Brought my car to the track on Friday and I was super disappointed with the results. My best time was a 15.08. My mods are
cam 280/280 are the specs I was given
slp box
magnaflow cat back with a cutout
Bigger TB (can’t remember what it is at the moment)
and a 3400 stall.

I was hoping for at least 12’s with everything that’s done to it. It was tuned with HP tuners by previous owner. My fastest speed was 87mph in the 1/4. It
seemed to bog down towards the end. It just didn’t have the power I thought it should have. I’m thinking I need to take it to get another tune by someone who knows what they’re doing. Any suggestions???

 

What year is the car and how much fuel was in the tank?

 

It’s a 2002 and maybe 1/2-3/4

 

Possibly still fuel starvation on the top end but the main reason I asked is the earlier cars do not have great tank baffling and do not use a venturi bucket pump like your model year does.

 

Oh ok, I was thinking that it could be the stall? Or possibly the tune that was done to the car. I wasn’t hitting the rpm’s that I should have been and it felt like the car was capped as far as power goes. I saw a few posts saying that a stock ls1 runs mid to high 13’s and I wasn’t even close. Given the upgrades that were done I was sure I’d be quicker than that.

 

My sons 02 Trans Am has slowed down around a half second in the 1/8 mile. So, we took out the Yank 4000 stall converter and installed a Yank 3200 stall converter to see if maybe the 4000-stall converter was broken. The car slowed down another .35 seconds. This is with a 373 to 1 rear gear and 26" slicks. With this car a 4000-rpm stall converter is worth .35 seconds in the 1/8 mile over a 3200 stall. Just throwing some numbers out there that may be helpful. Still haven't found our issue but the 4000-stall converter is going back in and maybe some 410 gears.

 

Back in the 4th gen days I ran as much as a 4400 stall with the 4L60E.

Generally speaking going less stall for drag racing, with a car with a cam doesn't make sense.

 

Should for sure be quicker than that, I would have the tune looked at and was you able to do any data logging while at the track?

 

Yea like I said, all the modifications and tune were done by the previous owner. So maybe adding a different stall converter might help? I’m definitely going to go for a retune. Even sometimes when I’m just cruising around town and i jump on it, it’s not very responsive. I wasn’t able to do any data logging. Just have my time slip after each pass.

 

Fyi never believe what you buy without proof and receipts with part number verification. I learned this the hard way, when I bought my truck i was told numerous different items on my truck were something they weren't and as each part failed and I removed i learned the truth.

 

Don't change anything yet Zach.

You have a few ways of approaching this.

Zach figures it all out on his own
-He buys an HPT cable and starts logging
-He makes changes in the tune because he figures out some stuff

Zach takes the car to a good local LS performance shop
-Shop figures it all out.
-They dyno it.
-They suggest changes.

My thoughts:
-3400 stall is not that loose. Maybe when it felt like it lost power was when the tune commanded the converter to lock up. Do you want the converter to lock up during a pass, yes. But figuring out when requires you use a tuner person or figure it out on your own.
-First, you should post a whole slip, even though it's pretty weak. Maybe you need to reset the ECU, maybe it's in low octane tables, maybe someone ran 87 in it for a while.
-Second, make sure all 8 cylinders are working. I'd throw a new set of plugs in there.
-Not knowing what RPM your cam pulls to makes this tricky. Again if you have HPT you can log a track pull and then look at the commanded shift points and what it's doing. Were it me, after I changed plugs, I'd look at my tune via HPT, make sure the timing advance is kinda in the zone (25-28 degrees), and I'd make a pass while logging. I'd make my first pull having the 1-2 and 2-3 shifts happening at 6200, then next one 6400, then maybe 6600. You should at some point feel the car nose over.
-Converter looseness is complicated. You go looser so it will stall higher, so when you hit the gas the engine can start off at 3400 vs 2500 for stock. The shift points are always some sort of compromise depending on how loose the converter is.
-Locking the converter, were I retuning it myself, I'd start off not locking it at all, then I would try locking it at 100 mph in 3rd. If it runs more mph it likes it. I might try then 97 mph and see what it does.

What gear do you have out back, 3.23 or 2.73? Are you racing on a DR or a street tire?

 

Thanks for the input! I’ll post the results of the 3 passes that I made later today. There’s a really good tuner who can tune and dyno the car in my area. He actually did my previous z28 and it made really good power. I’m going to contact the previous owner and see if he can tell me exactly what is in the car for sure (cam, stall, etc). He gave me the laptop he used to tune it along with all the HP connectors, cables, etc. but accessing it has been a pain. I’m currently running street tires. It was only a test and tune night at the local drag strip so I figured I’d try it out and see how it went.

 

Maple Grove?

 

Yea it was maple grove

 

Sounds like you have good resources to figure this out. 15.x is a weird 1/4 to run you know that.

You never mentioned what rear gear you have.

Did you spin your *** off at the hit on street tires?

 

 

Yea, 15.x is terrible. Im working on finding out what gears are in the car from the previous owner. Didn’t really spin that bad. First pass i just took off from a dead stop. Second pass I tried to foot brake it and left at around 1,500 rpm. Third pass I tried to foot brake it again but at a higher rpm and I ended up spinning a little bit when I left.

 

Just heard back from the previous owner. The converter is a Revmax with a 3000 stall. The transmission was rebuild with Trutech Performance level 1 with an extreme duty Raybestos GPZ105 3-4 clutch. the rear gears are stock.

 

Looking at your timeslips you are way down in power.
If there isn't a noticeable misfire,
pull the plugs and take a look at them.
Do a compression test.
If you have the funds I would put it on a dyno and check the tune.
Something is definitely not right

 

Yeah you have a lot of stuff to look at.

Does it feel like a 15 second car? My daily driver truck (2018 Colorado ZR2) is probably around there.

A stock 4th gen with 3.23s would run 13.4 and sometimes better back when they were new. I'd expect with headers, cai, 3400 converter on a tire with a tune it would run somewhere in the high 12s. With a cam, again on a good tire, would expect low 12s.

With skinnies, some weight reduction I went 11.7 back in 2000.