Borg Warner 5speed vs FS5W71C

[KenshinX]

I have researched and I know that although, the Borg Warner 5speed transmission from the 81-83 280zx's are good transmissions the amount of power they can handle is around 300-350whp. With that being said I currently have a FS5W71C from a 84' 200sx turbo installed in the 260z mounted to a L26 carb'd. My question is since I have gotten limited results from search. Can the FS5W71C handle high hp numbers like 400whp like claimed by some posts?

 

http://forums.hybridz.org/showthread.php?t=147255&highlight=FS5W71C

 

Plenty of posts on KA motor transmission but I dont think that is the same as the one from the 84-88 200sx..

 

Which is better suited for a built L28ET aiming for over 350whp?

[Xnke]

The FS5W71C from 86.5 and up has upgraded syncros, but structurally, they are all the same from 1984 and on. The way to tell is in the size of the countershaft bearing, as this is where the extra strength of the KA/VG transmission comes from. (by the way, the Z31 non-turbo VG30, RB20, KA24, SR20, CA20e, and CA18DET transmissions are all the same, just different bellhousings, gear ratios, and the 86.5 split in syncros.)

 

When you installed the C box transmission, did you swap the countershaft bearing, or have the L series bellhousing machined to fit the larger countershaft bearing?

 

If you have the small B box countershaft bearing, you are limited to the same strength as the original transmission, more or less. If you upgraded to the larger C box bearing, then you are good to about 350HP or so.

[KenshinX]

Well I bought the car with the 5speed already swapped in. I was just curious on whether or not to replace it with the BW T5 I got with the 280zx parts car I just bought. If there isn't any gain I'll just keep the BW as a spare. If the BW is a genunely stronger transmission then I will swap mine for it. Thanks for the info so far tho Xnke.