Hey Guys, I was wondering if someone could shed some light on choosing a rear gear for a turbo car. Ive seen tons of guys running 3.00- 3.08 gears, some with 3.23-3.55 etc, seems like the higher ratios are where its at for turbo cars. Is there a way to determine what ratio will work best for a certain combination? Ive said it before that this is my first turbo car so im still learning the ways of the wise. I grew up around raunchy cammed NA motors with 4.10-4.56 gears and were terrible street cars.

I picked up an 8.8 ford rear end with a 3.27 gear, i was planning on trying that ratio out to start off and keep costs down. Im just worried about it being a dog off the line with a 28" tire and a TH350 with a 3500 converter.

 

any turbo car will be a dog down low. Two ways to fix this....t-brake or NOS.

Gearing is all about the 1/4 mph that you think the car will run.

What RPM do you plan to cross at?

 

I have the 3.27 in a 28" tire in my mustang, on my stocklongblock 5.0 it's great.. Not too laggy and still breaks it loose nice on the 555r dr's

 

some time back I started a thread to get some info on what kind of gears would benifit a turbo car. take a look https://www.theturboforums.com/threads/358426-Turbo-cars-and-Gear-Selection

 

thanks guys for the info, Yellowlt1ta your thread really helped shed some major light on the subject. Looks like i should be at a great starting point with a 3.27 gear and 275 60 15 radial. The car should come in around 3200lbs and being on leafs and a wagon i think ill have a good torque to weight to gear ratio combo

 

makes me think the 4.33s i ran in the gremlin were way to steep. It would lay over around 1000 feet and when i went from a 10" converter and 28x9 to a 8" converter and 325 radials the car barely got the tires off the ground... good thing i still have the car so i can switch things up when i get back to running it someday

 

I hate it that people think this although I will admit that it seems to be 90% true. If everybody will quit taking their stock type intake and cams off and putting intakes and cams on that sacrifice low speed torque to gain mid and upper range power this will not be the case. Putting turbos on "high performance" engines is what give turbos their bad rap with regard to response.

90% of our setups here consist of an engine with poor low speed torque yet they make enourmous top end power which forces the use of a huge turbo. This is a terrible combination for a street car. Look at how many here have a turbo with a single plane intake manifold.

 

I had 3:73's in on the dyno and with the c4 and old converter (loose, was set up for my YSI that I had previously) the car wouldnt run above mid 140 on 325/50 drag radials @ 7500ish. Im going with 3:27's to make it more street and trap friendly. This is a built 2v w/ 76mm precision.

 

ok just read all the posts trying to get an idea of were i should be on my car as far as gears, so what i have is a 68 barracuda with a 411 ci motor and a 83 mm turbo installing a T56 Magnum 6 speed trans and running 373 gears with 305/35/18 tires (26" tall) mostly a street car was told the turbo should start kicking in at 2300 rpms with the 373 gears i will be able to cruz down the highway at 75 without the turbo engaging at least this is my goal so my ? is is this a bad combo would love some impute from you guys this is my first turbo car thanks

 

Im starting out with 3.23 gears on my 400 mopar and hope if I make over 500 hp should be able to drop down to 3.08. That 83 mm turbo is pretty big unless you have a pretty built motor. A friend of my sone is running an 83mm single on a LSX in a 98 Trans Am and is pushing over 1000 HP. That car is scary fast. http://youtu.be/q_YceBmwcAE

 

3.27's 331's is good choice

 

Any big turbo setup with a manaul is gonna be a bad idea. =\, should have enough mph for 9s though.

 

the motor is built top notch without the turbo about 450 to 500 horse the trans has been gone trough to handle 900 lbs of torque not looking to much at building a 1/4 mile car more for road racing but i keep reading that a lot of people are running about a 300 gear so i'm a little concerned with the 373 gears that i have sounds like i could be loosing power from the turbo of course i already spent a lot to build the rear end for the car so if i break it wanting an opinion on the gear set for next time


Damn that trans am is scarry