Bottom end ..fact or fiction ?

blksc

Registered User
Previously, i had seen on this board that the stock bottom end would need rebuilding at roughly 300HP at the wheels. I'd like to challenge that! Today marked the first time i've taken down an sc engine (have taken a plenty of chevy's down and build them up) and right off the bat i saw the weak points in the bottom end, and it aint the crank -- its the rods. To build your stock bottom end to take atleast 500HP at the crank, have yours rod beams polished, and shot peened -period.
 
depends on which year. If you think a 89-93 bottom end is going to hold up to 300+RHWP you are crazy. When Chris Wise pulled the rods out of his 300RWHP SC before it was super fast, he had some bent rods.

I have tuned a few 300RWHP Stock bottom-end SC's that are still running. They are getting close to the limits, but with a good tune they should last for a while. If you think you are going to get 350+RWHP out of a stock bottom end, you are just crazy. Thats 100% more than stock, no factory engine was built to handle twice the stock power.

Brian
 
I kinda agree with Chris. It is possible to coax a LITTLE over 300 RWHP out of a stock, good condition bottom end. Much over that, and it needs attention. XR7 Dave is running a bone stock bottom end at 300ish RWHP without problems (so far :) )

The 94-95 rods are better than the early rods and ARP bolts will help bearing life. Making sure the tune is right that will keep it from detonating and bending them. A bent rod is caused be detonation and detonation alone. If a rod's over powered or over revved, it will destroy the bearing or break.

The stock crank can handle just about anything if it's in good shape, same for the block.

The stock pistons are a weak point at high power levels. Ring lands and skirts will start to break. In a properly tuned stock motor, the pistons would break before the rods would.

Even a stock type rebuild with the rotating assembly being balanced will up the power level the motor can handle. The bearings, pistons and rings from Federal Mogul aftermarket in 2003 are better than the OEM pieces they designed for Ford in '87-'89 when the SC motor was being developed.
 
So are you guys saying that ford used a different process to forge the rods in our cars ? because other forged rods can easily stand up to 350hp at the wheels. Also when i say 'stock' bottom end i mean the rods and crank. I wouldnt attempt to throw that kidna power at stock bearings and stuff like that.
 
V8's can stand 350 hp easy.

350/8 = 44 hp/cyl

350/6 = 58 hp/cyl

58 x 8 = 464 HP V8.

You don't see very many 464 HP 302, 351 or 350 V8's running around with stock rods. Also, as power goes up, the boost is generally turned up thus making detonation more likely. The stock (early style, 94-95 rods were heavier) rods running at 300+ RWHP don't leave much in reserve for the occasional bad batch of gas that makes it ping.
 
But im talking about re working the stock components, and not just running them as normal. in the first post i said having the rods shot peened and the beams polished.
 
ARP bolts go a long way to strengthen a rod. That's usually where failure starts is with the bolts stretching and the journal going out of round. Then the bearing gets chewed up or the rod breaks.

Polishing will do some prevent catastophic failures, but the bolts will still stretch all the same. I polished the beams on the first set of rods I used (from a '90) and they bent rather nicely when I let it detonate at WOT for too long. I'm rather surprised it didn't break considering it bent about 1" from being straight.

Shot peening will also do some (again, very little but some) to prevent catastrophic failures. But, you can't make the factory steel stronger than what it originally was.

Most aftermarket rods are made of far better material than stock rods. That said, I'm using a set of 95 rods with ARP bolts in mine.
 
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