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Thanks for being objective Rumble........usually I get some silly remarks and get flamed :flame: when I point out the flaws with the 451. :)
A major selling point for the 451 is the "economy" of it. I don't see the savings, all factors considered in balance. In the long run, starting with the 440 in the first place makes more sense. Buy a 440 short block, bolt on your 383/400 pieces and go. 1)The 2.625" B crankshaft main journal is inferior to the 2.75" RB crankshaft main journal. Bigger is better. Main journal bearing drag is what, .0001 on the time slip? When grinding down the main crank journal, strength is decreased geometrically, not summarily. I don't have the formula in front of me, but the % decrease will surprise you (33%, IIRC). 2)Which goes first in a 451, the block or the crank? Which goes first in a 440, the block or the crank? You have two chains. Which is stronger? The weakest link will break first in each chain. The 451 with the cut down crank, will break before the 440 block/crank combo in this comparison, on paper and in real world observation. Your quote, "I say no way dude. Don't do it. I don't think it's a good thing to do since the "B" block is a little more beefy down low. You would give up that advantage." I'll take the 440 crank spec. advantage, over the B blocks beef advantage. The 440 crank/block spec's are good too 650hp, before the block's main saddles become prone too cracking (per a nationally known Michigan builder, 30+ years experience.) Don't see many 650hp or even 600hp 383/400s/451s, and if you do they don't hang around long. So, if your building a street engine the crank spec. doesn't play as big a factor. But the 451 intake flow for performance, cylinder distortion issue, and piston stability longevity issue does in my book. Did you do the 451 piston in an RB block math yet? What stroke would the crank be to require this piston? Heres to bench racing. :toast: |
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I'm going to do a 451 combo on it. 500 sounds better, but I did say money issue right. (OK, just checkin) :zzz: This is the basic Idea of it. typical 451 build with Edel heads. Intake and carb are on the table. Mostly due to unknown fittment, but a Dual plane and AVS are up to bat since there a inhouse part. (Carb) Headers are Headman street tube. 727/9-1/4 rear w/3.55 cogs and 26 inch tires in a '79 Dodge magnum. For the street, I think the 400/451 combo isn't a bad deal. The focus would be moderate torque over upper HP. A high performing 451, like a brute street strip engine should still hold well though. So long as it's not abused often. I guess like anything else. I did do some research on this combo, but no longevity results turned up or was sought. Nor did piston rocking issues turn up. No math yet. Just browsing. I looked into several areas. But I did not keep anything since looking. The build is still awhile away. I'm slipping in the stock 400 first. Going back to a S/B for the Cuda, then I'll start seriously looking @ strokers for the Magnum. |
OK, I'll muddy the water now. Weight of the car you put the engine into is a factor in engine longivity. 400's making big horsepower can and do live, but htey have to be done right. Get weight down, light pistons, light rods, knife edge the crank. Cap walk is a given in a race motor, but it isn't a killer if you keep on top of it. Race motors aren't supposed to be run for 50,000 miles before being torn down and looked at.
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I've weighed a bunch of them, 383,400,440, and there is not a great deal of difference. There is a lot of variance per size but the difference usually runs 8 - 12 lbs. The RB's are taller for sure but the main bearing bores are larger which helps offset the gain at the top. Also as I understand it the smaller crank main size with a radius is very close strengthwise to the larger main size with the undercut style.
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I have asked this before. Does anyone know what they ran in nascar back in the day? 426 cu in. B? RB? Was it 74 last time they ran one of these? What ever it was it ran for 3 hours at 7000 rpm?
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1) This is the most important reason: the stroker 400 will have the same physical dimensions as the 383 that my car came with, so nobody will know that i have 70 more cubic inches under the hood. 2) The rotating assembly will be much lighter, so I can rev the hell out of it :evil: 3) Everything from my 383 switches over, without spacers and whatnot 4) Smaller engine = easier to work on 5) Lastly, 440s are expensive and the cheapest one I could find was 500 bucks and needed a full rebuild. Whereas, I bought the 400 for a 100 bucks(with a trans) and the 440 forged crank for 50 bucks and had the components to build the stroker, I didnt factor in the rotating assembly because I would be doing the same thing if I went with a 440. Now if I could have found a cheap 440 and my car didnt come with a 383, than I would have definitely went the 440 route.....actually, more likely the 496-500 route. |
I called the Ross Piston tech line and asked about any problems they are aware of with short pistons, in particular rocking in the bore and in the case of pistons whose oil rings end up in the pin bore, if excess oil consumption is a problem. Now I know the first thing that comes to mind is "ya they will say what they want to sell pistons." Anyway here's the answers I got. First, he says they use a mathematical formula (which is a ratio) of how long to make the skirt versus what the compression height is,to prevent excess piston slap and they aren't aware of any problems or they would correct the problem or stop making the piston. Second, the engine IN THEORY might tend to use more oil with the ring in the pin groove, but in reality it isn't the case as long as the bore is sized correctly for the piston and the cylinder is straight and round. There you have it.................djs
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Killer Mopar, don't forget, it's just as easy to build 499 inches with a 400 block as it is with a 440 block-you use a 4.15" stroke. The only diference is you must use a shorter rod in the 400 than the raised block, which changes rod ratio, but not much else. And yes, I've done ALL the math :thumbsup: ......djs
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Really? I never looked at the math. The longer 440 rod is a no no for a 500 cube 400 based stroker?
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Rumble, in a 400 block with a 4.15" stroke the longest rod you would be able to use is the 440 6.765" length. This leaves 1.14" for piston height. Ross makes a piston that is 1.12" long, which would leave the piston .020" down the hole if the block was the factory height of 9.98". Of course you could cut the block to increase compression if required. This is using readily available parts. Dem's da berries............djs
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okay, here's a question for all: how many of you have seen a big block mopar actually snap the crankshaft apart? i have never seen a 440 block/ crank break unless it was 'creatively' put together. i have seen one 451 combo crack right in half; the impact was so strong it broke the tranny in half at the same time. there was a split from the timing cover seal to the tailshaft seal; crazy shit.
okay, so we've come to one general conclusion ; money makes it last. so lets apply this knowledge: a 451 is built with budget parts, and it costs 3000 dollars and lasts 30,000 miles. a 451 is built with all the trick, rare-alloy parts and building processes that are known to man. it costs 10,000 dollars and lasts 100,000 miles. so in the end, the only difference is with one method, you break cheap parts quite often and possibly empty the junkyards of big block mopars at a faster rate. the other way is taking out a loan to build a motor that you will almost be worried to rev because the crank is worth more than your wife's wedding band, and there is more man hours in the block prep than the body / paint prepping. just so when it actually does break, you can watch 3 times the money come flying out from underneath your car. either way seems to have its obvious, err, perks, but i would prefer to just tear the motor apart every year before anything can happen instead of going 5 years before thinking about those main bearings 'because the shop said it could handle it' just to have a rod blast a whole through block and take out a slick and put the car in the wall or something. hah that was a little exaggerated, but you get my point |
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