Good news / bad news ..

[erioshi]

I finally managed to trace the unnatural sound my Evo has been making. For a while I suspected the front diff, but the symptoms were a bit off. It turns out that the problem is wheel hop related as I thought, but what happened is that that the rear chassis mount ear on my transmission casing snapped off. Too much power with compromised traction.

It looks like the Evo will be skipping the race track until I can locate a new transmission housing & swap the internals over. Along with that I will also probably need to upgrade all of my chassis mounts for the engine bay, lol.

[kbrew8991]

yikes!!

do STis have that problem?

[Stig]

Originally Posted by kbrew8991

yikes!!

do STis have that problem?

no, they don't make enough power!

[Gairloch]

Neither do stock evos.

[kbrew8991]

Originally Posted by Stig

no, they don't make enough power!

well, not stock anyway

- KB, likely doing One Lap of America 2009 or 2010 in a 400whp STi

[erioshi]

I can tell you that scoobies tend to eat engines. The shop I frequent has 5 or 6 STi's in with blown engines .. but no Evo's. Alot of that is from abuse, but I know that the local Evos get driven just has hard. The ratio of scoobies vs Evos for other stuff (like clutches or tuning) is fairly even.

Scoobies also have some driveline issues. WRX's tend to have glass transmissions & a stock suspension that needs alot of help to be track ready. STi's are much better, but repeated abuse will eventually hurt the diffs in them as well.

5 speed Evos tend to blow the front diff if you abuse them badly and the early ones have a TSB on the 5th gear syncro. 6 speed Evos tend to burn out 4th gear if you don't install a transmission cooler & pump for regular track use. Any Evo that's going to be long-haul endurance raced (vs a 2-4 hour enduro) should probably have diff coolers added as well.

My car is comfortably in the 400 crank HP range even in it's current detuned configuration. Once I have the tranny sorted I plan to tune for about 28-29 psi for max power and probably 25-26 psi for track use (depending on how everything plays out). E85 is my friend... On the bright side I may finally have my onboard LC-1 wideband talking with my data logger.

[karl]

J-B weld!

that sucks. i wonder if there's a way to brace the new tranny case so there's less possibility of it happening again in the future?

[erioshi]

Originally Posted by karl

J-B weld!

that sucks. i wonder if there's a way to brace the new tranny case so there's less possibility of it happening again in the future?

Stiffer engine & tranny mounts are the usual solution.

After a bit of research it looks like I may try out a 6 speed this time around. It seems finding a 6 speed isn't any harder than finding a 5 speed or decent case and the costs are similar. Fourth will be a concern, but my long term plan is to just build a race car and keep the Evo for a driver anyway. I'd be willing to risk a few track days on the 6 speed.

I'll fab up a custom oil cooler set-up and see how that goes. The taller final gearing would be nice on road trips and the ratios are nicely spaced out. Right now the 4th - 5th jump is a bit long.