FBO Systems.....

What compression are you running? I'm running over 12.5:1 and a stock starter, though it would struggle a little.(7000' elevation)
Did a compression test and its only at 180-185 psi.

D-50394 said
Mine has 10.9:1 but my cranking cylinder pressure is 195-201 psi. I run on 93 pump gas.
662 hp at 7300 rpm on dyno.

Thanks for respond back! there is a good example of how altitude can control your combo.
I'm probably make around 500 hp and shift at 5800 rpm.

I can only get 91 pump gas up here.