Some noticed the easter egg hiding in the last picture I posted; a Rotrex supercharger hanging off the side of the LFX.
That’s a C38-92. The biggest one they make. Massive packaging challenge for everything involved. Have been working on this for a while.
C38s max at 90,000 rpms. I’ve done the math and chosen three pulley sizes for testing that are all in the “safe” zone. The smallest of the three still spins the Rotrex at a safe margin below that 90k at the engine’s 7200 rpm redline. There’s no reason to run it for all it’s worth and risk damage to the blower. The C38-92 flows some serious air and I expect I’ll be getting all I want without needing to go for broke.
Rotrex specifies that the oil should not exceed 176° F at the inlet. I’ll have a temperature sensor at the inlet and the Racepak programmed with a warning. (re-purposing the same temp sensor that previously measured power steering fluid temp, now that the blower has superseded the PS pump).
The LFX is 11.5:1. I consider the E85 mandatory for that reason. Given E85, hot damn that compression should make this killer.
There are a lot of reasons I chose this particular path. Right now I’m equal parts excited and apprehensive since there are some unknowns in the mix. It’s a lot of work to do without knowing how it will all work in the end, or if it will even work well at all. But, I have faith in the recipe I’ve dreamed up. Ultimately the same reasons I chose the LFX in the beginning compared to some other ways to make similar power (big turbo or V8) are what are behind this choice. The strengths of the LFX and the Rotrex should complement each other very well.
Haven’t set any power goals… seems a pointless exercise. Venturing into the unknown here. So few examples of boost of any form on this motor, and zero of them on E85, or with a Rotrex, or that are track-focused. There’s a lot of question marks. Going to build things ‘right’ on paper and then go see what’s what. Could say I want “X” number but that really means very little… ultimately it will make what it makes. Will be beginning with three pulley sizes to test. Very likely that the limitation will be fuel flow with E85 and direct injection, but there’s only one way to find out.