I have 3.73 gears in my 4l60e 1994 lt1 firebird. However, after recently driving my cousins Camaro, big cam, 3600 stall converter; it was quite painful to drive around town. This made me consider going the FI rout, on my firebird. Would it be recommended I switch to a lower gear such as 3.42's, or would it simply not matter because the turbo is so far away, the "loading" of the engine, letting out hot exhaust would lose energy by the time it gets to the turbo.

Which leads me to ask.... would the 3.73's be some what beneficial to a rear mount turbo set up ?

Does any one have experience using nitrous to cool their intake charge ? I currently have a nitrous system and I hope I will still be able to get use out of it in the future.

I appreciate the feedback.

 

You may spool earlier with the lower numerical gear, lots of variables. I would use that as a tuning aid after you get the turbo in and running. I think 3.73 are just fine for a mild street car.

You can use the nitrous, either to spool the turbo, or cool the charge... all depends on how far you want to go.

Do you have a power, or E/T goal?

 

For a mild street car, good way to put it. Might feel nicer to daily/ drive out of boost, but may be slower at the track. Cooling the charge seems safer and I might be able to get more timing out of it, plus is definitely in the scope of my abilities. Since yesterday I hald talked with some one about headers for a turbo. To my surprise and mentioned that the stock manifolds would be the best because of their small diameter to extract the exhaust; however, would shorties be better for this ? I can see why long tubes wouldn't.

My power goal is right around 500, just to keep up with most new cars now. As for a time... I dont mind being a bit slower for better drivability.

 

I would 100% turbo it first and wworry about the gear later. It might be perfect, it might suck. Only one sure fire way to find out.

 

They'll take some of the load off the 4l60 too.

 

I just put a turbo on my mustang with a stock engine t5 transmission and 4.10 gears. Can you say 13.7 starting line ratio? Everyone says it will be better with taller gears. I am going to get as much out of this combo as I can before worrying about the gears.

 

it should be easy to find someone who wants to trade their complete stock rear end for your 4.10 rear end. Just swapping rears is pretty easy, even for a novice. 10x's easier than a gear swap. As novice I found swapping gears to be more difficult than a complete engine rebuild. Definitely not as time consuming though, but more difficult.

 

My rear end is not stock. It has a full spool, after market axles, C-clip eliminators, aluminum cover. I have broken a stock axle they have no place in a stick shift drag car.

I have put new bearings in a 8.8 which is not much different than swapping the gears. It sucks but other than crushing the sleeve I would no say it's hard. Freezing the bearing races and the tool was the best advice anyone has ever given me.

 

Swapping bearings is physically the same as a gear swap but since your not changing anything the backlash doesn't need to be adjusted with shims. I've swapped 3.08,3.55,3.73 and 4.10. half the time I just reused the same shims and everything was fine. But when it's not and you have loud gear "whining"... It's a real pain in the ass to get the right backlash, which in the 3swaps I did only happened once.

 

Nitrous will cool the charge but heat up the combustion chamber/cylinder since you are adding oxygen to combustion. So nitrous is a bad idea if you are octane limited and don’t want knock. I can’t see you needing it for “spool” with a 500hp goal. Just size the turbo and hot/cold sides correctly and you’ll have plenty quick spool up.

Rear mount setups with alum charge piping actually act as an intercooler/heat sink somewhat. IMO spray a little water/meth pre turbo in the rear. It will help with charge temps plenty. Esp. with a 500hp goal.

What size piping do you have going to and from the turbo. Hot and cold sides. That’s where you pick up the most “spool time” on a remote setup. *Most* run too large of a diameter piping to and from the turbo.

You have OD, so no reason to change the 3.73’s. They are about perfect. But you will ultimately be limited by that transmission IMO. You don’t want 10lbs of boost instantly as you will just blow the tires off. I pull TONS of timing (power) initially and ramp in boost slowly VS speed to get traction on the street. And that’s with 30” drag radials.