I just swapped in Scoggin Dickey's upgraded Vortec Heads/ TPI intake, and a ZZ4 cam on my '89 5.7 GTA. Also installed Edelbrock coated headers. Car is idling a bit rough and doesn't really seem to have more power than before all of this. I know I can change the PROM but I want to see where I can take the car on the stock computer variables. The articles I read state over 300 for my setup and never mentioned changing the PROM. Anyone out there have experience with this setup and can offer some tips? Should I run stock timing, plug gap (I am using Vortec plugs). I have an AFPR. I can't even do a burnout off the line and I can barely get a tire chirp on the 1-2 shift so I'd expect more from what I have now. thanks in advance...

Wish I was posting with advice...

I'm planning pretty much the same thing for my 87 GTA, so I'm curious to see how yours turns out, so I can avoid headaches in the future.

I have it running smoother now - but I guess I am disappointed so far. I expected to be doing massive burnouts off the line and from 1-2 shifts - it feels about the same so far.

I plan on doing some dyno runs in the near future, and I will be able to do some tuning at that place too. I do think it pulls better from about 2k to 4500 but other than that it's the same. I expected to have it shift at more like 5k

I hooked up my old vac meter to the plenum and it was off the chart! (this thing just says "idle range, etc...") my needle was pegged at idle. Not sure what that means yet.

With the stock runners, that's what is going to make you top out at 4500rpms. You want higher? Get siamesed runners, or a Stealth Ram (short) intake.

I wouldnt expect it to run all that great. The MAF system is a little flexible to changes but those heads have different timing requirements then your original L98 heads did.

I have an 89 Iroc with the exact same configuration. I did port the plenum and put in 26lbs injectors. Also, I'm running stock runners. I changed the Prom config to smooth out the idle. add timing, and adjust the injector size to get BLMs in place. Started with a ARAP Prom. The car is lots of fun between stop lights. Strong bottom torq. But as others have said, falls on the floor before the ZZ4 cam has a chance to kick in. More air is needed

I don't have vortec heads, but I do have the ZZ4 cam and full exhaust. Tuning is bone stock. Car runs flawlessly, with just a smidge of cam lope. TPI is all original, but I feel like I gained a solid 3 or 400 RPMs up top (not much) but mid range is MUCH better! No doubt there's a difference.

I later added a 2500 converter, and the car just got that much better. Then added a 3.27 gear out back, and the car got better again! I do plan a whole new cam/head swap in the future to step performance to a whole new level, but I absolutely LOVE the way the car runs. It IS however still just a cammed L98, and in the long run I want more power. No complaints though, the car is great!

Ab,
You get no knock at WOT at the upper end of the SA table?
Are you running ARAP?

Thanks for the info but man I have a lot of questions...

I am planning on doing some dyno tuning and I want to get the most out of it but I am new to tuning (but I am a computer geek so I am ok with chaning the PROM but I don't know what it should be changed to!)

I've been trying different base timing and fuel pressures - stock PROM. It seems to have more power at 12+ degrees advanced, but it stalls too much and backfires through the intake when cold. I have it closer to 10 degrees and it's bearable. Fuel pressure seems to be better closer to 50 (or a little less) -stock size accel injectors. Would it run best with stock base timing but a steeper and higher timing curve in the PROM?

I also suspect my ECU is not always working right. I couldn't get ALDL data from it even though the cable/software tested out on another TPI car. Also my fan temp sensor was disconnected and I didn't get a code, but when I hooked it up I got more power. Weird.

I need to learn about the things that I would need to change for a PROM. I know there's lots of info out there. Maybe I should start with buying one? Do they sell custom PROMs for your particular heads/cam?

wow. okay a stock l98 runs okay at 8* advance, that's where im at right now actually but as soon as i get time with a timing light i'm going back to 6* and adding 2* to the SA tables. with your vortec heads you ought to need less advance, lik 6* base will probably be allright but you're really playing with fire cranking up your base timing with no datalogger. time for you to hit the books at the DIY prm board buddy.

Abubaca is most likely running ARAP as his car is an 89.

Our cars are the same except I am running 21 accel injectors but I have an AFPR.

I am datalogging now and I have had to set the base timing back - I'm at about 6 * now, and I still get a little knock retard during WOT acceleration. If I run ARAP wouldn't I get even more timing?

I'd really like to know what you have done to tune your car. I ordered a PROM burner and I am going to start fine tuning but I am looking for any information I can get.

shoot me your email address I will send the bin file

what kinda gears?trani?is the drive train stock?if u wana tune it get a air fuel gauge+fuel pressure gauge+how far out is ur timming and are ur injectors stock?throttle body?

yea and my car is a 91 camaro it has 373s locker unit 2400 stall 350 tbi stock motor and i can burn the tires first and second and on a cold morning even third .so ur timming is wrong or ur fuel aint right just by moveing timming u can get any where from 30 to 50 hp.i have a lil exp messing with the tpi and tbi have done alot of research on them.just tell me every thing that u have done and ile tell u if theres something out of wak stevo the torpedo

I run my base timing at 8* and have heavily modded my SA tables with more timing. After several runs and datalogs I retuned the SA tables and after all the tweaks, the timing is still quite a bit higher than the stock SA tables even with a base mechanical timing of 8*. I get 0 knock counts now. So, you can still run some decent timing with a vortec TPI motor.

Then again, my setup is Speed Density, not MAF......

Thanks for all the info : you can send a bin to flaggedatbest@yahoo.com (sacrificial email)

I have a stock drivetrain, 3.27 gears (forget the exact #) - ZZ4 cam, and Vortec heads though. Stock throttle body, accel injectors, stock size. stock 89 MAF setup.

I am about 8* base timing, 47 fuel pressure. I get a bit of a rough idle and stalls cold. I have been datalogging. at high RPMs I get some knock retard.

I would assume that you want NO knock retard, right? (even a little is bad?) but a little knock is ok as long as there's no retard?

Anything else to look for in the data? I notice that my O2 is constantly 400 during the hard accel the when off the gas it goes way up. What numbers are most important for tuning?

Another question - If I pick up more RPMs, will my trans automatically stay in gear, say to 5000 rather than 4800 or does that require some manual recalibration? I am shifting at about 4700.

thanks again

The general answer is no. The tranny will shift at the same point automatically. The tranny has a mechanical shift governor that relys on fluid pressure, spring pressure, and centrifical force. To change shift points you have to change the springs and weights on the govener. Pain in the butt process. There should be a thread or 2 on the Transmission boards

I actually disagree somewhat with this statement. A looser converter equipped automatic will shift at a higher RPM when put behind an engine making more high end HP. I've seen stock TBI cars shift @ 4,400 rpm all day. Cam, Vortecs, tuning, they suddenly start shifting at 5,000+, but at the same road speed. So technically they are still shifting at the same MPH, but the converter is flashing much higher because of the increased torque.

doesn't that mean the torque converter is slipping then? and wouldn't that just subtract from the power you just gained

Burned wells bin file and my car is a burnout machine! Much better. Datalog says that I shifted at 4900 RPM which is about 400 RPM more than before. I had run ARAP bin before and it was more responsive but idled crappy. The only mod to wells setup I made was for my stock O2 sensor and VATS disabled. By the way, I am running the transgo shift kit (the more expensive one)

I got some knock retard on hard accel though. I upped the fuel pressure to max (60) but that didn't help. (I have size 21 accel injectors) I do run premium.

I have more experimenting to do, but it's much better than before.

Anyone know what would have to be changed for larger injectors???

Injector constant in the PROM will have to be changed to match the lb. per hour of the new injectors. Also, you should set fuel pressure to match what your injectors are rated at. Example, SVO injectors are rated at 39.5 PSI, Bosch I think is 42 PSI and I have no clue about the Accel's, because everyone I've ever talked to say they are junk. Buy 24 lb. SVO's and retune the PROM is my advice.

Glad the Bin worked out. Guess I was wrong on the tranny shift points. The higher torque must be holding it in gear longer. On the knock retard try this. Increase the base timing in the prom by 1 degree and make a run. DO NOT INCREASE IT ON THE MOTOR. Repeat this until the Knock retard goes away. Then what every the final increase amount is add 1 more degree and substract the total from each of the Table enteries that correspond to the RPM/Load where the knock occurres. Then set your Base timing in the bin back to normal. The Timing table is total timing and the base timing is subtracted from the total to tell the ECM how much timing to add. By putting a higher value in the base timing constant and NOT changing it on the motor cause the ECM to add a lower amount of increase.

Hey I got a buddy with a truck that has this issue... does anyone make a good truc vortec tbi chip that I could refer him to? My stuff is all installed on my fiesta so I can't tune him myself. He's running stock injectors and fuel pressure but has played w timing. Or I have moates gear does anyone have a 747 bin for a zz4 cam and vortecs I could burn for him?