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

[Loren]

Originally Posted by Tamago

i've done it :(

3-4-3 :( didn't take too much speed

3rd gear is good to about 80 mph, so you'd have to be going considerably faster than that in 4th to get into trouble by going back down to 3rd, wouldn't you? Dunno how sensitive this engine is, I guess if it's particularly fragile, maybe it doesn't take much.

Or is it the immediate acceleration of the engine to 6000 rpm rather than high rpm itself that's causing it to break?

[Tamago]

Originally Posted by Loren

3rd gear is good to about 80 mph, so you'd have to be going considerably faster than that in 4th to get into trouble by going back down to 3rd, wouldn't you? Dunno how sensitive this engine is, I guess if it's particularly fragile, maybe it doesn't take much.

Or is it the immediate acceleration of the engine to 6000 rpm rather than high rpm itself that's causing it to break?

i'd imagine that the extreme acceleration to ANY rpm would cause a temporary flex of the valvetrain (cams, vvti setup, timing belt) enough to throw valves into a place they don't belong.

and yes, i was going considerably faster than i should have been.. it snapped the crankshaft pulley's rollpin (thankfully no harm was done to the crankshaft) and slightly bent at least one set of valves..