Snapped/ bent rods

[quake]

There seems to be alot of debate as to what the stock rods can take for abuse. We have seen 800 crank hp from a few memers with stock or shot peened / beam polished rods. Yes aftermarket forged rods are better but what can stock take for abuse day in and out.
This topic needs to be debated, i want to see a stock rod snapped or bent from horsepower alone. No stories please with bhg rod knock, detonation, too much timing advance. I think our rods are about as strong as the mkiv rods and i don't see them shot peening or beam polishing.


lets see pics and hear all the stories... Ill start i bent a stock rod hydro locking the motor on oil when a stock turbo blew. Still drove that motor another 3k then tore down for a rebuild was shocked when i saw the rod

 

[spoolint78]

its all in the tuning.

i think with a good tune, and some arp rod bolts you will be fine.

Most i've seen bent because of hydro locking, and rod knock.

 

[starscream5000]

Ask Malloy for a pic of his stock rods that gave out on him when he was making ~500 HP. He can fill you in on his story.

 

[Tun_x]

Hmmmmm..

 

[quake]

Ask Malloy for a pic of his stock rods that gave out on him when he was making ~500 HP. He can fill you in on his story.

im not worried about my rods and i read mikes story he over boosted and bent then broke one.

 

[supra_ed]

usually the rod bolts/studs will go before the rod- unless vapor lock. a good 7m rod that has been checked (magnafluxed, resized, rebushed, etc.) with arp bolts and shot-peened, oughta be pretty stout. i dont think anyone has really tried pushing them. why should u? 1000-ish for pauters is cheap in the long run. good insurance.

 

[TurboStreetCar]

usually the rod bolts/studs will go before the rod- unless vapor lock. a good 7m rod that has been checked (magnafluxed, resized, rebushed, etc.) with arp bolts and shot-peened, oughta be pretty stout. i dont think anyone has really tried pushing them. why should u? 1000-ish for pauters is cheap in the long run. good insurance.

heh, not after you just spent 2500+ on machine work, pistons, gasket set, head studs and headgasket, ect.....

I agree its good insurance but its alot of money that might not need to be spent. Im interested in what stock rods can really handle aswell.

 

[gilberjj]

i took mine to 1500rwhp, for 2 seconds........ but you'll have to take my word for it. i don't exactly have proof.....

 

[starscream5000]

Two seconds was enough to make you fear for the rods eh? :naughty:

 

[starscream5000]

im not worried about my rods and i read mikes story he over boosted and bent then broke one.

Think about it, how much power was he making at that point when he overboosted?

 

[drjonez]

and did he confirm that it was pure HP (tq) that cause the problem?

 

[MRSUPRA]

There have been people running much more power (600+rwhp) than Mike Malloy using stock rods. Remember, Mike was running high boost with a piggyback ECU along with methonal injection. God only knows how much detonation he could have had.

 

[starscream5000]

That's true, I don't recall if he ever mentioned detonation, but that is a very probable reality at the time destruction occured.

 

[drjonez]

There have been people running much more power (600+rwhp) than Mike Malloy using stock rods. Remember, Mike was running high boost with a piggyback ECU along with methonal injection. God only knows how much detonation he could have had.

exactly.

big power = standalone.

 

[Adjuster]

I've seen them break at the oil squirter hole in the shoulder, and the stock bolts fail. (Squirter hole failure was on a rod knock, the bearing was spun, heated up, and welded the rod to the crank, and bang goes the rod.)

The bolts were snapped and bent too, but there was a clean sheer point right through the squirter hole.

I went with the Pauters because on my engine, I'm using 6" long rods with custom sized pin and journal bores. (Honda pins, 237sbc rod size, both are smaller diameter than the stock, but make finding parts easy.)

Hopefully will never find out what it takes to break a Pauter rod.

 

[staticpat]

its all in the tuning.

i think with a good tune, and some arp rod bolts you will be fine.

Most i've seen bent because of hydro locking, and rod knock.

I love spoolint78s signature. Shows the engine bay of a true mkiii owner. Spent the money on a FFIM, but holds up the hood with a baseball bat .

 

[Mr. Y]

exactly.

big power = standalone.

Why? ECU just controls timing advance and amount of fuel. If they are ok, who cares is it stock or standalone? Of course, making stock ECU run adequate settings is not as easy and safe as standalone, but it's another story...

As for detonation... Doesn't it damage pistons, not rods? Or may be both... But I doubt detonation can damage rod without damaging piston.

 

[rakkasan]

Why? ECU just controls timing advance and amount of fuel. If they are ok, who cares is it stock or standalone? Of course, making stock ECU run adequate settings is not as easy and safe as standalone, but it's another story...

As for detonation... Doesn't it damage pistons, not rods? Or may be both... But I doubt detonation can damage rod without damaging piston.

When you lie to the ECU about how much fuel is being delivered, it doesn't know it so it runs thru the stock timing map as usual. You end up with a lot of boost with timing set for minimal, if any, boost. That's not a good thing.

Doc is right....

 

[IJ.]

Anything over 230 crank is no longer "safe" soon as you start modding it's a hand grenade that you've pulled the pin on.

The better quality Rods just give a bigger margin for error, ANYTHING no matter how good can fail.

People think I'm too conservative when advising on engine parts but I take this approach as I know most here can't afford to do 2 builds and prefer to be cautious.

Mike pushed the envelope and paid the price, it becomes a time/cost/hp equation and at those sort of increased load levels it WILL fail it's just a matter of time.

Personally the way my car is used tends to make this happen sooner rather than later and my Ferrea Valve spring failure highlighted this nicely, these springs are rated to 10K I ran mine hard at 8000+ sustained not just a 3>4 second run and button off.

I've found a lot of hard limits and now build accordingly and try to pass on what I've learnt when advising people here to save them the expense/hassle.

I've stuck my nose into a few threads here to have it bitten off by bench racers that now know it all without ever having run their motor hard and will think twice before doing that again.

 

[dbsupra90]

fyi-

friend of mine works at a metal shop and tested some stock rods. they actually contain a small amount of titanium. they were better built than the aftermarket/performance v8 rods he tested.

personally, i dont think rods are a weak point in our car. but given the abuse and lack of proper care, anything can give up. of course it would be best to go ahead and build it w/ forged rods like ij was saying.