rect.vs oval intake

[hotbo]

i have 781 oval port heads and a rpm oval air gap.i have been told to run rect.port on the oval heads and it will do better:confused:i think this is bullshit but wanted to ask anyway.tried to look under some old post but went blind:D so is this true motor gurus.i wouldnt think so but im wrong alot.also what would i gain by going to a tall single plane over my rpm.im turning 5500 right now and runs good for what the boat is.thats on a b-cut agressor impellor:idea:

[ck7684]

I've never heard that before...do you know what size cam you have?? You may be just getting to the point where a single plane manifold might help, but it's hard to say...In my BBC book there is a build using a single plane that makes 575 hp and recently in one of the car mags they did an almost identical build with an RPM air gap and made 579 hp and both close to the same RPM range (around 6500)...
If it were mine I would just stick to what works, unless you have extra parts you wanna play with...:)

[VAMI]

I Have Only Seen That Once And It Was On A I/o Boat And That Was 5 Years Ago.i Asked The Same ? The Answer I Got Was A Square Port Moves That Much Air Than A Oval Port Even Though The Ports Dont Match.i Think That May Have Been A Trick 10 Years Ago When Oval Port Intakes Where Not Developed Like They Are Today.i Dont Think I Would Try It.

[Danhercules]

I think that the peak HP is a little high for under 600 HP. Ya may not be able to spin the pump that high.

[Sleeper CP]

i have 781 oval port heads and a rpm oval air gap.i have been told to run rect.port on the oval heads and it will do better:confused:i think this is bullshit but wanted to ask anyway.tried to look under some old post but went blind:D so is this true motor gurus.i wouldnt think so but im wrong alot.also what would i gain by going to a tall single plane over my rpm.im turning 5500 right now and runs good for what the boat is.thats on a b-cut agressor impellor:idea:
The RPM Air Gap is hard to beat. I just got off the phone with Danny Crower about someother stuff and asked him your question. The short of his answer was this: Yes the rect. ports work great oval heads, lots of port match work though. Will probably out perform any oval port manifold dual plane until Edelbrock produced the oval port RPM Air Gap.From 5000-6000 rpm range the RPM Air Gap will be very hard to beat. And the dual plane Air Gap will idle better than any single plane you'll find. Also the mid-range trq numbers of the Air Gap will probably stomp the single plane.
Crower said if it was his, he'd just use the Air Gap for an engine up to 6,000 rpm's.
Sleeper CP

[hotbo]

yeah thats what i think.yes i know what my cam is i build all my own motors.not saying im good at it i just love it and they seem to stay together.:D anyway i run around with some ole school guys and they are all t-ram afizzed and im not im stuck on singles cuzz i beat there ass most of the time:jawdrop: well the ones in my class.:D they all tell me to put a team g or dart on there rect port.im thinking this is b.s.:devil: but they swear by it.:confused:
hoping someone has done this on the site cuase ive found more than 1 of these sobs to be full of shit:idea: well hell alot of them are;) thanks so far for the advice.i only have around 500 horse 516 to be exact hell if i know if thats true thats the damn dd 2000 series people tell me they dont lie that bad but i dont beleive a comp.dyno any more than sticking my finger up my ass and tasting it.but i guess agressor b-cut 5500 would be close to 500 maybe alittle less or more.:D

[MWJSOne]

Look at the numbers out of a Worlds Merlin round port head they do
make some impressive numbers and for torque in the right porting guys
hand you can get about 6500 before they go away.Kieth who runs
lake racer agaist Derns runs a set of ovals that John Mowery racing
ported the video is on here under Blarnneys Island.

[BUSBY]

i have 781 oval port heads and a rpm oval air gap.i have been told to run rect.port on the oval heads and it will do better:confused:i think this is bullshit but wanted to ask anyway.tried to look under some old post but went blind:D so is this true motor gurus.i wouldnt think so but im wrong alot.also what would i gain by going to a tall single plane over my rpm.im turning 5500 right now and runs good for what the boat is.thats on a b-cut agressor impellor:idea:
You can run an rectangle port intake with oval port heads ... but as Mr. Crower stated ... lots of port work ... lots. By the time you finished paying for the work, you could buy some nice 990's or even a set of alum Canfields.
The air gap by Edelbrock is the best out there right now from what I've seen. Some nice port matching and you're good to go.
Sounds like you have the right manifold. If you were to go with a single plane, you'd loose your bottom end power range. Stick with what you've got ... use the money for gas! Torco of course :D

[SmokinLowriderSS]

5500 on an Aggressor B is aprox 525HP.
Leave the Air Gap in place, and keep spanking the TR suckers. They just want to slow ya down. :D

[pw_Tony]

Hmm I might have to try doing the "rectangle port" on the oval heads...

[advantage21]

I had a rect port manifold on my boat for two seasons i bought it that way and it ran great, however i put a oval port manifold on a it still runs great so i don't know if there are really and advantages to this unless you are pumping out some big hp. I took my motor out to freshen it up pulled the manifold off and said why is there a rect port manifold on this motor so being a dumbass and not doing any research i sh#% canned the rect and went to a edelbrock rpm manifold.

[hotbo]

5500 on an Aggressor B is aprox 525HP.
Leave the Air Gap in place, and keep spanking the TR suckers. They just want to slow ya down. :D
hey arron you bet your ass i will.ya know its the same ole shit every where you go.do this and do that and it could be better:idea: sometimes we fall for it.like i said these guys are ole school and swear by it but they sure hate it when a sj takes them out for1/8 mile and they have a hard time catching up.but then again they all turds:eek: well that solves my question i guess unless someone else has a good reason cause so far the answers are what i guessed/thanks travis

[Running_on_Empty]

what do you think about the torker 2 alum. oval intake from edelbrock?

[pw_Tony]

what do you think about the torker 2 alum. oval intake from edelbrock?
Ummm.... no:devil:
If it runs leave it on. If it's ruined, or you need an intake just buy a RPM air gap...

[IMPATIENT 1]

what do you think about the torker 2 alum. oval intake from edelbrock?
if your runnin a heavy lake boat jet, you really can't beat a edelbrock rpm or air gap for boats turnin less than 6k. heavy boats need midrange balls, the high rise dual-plane intakes(rpms, airgaps) fit that need perfectly imo.

[Jetaholic]

rect. vs oral intake
Fixed!
:D

[396_WAYS_TO_SPIT]

Ovals with ovals and Recs with Recs;)

[BUSBY]

Fixed!
:D
LMAO :D

[hotrod56cars]

I have a BBC with oval port heads and a Edelbrock C427X rectangular port intake. I just found out via "the hard way" that if you run a rect. port intake on an oval port head you have to use the rect. port head gasket on the intake. Just thought you may want to know to avoid the same huge vacuum leak issue that I just ran into.

[Sleeper CP]

That's called port matching:rolleyes:
Sleeper CP

[ck7684]

Just sounds like an old school trick from before there were a lot of aftermarket stuff to choose from, or if you are trying to use all factory parts or something...

[pw_Tony]

Well porting is $free dollars so that's a trick I might just have to try:D

[Jet Hydro]

it works as I`v done it many times. I have a rectangular port tunnel ram on a set of 095 oval port heads and it runs pretty good ;) I just did a little port matching to make em work and made my own gaskets.

[78Southwind]

i have 781 oval port heads and a rpm oval air gap.i have been told to run rect.port on the oval heads and it will do better:confused:i think this is bullshit but wanted to ask anyway.tried to look under some old post but went blind:D so is this true motor gurus.i wouldnt think so but im wrong alot.also what would i gain by going to a tall single plane over my rpm.im turning 5500 right now and runs good for what the boat is.thats on a b-cut agressor impellor:idea:
For my motor I ended up going with the Air-Gap and had the intake gasket matched.
This is the torque and HP curves for a mild built BBC using Edelbrock RPM-0 Heads. The article said that the Victor out preformed the Air-Gap by 9 HP at 542 HP at 5,600 RPM but the Air Gap made 13 more lb-ft of torque at peak 565. However, in terms of overall average output, the Air Gap topped the Victor by 8.8 lb-ft of torque and 6.3HP.
http://www.***boat.com/image_center/data/500/1676454_Chevy_Dyno.jpg

[hotrod56cars]

I thought port matching was when a grinder type of tool was used to make the ports match, not just using the correct gasket for the job at hand? :confused:

[hotbo]

i knew you had to use rect.gaskets:D well when i freshend my mill this winter i port matched my heads to gaskets and intake to gaskets.didnt have to port much on the heads just alittle and i went down inside 1 1/2 inches and beveled out.so its pretty smooth.now the intake took alot to make it match the gaskets.i bought a video over christmas called bad ass racing engines valve train,and head porting.he highly stressed to never ever misamatch ports and if you have oval heads do not ever try to make them rect.:idea: . i know of more than 1 guy that runs rect over oval on there mills with oval heads,they swear buy it.:idea: but then again its probably like everything else they buy and bolt on.they swear it works but never once will they tell you it hurt them b/c in there minds it worked for the money they wasted:D

[Letscrashyours]

Here is my 2 cents. Running rec port manifold on oval heads can cause cold start problems due to fuel puddling in the ports. Sure you could get close to matching them dont bother theres not really enough meat on the heads to get close. And hotbo if these guys giving you this great advise were all that theyd be usin a good set of rec port heads anyway. Cuz thats the only way to make some good horsepower.

[pw_Tony]

I would figure somethni. My oval port heads have a very shitty short turn on the floor, so if you wanted to open it up to a rectangle port you would be pretty much getting rid of the floor short turn all together. Yea you could shape the roof better if they we're opened but the floor would suck. Bigger is not always better

[hotbo]

I would figure somethni. My oval port heads have a very shitty short turn on the floor, so if you wanted to open it up to a rectangle port you would be pretty much getting rid of the floor short turn all together. Yea you could shape the roof better if they we're opened but the floor would suck. Bigger is not always better
well what ive read heard and watched all the main flow is on the roof you do not do much to the floor:confused: this is what the guy in the video was stressing.he also said if you do not have a flow bench you can screw a good set of heads up by trying to be the hero.
yes most of them run rect.i personally think they are ole school.they also cant figure out why my boat runs so good with a 750 proform carb.go figure.i raced a guy 2 weeks ago with a 87 condor tx-19.bbc brodix heads 10.1 t-ram 750 carbs so forth he said he was running93.7.said his motor dynoed at 650h.well to start of his motor sounded good and his boat run good.my turd is no slougch:idea: we raced 7 times outta a 1000 foot cove.i run a 150 shot with around a 500 horse motor,my best pass on motor has been 73.7. never checked it with the bottle.i would take him bad outta the hole and he would pull to me by half track and i would continually win by 1 boat to 1/2 boat depending on who cheated the best on take off.we ran 1 time with me no nos he beat me by 1 full boat.so i won every race with my 150 shot should make mine close to 650.i have alot heavier v-hull taylor sj with e-pump i m having cavitation problems and he was pisssed and dissapointed to say the least.:D after the 1st pass he came back and said what do think we were running 95 -100 maybe.what a ididot lmao!!!!!.i said hell we were lucky to be running upper 70s maybe80.he was hurt.i find this alot with the big talkers:idea: they have a 80-90mph boat but they lose to the 70-75.:jawdrop:
i have pics and a video of 1 of the races which i fudged alittleon take off.we both cheated alot on our starts:D .you know my point is its not how fast you are its how quick you get there in the end in a drag race.you know if we ran a full 1/4 or more i would have probably come close to not winning them all.:idea: i think im going to listen to my instincks and leave well enough alone.:D thanks guys for the advice i really appreciate it.:)

[cfm]

Before the Ed Rpm intakes and Dart Single Plane Oval, pretty much all oval port intakes where made for trucks and heavy cars. There where many rect intakes made for performance applications.
The mismatch from intake to head doesn't create as much problems as you'd think. Air will collect at the mismatch and create 'eddy's' like in rivers and form a smoother entrance for rest of air to get into the heads.
Still not a good way to do things but if it works better than anything else you have, then you use it. Good intake/head porters tried to port match heads to intake and lost power. They also tried epoxying intake to match heads, and usually lost power doing this too. Didn't make much sense but it is what it is. The one's I've talked to - okay, listened to - can only figure out that doing these mods created too much cross sectional change to fast and screwed with the air speed. Other speculation is that the mismatch would help re-introduce fuel back into the airstream.
Enter a handful of yrs ago. We have much better intakes to choose from - again Edelbrock RPM and Dart - and we don't have to play this game anymore.
If higher rpm stuff is needed, we have the Holley Strip Dominator and Brodix single plane intakes.
Keeping runner (heads + intake) length, cross sectional area, taper, angle, etc,etc and overal design proper for each application is what works best. We have a ton of intake manifolds and cyl heads to choose from for a reason. Gone are the days we just have 1-3 intakes and/or cyl heads to choose from.
Don't always count the old schoolers out. Many times they come in handy when we get ourselves lost in the trick of the week stuff and using their basics get us back on track.
Lastly, make friends with the fastest one on the water or track. Getting info from them will give you a huge advantage by giving you the fastest baseline that is around. You can change things from there and see where you go. If faster, great ! Your the fastest ! If you go backwords, not so bad ! You know where to go to be tied for the fastest. LOL.