When I was doing my blower engine I had the good fortune to stumble across a Ford engineer with a lot of experience in that area. His official title was "Senior R&D Engineer, Boosted Engine Projects" or something like that. At the time he was working on a race program with one of the 10.5 Mustang classes, and had some contacts at Vortech that helped me out quite a bit. Anyway, what I learned from him were a few general rules, such as:
- Anything you do to the heads, intake, exhaust or cam that will help a naturally aspirated engine will also help a boosted engine. The old saw about not needing to do headwork because of the blower is not correct. Headwork and other induction system work, including a big cam, will help a blower motor just like it helps a naturally aspirated engine.
- Shoot for the widest lobe separation angle that you can, within the limits of the cam specs that you want to use. I used 116 for my supercharged engine, and the cams for my SOHC turbo motor are also 116.
- You may actually want less exhaust duration on the cam with a turbo motor, rather than more. This is counterintuitive, but has something to do with the way the exhaust pulse helps spool the turbo. My turbo SOHC cams are the same cams as the ones in my 585" SOHC, but with about 6 degrees less exhaust duration. This doesn't necessarily apply to a supercharged motor, though.
Also, I ignored DCR on my blower motors, because it was so low due to the static compression ratio and big cams. I'm not sure that the same rationale applies to a blower motor anyway; you are packing more air molecules into the cylinder with a blower, so from a fairly simplistic perspective DCR would go up with boost. I don't know how to calculate that; my Ford engineer friend told me that the formulas for calculating actual compression ratio from static compression ratio and boost pressure are not really accurate. (At 15 psi of boost, you are packing twice as many air molecules into the cylinder. This is not the same as doubling the static compression ratio.)
On other thing that I found very interesting on my supercharged engine was that it made more power with the Performer RPM intake than it did with the Victor. My motor was carbed, and this may have had something to do with it, but I'm not really sure. You could really see this in the exhaust temps on the dyno; the Performer RPM had exhaust temps that all wanted to converge at higher engine speeds, while the Victor's exhaust temps diverged. I assume that this was due to better fuel distribution in the Performer RPM intake than the Victor. If you went with EFI, I also assume that this would no longer be an issue, and in fact I have a Victor that I got from Barry R that is heavily worked over, and was planning on going to an EFI setup on the supercharged engine at some point...