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| 383tpimachine | 350 vs 400 mains | ||
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Master Guru
 
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What are the advantages of going with the 400 mains over the 350?
I know they are bigger so less heat but anything else? Blocks/cranks are the same price so that is negligible. |
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Posted on: 2014/1/17 21:36
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1985 Atomic Orange 400YSIT56-Racecar build 1970 El Camino-Awaiting LSX |
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| bogus | Re: 350 vs 400 mains | ||
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Grand Imperial Pooh-Bah
 
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bigger would also mean stronger... but what about weight?
I will be curious, too. |
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Posted on: 2014/1/18 0:24
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| 383tpimachine | Re: 350 vs 400 mains | ||
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Master Guru
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Bigger means stronger crank but bigger bore in block so weaker block/main.
Other side is bigger bearings to coat. Oil can get hotter in extended rpm runs. In a street/autox/weekend roadrace car keeping rpm under 7000rpm is the bigger bearing better or worse? |
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Posted on: 2014/1/18 0:51
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1985 Atomic Orange 400YSIT56-Racecar build 1970 El Camino-Awaiting LSX |
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| rklessdriver | Re: 350 vs 400 mains | ||
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Senior Guru
 
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I presonally run 350 main size (2.448) in my race car which uses a 4" stroke.
The smaller the journal sizes, there is less drag. The block is stronger in the main web. There is less weight. There is less pressure on the oil wedge. The 400 main makes the crankshaft stronger because it increases journal overlap but thats the only advantage. The strength of the smaller crank journal is easily overcome with better materials... the negatives of the bigger journal are more serious problems and some of them are serious limitations in certain applications. Racing engine builders run the smallest journals they can get away with. Will |
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Posted on: 2014/1/19 2:30
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1984 Corvette. 434 SBC with a Powerglide. Best pass - 8.48@160MPH 1.23 60ft on MT 275/60R15 Radials. 1972 Corvette. LS5 454 BBC with M20 4 speed. Best Pass - Doing good to just pass a gas station. |
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| 383tpimachine | Re: 350 vs 400 mains | ||
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Master Guru
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Does this include roadrace or is it drag racing limited?
I know the prostock guys run 283 mains. |
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Posted on: 2014/1/19 3:13
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1985 Atomic Orange 400YSIT56-Racecar build 1970 El Camino-Awaiting LSX |
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| rklessdriver | Re: 350 vs 400 mains | ||
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Senior Guru
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Quote:
Yes. Our latemodel dirt engines use 350 mains and the common IRL/Quad 4 rod journal which is 1.850.... these engines use 3.8 to 4 strokes... make almost 900hp and turn 8900rpm for 50 to 150 lap races... run all season before refresh and the cranks last 3 yrs. Rods last 1 year. We build limited latemodles with 283 mains and honda rod journals. These make 600hp with flat top pistons and flat tappet cams. 3.3 to 3.5 stroke. 7800-8200rpm motors. Cranks and rods last forvever. The only place we have run larger journals is in a Pro Charged Outlaw 10.5 engine. BBF Boss Hemi. Makes over 3,000hp and has run 6.30s over 220mph in the 1/4mile. Even there we didnt do anything special. Stock BBF mains and common BBC rods. Most of the time we run the smallest journal we can. Alot of classes these days are limited on min journal dia. Will |
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Posted on: 2014/1/19 20:16
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1984 Corvette. 434 SBC with a Powerglide. Best pass - 8.48@160MPH 1.23 60ft on MT 275/60R15 Radials. 1972 Corvette. LS5 454 BBC with M20 4 speed. Best Pass - Doing good to just pass a gas station. |
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| 383tpimachine | Re: 350 vs 400 mains | ||
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Master Guru
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Quote:
Understood. thank you for the help. I will stick to the 350 mains and a stronger material crank/main material. |
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Posted on: 2014/1/19 20:45
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1985 Atomic Orange 400YSIT56-Racecar build 1970 El Camino-Awaiting LSX |
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