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Discussion Starter #1
The 393 that I'm putting together has:
69 351 W Block
arp main studs
Scat 4340 forged crank
Eagle H beams
arp pro series rod bolts
probe srs pistons.

I going to have HP in the upper 500's NA.

I want to run a N2O system on it. two stage with equal power levels in each stage. I'll run stage 1 from 3000-7000. stage 2 from 5000-7000. Perhaps as much as 150hp per stage. Each stage has it's own independent timing retard.

Do you guys think this shortblock will live? I saw a 408 car craft mag put together with I beams and cast crank, same series pistons make similar power - but less N2O.
 

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Nope, Block will hold for a little while, but with a proposed 900HP your over the limits of even the older block..... 750 is the conservative belief, 800 reasonable.

You'll beat it to death, sooner than later.
 

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Discussion Starter #3
So maybe I should lower the amount of N2O!

At the 750-800 range do you think I could use a cast crank instead?
 

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DCook said:
So maybe I should lower the amount of N2O!

At the 750-800 range do you think I could use a cast crank instead?
IMHO, the stock block tops out around 650 HP. Many run more, but some break blocks, too. The false economy to an overstressed block is that when it lets go, it often takes a lot...or nearly all...of your expensive internal components with it. I'd be tempted to try 75 and 75 on the 2 stage shot, or maybe ~90-60 split.

I'd absolutely go with a 4340 crank in this power range. While a cast crank "might" live for a while at 600 HP, the problem is that it will flex like crazy under this abuse, generating stress, vibrations, and harmonics that will likely break the block. A stock block will survive more horsepower with a very strong crank, light weight reciprocating components, and an excellent balance job.

Steve A.
 

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I'm curious to see your top end with a proposed 600hp ...

As stated the block is not reliable to the amount of power you're looking to make.

Additionally that crank is rated to about 650hp in cast form, you'd be pushing the limits.

There are also better pistons out there when you're running that much boost. Probe makes a decent, budget piston IMO but JE, Ross, CP and others make a better one from my experience. When you're talking about the power that you are it would be a very wise investment if it were me.

Some people are lucky, some aren't. Are you willing to gamble your $5000 shortblock that you are?

$.02

Brian
 

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Discussion Starter #6
Well, I'm cheap and I'm crazy.

I don't plan on running that nitrous often or without race gas. I haven't spent anywhere near $5000 on the shortblock. Maybe half that.

The induction is a Predator on top of a victor JR with TFS-Rs. 12-1 compression. Custom big ass solid flat tappet cam.
 

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To each their own.

Either you've found some cheap machine work and purchased the parts used or you've got more than $2500 in that shortblock. Regardless, I'd rather spend a little extra now than to build it twice.

Best of luck with the project, keep us posted when you get soem #'s.

Brian
 

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Discussion Starter #8
Here's a thought...

What if I used a steel studded girdle, the the one coast high performance sells and half filled the block?
 

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Discussion Starter #10
stinkin' Lincoln said:
what pistons do you run with a 3.85" stroke in a 9.2" deck block?

Forrest
I have a 9.48" early 351W block, dude.
 

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stinkin' Lincoln said:
so what's the difference? are the early blocks only .020" shorter? :confused:

why do people always say there's such a difference?

Forrest
Fords "CLEVELAND" engine came as a 9.2 block. Windors are 9.48 for 69 and 70's and 9.5 for later yrs. New blocks like the FPP and Dart make a 9.2 now.
 
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