what rpms are the stock valve trains good till??? i know the amuse S2000 runs 9200 with there ecu.. and i heard spoon got one to go to 9800 no problem on stock valve trains... i know they run above 10k with there spoon valve set up.... thanks

 

As posted by Woodwork:

"The facts are: If the engine went over 9,000 then the cam is going too fast and sometimes the valve springs can not keep the rockers following the cam. (valve float). If the valves float then the valve spring slams the valve closed. If this takes place then the valve stem starts to pull through the retainer. This is the evidence.

If the car is driven above 9k the valves and seats are fine but the damage is on the other end of the valve, where the valve spring retainer will start to split which will give you a false valve clearance measurement.

If it goes above 10,700 RPM, then the valves can't close fast enough and the pistons come up to fast and it bends a valve."

 

^^cool

 

if that is the case how can the amuse ecu bring the car too 9200 with no problems??

 

Those numbers are by no means hard and fast.

Does Amuse advocate the use of that ECU without an upgraded valvetraion?

 

no they do not upgrade the valce train... on there car specified by a mag... it has amuse ecu, amuse header/exhaust/ mugen intake/ colder plugs... and i think that was it.. but i know for 100% it said stock valve train

 

there may be "no problems" but are you sure that damage isn't gradually being done? also, do you think the crank bearings will last just as long?

just because it works with "no problems" doesn't mean it is safe for the car.

amuse is selling you an ecu, not a warranty. remember that.

 

I have never heard of crank bearing degradation as a function of increased RPMs. At least not more than you would expect (like 10% faster RPMs equals 10% of normal life).

Valve springs do lose strength over time. I would not trust any stock motor spun that fast for as long as a stock one. I don't doubt it will take it, but time will take it's toll and it would not take much of an overrev to crater it.

 

I had a concern about a possible over-rev and did a lot of research to ensure the limits of the engine. To be sure, if you have a stock valve train, you don't want to spend much time above 9000 RPM due to the reduced life of the valve spring retainers and keepers - in other words: you'll drop a valve eventually. The engine will supposedly "scatter" (guranteed to do so) at ~10,800 RPM or lower. The engine can supposedly take an over-rev of 10,200 RPM, but the valve train can't handle anything above 10,400. If you've operated above 9,200 RPM on a continual basis (why you'd do it, I have no idea - because the engine just doesn't produce any power up there), you need to get the valve spring retainers/keepers inspected. This involves pulling the cams and carefully inspecting the retainers for 'dishing' and comparing the valve exposure above the keeper on every valve. If some valves appear to show more stem above the keepers than others, you need to replace all of your retainers and keepers. The inspection takes no more than 1 hour more than a standard valve adjustment, if you know what you're doing. The cams are very easy to remove.