Thread: B13 B15 P11 Trans Info You Must See

So I've blown up B13 tranny #6 and I'm tired of it. so I work at a Nissan delaership and I can pick up a brand new tranny for a B15 for $1,600 but wanted to really get a P11 trans cuz of all the hype about it being the best gearing for a turbo. And I can pick up a P11 for the same. But I can't put it on my charge at the dealership like I can the B15. So my buddy ( a master tech at the dealership ) says well lets spec out the gearing on these things. And see how different they are. You guys might be suprised at what we found. These are direct out of the nissan assist manulas. It shows that the B13 and P11 have the same gearing except the P11 has a taller 4th. And both have the same final gear ratio. It shows that the B15 has the same taller 4th like P11 but has a taller final gear ratio. Making all the gears taller. I know this is contradicting to what alot of guys report on these trannys. So read these and discuss..

B13 final ratio 4.176 4th gear ratio .975



P11 final ratio 4.176 4th gear ratio .926



B15 final ratio 4.437 4th gear ratio .926

Welcome to 2005...



From here:
Gear Ratios for B13 & P10\P11 - SR20 Forum

LULZ well I tried searching for something like that but couldn't find anything. And I was thinking about the B15 final ratio. Its lower ratio. Not taller like I was thinking. So basically the P11 trans is the same gearing as a B13/B14 just has a taller 4th. Some people think it has taller 3rd and 5th.

LOL It's all good.

I don't know what you are looking at but most of the gears are different comparing the SR20DE B13-P11. Are you comparing the B13 GA16DE ratios to the P11 ratios? Because they seem very similar.

Maybe what you meant to say was "So basically the P11 trans is the same gearing as a B15 except it has a taller 4th. Some people think it has taller 3rd and 5th."

In that case I'll tell you what. The final drive ratio of 4.437 on the B15 transmakes a world of a difference. The B13 trans first gear ratio of 3.063 coupled with the final drive of 4.176 compared to the B15 trans first gear ratio of 3.333 coupled with the final drive of 4.437 is a HUGE difference. My point is this....with a standard size B13 tire and rim combo (205/50/R15) the gearing is short. I have had a B15 trans in my B13 for a while now and I like to chime in on these threads.

Sorry for the noob question but what would this do in 5th gear?

Nate (DFW Nate) did this in his B15. IIRC, He has the B15 w/ Nismo diff, and the P11 FD, which makes all gears longer.

lots of money right there but i guess its worth it when your on the highway it kind of sucks cruising at a high rpm but i like it because of instant boost.

Nice.

Just to clarify I am not trying to bring the B15 trans down, just trying to inform of the short gearing. When I was turbo it really felt too short...especially from a dig. Now that I am NA again with standard bolt ons I don't mind it so much. The short gearing compliments the power band I am working with right now.



Are you referring to top speed?

Right. B15 trannies are never recommended for boosted applications. That's why P11 trannies are so hard to come by in the forced induction crowd. B15's are great for N/A or NOS.

The other alternative like I mentioned, is hybrid gearing swaps.

Andreas Miko had an idea but I don't know if he ever got around to getting someone to make him the FD gear he was wanting.