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Thread: can oval ports heads produce 700hp with 8-9 psi??

  1. #1
    IMPATIENT 1
    kinda runnin low on funds with my blown tx-19 build up and was wondering if i could get 700hp outta these heads:
    336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports
    the tx had a brand spankin new roller mill in it when i bought the boat and the heads are nice oval ports with fresh guides and so on, my blower intake is for rect. port. & what i was thinking is if i can buy a oval blower manifold cheaper than heads this winter if it'll produce 700hp with these heads, a nice blower roller cam, 9.5 to 1 or 10 to 1 compression, dual 850dp's.i'm trying to build a fast cove racer that'll still do 90+, with dominator b-cut, and would like to keep rpm's around 5800-6200rpms.is it possible and what do i need to do as far as compression and cam choices? thanks for any advise.

  2. #2
    TIMINATOR
    For an "on the cheap" deal, use the manafold you have. No! Really! Use a roller of 250+ deg at .050 intake and 260 at .050 exhaust. These heads when properly ported can make 550-600 HP without the blower. The Chevy heads use the same exhaust port for the peanut ports, oval and square ports, that means that your exhaust port ratio to intake flow is good. If you can't make that rig run 90, shoot yourself. For further info call me. TIMINATOR

  3. #3
    IMPATIENT 1
    For an "on the cheap" deal, use the manafold you have. No! Really! Use a roller of 250+ deg at .050 intake and 260 at .050 exhaust. These heads when properly ported can make 550-600 HP without the blower. The Chevy heads use the same exhaust port for the peanut ports, oval and square ports, that means that your exhaust port ratio to intake flow is good. If you can't make that rig run 90, shoot yourself. For further info call me. TIMINATOR
    use the square port intake on the oval port heads? would i be leavin any hp on the table by not just runnin a oval blower intake? thanks timinator for the info

  4. #4
    old flat
    Use FelPro 1211 gaskets on the square manifold to oval head; bolt it up get it wet. Like Timinator said "if it won't do 90mph" GET OUT OF BOATING!!!!

  5. #5
    IMPATIENT 1
    95mph is my goal, 100+ would be icing on the cake. so will it run better with the rect. port intake? better than an oval port blower manifold?

  6. #6
    Sanger D
    I made 610 hp with a ported set of 049's and a SINGLE 850 annular on a 461ci ,with a solid lift. It always wanted more fuel and air,you should have no problem getting 700 with a blower,but those heads are going to be MAXED after that,and its going to be a torque monster!!!!,the rect intake isnt going to matter cause theres only so much air and fuel those heads are going to flow.

  7. #7
    TIMINATOR
    Sanger's got it right. TIMINATOR

  8. #8
    LynnsJet
    I had a similar BBC rect port blower (B&M 420) intake with oval port heads this summer. When I would look into the intake it was an awful mismatch in ports but it did work but I really hated it. With a limited budget I figured that aluminum heads were a bit out of my budget. I upgraded to a nice set of iron rect port heads (and a few more cubes) and I anticipate a much better breathing engine.
    I just couldn't get the immage out of my mind of seeing those little oval ports bolted to that nice rect port intake.
    It worked. Did it work well????????
    just my .02
    L J

  9. #9
    IMPATIENT 1
    i pulled the mill yesterday and pulled the heads off today. i guess i'm gonna use these 781's, stick some stainless valves in em and do alittle port work. found an old link that show'd some flow numbers in a "oval vs. rect port" testing. pretty interesting that the oval ports out flow rect. ports on the exhaust side up to 650 lift, intake on oval ports out flow as well.i'm gonna order a cam with no more than 650 lift. it'll have monster torque up to @6k and that's where i'm wantin to build it all. i'll save up next fall and buy some nice brodix heads, change cam. i've gotta overhaul pump, do floor work, carpet, gauges, rewire it my way this yr. on top of mill upgrades.
    the guy that sold me the boat swore the mill had no more than 3hrs since a complete rebuild, guy actually was tellin the truth!

  10. #10
    IMPATIENT 1
    here's the superflow bench flow numbers between rect. and oval ports, good info!
    http://www.maliburacing.com/ovalvsrect.htm

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