BENT VALVES in the head: tell me how that happens....

[Loren]

Barring extremely unusual circumstances, don't valves only get bent when they come into contact with pistons? There's really only one way that can happen... the valve timing has gone off in a major way. Typically, that means something broke (timing chain broke or stretched, VVT messed up, whatever) or the engine was severely over-revved to the point that the valve springs couldn't keep up and one or more valves stayed open when they should have been closed.

I'm going with the "3-2 shift". Winding up 3rd and missing 4th, dumping the clutch in 2nd gear with the car going 80 mph. Ponder that for a moment. If the engine turns about 6200 rpm at 60 mph, you can easily zing it past 8000 in this manner... instantly. And if you're not quick enough to realize it instantly (or quite possibly even if you are), you can do some damage in a hurry.

I did it once in my old Saturn, but I realized it before I even got the clutch fully engaged and no damage occurred. From what I'm seeing with my son as he's learning the finer points of driving a stick... if he did it, he'd more likely fully engage the clutch and leave it there and wonder "why don't I have any power" until valves started poking holes in the hood. And I don't think my son is all that unusual as far as young folks learning to drive stick go.

Remember, a rev-limiter can save you from over-reving under power. The engine will simply never rev ITSELF far enough to hurt itself, the ECU won't let it. But NOTHING can save you from a botched shift! The solution is to learn to trust your shifter. Don't FORCE your shifts, "guide" your shifts. The shifter is spring loaded and will go into the proper place if you let it.

[Tamago]

Originally Posted by Loren

Barring extremely unusual circumstances, don't valves only get bent when they come into contact with pistons? There's really only one way that can happen... the valve timing has gone off in a major way. Typically, that means something broke (timing chain broke or stretched, VVT messed up, whatever) or the engine was severely over-revved to the point that the valve springs couldn't keep up and one or more valves stayed open when they should have been closed.

I'm going with the "3-2 shift". Winding up 3rd and missing 4th, dumping the clutch in 2nd gear with the car going 80 mph. Ponder that for a moment. If the engine turns about 6200 rpm at 60 mph, you can easily zing it past 8000 in this manner... instantly. And if you're not quick enough to realize it instantly (or quite possibly even if you are), you can do some damage in a hurry.

I did it once in my old Saturn, but I realized it before I even got the clutch fully engaged and no damage occurred. From what I'm seeing with my son as he's learning the finer points of driving a stick... if he did it, he'd more likely fully engage the clutch and leave it there and wonder "why don't I have any power" until valves started poking holes in the hood. And I don't think my son is all that unusual as far as young folks learning to drive stick go.

Remember, a rev-limiter can save you from over-reving under power. The engine will simply never rev ITSELF far enough to hurt itself, the ECU won't let it. But NOTHING can save you from a botched shift! The solution is to learn to trust your shifter. Don't FORCE your shifts, "guide" your shifts. The shifter is spring loaded and will go into the proper place if you let it.

hey, everyone, Loren's here! now you can believe what i said waaay back in post #2 lol

[Loren]

Originally Posted by Tamago

hey, everyone, Loren's here! now you can believe what i said waaay back in post #2 lol

Yeah. What you said!

(as is typical of me, I said the same thing, just used a helluva lot more words)