Cool test between head volumes
12-29-2017 | 08:41 AM
#12
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From: chicago
even the as cast non cnc ported heads made some good power. We have some nice head choices these days to fit various budgets
Last edited by MILD THUNDER; 12-29-2017 at 08:44 AM.
12-29-2017 | 08:46 AM
#13
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From: Murrayville Georgia
I think it could be that, or, that it simply isnt turning enough RPM to see the benefits of the larger intake valve. That 1.94 valve is probably enough valve area for that engine, until around 6000rpm or so. The big 220cc port and larger intake, smaller exhaust , would in my guess, start showing gains if the engine was revved higher , like closer to 7000rpm.
As much as we try to pick the right size head for our engine builds, which is easy to do when you are buying new, or have an unlimited budget, sometimes we must work with what we have. I dont see anything in this test, or the other magazine test that ran several bbc head sizes on a 496ci, that was dehabilitating to power production.
Big-Block Heads Shootout - The Big O Vs. The Big R - Super Chevy Magazine
355cc edelbrocks
574ft lbs at 4000 723hp at 6500
300cc afr's
587ft lbs at 4000 729hp at 6500
I doubt 6 peak HP will make a difference on the GPS, or 13ftlbs (2%) for acceleration. Prob why most big name head porters, dont get all worked up over port volumes.
As much as we try to pick the right size head for our engine builds, which is easy to do when you are buying new, or have an unlimited budget, sometimes we must work with what we have. I dont see anything in this test, or the other magazine test that ran several bbc head sizes on a 496ci, that was dehabilitating to power production.
Big-Block Heads Shootout - The Big O Vs. The Big R - Super Chevy Magazine
355cc edelbrocks
574ft lbs at 4000 723hp at 6500
300cc afr's
587ft lbs at 4000 729hp at 6500
I doubt 6 peak HP will make a difference on the GPS, or 13ftlbs (2%) for acceleration. Prob why most big name head porters, dont get all worked up over port volumes.
01-01-2018 | 02:56 AM
#14
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I wonder if given all that, if the cam had been changed to help the exhaust side would it have then picked back up? but in the end it did prove that port volumes are not the end all, be all of head selection. that and given that this motor did more than most people would use it proved that it is probably better to err on the conservative side than go overboard with everything. I was told a long time ago that what ever cam some one picks, go one or two milder and they would end up happier and never know the difference. in the case of this motor, how many real world guys are spinning more than 6000 any way? maybe once or twice a year but most just want quick response and to sound cool at the show. a while back I redid a mk5 454 for a '69 chevelle that the guy was told made 500 hp. it turned out to be a fresh, stock truck engine, cam, peanut ports and all. I change the cam for a small hyd roller that made power from 1500 to 5000 and the thing shakes the ground but only turns 4800 with peanut ports. thing is the guy is scared of it now so the heads keep it from hurting itself and the guy sounds racy at the shows.
I did that to a kid with a 421 sbc that motor scared the crap out of him he never did drive it old the motor a year later some guy dropped it in a Camaro and crashed into the wall at Friday night drags was a easy 700 hp 8000 rpm solid roller small block kid had a 290 hp 350 shoulda left it in the truck and made it go thumpy thump.... oh well he wanted big he got it...
