod as any small block and the results are probably better mod for mod also. The cost isn't going to be that much more, if any, for those mods than a small block.

Sorry so long....

Originally posted by RobsWS6
Here we go again:

The opti spark has gotten a bad rep because of the early non vented design. Once it got wet, it died. That changed in 95 with the vented design.

Its a pretty good setup, the best of any small block. Much better than a distributor. It was just in a bad spot right under the water pump.

The LT1 also came with the best rods ever put in a small block. A full point compression over a TPI. Better flowing intake. Better flowing heads. Better computer controls. Better y-pipe. Better transmissions. ETC...



Rob, the Optispark IS a distributor. The only thing that makes it different than most other distributors is its use of an optical trigger instead of magnetic. Perhaps you could be right about it getting a bad rap because of the earlier units but if that is the case why do I still see and hear about so many going bad, even on 97's? Besides that, just to maintain the stupid thing costs a lot of money and if you want to upgrade it you are automatically going to pay a lot more than you would if you had an L98's HEI.

Second of all not all LT1's came with the powdered metal rods. My buddy got his LT1 from a 94 Camaro and it had the old style X rods. While I have heard these are some of the best non-PM rods available stock, they are still not PM rods and are not as good.

As far as better flowing components I agree with you. However, there is a point you are going to reach that the stock stuff is simply not enough to make the power. I think the magic number for the LT1 is somewhere between 380 and 400hp. After that you better be ready to shell out some hard cash for trick porting or AFR heads or a nice LT4 heads and intake combo. Either way, you are looking at $1500-$2500 just to upgrade these components and for what? Another 100 HP or so. Contrast that with the $900 I spent on Trick flow heads, $900 for a Superram intake with edelbrock ported base, and $200 for a LT4 HOTCAM which all together gave my "L98" 380HP and 440TQ of dyno-tested power at the crank. Sure, you can get the same HP easily enough out of an LT1 but it is simply not going to have the TQ that my L98 does.

When it comes down to it, I think the best way to look at this debate is how heavy is your car and what tranny are you using... If you have a 3300lb car with a 6-speed manual than I definately say go with the LT1. If you have a 3600lb car and an automatic, I say the TQ from an L98 is unbeatible. Like I said before, it just depends what you want and how much money you are willing to spend.

I too am sorry, but the days of the LT1 are coming to a close. I know they are good engines and they were the first to pull the F-body ahead of the mustang after many years of shame but lets face it, everyone wants an LS1 and the aftermarket companies see this. There is already a vast selection of parts out there that will work with the L98 so I am sure there will be plenty still around in 10+ years. I honestly think that with the scramble to get products to the market for the LS1, the LT1 is going to be soon forgotten.

Hey, I hope I am wrong, but I am trying to be practical. I just don't see any incentive for companies to continue researching for and making parts for an engine that had a short life.

Yes, it is a distributor. I was talking about a conventional distributor. You'll hear about it because nobody says anything when its working. Mine never had a problem. Neither of my parent's cars had a problem. The vented kits aren't terribly expensive, nor the entire unit. The non vented ones are twice the price though...ouch!

And you're probably right about the LT1 going away. Happens with every newer style engine. What little aftermarket the TPI had when the LT1 came out, dried up pretty quick. The LT1 has lost flavor to the LS1. If its any consideration, look at the turbo V6 for R&D. Aftermarket is still coming out with new stuff after all these years. Could be encouraging.

My car weighed in at 3650 with me in it. 6spd and 4.10 gears were a perfect match. Great gear spacing and great economy at the same time. Might not have the low end grunt of a TPI but whipped through the rpm band. But it made quite a bit at 2000 rpm to not bother.

Torque monster, I'll stick with my V6 :D That thing makes some incredible torque :bow: Need to dyno it just to see what its doing as I'm curious. But that's another thread....

I've never remember putting down an LT1, all I'm saying is,"that for all of the "improvements" stock for stock, it only managed about a .4 improvement in ET(best case avg, heck it's only rated @30HP more.)...(I'm just trying to bring up the undeserved bad rep the TPI is getting.)
Now with that said, with all of the "improvements of the LS1, it too only managed about a .4 improvement...(I know results are varied but this is the average bests I'm seeing everywhere, believe me I'm seeing more slow ones than fast ones..I don't know if it's the gearing, drivers or what?..)

Ofcourse, ALL of this is just "moot points" once the mods start adding up...then it's up to who does his homework, and plans his combo out with every part accenting each other...
And Ultimately, "Speed costs money, How fast do you want to go?"

I read an article too somewhere that if an Opti' spends too much time over 6,000 rpm it can self destruct. But I'm no expert on them..

Rob, gears alone can make a huge difference...A Mustang guys' first mod.(you and your Dad's got some nice rides.:) )

MadMax, I gotta correct you on just one thing, "L98's especially '90-92 kept far ahead of the Mustangs..

LT1 for the cool factor of a swap and b/c u wont have to sink a ton of money into it right away. it is already fairly strong in stock form.

Originally posted by MadMax350
Either way, you are looking at $1500-$2500 just to upgrade these components and for what? Another 100 HP or so. Contrast that with the $900 I spent on Trick flow heads, $900 for a Superram intake with edelbrock ported base, and $200 for a LT4 HOTCAM which all together gave my "L98" 380HP and 440TQ of dyno-tested power at the crank. Sure, you can get the same HP easily enough out of an LT1 but it is simply not going to have the TQ that my L98 does.


I'd spend $2500 to get another 100 horsepower out of my engine. That's not a bad power to money ratio.

But I think you have a lot more left in your combo. I was running a long runner TPI intake and aluminum L98 heads with an LT4 HOT cam and getting 318 RWHP and 419 RWTQ. That's close to 375 and 490 at the crank. I havent dynoed it yet since I put on the SLP fully siamesed runners, but I'm guessing it'll be in the 350 RWHP range.

http://para.noid.org/~thresher/dyno.jpg

RobWS6: The 90-92 TPI's have 9.75:1 compression, and I know the LT1's arent much over 10.3:1, so its not a full point more. However, the 87-89 TPI's were in the 9.3:1 range, so I figure you are talking about those.

Originally posted by 90rocz

Rob, gears alone can make a huge difference...A Mustang guys' first mod.(you and your Dad's got some nice rides.:) )
Gears got me .3 sec and no MPH increase. It was all in the 60' times. 2.0 vs 1.87

But it was the single mod that I loved the most. Better than the cam and anything else. Just made the car so much easier and fun to drive. 6th gear was actually useful under 65mph!

Kevin,
Those numbers are great! But is that time in your sig with those numbers?

I dynoed 324/324 or something like that and ran 12.4@111 in the WS6. You should really be putting down much better numbers than that.

When the TTA was still on running on the stock stuff, I dynoed 318/455 at the rear wheels. I was running 12.1@111.

Just curious as that's where I would think your times would be at.

Nice debate there of the LT-1 v.s. L-98.......

But I'm haveing Fun with my TBI. my 91 GTA had a 350 TBI,700r4,3/42's when i got it .....
it would Hold it's own.....
But when i put the 3.73's in it and up the TBI to the 670CFM Holley TB that I gained bunch more.

91GTA Ramair2,350TBI,700r4,3.73's,and295/50r16's.

Best run was a 14.86@95.78mph with the G-tech .
my 87 GTA L-98 350tpi,700r4,3.23 gear's,and 235/55r16's.

best run was 16.11@88.9mph.
on G-tech....

witch I'm Not sure if the time's are right no But i know when i raced the 2 car's against each other the 91 with the 350TBI walked all over the 87 GTA with the 350TPI.

But thats cool Cause i was a TBI fan anyway this juist Helpped that and it have Beaten a few LT-1's on the avenue.....
But we only ran 0-50mph......

I did beat an LS-1 0-20 But that was no real yippy skippy there.My problem with the 350TBI it i was out of go power at 4,750rpm's.

But the 350TPI seemed about Done at 4,300rpm's.

But i am sure my 406 Dual Duce TBI,will stay with an Ls-1 if not beat it. But you know third gen's and traction.......

540hp@6500rpm&580FTLBTORQUE@5,000rpm, my Traction in the 91 is going too be almost non. thats why i need to ditch the P295/50r16's for some 295/50D15 drag radail's..........
so if there is link anyone might have to that size drag radail that would be aswome...........


But as fare as the L-98 V.S. LT-1.......

I'd have to say l-98 it;'s a third gen kepp it third gen..... Don't Down play an LT-1 like that or visa versa.............
depending on your piont of view......

Kevin and Rob, you are only confirming what I have known for a while now that a 6-speed manual makes all the difference. I am just waiting on enough money to buy a wreaked 4th gen that has everything I need for the swap into my 87 GTA because the outright cost people are charging just for the T-56 is out of this world. Very impressive times tho with the long runner setup. You are definately one of the exceptions as most long runner setups can't run with the big dogs around here.

Originally posted by MadMax350
Kevin and Rob, you are only confirming what I have known for a while now that a 6-speed manual makes all the difference. I am just waiting on enough money to buy a wreaked 4th gen that has everything I need for the swap into my 87 GTA because the outright cost people are charging just for the T-56 is out of this world.

yeah if part of your swap price includes tranny and you can get a t-56 with it (just not out of a 93 fbod) then it becomes much more worth it to step up to the LT1 and getting the T-56 with it. Despite what the LS1ers want to say, its the T-56 that was made by the hands of god ;)

Rob, 60' is where it's at, as you know...ET's are usually made or lost here, traction might become a problem and down play gains from gears...And gears keep you from falling out of the powerband on the 1-2 shift,(auto) and let you cross the traps in the band, or 500-700 rpm past, which is desirable!...My fav gears are the 355's, but unfortunately don't come in my size..so I'll roun up a little especially with an auto..
(a little off topic)
What boost / chipwere you runnin to go 12.1 with stock set up?Curios b/c I help my bud work on his '86 GN, I like to gather info that might help him...he's still dealin with Detenation @ 17psi up...

Kev, you're right my book says a little more = 9.8:1, '90-'92 SD cars..9.3:1 ;87-'89...(I know actual will vary a little.)
Yeah, as HP goes up it's harder and more expensive to get that 100HP, like for you, rather than me or other near stockers..
Dyno sheet looks funny with the "Negative"graphing, an untrained eye might think the HP is flat and torque falls off...but I used to graph production and product tests as a tech in the Engineering dept of a local factory...:) Nice!
I'd like to find a chassis Dyno near here, but they're scarce...I'll try to catch one this year at an event tho..

Originally posted by 90rocz

What boost / chipwere you runnin to go 12.1 with stock set up?Curios b/c I help my bud work on his '86 GN, I like to gather info that might help him...he's still dealin with Detenation @ 17psi up...

I was running 18psi on 93 octane with a Xylene mix. So roughly 99-100 octane. That was with a Thrasher 92 chip. Tune for 0.0 retard and you'll be golden. But it was traction that did it. I was running mid 12's at 110-111 with the Firestone's. It wasn't until I put the Nittos on that my short times dropped to the 1.6's. The stock exhaust was straining as were the stock injectors. I was getting duty cycles in the 120% range on Direct Scan. The stock D5 converter was doing a great job with the stock turbo. Almost wish I never would have started modding the car.... Here's the dyno from back then. Higher numbers are with the converter locked.
http://users.adelphia.net/~tta1387/1-13-02dyno.gif

Originally posted by Kevin91Z

RobWS6: The 90-92 TPI's have 9.75:1 compression, and I know the LT1's arent much over 10.3:1, so its not a full point more. However, the 87-89 TPI's were in the 9.3:1 range, so I figure you are talking about those. I don't ever remember the comp ratio being that high in the TPI. I think 3rd gen says only 9.3:1 for all 350's. I could be wrong but I think I would have remembered such a big jump in compression back then.

Of course that was awhile ago and my memory isn't what it used to be ;)

LT1's had 10.4:1.

Rob, I think you are correct, the compression stayed the same at 9.3:1 for all years of the L98.

I'm not remembering, I HAVE the service manual open right here, right now...1990 = 9.3:1, 1991 = 9.8:1, 1992 = 9.8:1
Switched the same time as the new body hit..and the "Oil Pressure" dropped for the '91-'92's from 55psi to 18psi@2000...
245HP@4400/345lbft@3200!...(NET)
Actually the '87-'89's are listed @ 9.5:1 in the service manual!..my bad.:) Only My 'lil ROC is rated @ 9.3:1..:cry:

Originally posted by RobsWS6
Kevin,
Those numbers are great! But is that time in your sig with those numbers?

I dynoed 324/324 or something like that and ran 12.4@111 in the WS6. You should really be putting down much better numbers than that.



Yes, those times are after dynoing those numbers in my sig. But I had a T5 at the time. I havent been able to get the same numbers since putting in the T56, for various reasons. But my biggest problem is the 60' time. 1.9 is horrible for that much torque. My best is a 1.88, but my dad got a 1.81 with the new runners, but didnt get in the 12's with it. I should be running a lot quicker but I just cant launch consistantly.

I can guarantee with 100% authority the 1990-92 TPI 350's have 9.75:1 compression. They got different pistons in 90 that gave them a bump in compression up from 9.3:1 the previous years. The 305's stayed the same at 9.3:1.

I can guarantee with 100% authority the 1990-92 TPI 350's have 9.75:1 compression. They got different pistons in 90 that gave them a bump in compression up from 9.3:1 the previous years.

Not according to thirdgen.org:

TPI Engine Tech Specs (http://www.thirdgen.org/newdesign/tech/techdb.shtml)

Or transamgta.com:

More TPI Engine Specs (http://www.transamgta.com/EngineSpecs.html)

Or according to the gtasourcepage.com website:

Even more TPI Engine Specs (http://www.gtasourcepage.com/techspecs.html)

The TPI L98 350 did not change compression ratio during any year of its run in the f-bodies according to the above tech pages.

Chilton, part#8260 (total car care manual)
And GM's Service Manual...

Beware of some Web Sites "Poll Data"...:)
Make sure they site their sources..:(

Well Go get'em Cleatuse............:D
Just thought ya needed so releif from da shutin/Arguein.
ok and continue on in 5..........4.............3............2........... 1:bow: :bow:

Make sure they site their sources..

Good point, but unless I'm mistaken, thirdgen.org is about as definitive as it gets on the net for the specs on our cars. The guys that run that site know their stuff. Check it out. :)

I used to be a regular there years ago, they're just , year specific, "3rd Gen", they are still human and on this one they're mistaken..
As said the 305's did maintain the 9.3:1, they probably assumed the 350 did also...
Think about it: 4.00"bore + Flat tops w/4cc reliefs + 64cc chambers +.028"Head gasket...I'll check my deck height and give you my specs, but it changed in '91 according to "2" manuals I have...
**I would hope companies in the "Information" buisness researched their subjects before spending all that money printing books...:think:
I guess it comes down to, "who would you believe?"...

Problem is, Helm's is wrong also.

My TTA shop manual has compression at 8.5:1 and 8:1 in the same book. That's a GM book!

The real compression is 8:1 just like the Grand National's but had different pistons because of the front wheel drive heads.

Also, why no bump in HP with almost .5 more compression? And when the LT1 came out in 93 for the F-Body's, one of the big "improvements" was the over full point in compression from the previous year(92).

Because your LC2 in the TTa had to use different heads to fit between the strut towers, it changed compression slightly. The book was quoting a standard LC2 and yours. You recieved better heads and a bump in compression, I know, most GN guys druel over your heads. The manual therefore is correct on both accounts..
A .5 increase in compression alone, won't increase output that much, and I believe my IROC cam was different than the '91-'92 Z's, acounting for the same output with .5 less compression.
(mine = 202*/206*, .403"/.415" 115*LSA)

The point about the LT1 is like I said, for the :
1 point increase in compression
MR style intake
reverse cooling
Tall port, vortech chambered heads
more cam
**For all that, it still only managed a 30hp(advertised)increase and aprox 4 tenths increase in performance..**
WOW!:rolleyes:

No, my LC2 and the GN LC2 compression is identical. That was the reason for the piston change. If you put my heads on a GN, it'll bump the compression almost a full point.

So the manual is right about the 8:1 and wrong about the 8.5:1. But it says both in the same book. And the TTA manual is only about the 89 TTA. Nothing else in that book is for any other car. It is a supplemental to the 89 Firebird book as it is only specific to the changes for the car. Basically engine, trans, electronics, and emissions. Everything else is covered in the regular book.

And it wasn't to clear the strut towers as most of the magazines said back then. I could put GN heads on and it'll fit with no problems on the strut towers. It was to keep the V8 GTA air conditioning. If I were to put GN heads on, I'd loose my A/C because of fit.

As for the LT1, true it only got 30HP. But it was also more of an economy move as mpg is quite a bit more. Same with the LS1. Performance is just a by-product. MPG is more important than performance in the corporate scheme of things.

GM makes mistakes all the time in their literature. I recall many years ago when I bought my 1987 Buick GN. I've got an original Buick Regal 1987 brochure lying around here somewhere about the car when it was new. I recall one part reading - "new for 1987, hydraulic-roller lifter followers for reduced friction and more power" or words to that effect. The LC2 never came with roller lifters in 1987, even in the later 1989 TTA. Yet there it was, plain as day in the 1987 brochure.

I have always read in road test magazines and various spec charts, the CR for the L98 was 9.3:1. The posts in this thread mentioning the CR was rated higher than that is the first I have ever read or heard of this, anywhere.

If you take a look at the 3 previous links posted about TPI info, you'll see all 3 jibe pretty much with each other on specs for all years of L98 and the 305.

Here's and iea...... throw that 350 out oput a nice carbed 406 in it and be done with .....

oh yea get the third gen 4 core radiator.........

L-98/LT-1 Yucky:

I've had exsperince with both there not as much fun as a solid 400chevy........Now 400 Poncho will Roast a 400chevy but in a thirdgen the 400 chevy is ideal but i am sure sombody somwhere made a 400poncho fit in a third gen.......
:bow: .................................................. ........................ :bow:

But what do I know about Engine I only Put a TBI injected 390Amc in the 9.60's................... :cool:.................................... :cool:

I did a search over on thirdgen.org where I thought I found the compression ratios, and I couldnt find it again. I know it was Glenn91GTA who said it, and a few other trustworthy people. The Tech Data mentions the 350's getting a "lighter piston" in 1990, which accounts for the 5 horsepower upgrade, but I figure it was also the change to speed density and the higher compression as well. The speed density engines have a smaller cam than the 88-89 TPI cars, but are still rated at 5 horsepower more.

There are lots of mistakes on those articles mentioned, so as was said it all comes down to who and what you believe.

From what I understand, the 5HP gain was due to the loss of the MAF as a restriction in the inlet tract. I can see the engine getting a lighter piston for '90, but that in itself will not give any HP gain.

Alright, I spent a couple of hours measuring my disassembled L98, here's the results...Kevin you're right it is 9.81 even on my '90 model, my bad...
Well, since everyone can look up formulas I won't list them, just my calculations.
716.7cc (converted measurement of swept volume for a 350)
64cc (chamber volume)
9.1cc (gasket volume on a .041" gasket, ithought was thinner...)
2.05cc (deck height at .010"roughly)
6cc (piston volume = reliefs + ring crevice)

716.7cc + 64cc + 9.1cc + 2.05cc + 6cc = 797.85
Divide by
64cc + 9.1cc + 2.05cc + 6cc = 81.15

= 9.83179!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!
read it and weep boys....sorry
:(

(Maybe I was wrong about the TTa, my bad, you know your own car better, and should...As I know my car better..:) )

Also, I found some interesting tid-bits in my archives:
A DIRECT quote from CHP;
"In many quarters conventional wisdom has it that the only way to squeeze impressive times out of a TPI Camaro is to yank the TPI. **As is often the case, conventional wisdom is foolishly out of touch with reality.".......:eek: :bow: :bow:
On their first pass with a built "TPI" Camaro, they netted a 12.651 @ 108.55, and after bumping the fuel up 2psi and adding a couple degrees on pinion angle they netted, 12.384@111.06...:eek: :eek: :bow: :bow:
And go on to say, "not all Tuned port Camaro's are easy pickings."

L98 Aluminum Vette heads
TPIS ZZ9 cam
BigMouth Base/largeTR/ported plenum
52mm T/B
24#'ers/Prom
12"convertor/3.42's
Pretty mild if you ask me...:)

deck height at .010"roughly

I have yet to see any stock 350 with such good deck height. Usually the piston sits down in the hole at .025", not .010". My 400 for example was .026".

Good discussion BTW, but let's stick to facts and not 'guesses'.

:)

I measured it as close as I could, rounding the ten-thousandths for clarity sake, NO GUESSING IN THERE!......

Originally posted by 90rocz
I measured it as close as I could, rounding the ten-thousandths for clarity sake, NO GUESSING IN THERE!......

Previously, you posted:

2.05cc (deck height at .010"roughly)

Big diff between .025" and .010" in deck height when calculating compression.

What's your point? I measured, I told you my measurements...
Yep you're right, there would be a big difference between .010 and .025...glad I don't have .025"...
Yeah that would drop it down to 9.583233 or 9.6:1, still a far cry from 9.3...

Third gen Claim's all TPI's are 9.3:1....LOL

my 89 RS had 9.75:1in it's LO-3,But i bumped it up so 10.25:1,then threw it nabck together droped somes 3.73's in it and got in to run 14.80's.
Just like my 350TBI was running with 190,000miles on it.

so worn 350 Built fresh 305 run about the same time's witch was cool.

350 pull 14.80's at 95.78mph as where the 305 ran 14.80's at 93.76mph.

350TBI 91 GTA 14.86-14.84.94-96mph. 190K miles bad comp.

305TBI. 89 RS 14.89-14.87. 92-94mph.6K miles good comp.

ya your right compression don't mean Crap.......:thumb: :thumb:

Originally posted by steve10358
You're cutting yourself short. Out of the thousands of TPI cars out there, there is no point in keeping to the original anything. These cars will never appreciate. There are two many of them. Not only that- but isn't the goal of all of this to go fast? Why cut power output down for the sake of a TPI fetish? There's no point!

Here's a tip. Many Thirds are already and have been appreciating. ;) I know because I'm always in the market and have been watching for 4 years. TPI cars especially. L98 G92s, LB9 G92 5-Speeds, and IROCs especially. If you've got a mint one or low-moderate mile nicely taken care of stock car, maybe you should find a high mile car to mod because they are gonna be worth more than you think in years to come. It always happens. It seems that these cars are getting up there faster than later 2nd Gens, which is wierd because they're newer. Maybe because of their popularity, who knows, all I know is that they are going up. Sometimes people like a little modding though when buying cars like these. :)

You mean a third gen might be worth more then $750????

Soon awsome,Good to hear man I was about ready to mod Out and Blow my L-98 all over 3 lanes of east wash.......

But maybe I'll have to rethink that thought...........

I still Like the Idea of Having a TBI406 and TPI406 powered F-Body's...............

But For some $$$$$$ I might keep the 87 GTA together even tho it's only a 16 second car...... :bow: :bow: :bow: :bow:

91 GTA Ramair2, what's wrong with your '87, I don't see many l98/350 TPI cars running that slow?
What mods have you done?

I wish I knew what was up woth it But 16.11's is all it would do I thought these where suposed to be mid to high 14 car's.......
or low 15's at least.

I've seen l-98 time's vary from 15.40's-14.30's.

That's why i was a bit ticked when my L-98 was running so slow.
I my LO-3 wasn't that slow......

Rebuilt LO-3 with a 10.2:1 compression 3.73 gear's ran 15.60's all day long,in my 89 RS i used to have.....

But My L-98 hasn't had a tune up sence 1989.
So that's first on the list this spring.

Yeah a GOOD tune up with quality parts is always the first mod. Using brass contact parts(cap & rotor), spiral-core plug wires, AutoLite or Delco's, maybe Accels. Change fuel filter, PCV valve and run some "B12 Chemtool" Fuel injector cleaner,"just Pour It, and Floor It!", like it says...
Then, set the TPS(0.54volts@idle & 4.50volts @W.O.T. for MAF cars), Idle(air bleed), timing(specs on underhood sticker)
MODS:
K&N air filter with a cold air pipe, eliminating the stock restrictive canister & tubing.
air foil, remove MAF screens, port plenum just behind throttle blades, bypass the coolant lines past the t/b, adjustable fuel pressure reg, relocate the IAT sensor to inlet tubing, a good free flowing CAT & CAT-Back exhaust, shift improver kit, and if you have 2.73 gears, get at least 3.42's.