IPMSP

Does anyone know if the new rx8 trans will fit on to the 3rd gen rx7. i think this would be a killer mod not that you will really be able to go quicker but just for the fact to say that you have a 6 speed. If anyone knows a pirce on the transmission that would be great to.

Mazda Family

I'll probally be a little off on this but most is right on.

The Rx-8 trany is very very close (may be the same) as the one used in the Miata. Now it can hold up to 300 hp and probally more but not too much more, it is untested in that hp range. Also the 6th gear ratio is the same as the 5th gear in the Miata. (and suspect the rx7 has a lower 5th gear the the miata making the 6 speed a much high gear) So swaping the 6 speed will lower your top speed, raise cruise rpm, and will slow 0-60 time because you will change gear more often. ie: go to 3rd to get to 60. Now i've run the numbers for a miata and a lower rear-end ratio makes the 6 speed have the same over all ratios as a 5 speed just another gear on the end for cruising/top speed.

Not saying it can't be done or even saying don't try it but look at the ratios before you swap the trany and make sure you aren't taking a step back.

Chas

IPMSP

Ya I figured there would be no performance extras from doing it but just to say you did would get peopl interested. But personally i like the 5 speed transmissions alot better becuase that is what I know how to drive.

911GT2

FD's have enough pulling power with the current 5 speed, but it would be fun to tell people you have a 6 speed. If the 6th gear were a lower ratio, it would be nice for saving gas on the highway, but other than that I think it'd be unnecessary. Especially if it would require more shifts in lower speeds, that wouldn't be fun.

ghiaracer

A six speed will show alot more improvement over a 5 if the ratios are tailored to the charactaraistics of the motor. Having to shift more at slow speed will slow you down. However... Having a loong first and second gear, and 3-6 pretty close, will give you a higher top speed while staying in the motors power compared to the 5 speed.

F1 cars use 7 speeds, and they have a pretty big power band these days.

rynberg

I agree with ghiaracer.

In an FD, a 6-speed would only be an improvement if 1st and 2nd were kept the same, and 3rd-5th shortened. Of course that would leave 6th as a big overdrive gear which wouldn't make a lot of sense with our poor low-end torque.

In other words, I don't see much of an advantage for a 6-speed for any kind of normal/hard street driving.

Wargasm

If I made a 6 speed for a street driven FD, 1st would be a good bit longer, 2nd a little longer, and third just a bit longer or about the same. I'd leave 4th at 1:1 just because it's easy to do that and 5th would be the 0.806:1 that I swapped into my tranny. 6th would be an overdrive somewhere around 0.69. Off the top of my head something like :

3.100
1.940
1.350
1.000
0.806
0.690

But realistically this would all be way too expensive I swapped my 0.719 stock 5th for a 0.806 5th and it's SO MUCH nicer to drive now. I can actually use 5th without having to downshift. Right now my main complaint is that 1st is too short and my car can't use it at all due to wheelspin problems. I've actually been thinking of swapping my 4.1 rear for a 3.9 to reduce the wheelspin in 1st. True, I'll have less power to the ground in the higher gears, but at least I'll be able to use 1st.

Brian

rynberg

Brian:

Your gear ratios would probably work great for your single turbo....my comments were based on my still 10 psi on stock twins car.

PFC is going in after the smog next month......