How much power is lost due to helical primary gears???

[tkent02]

Doing another 550/673 engine soon, one candidate is a 1980 550 engine, it has helical cut gears. Will this lose me any power compared to using a '79 engine with straight cut gears?

[posplayr]

Doing another 550/673 engine soon, one candidate is a 1980 550 engine, it has helical cut gears. Will this lose me any power compared to using a '79 engine with straight cut gears?

http://automotivethinker.com/transmission/straight-cut-gears-vs-helical/

Most people think that straight cut (actually called spur) gears are stronger than helical gears and that’s why their used. While generally race transmissions with straight gears are very strong, its not because of the straight teeth on the gears. What may shock you is that straight cut gears are actually weaker than a same sized helical gear. The reason for this is quite simple: helical gears have more teeth meshing and thus have a greater load bearing surface area. Another myth is that straight cut gears are more efficient than a helical gears; but the difference in efficiency is negligible with both spur and helical gears having about 98-99% efficiency.

[tkent02]

OK, thanks. That's exactly what i was looking for.

Using the '80 then just because it will be easier to get shined up.

The only other thing I can think of is the left - right forces on the crankshaft and the clutch, but I haven't ever heard of problems with this on a 550.