Cam selection for forged 402 twin turbo
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Staging Lane
Joined: Feb 2005
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Cam selection for forged 402 twin turbo This is the last piece of my puzzle. Forged 402, twin GT30R turbos with .84 A/R, AFR 225 heads. Full manifold with collectors and downpipe. Looking to run 7 - 15 lbs of boost. Needs to just squeeze by a CA sniffer test.
Single pattern? Split duration? Reverse Split?
What about something with similar specs to the LS7 cam? 211/230/120 59x/59x. Why do the stock cams do so well with turbos? Not so much overlap? Or is it that they have a negative overlap?
Single pattern? Split duration? Reverse Split?
What about something with similar specs to the LS7 cam? 211/230/120 59x/59x. Why do the stock cams do so well with turbos? Not so much overlap? Or is it that they have a negative overlap?
Originally Posted by hpcubed
This is the last piece of my puzzle. Forged 402, twin GT30R turbos with .84 A/R, AFR 225 heads. Full manifold with collectors and downpipe. Looking to run 7 - 15 lbs of boost. Needs to just squeeze by a CA sniffer test.
Single pattern? Split duration? Reverse Split?
What about something with similar specs to the LS7 cam? 211/230/120 59x/59x. Why do the stock cams do so well with turbos? Not so much overlap? Or is it that they have a negative overlap?
Single pattern? Split duration? Reverse Split?
What about something with similar specs to the LS7 cam? 211/230/120 59x/59x. Why do the stock cams do so well with turbos? Not so much overlap? Or is it that they have a negative overlap?
1. Add the intake and exhaust duration.
2. divide it by 4
3. subtract the LSA
4. multiply by 2
Example: 224/224 115lsa
224 + 224 = 448
448/4 = 112
112-115 = -3
-3 x 2 = -6 degrees overlap.
If I had that same cam ground on a 112 instead of a 115 then it would have 0 degrees overlap and should still pass emissions. People have passed with +12 degrees overlap in 383ci engines, but to be safe and considering you are FI, keep it at 0 or less. JMO.
