Install BP DOHC engine with F25M-R tranny
 

Can I install a BP DOHC engine with my stock F25M-R transmission on my 323 LX. The 323 LX came with a BP SOHC engine.

I don't want to install the G25M-R transmission since it's final ratio is 4.105 and this is going to increase my fuel consumption on the highway.

Yes, you can use the Fseries gearbox. No worries there.

It's what I'll be doing when I drop in my DOHC engine. I'm concerned with mileage also.

Be aware, however, that if you start launching the car at every light, you'll eventually break the diff.

The F-series tranny is strong enough for the BP DOHC engine. I'm not planning on nitrous or turbo.

On my 323LX at 100km/h(62mph) I'm at about 2300rpms
with the G-series tranny what rpms is your engine at when you're at 100km/h(62mph)?

My pro lx @ 60 ~ 3k
My 323 @ 60 ~ 2.4k

If you scrap differentiel it's not because of power it's because one wheel is spinning faster then the other and it wear the pin holding the side gear. The weak link for power in a tranny is either the pinion and couronne or the gear themself and that's on any make of car. The differentiel on the g-serie (i don't know for the f never open one) has a good freeplay between the side gear and the pin so they are well lubricate and it shouldn't cause any problem when using your head anyway your not going to accelerate faster if the wheel spin

The F25M-R has a final gear ratio of 3.619, is there a G25M-R transmission that has a final gear ratio of about 3.8?

I'm looking at slapping in a BP DOHC engine in my 323LX so I need performance between 1st to 4th gear but a 5th gear that will allow me to go 80mph and still be under 3500rpms.