Just dynoed my 89 GTA, L98 auto - best run:
234.6 @ 4390 RPM
316.4 @ 3395 RPM

I must say I'm pretty disappointed with my mods. Is this typical with a setup like mine?? I figured on much more RPM. I attached the printout.

Mods are: Scoggin-Dickey Vortec head setup with vortec TPI intake and heads, AS&M runners, cleaned up plenum, ZZ4 cam, edelbrock headers and flowmasters (stock dual cats), slightly bigger throttle body (forget size) LS1 injectors.

Ran several proms including ARAP and the best prom was from someone else on this board. Dyno guy said I'd get a little more hp if I could get my AFR closer to 13 but it was 12.7 so not too bad I guess.

 

Your torque is about where it should be, but your horsepower is way down, and peaked very low. What are the specs on your cam and heads?

 

These should be the specs on my head / cam. Also, all the intake pieces are port matched.

Upgraded SDP Vortec Heads:
True measured combustion chamber volume:63 ccTrue measured intake and exhaust port volume:185 cc; 63 ccSpring pressure: 70 lbs. on seat; 265 lbs. at 0.500-inch liftinstalled height: 1.850 inchValve size: 1.94/1.50-inchIntake flow at 0.400 lift: 212 cfm
combustion chamber volume: 63 cc
True measured intake and exhaust port volume: 185 cc; 63 cc
Valve size: 1.94/1.50-inch
Intake flow at 0.400 lift: 212 cfm

ZZ4 Cam:
Duration @ 0.050" Lift: 208/221
Lift: .474"/.510"
Lobe Separation: 112

 

that cam looks well, but those heads are very tiny, if you can I would upgrade to AFR 195's or something with a 2.02 intake and 1.60 exhaust, to really make that thing breathe. Those edelbrock shorties don't flow well either. Are they 1 5/8 primaries or 1 1/2?

 

ok, supposedly I am supposed to get 300 hp with the vortec tpi setup w/out the cam, etc... Maybe I have the specs wrong.
http://www.chevyhiperformance.com/te...ead/index.html

What I am wondering is, given my setup with no problems, are those numbers reasonable? I am wondering if a sensor or somehing could be failing but I'm not sure where to start now.

 

with your setup you netted 280 horsepower at the motor. Thats not to far off from what they got. If you switched intakes to either a mini ram or holley stealth ram along with bigger heads you would be much closer to 300 rwhp in my opinion

 

Back in the day I was running the SDPC crate motor that is similar to your setup. With the vortec heads, LT4 hotcam, stock intake, stock TB, 24lb injectors, SLP 1 3/4 headers, flowmaster catback, etc I dynoed 265 rwhp/373 rwtq after the car was dyno tuned. My first pull if I remember correctly was 245 or 250 rwhp.

I'm guessing there is a bit more left to tune on your car.

 

Just had a thought - do you guys think a bad alternator or battery could result in bad numbers?

On the way home from the dyno the car died - Volts was down to zero and wouldn't start. Had someone bring me a battery and drove home - volts is only 11 while running with the new battery so I need a new alternator.

Do you think with the new alt/battery I could get much better numbers?

 

im pretty sure that the alternator/battery has nothing to do with dyno numbers..... don't feel bad man.... with my old full bolt on plus crane 2032 cam l98 with highflow tpi only made 215whp by 283wtq....... but my engine was over 130,000 and blew up on the dyno... it was on its way out anyway..... the way i see it... horsepower numbers is just bragging rights anyway.... hell my 215whp gta was very fun on the street and felt very quick.... you nearly have 50 more wheel horsepower more than me... if i had that much with my old setup back then.. i would have a smile on my face.... if its fun to you on the street and fast, thats all that really matters....

 

Yeah, but it's hard to believe that a car with 245 or so stock would be around 280 with heads, cam, intake, runners, headers, etc... I figured on at least 300 rwhp heck I'd have just put an ls1 in there if I thought I'd only be adding ~ 35 hp.

Anyway, I haven't given up yet. Maybe I have a weak MAF, or maybe I'm not getting enough air into the TB. Is the stock Firebird intake (from the TB to the MAF) restrictive? Maybe I have a weak ignition system. Was thinking of adding a MSD box if they are any good. Also thinking of putting on a stroker kit over the winter.

I know the Vortec heads are small but I heard they flowed real good, and those damn as&m runners were almost 500 bucks. Just thinking of where to go from here to get closer to ls1 numbers.

 

yeah they say 245.... but thats at the motor.... more like around 190-200whp stock.... ive also heard that the vortec type baseplates is one of the worst designs..... and people praise these vortec heads.... they still are stock heads.... also how many miles do you have on your engine.... that plays a role to.... could be just worn out like mine.... that article about the vortec heads and intake it looks like they did it without any drag on the engine meaning no ac, smog etc.... 354hp does seem kinda high from stock vortec heads and vortec tpi intake and stock cam...

 

Engine is healthy with about 50k miles on it.

I am wondering why HP drops off at such a low RPM. All the parts seemed to indicate peak power at over 5k. I am still suspecting that the numbers are too low for my setup but I'm not sure where to start with investigating this.

 

I agree with the above poster. You need a custom tune. Also are you running the stock air intake system?

 

I am running the stock intake for the "black plastic" part - TB, runners, lower intake are aftermarket.

I am running a different prom. I tried 2 I got from the Moates site and one from another thirdgen member - that one was best.

Any suggestions?

 

Your graph is abit wavy... you need a better tune to smooth out the air fuel ratio and then play with timing overall. Wont take much effort on the dyno..few pulls should dial it in better. Not bad numbers for a base tune like that but ALOT left to gain.

There's no reason that setup shouldnt dyno 270whp or more.

Cut your bottoms out of the TPI air box..where the filters sit. That will help it breath abit more. After that your fine, that stock air box will support plenty of power.

 

[quote=Orr89RocZ;4240949]Your graph is abit wavy... you need a better tune to smooth out the air fuel ratio and then play with timing overall.

Yes - I was trying... I am new to tuning like this and the dyno guy admitted he mainly deals with ODBII and carbs and what I was doing "wasn't for the average joe-shmoe!" yet the meter was running @ $100/hr and this was the best I could do. He wanted me to make it a little leaner but we couldn't figure it out in tuner pro. I changed the injector scalar but it seemed to give unpredicable results.

I have a lot to learn - maybe need a tuning place that's good with TPI in my area. (don't know of one)

 

Orr, he has a Pontiac which has a terrible cold air intake intake system. He needs to upgrade it. There are numerous posts on this site as to how people tackled the problem.

 

Misread the GTA part... yes, upgrade the air box, you can easily build a 3" cold air package using exhaust pipe and silicone couplers

too bad your in warrington pa, thats 3 hrs from me atleast. I could help you out with tuning. MAF isnt all that difficult to do. set your injectors constant to your fuel injector size, and leave it. For WOT tuning, use PE mode %enrichment vs rpm. That will help you with the fueling. Leave scalars alone. You can try to play with table 4-6 for the MAF if you want but if its close leave it alone and work PE mode for WOT fueling. Keep reading and playing with it, you'll get alot more power out of that setup

 

try finding a slp cold air intake... i noticed a difference with mine over the crappy stock design... should help out alot... you need to move the charcoal canister down below...

 

I think it's time for a turbo.. lol

 

You definately need some tuning.
Yes, battery voltage absolutely affects both spark and fuel delivery.

 

what times do the car run

 

The biggest restriction is the manifold. It only flows about 230cfm. Dyno Don on the Southern Cal board made 372rwhp-410rwtq with the same manifold but the manifold was welded up and fully ported to flow 290cfm.

 

My Edelbrock 3817 flowed a fair bit more than that out of the box.. More like 245 CFM and I got it over 265 CFM without having to weld anything, just basic porting. My Vortecs flow around 260 CFM @ .500" so its not a restriction. I pulled over 345 RWHP with a mild cam.

 

how do you guys get these insane rwhp horsepower numbers from these tpi's.. i mean i have fully hogged out slp runners and plenum but my edelbrock tpi base is only slightly ported.... im running a gm hot cam and i know im not pushing 300whp i dont think... whats your secret besides vortecs.... i have everything to make a 300+whp tpi with vortec heads...

 

I think you would benefit from some tuning. My 1991 L98 Formula made 221rwhp with just CAI, headers/catted y-pipe, cat-back and tune.

 

Any one else notice that the power band here did not line up on the dyno the way its supposed to? 5252 rpm is supposed to be the HP/TQ line cross right? Or is that just a funky graph?