Does anyone know (Please leave any UNNECESSARY COMMENTS OUT OF THIS THREAD...) if the USDM STI Engine is an Interference type or Non-Interference type engine?

Jon

 

bump

 

Gimme a little more insight as to what that means and I'll help you find the answer. Also, tell me why you want to know. I'm curious if it's something I need to know.

 

well an interference engine means that the valves can hit the piston if they are lifted and a non interference engine means that the valves cannot hit the piston if they are lifted.

I just got a reply from Imprezer (Alex) saying and confirming that it is an INTERFERENCE type engine (meaning that valves and pistons can hit each other).

It is stated in the STI FSM but it doesn't exactly say yes or no to the fact that it is interference or not.

this is what it says in the FSM:

"CAUTION: Disengagement of more than three timing belt teeth may result in interference between the valve and piston"

"... in order to prevent mutual interference of intake and exhaust valve heads."

"Do not allow the camshafts to rotate in the direction shown in the figure as this causes both intake and exhaust valves to lift simutaneously, resulting in interference with their heads."

 

Hmmm, very interesting.

I'd imagine that it's along the same lines as det resistance and the rev limiter. A little det and a little bit of dancing off of the limiiter supposedly don't hurt much unless they are prolonged.

I guess I'm a little dense, though, because I can't see how both intake and exhaust valves can be open simultaneously, except for when they are overlapping.

 

Sorry I just saw this, it is.