OK, I've been a 3rdgen owner since last February. My wife bought me an '86 IROC 305TPI 700R4 for Valentines day. That car was good for mid 15's completely stock. I didn't want to waste time on the tired 305, plus I've always been partial to Trans Ams, so I sold the IROC and bought an '89 GTA w/an L98.

The car has Hooker Super Comp shorties, flowmaster muffler, single high flow 3" cat, 1.6 ratio roller tip rockers, mildly ported upper plenum, SLP runners, K&N cone A/F, AFPR set to 50psi w/the vacuum line pulled, and 168,000 miles. It also has an unknown aftermarket chip.

I don't know if the engine has ever been rebuilt, but it runs smooth and pulls strong is clean and doesn't smoke. The tranny shifts hard and doesn't appear to be slipping. Despite all of this, I only have a best ET of 14.94 and a best MPH of 94.73. My 60' times are pretty consistent at about 2.1 seconds and my ET's range from 14.94-15.3's. To say the least, I'm getting a little frustrated with the lack of response from the modifications.

Anybody have any ideas on getting this combination to run better? I have thought about a custom chip, but didn't want to drop $150-200 for little or no gain. I'd rather spend the money on a bottle .

Any help would be grealtly appreciated.

 

I'm no expert but the bottle is always an easy way to drop a second off your time. If you really want HP gains, pull the engine, rebuild it, use a bigger cam, higher compression....all that fun stuff.....other then that your just gonna be picking up little 5-15 HP gains here and there.....if you want substantial power then rebuild the engine for it.

 

I realize substantial gains require tearing the engine down. But I would expect this car to run high 14's stock, never mind with what has been done to it. Then again, I really don't know the internal condition of the engine or heads.

I was mainly wondering if the chip could be hurting performance that much.

 

Stock even the 350 engines in the late 80s run like 15.0-15.4.

The 80's were a sad time for muscle cars man....if we made a graph showing HP from the 70's to the late 90's it would be a U, with the bottom of the U being the 80's, damn gas crunch man....

If the chip is bad it can really screw you up, but your times dont' sound that off, 14.8-.14.9 sounds right considering what your running, I would think you could run a little lower, but the car has like 170k on it right?

If you want low 14's either spray the engine (at your own risk) or put in a 350 with less miles and better parts.

I've got a stock TPI 305 87 Iroc and I ran 15.5...probably coulda gone maybe 15.3 or 15.4. I just bought a 350 block, gonna build it up hopefully....no way around it, more power means a better engine....the returns on doing exhaust/intake/minor engine work aren't worth it.....

 

You car stock should have netted a mid 14 to high 14 time. What's your elevation and the weather like? First thing I'd do is get rid of that chip. Anything to test it out.

Run a bottle on that engine and you can kiss it good bye pretty quick, unless it's rebuilt of course. Check out my sig for my times and mods.

I honestly don't see any reason why you are not very low 14s to maybe even a 13. Get a full tune up done.

edit: Don't mean to show you up or anything Elephant, but you are a little misinformed about your times. Oh yeah, I've got 127k on my l98.

 

Thanks for the input jd13. And yeah, I'd say StealthElephant is a little off. His theoretical U shaped hp curve bottomed out in 1979 and started to pick up again in the 80's.

I expected mid to low 14s with the current setup. I guess I can remove the chip and try something different. I thought about a custom chip, but am not sure where to start with that process. The car is tuned, with new plugs, new plug wires, new cap and rotor. I've adjusted the TPS sensor, cleaned the throttle body and just about every other "tune-up" work needed. The car idles fine, pulls real strong out of the hole but falls flat in the top of 2nd and pulling through 3rd. I suppose if the chip isn't programmed properly, it could cause all sorts of issues. Any recommendations on where to start with the chip. Afermarket maybe, and if so which brand, Hypertech, ADS, SLP???? Or should I go straight to something custom.

The only thing I haven't done is compression tested the motor, but if it was having ring blow by I'd expect to be using a lot of oil, and it doesn't. I'm at a loss, and really don't want to tear the engine down...yet.

Oh and the elevation is 1200ft, temperatures were in the mid 70's, very dry for the 14.94 run.

 

I apologize if this question seems beneath you (I don't really know what your knowledge of TPI is), but where is your "cone" air filter? Is it right on the throttle body, or is it over behind the passenger headlight in the stock location? The reason that I ask is that if your car has had the MAF removed, it'll run bad enough to ruin your 1/4 mile times.

Personally, I don't find high 14s to be all that far off. I could see the car being 1/2 second better, but at lower elevations it probably would be.

 

You want to make your car faster reguires more HORSEPOWER which reguires you have to spend MONEY to get it. Nothings free
when you want a faster car.

 

I thought this was a 3rd gen tech resource page....maybe I was wrong. I got two good comments so far. As far as my knowledge of tpi, its pretty good. I do appreciate the comment Jim85IROC. And yes I have my MAF installed and yes the cone filter is in the stock filter location...not ideal for cold air induction, but better than the factory air filter box.


87DJP2001, I've already spent money to make the car faster. I've added SLP runners, AFPR, 1.6 rockers, airfoil, and performed the "free" mods suggested in High Performance Pontiac magazine. Its not a matter of not spending money, its more a matter of getting something for the money I spend. I would think high 14's should be the norm for this car if the engine was in good condition "stock". With the added parts, I should be pushing at least 20-30 more hp, if not more...and thus be running mid to low 14's.

My primary question is whether or not a chip can hurt performance, but still allow the engine to appear to function normally...and if so, by how much.

 

Well the elavation will certainly hurt your time. I say at 1200 feet .2-.3th is about right.And about 3-4 MPH.

Your rear end gear could be the issue also... make sure you have the 3.23 gear. That is the best factorty gear....you could have a 3.08 or a 2.73...though I doubt the 2.73.

Also. Hooker long tubes are no help to you. That is a header for a vehicle that make power on the other end. The L98 is a torgue motor. low rpms....4500 ur outa gas. Great LIGHT TO LIGHT vehicle though. The flow master is only good for about a .1th

So that leaves you about 14.7 at 98mph at sea level.

If I were you I would sell the hooker Long tubes...(I 'll buy them ) and get shorty style headers... The work in your RPM range. SLP or Edelbrocks. If you car has duals cats. The exhaust flows prety well. I would focus on the intake side ....

Runners..MAF...manifold.... Best thing to do for a L98 is BUY the HOlley Stealth Manifold.... That will put you right there with the LT-1 cars... Moves your power band up and Keeps that Torgue flowing.

then save for a LT-4 hot cam..... with holley manifold...LT-4 cam...Shorty headers....your all over a 13.9 at 1200 feet....or 13.7-13.6 down in Florida.....Get a stall converter...about 2800 and Drag radials....low 13's easy....

But what do I know?

 

Nothing you added is going to make your car faster and a New Chip is not going to help.

 

Actually at 1200ft, its about .1 -.2 tenths loss. But even at that elevation, I've run a 14.55 with a basically stock 5.0 LX at the same track.

The headers are shorties, and the intake has SLP runners (don't really know how much they did for me).

The car baselined at 15.46 with only headers and exhaust, but it was hot that day (over 100 degrees). With the additional changes, I've now run a best of 14.94. Should I expect more? Some of you guys are telling me a I shouldn't but I would think I should?

Anybody have any insight on chip upgrades??? Thats the biggest unknown on this car right now.

 

Nothing I added made it faster? So why did it drop almost .5 second from the first time I took it to the track?

Seriously, if you have something to add, please inform me.

 

how are you driving the car at the track? are you leaving it in drive? or are you shifting it yourself? if you are leaving it in drive, try manually shifting at about 5500, that way when it hits second you are just below your "sweet spot" as far as the revs go. also are you powerbraking it at the line? if not, experiment with that. i would try around 1500-2200 or so but each caar seems to be different.

also try an lt1 intake, that will give you the same gains as the stealth ram but it will fit under your stock hood. the stealth ram will not fit under a stock bird hood. also, you might wanna try another brand of catback, like a hooker or do what i might do and get a loudmouth which is designed for the 4th gens. be warned this exhaust is VERY loud. also you might wanna try a cut out, most guys see a tenth or even 2 to 3 at the track with that. port and polish you base and intake mannifold if you dont get an lt1 or the like. what ever you do, DO NOT get super chip or any other aftermarket chip for that matter. stay with a stocker until you do different heads and a cam, these cars dont really like different chips as far as i can tell. you might wanna switch you car over to speed density too. that will get rid of your maf sensor and gain a few hp out of it. also bump your timing to arounnd 12* or so and set your fuel pressure higher with an adjustable fuel pressure regulator. those 2 would net you probably about 15 or so.

i hoped this helped in anyway. if not hit me up on AOL instant messenger at Nog736 and i can give you some more one on one advice.

also, if you guys dont know what you are talking about dont respond. its better for the guy to wait for some one that actually knows what they are talking about than to give him some bs advice.

 

Thanks for the response. Umkay...I'm power braking and launching at about 1000RPM or a little less, just barely loading the torque converter. Anything more seems to get too much tire spin and increase my 60' times. My best 60' is a 2.08 and I pull pretty consistent 2.1's. From my experience, thats pretty good for street tires (Dunlap SP5000s).

I shift at 5000RPM...which even seems a bit high. I've tried leaving it in drive and it shifts from 1-2 at 4500 and 2-3 at 5000RPM usually netting very consistent 15.3's. Shifting myself I've run 14.9's.

Why not go with an aftermarket chip? I had pretty good luck with a hypertech street runner in the 86 IROC. I dropped about 2-3 tenths in the 1/8th with just the chip change, but really didn't gain much on the top end.

I guess there is no simple answer without tearing the engine down. I seem to get a bit of valve float anything over 5000RPM, so maybe the valve springs are just to worn (170kmiles?).

Screw it...I'll just work on my other Trans Am (1971 455HO, but unfortunatly needs a total restoration).