turbo cam selection

pro94

Well-known member
ok i was doing some reading about cams. trying to figure out what cams would work good with a turbo motor. the lobe seperation angle is how long the intake and exhaust valves are held open at the same time. so it seems to me that on a turbo motor you would want a cam with a low lobe seperation angle correct? or you will just blow boost right out the exhaust pipes. do i have all this correct? ive built performance na motors many times but this is my first turbo motor. just trying to get the facts straight before i start buying all the wrong stuff.
 
pro94":knf1yy2c said:
it seems to me that on a turbo motor you would want a cam with a low lobe seperation angle correct?

Correct, too much overlap is a bad thing.

Most V8 custom turbo cams are ground with 5-10 degrees less ex duration than the intake side. The exhaust port on the 200 is so bad this isn't necessary, a straight pattern cam will be fine.
 
When both valves are open this is called overlap.

Lobe seperation is the distance between lobes and the higher the number the less overlap.

It is easy to get these backwards.
 
ok, i got some of that. what would porting and polishing the exhaust port do to the rpm at which the turbo starts spooling up? would it decrese? "lower the rpm". how or would that effect cam selection? i live 10 minutes from bennett racing. I plan on having them flow bench the head before and after porting.
 
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