Rebel, you got 512 CID and an Indy single plane intake. What size cam, CR, ET/mph and rpm do you run? If the rest matches the race theme, I think you will benefit. But I don't have any feel for the Demon RS carb.

Although I think QuickFuel makes some good stuff I have never seen anyone compare them back to back, I know the Pro Systems carbs work well.

DartSport505,
Quote:

I ran the 505 with an 850 dp on it for the last 2 years. With a best of 9.45 et. Shifting at 6100 rpm, and crossing the traps at 6500rpm. I am hoping for a tenth or 2 increase in et?

That is close to my 511 setup but I pull a few hundred more rpm, I think you will benefit. I did some back to back runs at Norwalk in 2006 switching to the 10.00 class (trying to slow my car down). I took off my well tuned 1150 Dominator with 4150/4500 adaptor, and bolted on a good working, but not tuned (likely rich), 950hp with no spacer. The car slowed down 0.2 seconds in the 1/4 mile.

I think there were a couple factors to get that much, but 500+ CID race combos like more carb:
  • 1) The adapter was like a big carb spacer, helping this combo. So a 1 or 2 inch spacer with the 4150 would narrow the difference.
  • 2) The 950hp carb was likely too rich, slowing it a little more.

Another comparison on a different day/track I swapped my Holley 1150 with a friend's ProSystems 1050 for back to back comparison. I ran the same with his carb, and his 499 ran the same with my carb. No difference, except a slight A/F ratio difference on my LM-1 meter.

1993 Daytona, 5.50 at 130mph (1/8) 1.19 sixty ft (PG). Link to 572 B1 - Part 1