Team Chevelle banner

Rectangle vs Oval BBC heads

30K views 48 replies 27 participants last post by  blubu 
#1 ·
I built my 468 with Edelbrock RPM performer (oval ports) for a street strip application.would i have been better off with rectangle port heads:confused:
 
#4 ·
Post your combination...........
 
#8 ·
#9 ·
Re Bob's link: Carl (McQuillen Racing Engines) is a client of ours. It IS a compound in rural upstate NY!

FOr street cars using rects, I usually recommend going smallish on the cam to aid the intake velocities and driveability. With ovals, you can get bigger on that cam.


Bob (Godnrob) , naw, no mistake. Ya dun the right thing.
 
#11 ·
UHHHHH NO
Not on the street it has been proven more than once that sq port show very little improvements over OP Especially on a 454 which is a grunt motor and works on torque vs hi winding. Gear it right and you dont need all the rpm as well the breakage factor which can come with hi rpm motors
 
#14 · (Edited)
I see the old rectanuglar vs. oval port debate is still alive and well!:hurray:

I state this AGAIN for those that haven't read it here or elsewhere...

it is a FACT that my 11:1 467 oval port engine combo out performs EVERY n/a 454-502 combo regardless of bore/stroke/compression/heads/cam yada, yada, yada in a similar weight Chevelle(3880 lbs.) in Division 1 brackets as well it's makes more power/runs quicker than most 540's and GM's 12:1 720HP 572 again in a Chevelle of similar weight to which most comparables are hundreds of pounds lighther.:yes:



Further this car/combo is DEADLY consistent, typically varying thousanths in 60 foot from run to run and 2-3 hundreths over the course of a full day/night of racing!:yes:

OH and it sees over 6000 "regularly" as in EVERY pass, making the 1-2 shift at 6600 and 2-3 at 6800!!:yes:

FYI, my new 522 engine that will see north of 7000 RPM regularly will also have oval port heads!:yes:




So to answer your question....

NO:noway:
 
G
#18 ·
Thanks for dropping in Ed!!

Did anybody ever notice the 400 cc oval port race heads that I wanna say Brodix has...

Why would they make them if they aren't great heads when there are SO many rect heads out there in this size??

I honestly figure it is a wall drag thing that make's an oval port head some better than the rect is all!! Can't prove it, but an oval will have less wall area vs a rect for the same cc size and imho, that will cause less charge friction upon suck..

And a round port less drag yet!

pdq67

Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
 
#19 ·
When I grow up I wanna do a wheelie like Ed ;) Had a guy this weekend that runs No/E weekly with his alkie powered smallblock Vega (8.40's-1000ft). It never left the line with the wheels much more than 6-8" off the ground, he tore up his 4.56 gears and opted for 5.14's, his first pass last Saturday he put it on the bumper and had to clean his pants, after that he tied the front end down, didnt want to do that anymore. :D
 
#22 · (Edited)
Let's stay gentlemen here man. My 6 and 10 yr olds get "jail time" for name calling. I tell them I dont want them to get " as dumb as most of the world", and to keep their intellect running at a higher frequency than that. Kinda what their religion says to. Add to harmony, dont take away from it.

Y'all hear that?

But ovals on a 522, naw, unless they look like those big chief type ovals.. that pdq mentions. And fluid dymanics at that velocity, you;re splitting c hairs over rounded corners or square corners, something that no one here will ever notice..unless they're building very expensive race cars.

Its intersting that MMracing found the 074 more consistent. Which just goes to show, more than one way to skin a cat.

Me, I;d actually prefer AFR 305s over any GM oem head, bar none. But that wasnt the question! :) And I'd love to do a back to back, both ET and driveability between the oem 990s on there now, and the 049's I have sitting in the garage. Bet its splitting hairs, i.e., marginal differences at best, and not at all like WOW what a difference.....

which is what you'd gather seeing how passionate the debate can become.... silly really.
 
#24 ·
Bob, the "idiocyncracies" of each combo will tend to make generalizations like " ovals are always better" a bit too trite and very inaccurate.

BTW, since we're speaking of fast street/strip AND I;m always thinking of red 68's, let me please introduce the car I gave an award to at the MCC show:





Now, suppose these awards are always car AND driver, or, what the design criteria of the driver is...

Y'alll see that 11.55 in the second pic? This 68 DRIVES 1200 miles at a pop, lays down 11's, and drives home.

:thumbsup: :thumbsup: :thumbsup:

That is exactly why Mr. Bob Wilcox, of the great state of Marlyland, got the Can Am best of show award at the 20th MCC/ACES show, dubbed the ROAD KING award! You might have seen Bob's ad in Chevelle World.

Not taking anything away from any other red 68 Chevelle! This, to me, epitomizes street/strip. No power adders, no fancy efi/electronics. A very well engineered car whose owner is both a drag racer and master mechanic. If you're a fan of " Two Lane Blacktop ", and reckon this is exactly what muscle cars meant back in the day.... xcross country jaunts stopping at dragstrips/street races along the way, man o man, did Bob hit on a combo!

Wonder what heads Bob uses on his 68 bbc ride? ;)
 
#29 ·
Bob, the "idiocyncracies" of each combo will tend to make generalizations like " ovals are always better" a bit too trite and very inaccurate.

BTW, since we're speaking of fast street/strip AND I;m always thinking of red 68's, let me please introduce the car I gave an award to at the MCC show:





Now, suppose these awards are always car AND driver, or, what the design criteria of the driver is...

Y'alll see that 11.55 in the second pic? This 68 DRIVES 1200 miles at a pop, lays down 11's, and drives home.

:thumbsup: :thumbsup: :thumbsup:

That is exactly why Mr. Bob Wilcox, of the great state of Marlyland, got the Can Am best of show award at the 20th MCC/ACES show, dubbed the ROAD KING award! You might have seen Bob's ad in Chevelle World.

Not taking anything away from any other red 68 Chevelle! This, to me, epitomizes street/strip. No power adders, no fancy efi/electronics. A very well engineered car whose owner is both a drag racer and master mechanic. If you're a fan of " Two Lane Blacktop ", and reckon this is exactly what muscle cars meant back in the day.... xcross country jaunts stopping at dragstrips/street races along the way, man o man, did Bob hit on a combo!

Wonder what heads Bob uses on his 68 bbc ride? ;)
Did they have a race at Cecil associated with the Eastern Mid-atlantice Chevelle show?

If so, kinda wish I knew that as I may have tried to make an appearance at the track. My car's not very show worthy anymore, not like it ever was anyway. But always looking for another reason to burn up some VP C-12 fuel. :D
 
#26 ·
As far as i know there are only two companies making "true" oval port, conventional heads at this time that have sufficient volume to feed real big engines such as the one "Ed" is going to build. That is the Dart "330 & 383 cc - 18 degree heads and a 370 cc 24 degree ones. The other is from Sonny's and is the BB-5 oval by Brodix. The Profilers are called ovals but appear to be more of a square port as do all the Edelbrocks, Canfields and BMF's.
 
#27 ·
And to be fair, we're talking two different kind of ovals here. 290cc vs race at 330+.

Dave, I didnt ask Bob exactly what they are, but would have guessed Edel/GMpp small chamber rovals. Shiny bastids they is! :)

Hear, hear! :beers: to both 68's pictured in this thread!
 
#32 ·
So Ed, seeing as how your zinging the thing to 6800 for the 2-3 shift and I go back and read your old posts about keeping Rpms to a safe BBC zone are you willing to change heads to low chamber sized rectangles and see it find that 9 you have been chasing for ten years? Ovals or rectangles----- the simple thing is that it comes down to flow and its direct relation to port velocity... if you wanna play on the flow bench in the shop come on up-- Math is a pretty solid theory to test with.

for the record, I had to slow mine down this winter because I dont want to cage it-- but still run 11.50 on the hottest day of the summer on pump gas. And yes, I do that with a little 461 with rectangles and all around your 6800 shift point...

So not every one on the boards wants to limit their parts to meet your criteria.. Ovals ARE great---- but that doesnt mean rectangles are the junk you stopped playing with ten years ago.. Go back and read your master recipe---LOTS of changes since some of your original posts-- seems its okay for you to try stuff and then use it but your bored with everyone else that does it...

My agenda isnt to start a fight-- Only to point out that thinking outside of the box is WHY ours cars are better today then they were 30 years ago.. Additionally, if we encourage guys to think outside our box they will make them better again.
 
#35 · (Edited)
So Ed, seeing as how your zinging the thing to 6800 for the 2-3 shift and I go back and read your old posts about keeping Rpms to a safe BBC zone are you willing to change heads to low chamber sized rectangles and see it find that 9 you have been chasing for ten years? Ovals or rectangles----- the simple thing is that it comes down to flow and its direct relation to port velocity... if you wanna play on the flow bench in the shop come on up-- Math is a pretty solid theory to test with.

for the record, I had to slow mine down this winter because I dont want to cage it-- but still run 11.50 on the hottest day of the summer on pump gas. And yes, I do that with a little 461 with rectangles and all around your 6800 shift point...

So not every one on the boards wants to limit their parts to meet your criteria.. Ovals ARE great---- but that doesnt mean rectangles are the junk you stopped playing with ten years ago.. Go back and read your master recipe---LOTS of changes since some of your original posts-- seems its okay for you to try stuff and then use it but your bored with everyone else that does it...

My agenda isnt to start a fight-- Only to point out that thinking outside of the box is WHY ours cars are better today then they were 30 years ago.. Additionally, if we encourage guys to think outside our box they will make them better again.
For the record...
I would hardly call shifting at 6800 RPM "zinging"!:noway:

Next, I haven't been chasing a 9 for ten years!:noway:

IF all I wanted was a time slip I could have built/bought an engine to do it in a new york minute that would have me spinning the tire more often than not like most others that go this route, spending all their effort and $ under the hood while waiting for that magical day when the sun, moon and stars are in perfect alignment that will grace them with that 1 time slip that in their mind made it all worth while!!:sad:

THIS car has evolved from a daily driver to a serious street/strip car to a competitive weekly bracket racer.

However at no time was the objective to run any specific ET but rather to run as quick as possible/safe as possible while remaining as close to stock as possible!!

THAT was/is my prime objective!!:yes:

Thanks for the offer but I KNOW what makes a GOOD head as well I know what's required to make better than average power from a given combo!

Lastly, I don't care what you/they use, I'm providing cold hard FACT...PROOF as to what's achieveable, you'll/they will make your own decisions but WITHOUT question oval port heads make more power on EVERY n/a combo including 500 inch 1300+ HP Pro Stock engines no mind the BB engines found under the hood of most here, on the street and at the track!!
 
You have insufficient privileges to reply here.
Top