Re: Compression vs flow
[Re: twayne24365]
#2487100
04/24/18 02:33 AM
04/24/18 02:33 AM
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Joined: Aug 2003
Posts: 43,315 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,315
Bend,OR USA
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Flow is way more important to peak performance at WOT than compression is I built a 400 pump gas 511 C.I. stroker for my old 1971 Duster, it had a set of iron 906 heads on it that had 2.14 intake valves and 1.81 exhaust, mildly ported and 84.0 CC chambers that flowed around 264 CFM at .700 valve lift. I ran that combination for one summer up here and then put a set of Eddy RPM CNC by Jeff at MCH that had the exact same size combustion chambers that flowed right at 310 CFM @ .700 intake valve lift that winter. That motor had exactly 9.25 to 1 compression ratio with both sets of heads, it ran 10.69 at 124.3 MPH with the iron heads at Woodburn, OR in October of 2005. I put the Eddy heads on that motor that winter and the car ran 10.49 at 127.4 MPH with no other changes in June of 2006 I ended up doing other mods to that short block later to get the compression ratio up to 10.29 to 1 by installing a .050 longer stroke crankshaft in it(which made it run mid 10.30s with tuning and intake and carb changes also) and then later installing a set of Indy SR M.W. size heads on it that ran a best of 9.993 at 134.7 MPH with a single 1050 CFM Dominator carb. on the Indy 400-3 intake and then again another set of Indy 440-1 CNC ported heads, every time I increase the airflow through the heads or intake manifold and carbs. it picked up power on the engine dyno and went quicker and faster at the track Buy them heads and enjoy
Last edited by Cab_Burge; 04/24/18 02:36 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Compression vs flow
[Re: twayne24365]
#2487453
04/24/18 08:09 PM
04/24/18 08:09 PM
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Joined: Mar 2006
Posts: 9,883 MI, usa
dvw
master
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master
Joined: Mar 2006
Posts: 9,883
MI, usa
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Thanks guys, and if it helps any motor is .030 over, .557 mopar solid cam, Holley Street dominator intake, 750 mighty demon, 2” headers, and 4 speed with 4.56 gears.
12:1 would certainly up things a bit and I already run 100ll fuel in it so it wouldn’t be a huge deal.... but pulling up to the pump to fill it with 93 is a very nice thought! Buddy's 65 Plymouth. 440, bowl ported 906, 11-1,.557 purple, headers, low rise old Weind 2x4 w/2 600 eddys, 4.56, good converter 9x28 slick, race gas. Ran 11.60-70's. we swapped to box stock open chamber Eddy RPM's, 10.0-1. Runs 11.30's on pump gas with gear reduced to 4.10. No other changes. Doug
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Re: Compression vs flow
[Re: dvw]
#2487458
04/24/18 08:25 PM
04/24/18 08:25 PM
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Joined: Sep 2014
Posts: 181 Maryland
twayne24365
OP
member
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OP
member
Joined: Sep 2014
Posts: 181
Maryland
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Buddy's 65 Plymouth. 440, bowl ported 906, 11-1,.557 purple, headers, low rise old Weind 2x4 w/2 600 eddys, 4.56, good converter 9x28 slick, race gas. Ran 11.60-70's. we swapped to box stock open chamber Eddy RPM's, 10.0-1. Runs 11.30's on pump gas with gear reduced to 4.10. No other changes. Doug [/quote]
That’s a big improvement, this 383 was in my dads car with stock 8.5:1 compression, 528 mopar cam, 1 3/4 headers , same heads/intake, carb at 3500lb tan mid 12s. With the new pistons little bigger cam, aluminum heads, and a little lighter car I’m thinking it may go high 11s
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Re: Compression vs flow
[Re: twayne24365]
#2487489
04/24/18 09:13 PM
04/24/18 09:13 PM
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Joined: Oct 2015
Posts: 570 UK
rb446
mopar
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mopar
Joined: Oct 2015
Posts: 570
UK
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My old '69 Cuda, 3000lbs, 440SP bottom end, stock 906's, approx 9.8:1, Team G intake, CC.650/.650" sft cam, 850DP, 2" f/well hdrs = 11.23@118>
Bolted on some 2.14/1.81 ported 906's to approx 260cfm = 10.71@124.8.
1969 'Cuda 446ci, best 9.96@133.9 in 1990 1971 340 'Cuda, best 11.01@122.8 in 1987
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