Cam selection for turbo 200

67chrrybucket

67chrrybucket

Well-known member
I am doing a ground up build 200ci rec rods forged pistons 2v conversion with a holley or autolite 2 barrel carb modified for blow through with carb ,hat DSII dist, 4 spd manual with a 3.55 8 inch I wanted to go with a 274/274 with 108 lobe centers which i dont see any one using or recomended in any tech articles and i was wondering if 108 lobe centers are bad with turbo i like how close the rpm range is, I am only using this car for city mabey on the track if i get brave but i guess im looking for a technical explanation of why 110 or 112 lobe centers are more suited for turbo?
 
My setup is similar and I have the 274/274 110deg lobe centers dialed in at 107deg.

The lobe centers have a impact on rpm range. If you take two identical cams but one has 110deg lobe center and the other has 112deg lobe center the 110deg lobe center cam will make power lower in the rpm range
 
Generally you don't want any or very little valve overlap with a turbo. Remember a turbo basically sits with the exhaust valve on one side of the turbo and the intake valve on the other.
So if both valves are open at the same time, then air movement is reduced. (This is a VERY, VERY simplified way of looking at it!) :unsure:

In Kelly's Falcon we have a cam with 114 centers, and 4 degrees less duration on the exhaust. And I even increase the exhuast valve lash by .004" to also help seperate the two valves.

Later,
Will
 
After doing my reasearch i see what you mean by overlap my concern was with an engine that idles around 500rpm and the cam's with 110-112 duration rpm range starts at 2300 rpm, i dont know if that would really work for streat cruisng and off the line power? I want to pull hard off the line at the light :D
 
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