Originally Posted by Patrick G

Tommy,

The amount of split between the intake and exhaust is mostly a function of getting the valve events where you want them. We'll want the intake valve to open at a certain point and close at a certain point to work best with our rpm range and the tuned resonance of the head/intake manifold combo. The exhaust valve will want a certain opening point depending on its flow, the exhaust header size, the rpm range, and whether there's a power adder involved.

In your case, you are running a smallish exhaust port with a smallish exhaust header (1 3/4") on a large engine (416) with a 200-250 shot of nitrous. The larger split was my approach to extending your rpm range without having to run too big of an intake lobe. It's all about balance.

Originally Posted by Patrick G

For a daily driven street 346 ci LS1, you can have perfectly acceptable street manners with almost no issues up to 7 degrees of overlap at .050". You will continue to gain power with more overlap, but once you pass 15 degrees of overlap, the gains begin to diminish quickly. With 25 degrees of overlap, you will need a very skilled tuner to make this cam enjoyable with an EFI setup.

Here are some popular cams and their overlaps.

TR 224/224 on a 112LSA = 0 degrees at .050"
228/230 F-13 on a 112LSA = 7 degrees
G5X3 on a 112 LSA = 14 degrees
T-Rex = 25 degrees of overlap at .050"

Originally Posted by bortous

Hi Patrick. How much overlap can a ls2 408 handle before you start having drive ability problems?