Originally Posted by Dahlton
I was planing on using a wather/alky injection for cooling the air at higher boost (when racing).
Do you have any idea how much boost it would make if I run it approx 1:1?
BTW
Who makes the best Roots blowers theese days? I heard alot off good things about Kuhl superchargers when Mike Kuhl had his business.
Also one reason why I'm using carbs is that I've heard that part throttle "cruising" is impossible with a Birdcatcher, that it is sort of an on/off throttle?
Alky injection will help, but it doesn't come close to the volume of fuel needed to cool that blower, especially when it's under boost.
572 CID, 14-71 (about 520 CID Blower) at 1:1 will make approximately 12 PSI, with a final compression of 15.5:1.
Using the formula of {(CID X RPM) / 3456} X {Boost / 14.7) + 1} = CFM required, I can tell you that at 7000 RPM the motor will use ~2103 CFM. At 8000 RPM it'll use about 2400 CFM.
With just mild boost, and typical drag racing RPMs, you're coming woefully close to maxing out the carbs.
Best roots are going to be DMPE, PSI, SSI, Kobelco, Gibson-Miller, followed by Littlefield, Mooneyham, then the rest.
As for injection on the street, I would characterize it more as idle, high idle, WFO. I've driven injection on the street since 1995. Injection doesn't have nearly the resistance in your foot feel that a carb does because it uses ball bearings on the throttle shaft instead of bushing. It's very smooth. It can be controlled easily with a much better precision. Once you get used to it, it's not a big deal at all, just dont let your girlfriend jump behind the wheel or you'll be roasting the tires as soon as she hits the throttle.