Figure I’d share my lack of results.

98 trans am. Built 6 liter, flat top 2v pistons, 243 heads, trex cam, 90mm LS6 intake, 1 7/8 headers, 4L80 with HD2, 4000 converter.

Car went 7.8 at 91 MPH with the stock 3.23, 28” tire, race star wheels. 1.8 60 foot.

that is ****** pathetic for what the combo is, since my 2002 TA with a gear and exhaust ran 8.0 on the same 60 foot time.

So, figured the 12 bolt swap, 4.30 gears, 26” tall tire, and lighter pro star rear wheel would help.

wrong. 1.8 60 foot, 7.8 at 90 MPH.

I figured the 60 would drop with the additional gearing. But no.

so, I’ll probably see if I can get the converter loosened up. If that doesn’t work, I’ll just have to build the spare Th400 I have.

Same issue I had in another car. But the car was lighter. Didn’t go much faster.

What’s the suspension like? You try unhooking you front sway bar? Adjust the torque arm angle? Shocks? Etc?

Think u mightve been better off staying with the 28” tire. More moh up topp

No front sway bar at all on the car. I want to restall and start cutting weight off the car.

Rear diff is 4” narrowed so wasn’t a option. Threw the spare wheels and tires on that would fit.

it is dead hooking. We are gonna mess with the tune. Car was 3580 before a 12 bolt rear end and was with 18” chrome wheels. So should be 3600ish and I’m 275. Near 3900 down the track. Just doesn’t leave hard as none of my 4L80 swaps ever have with NA attempts.

Are you launching the car off idle or stalling it for the launch?

I launched it off 1200-1400 before and after. That way it was back to back comparison.

stock trans I had from a truck I had totaled. Revmax converter.

I would lose that converter to start. Go with a Circle D 3E which is very efficient. I was running a fast 92 with a GM 85mm MAF, 799 heads that I worked over myself, Tick 235/242 cam, Circle D 3E (would flash to 4500 behind my setup), built 4L60e and a 3.73 gear on a 26” drag radial. My car was full weight minus the rear seat and front bumper support. It would pull a consistent 1.45 60ft and went a best of 10.84 @ 123 mph.

The other thing I would suggest is stalling the car up to 2800-3000 rpm on the foot brake before you launch. With the 3E the higher I would stall it the lower my 60ft and et would be.

I had a circle D 5c and it would 60 worse than this current converter. I’m assuming you have a 4L60? If so, that’s the big difference. My research has me finding that FTi is one of the few companies that can build a 80 converter for NA applications(loose).

If you’re dead hooking and only pulling a 1.8 60 then there’s something going on there. I pull 1.58-1.60 with a 4K stall, S60 with 4.10s, 26” et streets, and 321 rwhp... stock ls1 intake. Exhaust and cai are only power mods.

So I’m wondering if it’s a tuning issue or a timing issue because you should be pulling more of a 60 than I am... because you have more power... which makes me wonder if the car is bogging for some reason?

Or is it a converter issue?

You mentioned FTI, I run a FTI hard hit 4,000 stall on mine and absolutely love it... couldn’t be happier with it.

Do do you feel it bog down? Do you have videos?

Just doesn’t bit the converter hard. It’s a Trex cam in a heavy car. Needs more stall speed for sure.

you running a 4L80?

I’m running a 4l60 built by Performabuilt.

Googling dyno graphs with a Trex cam I think you’re right. You need more stall to get that heavy car rolling. I’ve had light and heavy cars and the heavy car always needed more stall to get it rolling.

That’s helping you a ton. The 60s first gear and lighter components are day and night.

I agree. But I think you’re on the right track with your car. Are you gonna try a 4500?

I need to call my converter guy and see if he can get my current 10” converter to a 5000 stall speed. That’s where it needs to be I think.

If it won’t 60’ with a 5000 there’s an issue somewhere! Lol