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Thread: 800+ hp, 2400lbs and PG

  1. #1

    800+ hp, 2400lbs and PG

    My goal is to have my 2400lbs door car closer to 8.5's which is a limit for the chassis. It now has ran 8.96 / 151 in good air with a 509. So it has now about 700+ hp.

    My PG is stock case, stock pump, 1.76 stock planetary and 7 high gear clutch discs. It has been working fine for about 80 passes. I'm using transbrake with only 3600 launch rpm (because of full .500 tree, bottom bulb start) with 5000+ stall speed 8" converter. 4.33 gears, 32x14x15 GY slicks.

    Usually it runs 9.10's in normal air so I think 800-850 hp would get it always in to 8's, but will the PG hold up? If not, what should be upgraded?

  2. #2
    Senior Member DYNO OPERATOR
    Join Date
    Aug 2005
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    Rifle Colorado
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    585
    If it was mine, I'd upgrade the input shaft unless you already have a good turbo shaft in it, and the planetary. The case and the rest of the internals should be fine. A dual ring ring servo and a Kevlar band wouldn't hurt either.
    It will probably hold up the way it is for a while in a light car, but why chance it.
    Johnny

  3. #3
    Senior Member MASTER BUILDER
    Join Date
    Dec 2003
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    185
    What kind of car are we talking about??? If your running a 509 now what are the specs on it??

    I have a door car that is a 100 lbs lighter than yours and in good air it will go low 8.70s @ 155mphwith a mild 472 on gas...

  4. #4
    It has a turbo spline input shaft and the Kevlar band. I thought that 1.76 planetary would take more horsepower than the stock case. Am I wrong?

    Engine specs:

    -4.500x4.000 Gen V block & crank, 6.385 h-beams, arias 12.5:1 NOS-pistons (never sprayed)
    -Merlin iron heads, about 320cc intake runner, ported, 2.19/1.88 valves
    -272/278 @ 0.050 cam, .700 lift
    -Dart single plane, 1050 dominator
    -2 3/8 headers, collector mufflers

    I'm considering AFR 335 or 345 (with CNC chambers option) heads. That should pick up around 75hp according to AFR and get the car to the eights. They would also would lose weight on the front end as the car is now a little noseheavy (56%).

    sg1586, what kind of 60ft you get? Mine are 1.29-1.31 on a good track.

  5. #5
    Senior Member MASTER BUILDER
    Join Date
    Dec 2003
    Posts
    185
    Quote Originally Posted by triniemi
    It has a turbo spline input shaft and the Kevlar band. I thought that 1.76 planetary would take more horsepower than the stock case. Am I wrong?

    Engine specs:

    -4.500x4.000 Gen V block & crank, 6.385 h-beams, arias 12.5:1 NOS-pistons (never sprayed)
    -Merlin iron heads, about 320cc intake runner, ported, 2.19/1.88 valves
    -272/278 @ 0.050 cam, .700 lift
    -Dart single plane, 1050 dominator
    -2 3/8 headers, collector mufflers

    I'm considering AFR 335 or 345 (with CNC chambers option) heads. That should pick up around 75hp according to AFR and get the car to the eights. They would also would lose weight on the front end as the car is now a little noseheavy (56%).

    sg1586, what kind of 60ft you get? Mine are 1.29-1.31 on a good track.


    My short times are 1.20 to 1.22 and 1/8 mile are 5.64 to 5.67... This just my 2 cents on that manifold...Get a victor... Your short times and 1/8 will pick up..If you go aluminum I think it's almost 80lbs difference but not positive..One other think if you have room rase the compression up closer to 14 to 1 that alone will make alot more power for you without a head change...I run a stock PG case and 1.76 planatary also with a 4.30 gear and a 16x33 tire...On a real good day with good track it will go 8.60s @ 158........

  6. #6
    Senior Member EXPERT BUILDER
    Join Date
    Aug 2007
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    Orient, OH
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    384
    I would say the little valves are choking to motor back. On my 468 I run the 320cc Merlin heads with 2.30 and 1.88 valves....

    The biiger valves and weight reduction will make a world of difference, see if you can get something with a smaller chamber than you have and that should help you too.. I would say the heads and intake change will pick it up a bunch .3 or so....

    Just a thought
    Josh VanHorne

    1964 Chevy Nova
    Worlds quickest and fastest tow truck. (9.92 @ 137)

    http://static.racingjunk.com/63/ui/7...247837-479.jpg

    http://www.racingjunk.com/profile/211708

  7. #7
    Senior Member DYNO OPERATOR
    Join Date
    Aug 2005
    Location
    Rifle Colorado
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    585
    I wouldn't worry about the stock case. If everything is mounted properly, you probably won't hurt it. In my opinion, the stock 1.76 gears are marginal at that power level. I run a stock case, stock 1.76 carrier with 1.80 straight cut gears in my SG Vette with a 522 and am not worried.
    Aftermarket cases are nice, strong, heavy, and don't require shields. If my budget would allow, I might get one, but it's not a necessity...
    Johnny

  8. #8
    I broke one tranny last year. I got like 40-50 passes on it before stock 1.82 (yes the original inline 6/small block) gearset surrendered. So I'm telling myself that the 1.76 is bulletproof stuff compared to 1.82 and it should take all the beating my 509 deliveres or even more. I think that the low starting line rpms are helping everything to survive.

    I was surprised to know that the stock case can take more hp than the stock 1.76 gearset.

    But I hope that the stock case & stock 1.76 gearset can take all the horsepower to get the car closer to 8.5's. The next step, 7.9's car, starts really to cost money. 1000+ hp engine, chassis upgrade, aftermarket tranny case & gearset...

    With AFR heads I would:

    -lose weight on the heavy front end
    -Get bigger intake valves (2.19->2.30)
    -bigger intake runner
    -beefier springs = more rpm (merlins have only 1.550" double 180lbs seat - 500lbs open)
    -more flow on intake and exhaust

    Besides, the Merlin heads have to be serviced this winter and I'm not willing to spend a lot of money on them. AFR's aren't a must, Dart also has similar 335 or 345 heads which I believe are in the same level than the AFR.


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