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Could anyone explain to me why an engines idle is lopey when it has bigger cams.
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ah-see said:
Could anyone explain to me why an engines idle is lopey when it has bigger cams.
Thanks
its the longer duration, in addition to lobe separation that affects your idle.
 

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I don't know...I've witnessed first hand my friend's single turbo supra with HKS 272 cams idle like stock. I couldn't believe it, no loping or any other noise to indicate bigger cams in there. He bought the car modded and verified they were HKS cams when he took the valve covers off. Could it be because whoever installed them (SP I beleive) took the time to properly degree the cams?
 

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My question is, can you run 272 cams on a Supra with out tuning?
 

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the reason there is a "lopey" idle is because of longer durations, noone really makes a very big duration cam for the supra (except custom) so none of them really have a lopey idle, the reason BIG duration cams give a lopey idle is because of "overlap" which is when the intake and exhaust valve are open at the same time. overlap is good for high-rpms because it keeps the exhaust valve open later to expell burnt gasses and opens the intake early to start the valve moving before the piston ever even starts on the downstroke, however at idle things dont work the same.
 

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Also it also depeneds on your idle. The higher the idle setpoint, the less you will hear the lope.
 
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7THSIGN said:
My question is, can you run 272 cams on a Supra with out tuning?
there's really no point to it. the 272 cams shift your powerband into RPMS that the car doesn't and can't reach on stock tune.
 
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