Hey all,
I was driving pretty hard saturday, and for the first time accidentally money shifted, but luckily I felt it and quickly pushed the clutch back in before it passed ~6500. I was just curious, for it to be a true "money shift," causing major damage to the engine/tranny, how high can a 330i engine rev before major damage ensues? I know my ZHP does 6800 and with a software tune 7000 safely.

Nick

7000 is your answer. Anything higher is too much stress on the valvetrain. That car doesn't need to go past 6,500 anyway - it makes peak hp at 5,900 if I remember correctly.

 

It peaks at 5900, but in a race setting, the ability to rev to 7000 (or beyond) is definitely beneficial, at least in the lower gears.

Anyway, ~7K is the highest I'd be willing to go with on an M54. Maybe you can do 7200. From what i've read, you do get valve float by 7500. Not to mention the crazy harmonics the M54 has from 6K and beyond.

 

I have been to several HPDEs in my old Civic (Mid-Ohio and Putnam Park) - never came close to money shifting. How does ones accidentally do this? I don't get it...

 

Simple. After seeing Fast Five

 

+1:thumbup:

 

Catching the revs at 6500 can't really be called money shifting because you caught it in time.

If you read my thread, a n00b buddy of mine accidentally did this to my car reaching over 8k rpm before clutching. Luckily for me, compression test confirmed I bent no valves.

 

The top end of the motor is fine, you should be worried about the bottom end.

 

It runs like poo below 600.

 

Most of the replies here are that you ought to shift at a certain point. While I agree, that isn't the asnwer to the question. You stated that you downshifted in error, not that you carried a gear well into the red zone on the tach.

If you hurt anything, you'd know it by now.

Overrevving generally results in floating valves that might remain open (lowered) at the same time the piston is at the top of its stroke. The resulting collision of the valve and piston would be catastrophic and immediate.

You should learn to shift properly so that you avoid doing this again. But, if you did damage, you would have posted, "I screwed up, what now?"

 

Rotaries and non-interference piston engines FTW!!!!

 

Would you guys say the m54b25 can handle about the same revs as the 30?

 

Since the limitation is the valvetrain, the maximum safe rev is about the same. Now if you were to upgrade the valvetrain to handle faster revs, the 325 might be able to handle more since the piston speeds are significantly lower

 

i dont think you damaged your engine if you caught it in time.

however, if your clutch was fully engaged (pedal all the way out) then you were too late. the only way to catch it in time would be to recognize something is wrong halfway through the clutch pedal travel... and you quickly kicked the clutch back in.

get it compression tested. if it drives normal, its most liekly fine. ggood luck

 

Not necessarily. Even if the clutch pedal was all the way out, that doesn't always mean the engine got up to full speed. The clutch disc can slip on the flywheel for a few milliseconds (or whatever) until the engine is locked with the wheels. It really depends on how fast he let the clutch out etc.

 

It takes a little getting used to, but this technique quickly becomes habit and makes it much less likely that you'll moneyshift: http://www.shortshifter.com/techniques2.htm

Like has been said, if the car drives normal you likely caught it in time and you're ok but it's still possible the revs were higher than you think. If the clutch was fully engaged the engine might well have been zipping along at 7,000 rpm you just caught it before the tach needle was able to catch up to the correct reading.

As far as head work to increase the safe revs on an M54, I wouldn't bother unless the entire engine was being beefed up. From what I've read, sustained revs over 6,000 are not a happy place for our lower end. That's where the oil pump nut starts backing off, and where resonance in the crankshaft can get nasty. Too much of that and internal parts make a break for daylight. I'm no expert though so take this with a grain of salt...

 

I redline mine erday n it goes up to 7200 rpm. N it's a m54b25.

 

That was one hell of a first post

 

If it starts and runs then relax and move on.

Simple.

 

The only way to find the real answer is to hand grenade the engine. Next time shift at a slightly lower RPM than that.