Why is my 408 not making power?
I can tell you exactly why your car is down on at least some of it's power. Your cam is horrible. You're missing 20 degrees on the exhaust side, and you need to advance the ICL about 8 or 9 degrees. You have huge CC runners with crappy low flowing exhaust ports in the L92 heads. You need to open the intake valve a LOT sooner to compensate for the low velocity intake, and you either need more duration on the exhaust or more lift on the valve, either way, there's no way you can be clearing the entire combustion chamber through that exhaust port with a 2 degree split. The intake/exhaust ratio on those is only slightly above 60% iirc. Katech is running a 233/277 in their L92 headed budget 427. I would go at least with a 236/260 on yours and try to get the ICL around 105-106. (not the LSA, the ICL.) The heads are very different from cathedral port heads, you cannot use the same thinking as any old LS1-2-6 motor.
Banned
Joined: Apr 2006
Posts: 1,875
Likes: 1
From: Naperville, IL
What about the recangle port L92 head makes it want a cam that is generally seen in Cathedral port heads with completely different intake-exhaust flow ratios?
I'd just like to hear your thoughts about this as it pertains to valve events.
