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Discussion Starter #1
I'm curious as to how much power each rod journal diameter can hold. Obviously they can hold 1400-1500hp, but past that opinions seem to vary by quite a bit.

1.770?
1.880?
2.000?
2.100?
2.200?
2.300?
2.500?
 

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Well, like I said in another post, Bryant told me a few years back asking about the strength of a 1.888 rod journal that the crank would handle about 2700 hp....

How they figured that number, or if it was tongue in cheek I have no idea....
 

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Discussion Starter #3
Well, like I said in another post, Bryant told me a few years back asking about the strength of a 1.888 rod journal that the crank would handle about 2700 hp....

How they figured that number, or if it was tongue in cheek I have no idea....
Funny you say that. I checked into ordering some rods and all manufacters had a heart attack when I mentioned 2800-3400hp on a 2.100 journal. I'm feeling much better now that a few have said don't worry about it.
 

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I'm curious as to how much power each rod journal diameter can hold. Obviously they can hold 1400-1500hp, but past that opinions seem to vary by quite a bit.

1.770?
1.880?
2.000?
2.100?
2.200?
2.300?
2.500?

We have done 1465 HP with a 1.888 rod journal.















At 10,000 RPM and 60 PSI boost with a 4 cylinder!:rolleyes:
 

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All motor wannabe
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We have done 1465 HP with a 1.888 rod journal.















At 10,000 RPM and 60 PSI boost with a 4 cylinder!:rolleyes:
What the hell was that in? and Old RS200????

damn and i was told my 1.888 would have the rods breakings the crank at over 1100 hp FI
 

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Discussion Starter #6
Learn new stuff everyday. Stroke plays a huge roll in journal strenght I learning, along with center counter weights.
 

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I don't think it's the journal diameter alone that determines how much power the crank can take. You have to figure the stroke into it. The longer the stroke, the less overlap with the mains you have. A 1.88 journal 2.75 stroke crank would handle more power than a 1.88 journal 4.25 stroke for example.
 

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Discussion Starter #10
My crankshaft is 2.750 mains, 3.750 stroke, 2.100 rod journal. After talking with a few rod manufactures, they got me scared on the 2.100 rod journal in a 2900-3400 hp engine that will see 9000-9500rpms. I'm all squared away now, a few people helped to eliminate my worrys. Yes the crankshaft was purchased new for the power level and rpm range.
 

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to add to what lil john has stated,
...the ultimate cranks strength will depend on
the main bearing diameter being able to overlap or be as close to as possible to the rod bearing surface.

there is little strength when only the WEB or counterweight is the only material between the two journals apart.

a old model T or model A is like this,...and they twist all the time, even though they are a "flat" design.
 

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Outlaw bill, doing the math on your crank it shows that there is .550 of material overlap between the main and rod journals alone. That's a linear measurement not an area measurement obviously but I wouldn't be worried about that crank at all. I've seen -.250 overlap measurements on 1500+ cranks before. Yours should be more than strong enough.
 

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Well, like I said in another post, Bryant told me a few years back asking about the strength of a 1.888 rod journal that the crank would handle about 2700 hp....

How they figured that number, or if it was tongue in cheek I have no idea....
there are 4 cylinder making 1200hp on 1.7-1.8 journals and they have fiarly long strokes to 90-100mm. they have equally small main under 2 inch IIRC.

the answer is, pretty god damn strong.
 

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forging or billet material has not been mentioned , the crower forgings are made in ky. they are dense forgings in real 4340 . the material needs to be accounted for there boys. no junkalloy. heat treating is a big factor and radius flexxing and stress relieving makes a big diffence in ours. the forgings are stronger than billets at the same dimensions
 

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to add to what lil john has stated,
...the ultimate cranks strength will depend on
the main bearing diameter being able to overlap or be as close to as possible to the rod bearing surface.

there is little strength when only the WEB or counterweight is the only material between the two journals apart.

a old model T or model A is like this,...and they twist all the time, even though they are a "flat" design.

Very good points. Thanks for clarifying.
 

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forging or billet material has not been mentioned , the crower forgings are made in ky. they are dense forgings in real 4340 . the material needs to be accounted for there boys. no junkalloy. heat treating is a big factor and radius flexxing and stress relieving makes a big diffence in ours. the forgings are stronger than billets at the same dimensions

Thanks for the input. That seems to be a hot topic, forgings versus billet...
 

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most companys wont invest the 90k in a good USA forging like we did , they have to rework the dies on occasion to keep the parts in spec. the dies overhauls are very costly , bryant makes a sweet billet and so do we but forgings are where its at. grain flow , density , certified materials are all accounted for in a crower. some other brands are offshore forgings which are not certified material. most builders find this out the hard way.
 

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How about cranks with individual rod throws (meaning one rod per throw like most honda/import engines vs a crank with two rods per throw like our american engines. Does this have an influence on the hp capability of a crackshaft due to how the powerpules transfer torque to the crank. Also does the distance between the main saddles (basically bore spacing) have an influence on the power capibility. I dont know the answer to these questions just have opinions on them but would be interested to see what some of you men have to say.
 

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forging or billet material has not been mentioned , the crower forgings are made in ky. they are dense forgings in real 4340 . the material needs to be accounted for there boys. no junkalloy. heat treating is a big factor and radius flexxing and stress relieving makes a big diffence in ours. the forgings are stronger than billets at the same dimensions
Really, Forged in KY. would have never thought KY had a forging facility
 
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