About that time 470,500, or 512

Forced Induction Mopar

  1. MidTexCuda

    MidTexCuda Ancient Member

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    I am about ready to buy my rotating kit form my 400 stroker build and I need some input.
    The car will be a F1x pump gas "street" car 6500 max sealing.
    I want to keep the piston CH above 1.300 and have made a matrix of my rod options. I know rod ratios are not that big of an issue but because this is a forced induction build I have read that a lower RR will lend itself better for detonation, filling of the cylinders, and getting the exhaust out.

    All of the numbers below will still allow me to run a 1.300 CH or larger piston.
    470--6.600 to to 6.700 rod will yield 1.72 to 1.73RR
    500--6.535 rod will yield 1.57RR
    511--6.535 rod will yield 1.54
    Please let me know what looks best to you. Will there be a huge issue with side loading with any of them.
     
  2. famous bob

    famous bob mopar misfit

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    they say, longer rods have less side loading than short rods .:coffee2:
     
  3. bOb shingler

    bOb shingler Well-Known Member

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    I use a 7.125" inch rod in my rb512" with the 4.250" crank. you won't be able to get that long a rod in your little "b" motor. use the longest rod you can and the shortest piston like you want with a 1.30"+ or- compression height.
     
  4. Old Man Mopar

    Old Man Mopar Righteous Dude

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    My 400 will be a 440 Source 470 (1.48 CH) 3.915" stroke/6.535" rod Approximate Bobweight:
    2160. This kit has the smaller 2.200" (big block Chevy sized) journals, and the counterweights
    are finished at the smaller "B" engine size. All good as far as I'm concerned.
     
  5. 451Cuda

    451Cuda Well-Known Member

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    X2 on the 470.
     
  6. MidTexCuda

    MidTexCuda Ancient Member

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    I have been leaning toward the 470 just wanted some one to give me the warm and fuzzies.
    My main question was which combo would react better to boost from a timing and exhaust standpoint. Or would the difference between 1.54 to 1.73 RR be to small compared to the side loading increase on the block from the bigger stroke and shorter rods.
     
  7. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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    The rod length thing is splittin hairs. Build whichever one is easiest and most economical for YOU.
     
  8. MidTexCuda

    MidTexCuda Ancient Member

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    rusty that's part of the problem. The cost is the same no matter which way I build it.
     
  9. charger426

    charger426 Well-Known Member

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    The cost of the stroker kit is the same but the supporting parts have differnt costs. Going through the same thing with my RB build. Same price for a 500 or a 523 kit. I'm leaning on a 512 kit as it sounds like A LOT more work to get 523 oiled and needs some major heads and carb to run oh and streetablity because a concern.
     
  10. 451Cuda

    451Cuda Well-Known Member

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    Go with the longer rod as long as it leaves room for a good ring package
     
  11. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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    Then build the biggest un. lol
     
  12. BlueDream

    BlueDream Aspiring Mopar enthusiast

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    What's that old saying? Something about replacements for something. I forget.
     
  13. 451Cuda

    451Cuda Well-Known Member

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    470 will possibly save you some money if you use a stock forged crank and have it offset ground. It's also (supposedly) easier on the bearings over a 4340 crank.

    If you're starting from scratch and buying a kit with a new crank, just go with the 512.
     
  14. oldkimmer

    oldkimmer FABO Gold Member FABO Gold Member

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    .................the old saying was that theirs no replacement for displacement, but now theirs boost and nitrous....................kim........
     
  15. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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    Splain please. I thought with a longer rod, the compression distance has to be shorter and that would give less space for a good ring pack because it starts to cram the pin into the oil ring area.
     
  16. Abodybomber

    Abodybomber Breaking street machines , since 1983.....:) Legendary Member

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    What are, the piston options? R.R.R., brings up the ring pack, this is necessary information. Some of the newer pistons, move things around(thinner ring packs, shorter skirts,etc.) This would ,help....
     
  17. MidTexCuda

    MidTexCuda Ancient Member

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    Most of the off the shelf pistons I have been looking at are diamond or icon. I may also get a custom set of Steve Morris/ diamond pistons. The CH of the piston will not be shorter than 1.300 because I don't want the ring pack getting into the pin area and also I want the stability.
    I understand the adage of "no replacement for displacement" but this engine has a multiplier on it. I can create the defiance of 40cubes fairly easily. My goal is to find the more stable platform. I have read that the higher RR will give the piston more time at TDC and narrow the window for the tune but stabilize the piston and reduce the side loading of the cylinder wall. While the lower RR will widen the tune window and promote better cylinder fill on a boosted engine. This however comes at the cost of piston speed and side loading of the cylinder walls. This is my dilemma unless someone can tell me the RR is so close that it will not matter (my green light to go big) or the side load of the 512 combo mixed with boost will cause issues (my green light to go small).

    let me add this: Stock block (I know it will be a grenade but it will be as bullet proof as I can make it) and I plan to make about 1200HP at the crank.
     
  18. 451Cuda

    451Cuda Well-Known Member

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    Exactly, hence why I said "as long as it leaves room"


    Stroker BBC's survive with much less rod ratio and make damn good power...any of these combos listed has the same or better rod ratio than those. If you're buying a kit with a new crank, just go for the 512 IMO.
     
  19. bOb shingler

    bOb shingler Well-Known Member

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    that chevy guy smoky yunick stated, select your stroke and piston compression height then use what ever rod length fits. so if that is true go for it. it also doesn't, matter one bit if the oil ring is in the piston pin area.
     
  20. mike1965

    mike1965 Well-Known Member

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    Go BIG or go home LOL , I would go with the biggest cube you can go with , I went with a 540 RB in mine and a 505 in the wifes car you will regret it if you don't down the road and it\s always twice as much to do it twice LOL

    Mike
     
  21. bOb shingler

    bOb shingler Well-Known Member

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    get the 512" kit like every one suggests. heads are going to have to flow big time because of the short rods so you might want to consider something like ported 440-1's etc, even with the supercharger pushing the air in.
     
  22. nitrojunkee

    nitrojunkee Well-Known Member

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    I'm not sure why you'd try to make that kind of power on a factory block. And I think I'm in the minority here when I say that I believe they can handle more than people think. I also believe things like girdles are basically a waste of money. The right and good machine work with head/main studs will go a long way, but not 1200hp imo. And you already seem to know this, so why possibly waste the cash? I wouldn't go over 800-900hp... I built a Procharged 496 last year, and even with a little D1SC I know it's more than capable of producing factory block breaking power. I'd reassess your block situation or power goals, before continuing.
     
  23. famous bob

    famous bob mopar misfit

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    all lot of you people don``t believe in cryogenics, but I had my block and mains done (froze), using a girdle w/ studs-line honed the whole bit. if you don`t think a girdle will help a r/b, you better install one (right) and stand back and think about it a long while, and do some research. It`ll probably help this design block more than any other out there !!
     
  24. MidTexCuda

    MidTexCuda Ancient Member

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    I knew I was going to get the block comment and that's ok.
    Love to have one but don't have the cash and if I could buy one it would be a waist of money to not go aluminum and 4.50 bore and maybe 55mm raised cam. At that point I don't have the heads for 4.5 bore, ect, ect.
    I will keep the tune low. I really don't want to make more power that I can plant so I will tune up or down accordingly.
    I am looking at cyroing the block and I have arguably the best aluminum cap system. My heads are on the small size but can do the job.
    Thanks for all in input guys.
    I think I am going to do the 470 because it gives me a bigger window for piston compression heights and rod lengths. On the 500 and 511 you can really only run one rod the 6.535 or shorter because the comp height of the piston gets too short.
     
  25. 273

    273 Well-Known Member

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    Bore size is the ultimate factor on power, piston speed if taken out to the max rpm each combo will ruffly have the same power potential. But since you put a 6500 rpm limit the largest Cid will have the most potential. 400 block is the best choice for sub 500 inch engines but over 500 I'd go with 440 you ain't gonna miss to extra .020" bore size.
    Yes longer rods with have less frictional hp loss but the cubic inch will make up for that and more bore life how many miles do you plan on putting on it.
     
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