rod failures?

[AirFishAutomotive]

Are there many high hp rod failures to speak of ? In the 800+ range? At what point to the stock rods seem to give out?

 

[Spatel23]

If you are planning on 900+ and doing a build, id do rods without a doubt, especially since it's gonna be open anyway for pistons I'm sure.

 

[Radioflyer]

Isn't around the ~700hp mark when they start failing? I know the pistons are not if but when situation. I'm curious as well.

 

[AirFishAutomotive]

If you are planning on 900+ and doing a build, id do rods without a doubt, especially since it's gonna be open anyway for pistons I'm sure.

rephrased the question


My assumption was to do them so we did not destroy a motor because of cheaping out on the rods I was more curious about the failure point of stock rods. And yes it will be apart with new bearings and hd coated pistons etc.

 

[78f100]

I have stock rods for 30k miles now making 800ish, best dyno was 754hp but that's only the 2nd time on a dyno. I think 900 up would be a good guess.

 

[UpstateDieselGuy]

I would think it may depend on whether you are going to run compounds or a single.

 

[Spatel23]

I bent a couple

 

[ramonpowerstroker]

You gotta look at torque and where that power comes in.. If you got 1900 foot pounds of torque at 1500 Rpms, think that crank only has 1500 revolutions to create all that torque, hence why stock rods bend and break. I think ryan had a bent rod with his and it was only making 800hp... And people are pushing 1000hp on stock rods (use too) with no bent rods why? Dan had twins which brought on peak power real early in the powerband and caused emence stress on the rods while those pushing 1000hp plus only have a huge single turbo that comes on later in the powerband and rpm range.

 

[ramonpowerstroker]

This is why if I was gonna go big horsepower I would do stock rods and hd pistons and a huge s480 or larger with a ****ton of fuel and nitrous

 

[jdgleason]

Torque will be the biggest killer of rods. I'd be willing to bet you could make 1,000+ with no issues as long as torque wasn't through the roof.

 

[Morgan@Midwest Diesel & Auto]

Honestly, anything much over a consistent 1500 ft lbs I would be doing rods. I've replaced a LOT of bent rods in tuner only trucks. Stock compounds make super low rpm torque and a lot of back pressure on a big tune.

 

[powerstroked08]

Like JD and Morgan said the torque is the killer of rods, low rpm high torque.

 

[6.4 Stroker]

Honestly, anything much over a consistent 1500 ft lbs I would be doing rods. I've replaced a LOT of bent rods in tuner only trucks. Stock compounds make super low rpm torque and a lot of back pressure on a big tune.

So with that being said, would it be safer to pull back fuel a bit down low. Then maybe it would live longer on stock rods?

 

[Dzchey21]

yes just bring the power in later and that would def help the rods

Like stated 900 hp is about the point to start considering rods, nitrous/wastegate configurations seam to do a little better on rods since back pressure is lower and usually doesnt make big power down low. I know you were planning on doing a single and spray, stock rods might do just fine for you on that.

 

[dmkolb]

I'll second Morgan as I was around the 600 rwhp mark and 1200 rwt and I have a bent rod that says it didn't like that. I'm sure somethings are a fluke and mine could have been but if I was going to be building an engine skipping the rods and then having a failure later on is going to cost way more to fix than billet rods would have originally. I got my R&R rods from Morgan.

 

[madman1234509]

You gotta look at torque and where that power comes in.. If you got 1900 foot pounds of torque at 1500 Rpms, think that crank only has 1500 revolutions to create all that torque, hence why stock rods bend and break. I think ryan had a bent rod with his and it was only making 800hp... And people are pushing 1000hp on stock rods (use too) with no bent rods why? Dan had twins which brought on peak power real early in the powerband and caused emence stress on the rods while those pushing 1000hp plus only have a huge single turbo that comes on later in the powerband and rpm range.

Ryan sprayed and made over 1000hp with a vgt set up that spooled fast and probably made large torque numbers at a low rpm

 

[Fast-6.0]

Cylinder Pressure is the true component of what bends the rods.

Cylinder pressure on a 1500 ft-lbs of torque can be totally different on what rpm that is achieved and how it is achieved.

A fuel only compound truck has much greater cylinder pressure at 1500 ft-lbs than a small turbo setup (compound or single) with a lot of nitrous does.

Shone's bent rods at 1000hp fuel only.

 

[blk350on20s]

860 and 1600 ft lbs. Fuel. Turbos lit ungodly fast and power came on fast as well. Sprayed to 1100 HP and over 2000 ft lbs. 11.90 at the track on fuel and 11.60 on a small stage. The truck was a dd and got absolutely beat. Had a few bent rods when I built the motor. Very slight and I drove the truck like that but where it happened who knows. Valves had hit the pistons but it had 60k on it since the last time the heads were off. I'd say anything over 800 in a daily truck that gets beat is asking for trouble.

 

[Morgan@Midwest Diesel & Auto]

Cylinder pressure=torque. Cylinder pressure=force exerted on pistons=force exerted on rods=force exerted on crank=rotational force at flywheel=foot pounds of torque.

In short cyl pressure= force=torque. Hp is the acceleration of that force or how fast it can be applied.

The general analogy of using torque as a factor to be more aware of, is in order know what rod failure can happen at. Especially since most people don't have cyl pressure gauges.

 

[Mike@MPD]

Big single ftw! Lol

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