Quote:
Originally Posted by Jerry Clayton
Brent---you don't have much control over the amount of vacume you will pull with this set up---it will pump so much according to the pump sizes and speed(rpm/belt drive ratio)that you choose and be countered by amount of leakdown /blowby and volume the pressure pump puts back into the crankcase----your relief valve ??????????will hopefully prevent the loss of intake gaskets with the push/pull/push pulses in the ports
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Jerry, you nailed it buddy. We were pulling about 3-4 inches of vacuum today without any change when we were playing with the regulator. I used a teflon rear main seal and tried to seal the engine up as best as I could on the other gaskets. I honestly just don't think the dry sump pump was big enough to pull the big amounts of vacuum.
It's kinda hard for a street engine that will be raced part of the time. Of course the vac part of the pump probably could have been more worthwhile with some pretty low tension rings, but I really didn't wanna go there if Mat's going to be driving it on the street a lot of the time. This engine is a balance of street car/race car. Sometimes it's hard to draw lines.
Well, for the results...
573hp @ 6400, 562 lb-ft @ 4800.
It ran very well. No issues, no leaks, just a good strong engine. I think the horsepower peak is a testament to the cylinder heads as the cam is just 240° @ .050".
AL427SBF, the compression ratio was around 10.3:1. I can routinely get away with about 11:1 SCR around here with 93 octane, but when I send engines out, I want to be sure that they will run on the gas that's available where the customer is. A lot of cities only have 91 octane, etc.
This thing needed about 10 more degrees duration on a solid roller cam and it would have been real fun.
I'll post the dyno sheet later on. I got back, trying to beat the rain, then cleaned the engine for Mat and taped everything up. I'm pooped. I also had a customer who was rear wheel dyno'ing a 408 LS2 engine this morning. Needless to say, my nerves are shot....hahaha That one made 501hp at the tires @ 6000 rpm. Not too shabby.