Stock 4.6 2 valve shortblock RPM capability

budman5023

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I have been searching for a while now and haven't found anything. Given the right cylinder heads, valvetrain, and maybe even upgraded oil pump, what can I safely spin the cast crank, cast rods, and hypereutectic pistons too. I would assume a rod would go first, but doesn't the 5spd cobra and mach 1 spin 7k on that same rod. I was told by one big mod motor building company 6.2k. But idk. Any thoughts? My head has been going crazy with motor builds for the race car.
 

Jwilso53

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The nodular cranks flex more than forged and rpm is what kills them. I’d rather run more power with boost at a lower rpm than spin a cast crank to 7k.

Just made 460/465 this weekend with stock intake, valvetrain and heads.
 

StrayBullitt

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I'd say 6500 if you want to keep it together, what are your build thoughts to make power past this point ?

My last 2v with stage 3 cams, trick flow heads and Eddy intake started to nose over at 6400, there wasn't much reason to rev too far past 6500.

I've never seen Cobra/Mach rods in person next to 2v rods, but I believe there is a little bit more meat on the bones of the 4v rods.
 

blownstang4.6

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6500. My Mach makes 508rwhp through an auto on the stock motor. Have it shifting at 6k on the street and 6.5-6.6k at the track. 4v and 2v cast crank and rods are the same. The cast crank is perfectly fine if keeping rpm under 7000 and power under 700rwhp.
 

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