turbodano

We have a customer with one of our turbos on it and it made great power 390whp@15psi on our S256 but it broke a rod while the customer was out street rodding around town. The question here is when you over power a stock rod what end of the rod does it normally break? This one broke at the crank. Is that normal?

This car had upgraded pistons but stock rods. Not a good combo with over 300whp.

tony1

Since it has upgraded pistons, that means it's been apart, I wouldn't be surprised if the rod bolts weren't torqued correctly or something. I'm not sure what the logic behind building a motor with upgraded pistons and stock rods is, they're not good for a ton more than the stock pistons are.

agrn93ls

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">Since it has upgraded pistons, that means it's been apart, I wouldn't be surprised if the rod bolts weren't torqued correctly or something. I'm not sure what the logic behind building a motor with upgraded pistons and stock rods is, they're not good for a ton more than the stock pistons are.</TD></TR></TABLE>

broke people like me that busted the DD and can only afford pistons at the time..

turbodano

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">Since it has upgraded pistons, that means it's been apart, I wouldn't be surprised if the rod bolts weren't torqued correctly or something. I'm not sure what the logic behind building a motor with upgraded pistons and stock rods is, they're not good for a ton more than the stock pistons are.</TD></TR></TABLE>

Thanks Tony I was kinda thinking that same thing with the rod bolts. The rod bearings were replaced recently. How would you tell the difference between the 2 types of damage?

tony1

Don't know, don't care too much. Fix it with good rods and put it together right and you don't have to worry about it anymore. I try not to waste time pondering things that don't matter too much.

miller

Dan post pics of the broken rod we will be able to tell you alot more by seeing the rod and how it broke or i should say why it broke.

turbodano

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">Don't know, don't care too much. Fix it with good rods and put it together right and you don't have to worry about it anymore. I try not to waste time pondering things that don't matter too much.</TD></TR></TABLE>

Your all heart.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by miller &raquo;</TD></TR><TR><TD CLASS="quote">Dan post pics of the broken rod we will be able to tell you alot more by seeing the rod and how it broke or i should say why it broke.</TD></TR></TABLE>

Thanks and we will post them when we get it out of the car. I was just wanting to be able to tell if it was from too much HP or if it was a mistake on the mechanics part on the rods.

tony1

My stockish motor broke at 3 times it's stock power, do you know why? C'mon...

PrecisionH23a

I would agree with the rod bolt. I wouldn't waste anytime finding the guilty culprit because you were making 390whp on stock rods. These rods were designed for 160hp... not over 400. Bolt-stretch or not, you're definetely pushing the limits on stock components. I've tuned a few 500whp stock block set-ups but again it's pushing the limits. We can get into the nitty gritty here about the tune, timing, peak cylinder pressures, bolt-stretch and all sorts of other variables but it's a waste of time.

I typically stay away from using stock rods on anything over 300whp on B series. Skimping out on $300 bucks for rods is going to end up costing this guy 2x as much now.

Kyle R

iTrader: (1)

Post some pics

Joseph Davis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">Don't know, don't care too much. Fix it with good rods and put it together right and you don't have to worry about it anymore. I try not to waste time pondering things that don't matter too much.</TD></TR></TABLE>

I agree that using forged pistons on stock rods was a waste of time, but I disagree that diagnosing the failure point is useless. I am a geek who likes useless real-world-inapplicable trivia, and you will not deny me access to such info!


Post up the carnage pics. I want big glossy mega-mega pixel closeups of the rod bolts, bearing halves, beam, etc.

agrn93ls

in for pics to see what my stock rod motor is gonna end up looking like.

tony1

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrecisionH23a &raquo;</TD></TR><TR><TD CLASS="quote">Skimping out on $300 bucks for rods is going to end up costing this guy 2x as much now.</TD></TR></TABLE>

2x? Ha, ****, 5 times easily, and that's if your time isn't worth much. If he's paying labor, well over 5 times as much. I just don't understand it.

Odds are the crank is trashed, piston probably hit the head and valves, hopefully no valves broke and the rod didn't come through the block.

mar778c

iTrader: (1)

Every engine with a broken rod i've seen, requires at a minimum a full rebuild of the bottom end and serious work on the head.



Modified by mar778c at 8:21 AM 8/13/2007

PrecisionH23a

That's funny... because I meant to type 5. Stupid number pad.

SOHCD16y8

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrecisionH23a &raquo;</TD></TR><TR><TD CLASS="quote"> Stupid number pad.</TD></TR></TABLE>

You cant trust them.

PrecisionH23a

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHCD16y8 &raquo;</TD></TR><TR><TD CLASS="quote">

You cant trust them.</TD></TR></TABLE>

It's worse than a stock rod

SOHCD16y8

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrecisionH23a &raquo;</TD></TR><TR><TD CLASS="quote">

It's worse than a stock rod </TD></TR></TABLE>

Lol

turbodano

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Joseph Davis &raquo;</TD></TR><TR><TD CLASS="quote">

I agree that using forged pistons on stock rods was a waste of time, but I disagree that diagnosing the failure point is useless. I am a geek who likes useless real-world-inapplicable trivia, and you will not deny me access to such info!


Post up the carnage pics. I want big glossy mega-mega pixel closeups of the rod bolts, bearing halves, beam, etc. </TD></TR></TABLE>

I agree about it being a dumb move to not install rods. Plus he knew it was big power for such stock parts.

hotimportcrx

Thats Insane. You rebuild the bottom end with new bearings, pistons, rings, fresh hone, and whatever else you decided to do while the motor was apart, but you didnt spend 300 on aftermarket rods. Then decided to go make 390whp on those stock rods. Thats insane. Thats like throwing money in the toilet and if your paying for labor (assuming you are), thats like throwing a shitload of money in the toilet. I would have rather built the motor the right way and drove around NA until i had the rest of the money. "If you wanna play you gotta pay" and if "you dont wanna pay, you learn the hard way".

turbodano

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hotimportcrx &raquo;</TD></TR><TR><TD CLASS="quote">Thats Insane. You rebuild the bottom end with new bearings, pistons, rings, fresh hone, and whatever else you decided to do while the motor was apart, but you didnt spend 300 on aftermarket rods. Then decided to go make 390whp on those stock rods. Thats insane. Thats like throwing money in the toilet and if your paying for labor (assuming you are), thats like throwing a shitload of money in the toilet. I would have rather built the motor the right way and drove around NA until i had the rest of the money. "If you wanna play you gotta pay" and if "you dont wanna pay, you learn the hard way".</TD></TR></TABLE>

I just sold the guy a turbo other than that I did nothing to the car. I was trying to figure out if an error was made other than not getting upgraded rods. Like the guy who installed the rod bearings.

sewell94

You make it sound like the new bearings were installed later on after the pistons. If so theres your culprit, a bearing prolly started to make noise, they put another set of new bearings in prolly w/o recon'ng the rods which one was probably out of round, spun a bearing and rod broke.

turbodano

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sewell94 &raquo;</TD></TR><TR><TD CLASS="quote">You make it sound like the new bearings were installed later on after the pistons. If so theres your culprit, a bearing prolly started to make noise, they put another set of new bearings in prolly w/o recon'ng the rods which one was probably out of round, spun a bearing and rod broke. </TD></TR></TABLE>

What are you psychic that is the story I was told to the tee. I bet you are correct about the rods being out of round.

SOHCD16y8

Why would a spun bearing break a rod? Where the bearings spun when the motor was pulled apart.

DaveF

extra power + high rpm = broken stock rod.