RenoLB8

I've been told more seperation is good, but don't most aftermarket cams have that? wopuld any aftermarket be better then the stock cam for a blower, or should I be looking for a custom cam?

-Reno
V6 2.8 Firebird

IROCKZ4me

Most aftermarket cams for natural asperated engines have less lobe seperation angle then stock cams. Smaller LSA numbers means more overlap which means the intake valve & exhaust spend more time open at the same time. In a Non force fed engine that allows more air to be drawn into the combustion chamber. On force fed engines too much overlap allows the supercharger to blow the intake charge out of the exhaust valve. More cylinder pressure and thus more power will be made with a wider LSA on forced induction engines. Anything less than 114° LSA will cost you power. Of course the engine will run OK with smaller LSA but not at best power or efficiency. As an example, Almost every over the counter Comp Cams camshaft for natural breathing Small block Chevys has a 110° LSA. If you ask them for a camshaft for a blower motor it will have an LSA of 114° or higher. Most natural asperation cams are 108°-112° LSA.
The standard rule of thumb is 114°-116° LSA for forced induction. Anything less just isn't optimal. Why spend thousands for a supercharger and not get the most out of it because of a mismatched $200 cam? Get a blower specific cam!!, with lift numbers to match your cylinder heads requirements and duration numbers to match your engines intended RPM range.

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• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

My IROC-Z
EFI Performance Club on Yahoo

IROCKZ4me

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[This message has been edited by IROCKZ4me (edited December 06, 2000).]

RenoLB8

wow... thanks for the help, that has got to be the most informative and complete answer I think I've ever gotten on the thirdge.org boards in two years. =) Now where to find a blower cam for a V6...

-Reno

IROCKZ4me

Well, I've never tried to find a performance cam for a 2.8l but it wouldn't be impossible. Most every Camshaft manufacturer will custom grind a cam for you if they don't already have one to fit your needs. Even if raw camshaft blanks aren't readily available for them to machine a cam from they can regrind a stock cam. They can regrind it to get more lift & add duration and change other specs within the limits of the amount of material they can remove. They mostly remove material from the base circle and ramps of the cam and don't remove much from the tips of the lobes. That way they increase the difference between the base circle and the tip of the lobe. That makes more lift. The material they remove form the ramps (the side of the lobes) will affect duration. The shape of the ramps + the tip will affect lobe seperation & how fast the valves open & close. So in the worst case you can at least get a regrind done on a stock cam. If you have to get a regrind done you will also need longer pushrods to make up for the reduced lobe base circle. They should be able to tell you the length you need or you can use a pushrod length checking tool. Just give your favorite cam companies a call. If they don't already have one on the shelf for you they can make it. It usually doesn't cost all that much more to get one made or to get one reground than to by an over the counter one.

------------------

• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

My IROC-Z
EFI Performance Club on Yahoo