986 Gearboxes

[OlberJ]

Are they all the same or different ratios for 2.5, 2.7 and 3.2?

[Richard Hamilton]

Possibly different ratios in the 2.5 and 2.7, which are 5-speed, whereas 3.2 is 6-speed.

[OlberJ]

Spot on, thank you.

[F3RNANDO]

Why put a boxster gearbox in a MX-5??

[OlberJ]

No i'm just thinking i like the look of the early silver 2.5's and their price points. Contempleting if a 3.2 would go in there too.

Thinking out loud as per.

[Rockster]

OlberJ said:

Are they all the same or different ratios for 2.5, 2.7 and 3.2?

[Rockster]

OlberJ said:

Are they all the same or different ratios for 2.5, 2.7 and 3.2?

What I recall is the 5-speed in the 2.5l car had lower ratio gears (at least for some gears) than that of the 2.7l's transmission.

The 2.7l engine offered more torque so Porsche made the gears a bit taller because the engine could pull the taller gears.

And of course the 6-speed's ratios are different yet.

If you want some numbers;

G 86/00 (and I'll put the G 86/01 in parens)

1st: 10:35=3.50 (10:35=3.50)
2nd: 17:36=2.117 (17.36=2.117)
3rd: 28:40=1.428 (28:40=1.428)
4th: 34:35=1.029 (33:36=1.090)
5th: 38:30=0.789 (37:31=0.837)
Rev: 9:31=3444 (9:31=3.444)
Fin: 9:35=3.889 (3:32=3.555)

I do not have handy the 6-speed's ratios.

Sincerely,

Rockster.

[ATM]

OlberJ said:

No i'm just thinking i like the look of the early silver 2.5's and their price points. Contempleting if a 3.2 would go in there too.

Thinking out loud as per.

There are quite a few differences with the 3.2 to the 2.5. The easier option is to use the early 996 3.4.

[OlberJ]

Cheers. Probably better putting engine and box combo in.

If it's not just a case of engine and ECU swap, it's not going to be worth it over buying a 3.2 in the 1st place.

[ATM]

OlberJ said:

Cheers. Probably better putting engine and box combo in.

If it's not just a case of engine and ECU swap, it's not going to be worth it over buying a 3.2 in the 1st place.

No its not. There are some wiring differences between the early 9x6 engines and the later ones. I dont want to quote the differences but I think it includes various sensors and the throttle is fly by wire on the later. Most of the engine swaps I read about were based in the US. They used the early 3.4 in the Boxster 2.5. Moving on from there you can use the 3.6 in the newer 986 [2.7 and 3.2].

The other option is getting the engine's capacity increased. Autofarm can do this. I dont know if there are any serious internal changes which someone like Autofarm could not work around. http://www.autofarm.co.uk/engines/water_cooled/pri...