installed in my 1985 iroc, I have a 1998 vortec motor that came out of a silverado. The pistons are forged speed pros. I'm wondering how much horsepower the bottom end of these motors are good for. The crank and rods are stock. My buddy had the exact same motor (98 vortec '880 casting) with a stock crank, but had forged mahle pistons and gm pink rods and sprayed 250, running 10.80s at 127mph on mutliple ooccasions and it has right at 100,000 miles on it since it was built. I spin my motor up to 7000 rpm on a daily basis, and so far so good. I'm planning on spraying it soon. i want to spray atleast 150. Also i believe i'm running moly rings, so how nitrous could i sppray before this baby falls apart? It's ~400fwhp at the moment.

 

Why didn't anyone reply to this?

 

Probably because any comment would be a guess.
http://www.stevesnovasite.com/forums...ad.php?t=10093

Vortec has cast crank and PM rods so is no different to any other SBC with those parts
http://www.ls1tech.com/forums/9145330-post10.html

 

10.80s at 127 impresses me, I may try that.

 

There really is no true answer for this. You cannot take a used engine, and say

"WELL, this particular crankshaft will handle 498 FT.-LBS. of torque and is good for 7,200 RPM's."

Depends on if the engine was beat up a lot in the past, what kind of specific driving they did, it all will come into play. You might have a bottom end that will just handle that 400 FWHP that you claim, or that could handle 450-500+.

Especially with nitrous, it's a pretty tricky thing to get down, even more so true if you want to run a bigger shot. If your timing is too advanced, and you have a single stage 150-200 shot, say bye bye.

My opinion is, if you want to run an engine that will have nearly 600 horsepower, invest in the good parts, then you will be safe and sound, with a warranty also.

 

the stock OEM components are rated by chevy, to with stand 350-400hp and 5700rpm-6000rpm,obviously we all know guys that have pushed their components to exceed those limits, but stress is cumulative, and the harder you push or the more frequently you push past those limits the more likely you are to experience component failures
look at the rated hp

http://www.sallee-chevrolet.com/Chev.../10105123.html

the DART SHP Chevy Small Blocks are significantly stronger castings in the stressed areas and are rated UP TOO 600hp, the little m blocks are even stronger

http://www.dartheads.com/products/sh...ll-blocks.html

http://forum.grumpysperformance.com/...hp?f=53&t=1110

http://www.dartheads.com/products/en...-m-blocks.html

it would make very little sense to build an engine thats intended to produce over about 500-550 hp on a STOCK PRODUCTION Chevy block, risking most of the other components, simply because the main caps will walk or the lifter bores will crack or the cylinder walls will begin to flex ETC. at some point, and that point will be noticeably lower in the power curve than an aftermarket block , thats been properly machined, Ive got splayed 4 bolt main caps and use all ARP hardware in my block and Im still reluctant to push it much past those limits, because I see the results far to often in my shop, when guys insist on spinning the nearly stock engines to 7k plus or dropping a 150-200hp worth of nitrous,or use of stock bolts on an engine without the proper mixture and ignition controls and all forged components.

 

The weakest link in Gen I SBC's is the rod bolts. If you don't know whether something like ARP rod bolts were installed in your engine and you're spinning it to 7000 RPMs, you're on borrowed time.

BTW, it's RPMs more than HP that is the limiting factor here.

 

RPM's essentially are horsepower.

Horsepower = Torque X Engine RPM / 5,252.

His real problem will be when he's down low in the torque range, and decides to spray. An instant 100-200 more FT.-LBS. will probably destroy a stock bottom end. Just doesn't seem like a good idea at all to me.

 

That's to say nothing of will the 700R4 behind the engine handle the extra 200 lb-ft any better.

Honestly, any time you spray like that you're going to be rolling the dice.

 

It's actually more of a combination of power and rpms but scaling rpms up quicky puts more and more load on the internals than scaling just hp up. In other words, an engine making 500hp and 5k will have a bottom end hold out a lot longer than one making 350hp at 7k (granted those are very rough numbers Im throwing out, it's just demonstrating a point).