The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

Super73 · 05-29-2015, 07:37 PM

DynoJet

I know a 3.90 with a PG is going to sacrifice some 60' compared to the 4.56. I agree the only way to get that back would be to increase the stall speed, but that will create issue on the bottle.. Oh the lovely balancing act.

I just don't think the new cam is working well with my complete package. Perhaps it will work better with more N20, but IMO the 40rwhp drop already would be hard to make up.

One other thought I have is I forgot the rear end change. When I went from a 4.56 to 3.90 I also went from a truck 12 bolt to a 9", 31 spline axles to 35 spline, posi to locker. I could be loosing some power there too..

05-29-2015, 07:37 PM	#9
Super73 Registered User Join Date: Nov 2007 Location: Bay Area, Ca Posts: 2,841	Re: On the dyno in the am DynoJet I know a 3.90 with a PG is going to sacrifice some 60' compared to the 4.56. I agree the only way to get that back would be to increase the stall speed, but that will create issue on the bottle.. Oh the lovely balancing act. I just don't think the new cam is working well with my complete package. Perhaps it will work better with more N20, but IMO the 40rwhp drop already would be hard to make up. One other thought I have is I forgot the rear end change. When I went from a 4.56 to 3.90 I also went from a truck 12 bolt to a 9", 31 spline axles to 35 spline, posi to locker. I could be loosing some power there too.. __________________ ------Motor---------------Bottle 60'---1.53---------------1.41 1/8---6.58 @ 105.92----5.87 @ 118.41 1/4---10.38 @ 126.97----9.24 @ 142.49