I am pretty clueless when it comes to tranny ratios and how they work, after doing some searching i've come up with the following. I hope someone can elaborate.

BTW, i have an EG with a '99 b18b1 going in it soon, i was curious as to what tranny would make the car faster with shorter gearing.

Y80/S80 B18B 3.230 1.900 1.269 0.966 0.714

S4C/Y21 B16A2 3.230 2.105 1.458 1.107 0.848

Y80 B18C1 3.230 1.900 1.360 1.034 0.787

S80 w/LSD B18C5 3.230 2.105 1.458 1.107 0.848

So it looks as if all b series trannies have the same first gear ratio 3.230.

The GSR and LS also share the same 2nd gear ratio which leads me to think GSR ratios are generally longer than Si/ITR trannies.

It also appears that the only difference between USDM Si and USDM ITR trannies is the LSD that the ITR has, gear ratios are the same.

Would it be possible to swap a tranny from a b16 on my LS motor and put in the 5th gear from my LS in the b16 tranny. I want my rpms to stay low when cruising on the highway (to save on gas).

Thoughts/opinions/suggestions

 

The b16/b18c5 tranny will give you the fastest acceleration, next in line is the b18c1 tranny, last is the b18b tranny.

Although the b16/b18c5 tranny may give you the best acceleration, i believe it will put you out of your correct powerband stock for stock. The b18b tranny is geared to keep you more in the midrange, to take advantage of the extra tq and low rev of the ls motor. Im merely talking about stock motors. Correct me if im wrong.

 

depends on what you are going to do with ur engine .

b16 with ls fifth with lsd of some kind even if it is a phantom grip
this is the best way
even if you decide to boost later on ls fifth absolutely kills acceleration , perfect for highway cruising

 

ttt

 

I have a b20 and going with a b16 vtec head,I also will be putting in type r pistons boring the motor out to 84.5 low comp with a Jackson racing supercharger.my question is what transmission will be better for what I am building I also have a ls transmission and have a gsr transmission

 

Are you also changing the connecting rods to aftermarket forged rods so that you can safely rev the engine higher? If so, you could go with the shorter gearing GS-R transmission.
If you have stock connecting rods, then you shouldn’t be revving the engine very high, so I’d choose the LS transmission if you are limited in your RPM range because you’ll want longer gears.

 

It will depend on what kind of driving you plan on doing.

A little clarification - stock rod bolts would be the limiting factor in the bottom end for revs, not the actual rods.