383s Why is every LT1 I see a Complete Turd?

Ok in the quest that I am getting ready to build my motor, I am still stuck on wether I want to just do a 355 with about 12:1 or a 383 with the same compression. The only thing is when ever I read GM Hightech the featured cars or for a fact the recent LT1 vs LS1 shootout the 383s are JUNK!!! They run High to barley mid 11s NA with fully built 383s and A Great set of heads, where I am running a Home port head, with a Nitrous cam and run well into the 11s all day NA and 10s on spray.

I would love the extra cubes but what is with the LT1 and not working with the 383s? I see more junk ones then I do good ones. Can anyone help?

The reason in my opinion is they do not have enough cylinder head to feed a 383 properly, and or they are cammed wrong. Hard to get stock castings to flow over 280 REAL cfm, which in my opinion is the minimum need for a 383 to be healthy. Alot of 383's have the wrong combination of parts, folks think because it works good on a 355, it should be sooo much better on a 383, not always the case.


David

A high horsepower stroker LT1 can be built no problem. As with anything else, it's just the right combination of parts.

What are your goals? (rwhp/et/mph/driveability)

Basically I want to keep the stock appearene aka oil pan, so everyone says it can be done.

After finding that out I basically want a good nitrous motor with 12ish area for compression, get a good nitrous cam in there and have it creep low 10s or even a high 9. Right now I have done a best of a 10.60ish, and I figure if I did a good 383 and a fogger I should have no problems considering the over stock components that my engine consists of now.
I have no problem running race gas but I still want to be able to cruiz it when I want to.

Listen to FASTFATBOY. He's right.

So you are saying that even a fully ported (good) stock casting LT1 head, it is not feeding the 383 enough. Even if it is cammed right with a TRUE (steel billet) custom cam by a professional??

I would think that 450rwhp/tq is easily attainable with stock castings and a 38x??

And that, considering it is at the right time, should be plenty for a 10 sec N/A timeslip. I mean guys runnings heads/cam+100shot are in the tens with traction right?

Throw that direct port on there with a 200shot and you are in the low 10s high 9s, all considering traction.

Originally posted by OBDIICamaro
... I am running a Home port head, with a Nitrous cam and run well into the 11s all day NA and 10s on spray.

I would love the extra cubes but what is with the LT1 and not working with the 383s? I see more junk ones then I do good ones. Can anyone help?

If you are in the 10s with your home-ported 355, why spend money on another engine? Just tell everyone it's a 396 and that's why you blow off their sprayed motors.

I'm impressed with your 10 sec. Camaro. Post some pics and a few time slips. Don't be so shy.

Just a few examples.

I had a 383 with GTP ported LT1 castings, ported LT1 intake, 250 duration/.600 lift solid roller.

Made 452rwhp 416rwtq through full exhaust.

Larry, who I work with, has a 96Z, 383 RGR ported LT1 heads/intake, solid roller, turbo 400. Made 420+rwhp through a loose converter, runs 11.0 @122 on motor, and 9.80's at 137 on the hose.

I think those are some good running setups for the parts they have, and theres no reason that you couldn't build a stroker LT1 to have substantially more power if you stepped up to some aftermarket heads/intake etc.

12:1 is a lot of compression. You aren't planning to run that on California pump gas I hope.

my 383 has a 260/260 solid roller with 12.3:1 compression. I run pump gas because its my daily driver. But It loves the Leaded 114. With a peak HP at 7000 RPMs its a high RPM screamer. ITs no slouch.

Originally posted by Bud M
12:1 is a lot of compression. You aren't planning to run that on California pump gas I hope.

I don't know much about California gas, but if the cam has enough duration, it will bleed off enough cylinder pressure to make 12:1 tolerable with pump gas. Static compression is only part of the equation.

Hey FATBOY what about my heads!!!!:cool:

[DELETED]

Note from moderator - knock it off.

why wouldnt an injected car dislike leaded anymore then a carb car setup for mostly unleaded?

we have a 87 Formula,runs low 9's@150+ and it runs on C16 at the track,pumpgas on the street. been doing so for a few years with various combo's and no problems.

[DELETED]

Play nice.

Originally posted by OldSStroker
If you are in the 10s with your home-ported 355, why spend money on another engine? Just tell everyone it's a 396 and that's why you blow off their sprayed motors.

I'm impressed with your 10 sec. Camaro. Post some pics and a few time slips. Don't be so shy.

Its a stock shortblock minus cam and timing chain.

Guys lets keep it on topic thanks!!!

I dont live in Cali anymore Im in south dakota just havent updated it in awhile.

Most of the cars in GM hightech performance pass emissions for NJ. I think that is the reason many of them are not on the "big dog" list. Their track requires cars to have mufflers on them!
That a long with many owners having a preference for a more streetable car keeps the power down. There are plenty of 600+rwhp 383s rolling around you just got to know where to look. :)

This one isn't a 383 but you get the idea. ;)
612rwhp NA (http://www.ls1tech.com/forums/showthread.php?t=128053)

Originally posted by KCFormula
This one isn't a 383 but you get the idea. ;)Looks like an LS1 to me. Wasn't the thread about LT1s? :)

Originally posted by jimlab
Looks like an LS1 to me. Wasn't the thread about LT1s? :)

Yea, I was looking for a link to the Harden Performance LT1, or Joe Overton's (although I don't think Joe has any dyno numbers of his car) but couldn't find one. The Harden car is making more than that LS1, and I bet Joe's is making very close to the same power.

:bow:

Wow, maybe I'm just old school but isn't 12:1 awfully scary with nitrous?? Maybe if you are running all top shelf nitrous parts with a very qualified engine builder well versed in nitrous engines you could get away with a small shot......but all of the guys I know running serious N20 are all in the 9.x:1 range. I am new to this fuel injected thing so if I am wrong here please school me.:confused:

N2o loves compression. 12:1 with a N2O set up is mild in many peoples books. Assuming the short block is build to handle the power (forged, 4-bolt, etc.) you can throw a whole lot of N2O at a 12:1 motor.

Hmmm. I thought that N20, like boost, prefer lower compression due to the increased cylinder pressures.

Nitrous has a cooling effect that boost does not have, pro mod motors run 15 or more to 1 and spray god knows how much to those engines.

David

Originally posted by lemans1
Hmmm. I thought that N20, like boost, prefer lower compression due to the increased cylinder pressures.

Like mentioned, N2O will cool the intake charge considerably which will reduce the chance of detonation. The main reason that N2O likes compression is that it requires a high specific amount of heat to seperate the Oxygen from the Nitrogen. The high compression helps that process. Also, N2O does not add air molecules to the cylinder on the intake stroke like boost does. Therefore, you do not need a lower static compression to obtain acceptable dynamic compression. The Oxygen from N2O is released on compression/ignition.

Hey now...I have a 383 LT1 and it isn't a 'turd'....if it wasn't for me trying to skimp by with a RaceTronix fuel kit I'd have a full dyno graph for ya...but at 4300rpm it made 567/580 rwhp/rwtq....not bad considering she's going to 7k and it wasn't tuned worth crap since I was running out of injector and fuel pump we just called it quits for the day. Those numbers were also on a Mustang Dyno...not a DynoJett. I'm guessing right now it should be well over 650 rear wheel by the time its all said and done....be nice to hit 700 though ;)

I'll have full numbers for ya hopefully this summer when I get time to finish it.

There are a few 383/396 cars that put down quite a bit of power...you just don't see them post on the net all the time about them.

Originally posted by 1LEThumper
Hey now...I have a 383 LT1 and it isn't a 'turd'....if it wasn't for me trying to skimp by with a RaceTronix fuel kit I'd have a full dyno graph for ya...but at 4300rpm it made 567/580 rwhp/rwtq....not bad considering she's going to 7k and it wasn't tuned worth crap since I was running out of injector and fuel pump we just called it quits for the day. Those numbers were also on a Mustang Dyno...not a DynoJett. I'm guessing right now it should be well over 650 rear wheel by the time its all said and done....be nice to hit 700 though ;)

I'll have full numbers for ya hopefully this summer when I get time to finish it.

There are a few 383/396 cars that put down quite a bit of power...you just don't see them post on the net all the time about them.

I'm curious. That's the MOST power I've heard of coming off of a NA 383 LT1. That's incredible. Care to share some specs on your combination??

I dont have any dyno #s but I was dissapointed when I first put my 383 together, from my trap speed we guessed the car was only making 360 something at the rear wheels. After long thought I changed the cam from the 224/230 XE to the 230/236 XE. and the thing woke up big time. My next step is to have my AFRS ported. All the guys that drive the car think it is screaming for more air. I settled on 10.8 to 1 compression finally and it runs fine on pump gas. The smaller cam made more low torque but I seen very little low loss and a but load of linear power increase with the bigger cam. This winter as I said I amd pulling the heads off and having them done to flow alot more. I beleive I am going to try the GM 847 cam as well , just to see if it moves up with it as well. Still though on the smaller cam with poor traction in second gear (it was weird , it would hook good then break loose) it ran 12.50s with no sorting done full weight(3750 with me).

1le, is that n/a? doesnt sound like that is right unless you have some pretty extreme 15 or 18* heads on there. Im guessing either FI or N2O???

Originally posted by 1LEThumper
Hey now...I have a 383 LT1 and it isn't a 'turd'....if it wasn't for me trying to skimp by with a RaceTronix fuel kit I'd have a full dyno graph for ya...but at 4300rpm it made 567/580 rwhp/rwtq....not bad considering she's going to 7k and it wasn't tuned worth crap since I was running out of injector and fuel pump we just called it quits for the day. Those numbers were also on a Mustang Dyno...not a DynoJett. I'm guessing right now it should be well over 650 rear wheel by the time its all said and done....be nice to hit 700 though ;)

I'll have full numbers for ya hopefully this summer when I get time to finish it.

There are a few 383/396 cars that put down quite a bit of power...you just don't see them post on the net all the time about them.


Blower or N20, no way thats normally aspirated:rolleyes:

What gets me is that 2 of my friends have stock bottom ended LT1's and they are pushing 430+ and 452rwhp.
another friend has a built 385 with custom fuel system and is pushing 420rwhp.
The 385 has more torque than the 350's but it's amazing what proper heads & cam selection, and tuning can do.

No its not NA.....its D1SC force fed.....sorry it didn't say NA on the topic heading....guess I was just kind of scanning over the topic.


500 rwhp shouldn't be that hard to do with a good set of 18 degree heads and a custom intake though. Hell look at Jim's motor he made over 650 flywheel hp with his NA 396.

Originally posted by FASTFATBOY
Nitrous has a cooling effect that boost does not have, pro mod motors run 15 or more to 1 and spray god knows how much to those engines.

David There was an Ozark Mountain Motor class running at a local track last year. I saw a Mopar with a direct port plus two two-stage plates :eek:. How much spray????!?!?

The 383/396 will make more power and beat the 355 any day all else being equal. Just running a 383/396 with all the same stuff will not result in much power increase over the 355. However you can run more head and cam before running out of rpm or streetability with the larger engines than you can with the smaller ones.

A well built 327 with great heads and intake with a big cam can blow away a 406 without that stuff but if you have the 406 in a similar state of tune it will again be faster. The 383/396 can run a more radical combination before "seeming" radical so it's nicer for the street than a 355 for most people. It's also a little extra free low end from the larger displacement.

I havnt made a full pull on a dyno,and to be honest i have no reason to...Track is where I like to string her out ,not on a dyno..however I did make half a pull before it hazed the slicks on the rollers at 4200 rpm is put down 468 rwhp torque was 652ft lbs at lil under 3000.. I will try to dyno it again in a month or so just to find out how much she is putting down...but if its any concellation my shift points are 7600 rpm...

Just a side note though this n/a lt1 got beat on the tree at the thunder shootout..it did however out ET the fastest n/a ls1 in the country side by side in the finals..;)

Originally posted by Joes94TA
Just a side note though this n/a lt1 got beat on the tree at the thunder shootout..it did however out ET the fastest n/a ls1 in the country side by side in the finals..;)


congrats joe!.......show those LS1's we still have some balls left.

my HP and TQ are listed in my sig. those numbers where with my old setup and a t56. Ive now installed a solid roller setup and a th400 getting retunned on feb 14th

Originally posted by Joes94TA
I havnt made a full pull on a dyno,and to be honest i have no reason to...Track is where I like to string her out ,not on a dyno..however I did make half a pull before it hazed the slicks on the rollers at 4200 rpm is put down 468 rwhp torque was 652ft lbs at lil under 3000.. I will try to dyno it again in a month or so just to find out how much she is putting down...but if its any concellation my shift points are 7600 rpm...

Just a side note though this n/a lt1 got beat on the tree at the thunder shootout..it did however out ET the fastest n/a ls1 in the country side by side in the finals..;)
:eek: :bow:
Nuthin but respect here.....

<spam>
I'm selling the LT1 heads that went 9.82/145 with my ys-trim on a lazy launch and 9.94/139 with the s-trim.
http://para.noid.org/~lj/ForSale/ForSale.htm
They are 100% fresh, clean, bagged, and ready to bolt on.
</spam>

Originally posted by Joes94TA
Just a side note though this n/a lt1 got beat on the tree at the thunder shootout..it did however out ET the fastest n/a ls1 in the country side by side in the finals..;)

Do you have a site or somewhere we ca look at that beast at?
Good job, were you sleeping....lol
That is one bad car you have!!!

one of our "turds" made 457 rwhp at 6000 rpm and 433 rwtq at 5000 rpm uncorrected last saturday; the corrected numbers were 445/422. this is a 383 LT1 (5.7" rods) M6, stock heads done by combination motorsports, 236/242 XE hydraulic roller, 36# injectors, long tubes and an open cutout. a/f was 11.8:1 on the last pass. this engine was built for nitrous and should make 600 to the wheels with a conservative tune-up on a single stage hit of the giggle gas.

my car hasn't been on the dyno yet, but it is very similar to this one. only differences are 6" rods, a little smaller (230/236) cam (mine has more lift though) and my heads might flow 13-15 cfm less at higher lift (.650). i won't have my car on the dyno in the near future, but it went 93 mph in the 1/8 a couple of saturdays ago. this was with a dead PCM (flashing SES light), no tuning for the stroker and a dead driver's side O2 sensor. PCM and O2 will be replaced this week, and i'll have the same program flashed that was in the other car before going to gainesville on thursday afternoon. i'm hoping to see 94-95 mph in the 1/8 and 118-120 on the big end if the conditions are favorable and it doesn't break. i'll post results thursday night.

Originally posted by Zepher
What gets me is that 2 of my friends have stock bottom ended LT1's and they are pushing 430+ and 452rwhp.

Please show dynojet SAE graphs for these cars :think:

Originally posted by Zepher
What gets me is that 2 of my friends have stock bottom ended LT1's and they are pushing 430+ and 452rwhp.


The highest RWHP for a stock bottom ended LT1 that I know of is SAR2K's Trans Am that made 450 or so with the cutout open, drive belt off, and converter locked with a BIG hydraulic roller. Normally aspirated.

I am hoping for 500 RWHP with mine, Its not gonna be your average solid roller 383.


David

Originally posted by FASTFATBOY
The highest RWHP for a stock bottom ended LT1 that I know of is SAR2K's Trans Am that made 450 or so with the cutout open, drive belt off, and converter locked with a BIG hydraulic roller. Normally aspirated.


sar2k made 440 rwhp 395 rwtq with those things you stated.

one of joe overtons customers (board name 97 WS6 T/A Conv)made 452.0 RWHP and 398 RWTQ on stock bottom in street trim (no belt off) n/a in an M6.


i think those are the two highest rwhp stock bottom n/a lt1's.

Originally posted by LT4POWR
Please show dynojet SAE graphs for these cars :think:

sar2k's dyno sheet (http://www.thunderracing.com/images/steve_tuning_comparison.jpg)

97 WS6 T/A Conv dyno sheet (http://www.homestead.com/my97ws6/files/452dyno.jpg)

Originally posted by WS Sick
Do you have a site or somewhere we ca look at that beast at?
Good job, were you sleeping....lol
That is one bad car you have!!!
site :
Lethal EFI/Joe Overton (http://hometown.aol.com/one94ta2try/myhomepage/index.html)

link to ls1 vs lt1 n/a race:
mikey vs Joe (http://www.quarter-mile.net/video/SS03/Sunday/Sunday37.wmv)

Originally posted by got_hp?
sar2k's dyno sheet (http://www.thunderracing.com/images/steve_tuning_comparison.jpg)

97 WS6 T/A Conv dyno sheet (http://www.homestead.com/my97ws6/files/452dyno.jpg)

Good numbers,

That one was done on that off brand dyno and I remeber that guy got a lot of **** for that. Would have been better if it was on a Dynojet(apples to apples), but good numbers anyways. One thing you can tell is that software that dyno runs has some serious smoothing going on with the power curves, big difference from most Dynojet sheets you see. Looks a lot like a Superflow chassis dyno printout in comparison.

Bret

Isn't big horsepower about getting a lot of air into and out of the engine? And isn't the main determining factor (once the easy stuff has been done) the flow of the cylinder heads?

If you've played around with any of the commonly available computer-simulated dynamomenter programs it becomes apparent real quickly that if you shove a 383 in place of a 350 short block, peak HP doesn't improve much, all else held equal. Low end torque jumps quite a bit, of course. But a 10 second race motor doesn't spend much time revving though the low RPMs. It's set up to jump straight to peak torque at the line (converter selection) and shift maybe 500-1000 RPMs beyond peak HP. In short, big HP up top is how to go fast in a real race setup. That only happens with LOTS of airflow.

Maybe I'm way off base here.

I'll note for the record that I build STREET engines exclusively (and I don't earn my living this way, either- just a hobby and passion of mine). Extra cubes make a big difference in the world of street engines where torque the main goal. Especially against a low 2200 stall converter. But for racing where life BEGINS at 4000-4500 who cares about low end torque? Build as much HP as you can and then gear and converter appropriately.

Originally posted by Joes94TA
site :
Lethal EFI/Joe Overton (http://hometown.aol.com/one94ta2try/myhomepage/index.html)

link to ls1 vs lt1 n/a race:
mikey vs Joe (http://www.quarter-mile.net/video/SS03/Sunday/Sunday37.wmv)


holy freakin crap joe..........thats about as close as it gets!

Originally posted by Damon
Isn't big horsepower about getting a lot of air into and out of the engine? And isn't the main determining factor (once the easy stuff has been done) the flow of the cylinder heads?

If you've played around with any of the commonly available computer-simulated dynamomenter programs it becomes apparent real quickly that if you shove a 383 in place of a 350 short block, peak HP doesn't improve much, all else held equal. Low end torque jumps quite a bit, of course. But a 10 second race motor doesn't spend much time revving though the low RPMs. It's set up to jump straight to peak torque at the line (converter selection) and shift maybe 500-1000 RPMs beyond peak HP. In short, big HP up top is how to go fast in a real race setup. That only happens with LOTS of airflow.

Maybe I'm way off base here.

I'll note for the record that I build STREET engines exclusively (and I don't earn my living this way, either- just a hobby and passion of mine). Extra cubes make a big difference in the world of street engines where torque the main goal. Especially against a low 2200 stall converter. But for racing where life BEGINS at 4000-4500 who cares about low end torque? Build as much HP as you can and then gear and converter appropriately.

Great post.....

That's why on a M6 car you could build a cheaper 355 and still do extremely well with it. Cause you can launch the thing at 5000rpm and only stay in that top 2000rpm band where the 383 doesn't have much of an advantage UNLESS you have some crazy cylinder heads.

Another good reason for a 383 over a 355 for street use is that the 383 will eat up more camshaft and stay driveable. Then again the 355 with the same heads doesn't need as much camshaft.

Bret

But..383s dont have less HP than a 355 right? They just might not have enough more to make the bigger pricetag worth it correct? If you are arguing for price I agree, but if not you are arguing the "no replacement for displacement" theory. But I think you are strictly speaking in funding terms.

Originally posted by jonaddis84
But..383s dont have less HP than a 355 right? They just might not have enough more to make the bigger pricetag worth it correct? If you are arguing for price I agree, but if not you are arguing the "no replacement for displacement" theory. But I think you are strictly speaking in funding terms.

Same heads, same relativly high HP peak and different cams, it's possible the the 383 might be down a few ponies.

Bret

355 ,383 with "same" cam and "same" heads hp and moreso torque is better with the 383.....on that level all things being the same yes 383 doesnt have much on a 355...now on the other hand there again using the heads being "same" a cam change to optimize each combination the 383 surely will be higher hp and torque unless the heads are holding back the air flow the 383 wants...If the heads are up to par then you would see a noticeable difference between the two...

update- my car went 11.94 @ 119.84 yesterday with the tune from my cousin's car. i was hoping for 120 but i tapped the rev limiter at the top of 3rd and only got 2 passes in due to other issues.

Nice numbers Rumair!

beats my 114mph N/A on a 11.85!

Originally posted by OneFlyn95z28
Nice numbers Rumair!

thanks...i'm hoping there's more mph there with some more tuning (won't be back at the track until after i fix whatever's wrong in the drivetrain). i can probably get a little more ET with less air pressure in the nitto's and 4500-5000 rpm launches, but that won't matter since i'm not legal anyway.

Ah just toss a bar in it and have at it. I notice my car is more stable with the bar ;)

hehe...i'm not trying to spend any more money on this chebby powered car anyway. i've already got a "real" race car. :)