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Dyno Day for the 502

Discussion in 'Engine and Drivetrain/Mechanical' started by tarafied1, May 11, 2018.

  1. tarafied1

    tarafied1 Well-Known Member

    anyone care to guess the numbers....? dyno day.jpg dyno.jpg
  2. johnpsz

    johnpsz Member

    OK, based on my limited details of your build. all I know is that it's a 502, 10:1 CR, 75CC heads, custom grind cam (specs unknown to me) and a smaller single plane intake (I assume pump gas setup based on these). I assume with all the work into this and that you seem to know what you are doing, that the heads have a decent port job and that the intake is port matched. The big outstanding question is carb choice and jetting and header size. But, all that said here is my "guess"...

    685 - 690 HP close to 6K RPMs (+/- 3% or 20HP based on altitude/correction factor)
    605 - 615 LB/FT in the 4800 RPM range (I think it will be limited by the intake)
  3. Fst Blk

    Fst Blk Well-Known Member


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  4. msell66

    msell66 Burning Fossil Fuels as Fast as Possible Donator

  5. Larry G

    Larry G Member

  6. Horseplay

    Horseplay I Don't Care. Do you?

    I will go with 200 ponies less than every single one of the Honda nitrous injected, turbocharged street racers gathered over in the local Walmart parking lot. Had you done it right and invested in VTech you might have been able to keep up.
  7. tarafied1

    tarafied1 Well-Known Member

    Well you do know most of it! It was on 93 Pump gas which I bought the local Shell station. The carb is an 850 which may be too small but was definitely lean. We increased 6 jet sizes and HP jumped almost 75 HP. And it is still lean but we ran out of time. The headers we used were the FPA headers made for the car (not best for high HP but allow the engine to fit). You were pretty close, 615 @ 6K (we made a pull at 6200 and it dropped to 614.4 so the peak is at 6K). Torque was 621 at 4200 but was pretty flat from 2K on up to about 5K. it was still really lean, about 14:1 down low and 16:1 at the top end. We just ran out of time.
    Yes but I don't know how to upload them here
    I wish! but I am pretty happy with what it did
    Around here they are all 4x4 trucks with only half a lift kit (in the front) and glasspacks on 1" pipes so they make a horrid sound!
  8. tarafied1

    tarafied1 Well-Known Member

    lol, Thanks Larry!
    Larry G likes this.
  9. tarafied1

    tarafied1 Well-Known Member

    I will upload to YouTube and then post video here.

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  10. tarafied1

    tarafied1 Well-Known Member

    cam break-in


    pull 2
    Last edited: May 11, 2018
  11. Horseplay

    Horseplay I Don't Care. Do you?

    I know you are 100x more the carb guru than I, Craig, but that 850 is getting close to undersized at this point, IMHO. I don't think you need to go out and buy a 1150 Dominator but a larger cfm 4150 style seems applicable. With your heads, cam and valvetrain your engine is likely pushing into the 90s on VE where that 850 is just meeting air volume requirements for maximum power. I know that's not your goal but a slightly larger carb will yield more power AND maybe better economy performance. 900-950 would seem a good compromise of peak power and street manners.
    tarafied1 likes this.
  12. Grabber70Mach

    Grabber70Mach Well-Known Member

    Way to go Craig, that thing sounds bad to the bone.


    Never argue with a Moron. They'll just drag you down to their level and beat you with experience.

    If the women don't find you handsome, they should at least find you handy.
    tarafied1 likes this.
  13. Mach1 Driver

    Mach1 Driver Active Member

  14. tarafied1

    tarafied1 Well-Known Member

    thanks guys! I was super excited about the results.
    And Terry I wouldn't say I was a guru but I am not afraid of carburetors (although I still have trouble spelling it). But yeah you are right, for max power it is the wrong carb. I have already researched options and a 950 HP Holley would be a great option. However, you guys and my boys are influencing me! I am strongly considering EFI as a future upgrade. I literally grew up tuning Holley carbs because of dad and as some have strong brand loyalty to Fords or Apple or whatever, I have a strong brand loyalty to Holley so I would consider Holley EFI. But for the short term, this 850 will be okay. I really don't know how this thing will be on the road. I estimate it was 400 or 450 HP at best before and that was in reality plenty. With this kind of power and torque it might be a chore to drive! Right now my goal is to get it put back together so with the engine pretty much done I need to focus on the TKO part of the project. With less than a month before the power tour and I am leaving Sunday for two weeks I have a lot on my plate if it's going to be ready. To be honest I don't think it's giving up or failure to say I need to think about plan B because this isn't a Gas Monkey episode. I am just doing this as my hobby and it's supposed to be fun right!?! So if it sits out another power tour then so be it.
    But right now I am pretty happy! I honestly thought is would be closer to mid to low 500HP and its really a mild build by BBF standards. There are much better flowing heads and intakes than what I chose and I actually dropped CR a little too so it would be pump gas friendly.
  15. Fst Blk

    Fst Blk Well-Known Member

    That is a beast. I’ve drove the car before and it had torque to spare. This whole combo will make this a completely different machine.
    Good job.

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    tarafied1 likes this.
  16. tarafied1

    tarafied1 Well-Known Member

    thanks son, when I drive it out for the grand opening of Bill's Speed Shop I will let you drive it again!
    Fst Blk likes this.
  17. Fst Blk

    Fst Blk Well-Known Member

    It wouldn’t let me like that post more than once. I clicked like a couple hundred times lol.

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    tarafied1 likes this.
  18. tarafied1

    tarafied1 Well-Known Member

  19. tarafied1

    tarafied1 Well-Known Member

    oh by the way, the avg VE was 107.9, min was 104.3 and max was 110.2 according the the dyno data. That's pretty good for an N/A engine! I understand some DOHC 4 valve N/A engines can reach as much as 130% but I am pretty happy with this result. Usually over 100% is from forced induction. He said on the pull that we got that data he ran it up slower because it's more accurate.
  20. Horseplay

    Horseplay I Don't Care. Do you?

    Then you have to buy that bigger carb. 850 cfm can't feed something that big and efficient no matter what jets you put into it. I love how this hobby just forces us to spend, spend spend! lol

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