Limitations

[Husky]

What's the biggest limitation on how high this engine will rev? I'm assuming valvetrain, but what's the bottom end good for? If I removed the rev limiter, and just got on the gas, how high would it go before something failed, and what would fail first?

All this assumes that the engine is a freshly broken in, new, crate motor. 1995 engine and top end.

[Fiero Brick]

From all that I've read, the biggest limitation is the oiling sysem/bottom end. One way or another, bearings in the bottom end seem to fail if the engine is run up to 7500-8000 rpm for too long. The high volume oil pump suppossedly throws all of the oil up in the engine, but the poor oiling system causes it not to be able to drain back quickly enough.

I haven't heard of anyone going high enough to get valve float, break a rod or piston, etc. Doesn't mean it hasn't happened, though.

[dohcfiend]

just guessing here but every day aggressive driving i would say 7500 and 1 time 8500-9000.

i agree with fb, the bearings would go 1st. despite appearences the bottom end seems designed well(probably something to do with the 60 degree angle). there is one guy pushing around 13lbs of boost on it somewhere and another around 10-11 on a stock high mileage one.

if somehow the bearings held up maybe the head gaskets.

[Emc209i]

I've never seen anyone with a built motor actually give it a really good rev. The motor has a well built upper end, valves don't seem to float or smack unless something as a belt fails (This is from the literary sources I've been reading, I don't have personal experience with the motor as of yet).

Just a thought though. The 2.8 in my Fiero was said to not rev higher than 6K. With a cam and good ignition system I was easily able to rev it a good bit past 6 to what appeared to be 7 on the Tach. Of course Tachometer's are rarely spot on after 5K RPM's on stock dials but... still I've watched others spin the same motor to 6 and stop saying that's as high as it would go. I don't think anyone really wants to put the cars up to the ultimate test.

With a few things such as an underdrive pulley and no power steering pump, and lots of oil (oil cooler + big filter) I personally think that the motor could easily spin up to 8K. I guess I'll find out soon enough.

[Will'sFiero]

It's not that a 2.8 won't spin that fast... it's that it's pointless to do so because the power falls off so sharply after peak. You should shift a Fiero 2.8 at 5500 or so for best acceleration.

[Emc209i]

That's not the point. People said that if it were revved past 6K the motor would detonate (Valves would float, a mess basically) I remember them swearing up and down "OMG if I did that there's not telling what would happen to the motor." The thing is, it is risky, but often times people are just to scared to rev up high when the motor is very capable of making high RPMS. It's just a risk factor and who is willing to risk the motor to see what the engines limits are or try to come close.

I agree with what you're saying though Will, the thing is we're not talking about power band, we're talking about max rev.