MillsMotorvation

I have a 1981 Turbo TA, Comp cam 239/247,GT91-1.08AR,408,4L80E-3600stall, and 3.08gear. Car is a street car, but weigh 4000lbs. Will 3.42s help with the 60ft, or make car spool slower?

hellbents10

iTrader: (10)

I would choose the gear based off trap speed and where peak power falls. With that said it should always go quicker to the 60 with a numerically higher gear.

ajrothm

3.42 will definitely help the car leave. Are you able to launch it in boost? 2 step? Trans Brake? What converter? Building boost on the line will be paramount.

Sounds like a cool car! Pics?

Mike@Diablosport

iTrader: (2)

How did you get that thing to weigh 4000 pounds??

I haven't messed with it on an auto car, but my buddy's M6 C5 would barely make boost in 1st with the stock 3.42s, a swap to 2.73s turned the car into an absolute animal...

MillsMotorvation

Its the Turbo TA, after I did the swap it weigh 3950, Since then I added Comp eng traction bars, and tied the frame in. Also I know the new turbo weigh more. I was thinking I will spool slower with higher gear. Havent left with a lot of boost at the track, cant leave with any in the street.

Twin turbo c5

Your probably not gonna see much difference in track times In my opinion. I've changed gears numerous times in turbo cars and it seems like it doesn't change at all .

Slowhawk

iTrader: (12)

You probably just need a brake and converter work. I run 3.00 gears with a 3400 stall and brake. Consistant 1.22 60's.

hellbents10

iTrader: (10)

I agree the converter is one of the most important items in a turbo car that works.

Twin turbo c5

I agree. A converter is the ticket getting a turbo car to work. You could go to a 342 like I am especially with a 80e. It would still drive great on the interstate at 75 but other than helping your 60ft or trap speed I doubt it.

MillsMotorvation

How much boost you leave with? I never have left with more than 3psi, I got the 2 step set on 2,800. Got a 3600stall. What should I set the 2step on? I got great brakes(Hydro Boost)

Twin turbo c5

Have you tried to spool it at a higher rpm on your 2 step? You should be able to get 3 psi just on foot brake.

MillsMotorvation

I turned it to 3,100 and it went to 5psi.

Twin turbo c5

Are you just having trouble spooling . And what have your 60's been at tha track.

MillsMotorvation

Well went to the track Thursday and made 5passes, The car go thru the trap at 5,900 rpm, and 128mph. The 60ft is a best of 1.75 leaving at 5-10psi. The cam rpm range is 2200-7200.
So I installed the 3.42 gears, and haven't been to the track yet, but the car makes boost at 3,000rpm, with no changes it gets 3-4 more boost at 6,000rpm. Being my car is 4,100lbs or more. I like how the car feels lighter on its feet. At 6,300rpm it is running 133mph in 3rd gear. I think it will be a lot faster with this gear change.

Heavy H.P.

My car is around the same exact weight if not a tad more.
At the moment the car has a 3.73's in it. I have a built 10bolt with 3.42's going in. I was going to bull those gears out and go back to 3.73's but that was when I planned on going n2o. Now that i'm going turbo i'll just leave those gears in there. Every one I talk to seems to think that the 3.73's will hurt me more then help.

MillsMotorvation

My buddy wants me to go with 3.73s, but I have 3.42s in my Grandnational, and they really work well with my V6, and big turbo. I think the 3.42s will be perfect for this heavy car. I think it heavier than 4,100, cause it weigh 3,950 before I added traction bars, frame braces, and 4L80E, and a 3inch steel drive shaft. Had a TH350 before.

stock48

iTrader: (17)

How much boost are you running and what are you looking to run?

MillsMotorvation

Boost on 14-16psi, looking for mid to low 10s.I think the gear help the cam work better, and the higher rpm help the turbo spool quicker.