M66 Vs. M56?


bfrance

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Quick question as I'm making my long-term plans for my 855.

Any real benefit to a M66 versus a M56? Plans are for a manual swap with a reasonable power level for a streetable, fun car, (300whp?). Other than the "coolness" of the 6 speed, is there any real benefit of the M66?

Thanks,

-Ben

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no real world experience on the m66, but assuming its simmilar ratios to the m56, that 6th gear would really be killer on the freeway.I like to cruise at 75-80mph and im right around 3000rpm at that speed, it would be great to be able to drop that another 4-500 rpm.

that being said, i wish all every gear was just about that much longer.

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Don't know the M56 ratios - here's the M66

Picture1-4.png

not taller ratios, probably shorter.

80mph in 6th is about 2800rpm

I like the M66, but I used because of the AWD. If you go with the M56, get the newest one you can, it should be beefier than the old versions.

M66 also uses the S60R clutch, which I know is good for over 350WHP.

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Don't know the M56 ratios - here's the M66

Picture1-4.png

not taller ratios, probably shorter.

80mph in 6th is about 2800rpm

I like the M66, but I used because of the AWD. If you go with the M56, get the newest one you can, it should be beefier than the old versions.

M66 also uses the S60R clutch, which I know is good for over 350WHP.

2432035653_c80eabaa76_o.gif

so 5th and 6th are the same between the m56h and the m66, but the FD is higher (lower numerical) on the 66

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Yeah from what I remember hearing, the m66 wasn't necessarily a better option for some. I believe you would end up finishing a 1/4 in 4th gear where as with the M56 you can eek out 3rd gear with a higher rev limiter. I would have to ask my buddy Justus since he was doing a lot of research on the ratios of the two when he needed to swap his M56.

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Depends which M66. The T5 M66 FWD has longer 3rd gear compared to the R AWD. My RS's M66 has shorter everything. 3rd up to ~87, 4th up to ~112, 5th up to ~132 and 6th will probably top out near 180.

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Yeah from what I remember hearing, the m66 wasn't necessarily a better option for some. I believe you would end up finishing a 1/4 in 4th gear where as with the M56 you can eek out 3rd gear with a higher rev limiter. I would have to ask my buddy Justus since he was doing a lot of research on the ratios of the two when he needed to swap his M56.

It's great to drive, but you're right about the track. I have to shift right before 90, so I'm crossing the finish in the bottom of 4th. :(

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Talking US spec.

M66 better suited for big turbo high revs and track application

M56H Great everyday fun option

M56L probably the best for the track unless you have a ridiculess high redline (>7600rpm) or better than m56h top end.

Not sure which one would be best suited for autocross.

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