I8urLS1

Hey, I know that your supposed to run 3.55 or taller gears with forced induction motors, but i don't know why. Somebody told me that it's because you'll be shifting before the turbo spools completely, but logically i'm thinking as the rpm's go up the turbo will spool completely anyway because the heat generated from the exhaust should be the same as if you took longer to get to the top of the gear you're in. Is it more because you'll be shifting more than you will be on the gas and u'll run out of gears?

just wondering... thanks

StickShifty

its pretty much because you will be more able to spin the tires with the gears.

HaV

You dont have to change your gears out to run forced induction of any type. All gears change is the number of times your drive shaft turns per wheel rotation, which effects what speed your going at what RPM, nothing in the engine as far as can or cannot run FI

The steeper the gear the more acceleration you will get from them. It will take from the top end, which you really dont need. I would definatly switch to a steeper gear ratio though.. 3.73's or 4.10's for sure as you probably have 3.27s (99 up GT) already and wouldnt notice much of a difference switching to the 3.55's. Not a have to but why not get the full acceleration effect from your turbo/supercharger if your going to do it?

I8urLS1

oh ok, but does that mean then that with slicks and a little clutch slippage off the line there's no reason you couldn't run just as fast or at the very least make as much boost out of the turbo before you shift?

I8urLS1

i actually posted this in the classified section cause I'm a retard, so somebody moved it to 4.6 stang. I actually have a 90 LX w/ 3.73's I actually do know how the gear ratios work and the reason for having them i was just wondering why everybody i talk to lately says to get taller gears but can't give me a reason. i understand traction issues but i thought it was a problem spooling the turbo or something cause it wasn't making much sense. I guess it must be easier to hook and go with all that power. thanks guys!

JD1969

This is a myth and is misinformation that I see on here all the time. If your spinning you need to get your suspension dialed in and run the proper tire. To answer the question; it has more to do with forced induction having a lot of torque and being able to turn that high easier. There are still lots and lots of people who run 4.10 and lower geras in a turbo/blower/n2o car, they just have specific performance goals in mind and a combination that calls for that gear in particular.

jelam

If I'm not wrong (I read this on a site) your turbo whould be at bosst power between 2000-2300 rpms and will stay at full boost till it drops below.

jelam

Turbochargers, on the other hand, are exhaust driven, and come up to speed very quickly (almost instantly if properly sized), and will reach the same 8 lb. peak boost level as low as 2,500 rpm. The result is much more horsepower and torque being produced earlier at lower rpm levels with a turbocharger vs a centrifugal or roots supercharger.

thats from turbochargedpower.com
still don't see why you would need diffrent gears

nanaki

yep, you'll reach max boost very soon after it "spools" up. with a centrifugal, you're not reaching max boost until almost redline.

JonBeast

Depending on the size of your turbo.....it will spool at different times. Bigger turbo's sometimes won't spool until redline, and won't reach their full boost potential until deep into/past redline. Its referred to as turbo lag.....some big turbo guys will add a little 50shot or so to help spool up their turbo and hit full boost earlier in the rpms.