Its hard to say what exactly will fail when an engine is over revved but its ussually the weaker links in the valve train and/or rotating assembly.

Bent and broken pushrods are common, bent or dropped valves are also common.
Crank bearings also like to fail in the bottom end. Connecting arms can also be damaged.

Essentially anything in the engine that spins or moves can be potentially damaged. It all depends on the conditions the engine experiences.

 

Well say your racing a little, shifting right before you hit the rev limiter, like drag racing. Is that bad too. I mean it isn't just reving continuously at the peak rpm, you shift. ? anything? Is that bad like getting in the high Rpms but not holding it there?

 

Its normal and not harmful to take it up to near redline and to lift to shift. Will not hurt the engine. The stock rev limiter is set low enough that its not going to hurt anything. Hitting the rev limiter doesn't hurt the engine, but its hard on the drivetrain..... the fuel cuts completely off... it feels like a huge "bang" and that shock goes all through the clutch, gears, u-joints, etc. And if you keep your foot on it on the rev limiter, its going to keep turning the fuel on and off and beat the crap out of things. But no one with 1/2 a brain would drive it that way.

The worst thing you can do is miss 3rd gear and put it in 1st, and release the clutch.... the engine will over rev, because its not the fuel that causing it to over rev, its the wheels that are forcing it to over rev. A bent pushrod is a very good possibility in that case. That being said, I've had a couple misses on the 2->3 and my stock engine was not damaged when it happened.

I think you're worrying too much. Its a pushrod engine and you have to understand the limits of the valve train. Once you grasp that, you'll understand what you can do and what you can't do.

Doing donuts with your foot on the floor, and banging it off the rev limiter is just stupid.

 

Did you see the video on this site? The guys does that and then shoots flames out the exhaust the clip ends with some people saying OOOOOOOOHHHh, so i think he ****ed something up, amd the title is something about blowing the bottom end of his camaro.... i am not worried about doing that i just was wondering about it. So engine breaking is shifting down to slwo the car down right? Thats bad to do?

 

Engine braking isn't bad for it at all. I usually engine brake my car just out of habit. It's alot easier than getting on the brakes and holding in the clutch, then having to reselect a gear and let it back out trying to adjust to the speed. Just downshift and be happy.

 

its not.. i don't really know how to do it, someone want to explain. I thought it makes the engine over rev sort of... i mean with out you hitting the gas. I don't know, lol if someone wants to explain how to do it....

 

Basically you select a lower gear than is normal for your speed, then let off the gas. At this point your car's forward momentum starts working against the compression of the motor. Because you aren't giving it any gas, momentum is all it has. Compression will win and the car will slow down rapidly. That's the gist of it, I'm sure someone can give you a better, more technical, explaination.

Here's how you do it:

Say you're cruising at 40 mph, in 5th gear. Probably around 1600 rpm or so. You see traffic ahead, so you pull the car out of 5th and put it in 3rd (prolly what i'd do) or stick it in 2nd and your car will really slow down. Yes the RPMs will rise rather high (they have too - the rear gears force high RPMs at slower speeds in a lower - numerically higher ratio - gear) but the compression of your engine will slow it down, and bring the RPMs down. Make sure not to downshift to where your car will over-rev though.

Next time you drive a car, hold it in first gear (works in autos too). Drive it up to about 30 mph and let off the gas entirely. See how fast the car slows down, all on it's own? That's engine braking.

 

Question: If i'm steadily accelerating upto say 80mph within 3k rpm on my stock z28, would that classify as pounding the engine? If not what action would classify as pounding on the engine? Thanks.

 

Pounding on an engine would be winding it to 6000 before shifting at WOT, powershifting, burning the tires.. basically anything that isn't normal.

Taking it up to 80 shifting at 3000 is pretty normal imo for getting on a freeway.

I usually drive my car pretty conservatively. Gas prices and all. I shift into 2nd at 2000, wind that up to 2k, shift into 4th, wind that to 2k then if I have to I'll shift to 5th. Saves some gas.

 

How do you power shift... Thanks for the rest but i don't know how to powershift, lol. well i don't own a Manual car never did, but i know how to drive one. Thats a big reason why i want one besides it'll last longer then an A4 correct?

 

In order to power shift do everything you normally do, except don't let off the gas when you change gears hard. Heh, that's powershifting.

You want one to power shift? Ehh.. powershifting isn't a good thing to do by any means

 

Clutches last 100-200k
Automatic Transmisions last 150k+

Manuals are more fuel economic.

 

How is it hard to powershift? Its hard to hit the clutch when your ay WOT? is that what you do in teh quater miles to get in the High 13's stock? you have to beat the **** out your car in order to make it to the high 13's stock? I just wondering... thanks

 

No, by pounding I meant erratic, hard accelerations. Throwing the car around every corner with your foot to the floor, taking it to redline as often as you can etc. I will also qualify this by saying if you do this once in a blue moon, and in a controlled manner you should be ok. 4th Gens were engineered with a bit of owner "abuse" in mind. Proper maintenance is also key. If you drive your car hard one and awhile and you stay on top of the repairs and service, the car will still be fine. Neglect the service at your wallets peril. There is a reason why mechanics like to say "pay me now or pay me later"

The situation you described is very normal. Bringing an engine up in the RPM range at a steady rate is fine, even if its a quick rate. However, revving the engine needlessly is, well, needless. Especially in LT-1's. They make all their Torque between 2500-3000RPM.

 

It's not hard to do, its just hard on the clutch and tranny. See Injuneer's comments about drive train shock.

Powershiffting+stock clutch= Sudden death.

High 13's in an Stock M6 LT-1 are achieved with

A- The cars condition
B- Driver skill
C- How much HP is actually going to the wheels (Remember some cars are Factory freaks).
D- A little luck from the Drag racing gods.