What a camshaft looks like, in an engine @ 14k

[KrisZ]

Originally Posted By: chrome
I guess this brings up the point whether the occasional high rpm WOT run is good for the engine. Some advocate it, some goes against it.

The point is, the valves are indeed designed to rotate above a certain rpm, which helps in maintaining an even sealing surface at the valve seat.

An engine that never sees higher rpms will have the valves wearing a certain pattern on the seats, which may hurt sealing efficiency and ultimately hurt power output?

Any thoughts?


Sounds very reasonable.

 

[rslifkin]

There's actually a TSB out somewhere for 4.0 Jeep engines about exactly that. They mention that if the engine is rarely or never taken above 3200 rpm, the valves don't rotate enough to keep carbon from building up on the sealing surfaces, causing a bit of a power drop, etc.

 

[MrRPM]

Originally Posted By: rslifkin
There's actually a TSB out somewhere for 4.0 Jeep engines about exactly that. They mention that if the engine is rarely or never taken above 3200 rpm, the valves don't rotate enough to keep carbon from building up on the sealing surfaces, causing a bit of a power drop, etc.


good to know! I have read several reasons now why you need to rip on jeeps 4.0 I6 every now and then. Good thing i do just that