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Thread: choosing an intake

  1. #1
    nos1967
    first off i dunno if this should go here or just jets, so it needs to be move will a moderator please help me out.
    let me give you a rundown of the boat first. its a 67' 16 foot tahiti jet boat with a B cut impeller and through transom nicson exhaust, came with a 327/300hp that i recently rebuilt. engine specs:327 .030 over, forged 3.25 crank(original), forged aluminum pistons, 10.35 to 1 compression, 1.94/1.60 valves with 3 angle valve job and some porting and polishing(as much as i could do myself with a drill motor), cam i used http://store.summitracing.com/partde...16+4294925084+ 400114+4294861490+4294887375+115&autoview=sku
    the boat with the 327 and 650 holley/dual plane spun 5000 rpm, and with a mild 350 750 eddy/single plane spun 5000 rpm. so i want more rpm! haha. i think this engine setup will perform better with headers and a C cut impeller, but i gotta deal with limited funds for now so im just tryin to get the damn thing runnin.
    SO back to my delima...intake manifold. single or dual plane? the only thing it HAS to have is the front oil filler tube, i really like that look and want to keep the boat as original as possible. i think the performer rpm has a spot for the filler tube to be drilled and pressed in, only new intake that i know of that has that. thanks a lot to whoever responds-scott

  2. #2
    nos1967
    also does anyone know how the "summit" brand and "professional products" brand intakes compare to name brands, they look like exact clones for a better price, maybe dont perform as well?

  3. #3
    SUI-CY-COLE
    try the rpm airgap....very good all around manifold.

  4. #4
    nos1967
    thats the manifold i wanted but i dont think theres a place to put the oil filler tube, only the performer rpm has that. i replaced the old performer with a rpm air gap on my charger and she pulls hard to 6 grand now, wish i could get one with that front oil filler tube.

  5. #5
    nos1967
    well i just got desktop dyno and heres what it says about single vs. dual for my build. i put large tube headers w/mufflers, figured thats the closest thing to the nicson logs im running.
    dual: torque 381@4500, hp 395@6000
    single: torque 398@5000. hp 430@6500
    3000rpm-5500rpm numbers....3000 being cruising speed and 5500 would be my goal with headers and C impeller.
    dual:337-368 torque, 193-386hp
    single:326-393 torque, 186-411hp
    now these numbers dont seem realistic for a 327 with an out of the box 750 eddy carb with no dyno time, but i assume that the power band is right.
    im leaning towards a single plane now....

  6. #6
    SUI-CY-COLE
    If You Wanna Go Single...go With The Victor Jr. Or The Super Victor 2954

  7. #7
    SmokinLowriderSS
    I don't think a manifold change is going to get you anything that you want.
    You are already running a decent single-plane aftermarket manifold. IF you were leaving a stock iron manifold, I'd recomend the RPM or RPM Air Gap as a 5,500 RPM preference over a standard performer. You want more RPM, but you have to make HP to get it and you are going to need aprox 25HP to get every 100 RPM. How many HP do ya think you're going to get from 1 aftermarket manifold to another? IF the one you have is really poor fit to your setup, and the replacement is perfect, MAYBE 25 HP. I don't think the manifold you have is that bad, so the improvement will not be nearly that good, if any at all.
    Headers MAY net you 25 HP, and 100 RPM. I got 50HP and 200 RPM, but that is attatched to a 400HP 454 that was being cramped badly by the Niccson logs she used to carry.
    Personally, if you want more RPM, you've got 3 choices, well, 4 really but I'm leaving out the Big Block option.
    1. Cut the impeller & suffer the holeshot loss of a "C". Gain 300 RPM or so.
    2. rebuild the engine for more 100+HP, and torque, and plan the setup to peak arround 5,500 RPM MAX.
    3. Nitrous it, 100HP shot is 400 RPM.

  8. #8
    victorfb
    IMHO, id keep the intake you are running, and spend some money on bigger valves. with the cam you are running you can gain by useing larger valves and some better port work, or with even more money get some better heads. keep the "B" cut. and do some fine tuning with the carb. i think youll be pleasantly surprised.

  9. #9
    SmokinLowriderSS
    well i just got desktop dyno and heres what it says about single vs. dual for my build. i put large tube headers w/mufflers, figured thats the closest thing to the nicson logs im running.
    dual: torque 381@4500, hp 395@6000
    single: torque 398@5000. hp 430@6500
    3000rpm-5500rpm numbers....3000 being cruising speed and 5500 would be my goal with headers and C impeller.
    dual:337-368 torque, 193-386hp
    single:326-393 torque, 186-411hp
    now these numbers dont seem realistic for a 327 with an out of the box 750 eddy carb with no dyno time, but i assume that the power band is right.
    im leaning towards a single plane now....
    I've found "HP Manifolds with Mufflers" is much closer to the log manifolds. At least it sure comes up spot on with a Big Block. They may be a bit freere for a small block, but I don't think a whole lot.
    I wish I had casting numbers for your heads, I'm guessing here on DD. I decided to bolt a set of iron 462's on it.
    A Berk "B" is 338HP @5,000 RPM.
    Set up my way, I'm getting:
    RPM .... HP ... Tq
    4000 .. 258 ... 339
    4500 .. 296 ... 345
    5000 .. 327 ... 344
    5500 .. 347 ... 331
    6000 .. 358 ... 313
    6500 .. 346 ... 280
    Charts a nice wide, flat torque curve, pretty good cam selection IMO. Don't know how much earlier it could be gotten to pull tho, to try to bring that HP peak lower toward you.
    If you don't have a good loader feeding a real solid stream to the pump, you can easilly turn that 5,000 with only 320+ HP instead of 340.
    If it were me, Nitrous. Otherwise, an engine build.

  10. #10
    SmokinLowriderSS
    Just finished a camshaft iteration run to try to improve it, and can't really. Your exhaust is a major problem IMO. Several head changes, both GM and aftermarket, yield very little improvement, if any, some losses, but a set of headers would be worth it IMO. You may get 5,300 RPM out of it. That takes 402 HP and that is crossed at just about 5,300RPM on these curves I have.
    Your HP peak is still way up at 6-grand, but no way to get arround that I don't think.

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