the title says it all. how much power can the transmission and open diff take before bad things start to happen?

 

Miata guys routinely run 250hp/250ft-lb through the Miata gearbox, which is slightly stronger (different transfer ratio) and in a lighter car with less traction.

What I have found is that what they really don't like is RPM. Keep the engine RPM below 8000 and they last okay-ish. As RPM goes up, the bushings that the gears ride on start to get unhappy. The synchronizers don't much like shifting up there either.

When the synchronizers get unhappy, the fluid gets metal in it and wears the bearings and the gear teeth. When the bearings are unhappy, and the gears get a loose fit on the mainshaft, you get vibrations in 5th gear that go away in 4th, and eventually you will strip a gear (usually 3rd, although I've done 2nd, and the input shaft gear) because they aren't in good mesh anymore.

The rearend is actually pretty tough, it's the axle housing that is the weak point. With an open diff try not to allow one tire to spin, that is how you kill a differential.

 

interesting, so my power goal of 200ish seems feasible. just dont let a tire slip. does that aply to drifting on dirt? XD the redline shouldnt be a problem i get nervous over the 7k, and i occasionaly hit 7.5 on accident.

 

Open diff on dirt sucks hard, it's really uncontrollable.

 

for sure, i cant do donuts very contrable counter clockwise, but clockwise is imposible. it feels like the tires arent properly slipping, one day ill get an lsd XD