Quote:
Originally Posted by grandam1979
My buddy’s purestock ram air II car runs mid 12’s at 114-115 mph with long branch manifolds and full 2.5 exhaust. I know Jim’s car went 118+
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I found PSMCDR times in the 12.30 range for Rick's RAII Bird, and I think there is a 12.2-something for the quickest et at one of the races. Rick Mahoney has a couple 11.50 et's in his former Teal Turquoise RAII Bird (TH400) at over 120 mph (takes every advantage the rules allow) and the late Jim Mino's '68 RAII did run 11.80 once, and very low 12's regularly (tough to be consistent with a 4-speed) at over 118 mph (not quite as enhanced as RM's RAII). Both cars weighed at 3475 lbs. with driver. Adrian Beltrame's '69 RAIV Bird run's high 11's at 118 mph, so
We found over the years dyno-ing RAII's, RAIII's, & RAIV's of both A & F varieties that the long branch manifolds make an average of 3-5 hp/3-5 lbft torque more through the RPM range (3000 - 5500/6000 rpm), probably due to their gentle turns vs. the 90 degree turn to the downpipes of the A-body manifolds. So, we're talking 5 - 10 hundredths of the second in the 1/4 mile advantage all other variables being equal.
The FAST guys are cutting their LB manifolds in half lengthwise to port them as much as they can (Greg Gessler used to do those), then weld them back together (not cheap!).
The RAII/IV's are making 450 hp-475hp on the dyno with 12.0 - 12.25 compression (max. 1.5 points over advertised 10.75 allowed).
Dennis