ziggs

hey guys
i'm building a motor at the moment and thinkin about an actual hp limit. how much hp and torque can a 351 4ma crank take using std rods maybe wif arp studs and forgies??
im guessing a few of u fellas may hav streched these engines right out so wat kinda numbers cause them to fail. and i'm not goin for crazy rpm either prolly 6500rpm max obviously i was thinkin of using a better bearings than std.
any feedback would be great

shaynet

Unless you are supercharging you are unlikely to break it.

My 351 happily spins to 7000rpm with 11.4 : 1 comp using 302 rods & arp bolts

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The cop said "Do you know why I pulled you over". I said " Well, that all depends on how long you have been following me!"

TruBlu351

Welcome to FF ziggs.

First off, how much HP did you have in mind? Any drag racing performance goals?

Block no more that 30thou
Good crank (there are people using standard cranks and 4MA's with what seems equal results)
Prepped rods (shotpeened & polished)
Good bearings like you said
APR rod bolts and mains stud kit
Forged pistons & good rings.

There are several here with 500hp and going strong.

You'll obviously need the heads to make that power and valve train to keep it together.

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XE Falcon
393 Tremec TKO 9"

brenx

If prepped right you'll have no issues with just about any hp.

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XB Fairmont (street car) 11.07@123.02mph.

ziggs

thanks guys.
i'm goin 4 as much as a 302 head can flow which i think will be within the limits of the crank and rods.

XD408

ive been told no more than 7500rpm or 700hp but with 2v heads unless supercharged u dont really have to worry bout that.

Rhett

Why forged pistons?

I thought you only needed those if your were using NOS. I've heard they can be a bit of a pain. My XE came with a spare 351 and when I pulled it apart, 3 of the forgies had broken skirts.

TruBlu351

Good Q.

Speaking to various engine builders forgies with moly rings are not as tollerant to daily driver cold start/go driving as casts and hypers.

Forgies for excessive nitrous (>150hp shots), otherwise hypers are OK.

What cylinder pressures (HP levels) would warrant forged pistons for a naturally aspirated setup only?

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XE Falcon
393 Tremec TKO 9"

brenx

I run forgies with chromoly rings. What I'd think warrants them is use. ie drag racing. If you have a valve failure or high compression. A forgie is more likely to live. I don't have to usual forged piston issue of piston slap during a cold start. Chromoly rings just take more punishment.

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XB Fairmont (street car) 11.07@123.02mph.

Rhett

Does a forgie warrent a greater or lesser clearance in the bore?

I've heard that it's more critical to warm up the motor as early as possible with forgies (old wive's tale ???)