SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: Blue on August 13, 2007, 07:09:14 PM
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Ok my 496 is done (pics coming) as soon as my freakin trailer is fixed (pics coming) I am gonna build a "moderate" 454 and maybe put that in the jet until gas prices come down (yeah right). My "race" 496 is 13.5-1 compression and as you know that takes some expensive gas for a non race boat. Anyways I am looking at cranks and here is the question...
I see alot of motors that have stock GM steel cranks. I see alot of fast motors that have basic cranks without any problems.
So should I invest another big chunk of dough on another forged crank of get one of the Scat Steel Cranks that are stronger than Gm steel?? My engine builder says there forgings are really clean and I can get a 4.250 crank for $219 Brand New and Balanced.
The crank in the race motor was $700 with a graciuos discount so which one would you do for a moderate boat engine??
El Cheapo or $$$$$$$$$$
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You'd be surprised what stock chevy chit can take .
-beerjet-
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Stock steel is fine, I run one in my mild blown 454. The thing is, they're getting harder to come by therefore people started offerring them repop at a resonable price. The Mark IV stuff hasnt been made since the early ninties I think, since they came out w/ the one peice rear main seal blocks which none of the parts work for what we want to do with them.
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I truly trust stock steel but what about a Scat Eagle etc.?? They all claim there forgings are better and stronger. If I find stock steel i am gonna probably have to have it turned, re nitrited etc. so I am leaning towards the Scat Series 9000 Super Duper Space Age Steel
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What kind of power would you expect to get out of a moderate 454?
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I haven't heard of any complaints with the Scat cranks, but I've been out of touch on those kind of parts lately.
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What kind of power would you expect to get out of a moderate 454?
I am thinking 450-500 HP
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Ask around a few machine shops. I think some will tell you to expect to do additional machine work to get those cranks ready to use. Quite a few come through with sloppy machining. Just my .02
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450-500HP should be fine with a factory steel crank.
With that much power I don't think it's necessary to go stronger unless you like to spend unnecessary money.
But I would put the 496 still :D
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I talked with a well known reputable engine builder and he said cast cranks and cast rods are not usually a problem until at least 600 HP.
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I talked with a well known reputable engine builder and he said cast cranks and cast rods are not usually a problem until at least 600 HP.
And usually the rods are the ones that fail at that point .
-beerjet-
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Scat cast steel good to at least 600 HP in jet boat use. Don't get greedy with the timing and compression so you don't detonate it. Detonation and hyper-you-screwed me pistons are the 2 major causes of blown up stuff we see. Never seen a crank fail in a jetboat that wasn't caused by somthing else. We used to offset grind stock Ford 460 cranks (2.5"throws) to Pontiac size (2.250") before the 514 kits came out. That allows the use of stock Poncho rods(we used ARP bolts and beam polished, and shotpeened them)and 403 Olds trw forged pistons. Depending on the oversize, you got about 498" with off the shelf parts! We have a bunch of them out in boats, street/strip, and tow vehicles.One has an 8-71 blower with a bugcatcher on alcohol in a yellow Kachina, the last I heard of it, it was still running 7+ years later! As long as there is no detonation, these live forever, and its an offset ground,STOCK FACTORY CAST crank! Moral of story: make sure the oiling system is up to the task,the clearances are correct, don't detonate it, and no problems. TIMINATOR