H and I beam rods

[dons vs]

its not just revs, boost and outright hp can kill them, poor oil pressure, detonation, there are heaps of reasons for rod failure.
Most of the rods we buy state a hp and rpm rating in there specs

 

[Reaper]

Greenfoam, the state of the rods after a race wern't to healthy lol, engine failures wernt due to piston shattering either hehe.

The point I was getting across is there is no set HP limit on a set of rods They should be rated with revs in mind, even a perfectly balanced billet rod will still banana if you push it to hard, but no need to get into engineering lessons!

Most of the engine failures in that era were not the fault of the rods. During the 70's root cause was due to a poor oiling system exacerbated by a stock sump and oil pickup particularly in the L34's. They did get around it somewhat by running an "oil cooler" which acted as a quasi dry sump however it took some time to iron out all of the glitches.

During the mid 80's there were a lot of failures due to the new "A9L" heads being poorly cast with flash being left in the coolant galleys causing hot spots, head gasket and other failures. This showed up at the HDT effort at SPA.

The later engines from the mid 80's onwards failed around the rear main where the blocks cracked. Check out the latest "Australian Muscle Car" magazine which documents these failures quite well.

Reaper

 

[SilverVH]

Where did I say rod failure was the main cause of engine failure? :S I said they wern't to healthy, if anything, the fact they held together should be a testament to their durability.

All I was saying is there should be no concrete HP rating on a set of rods. A 400HP engine revving to 8000rpm will damage a rod long before a 400hp engine revving to 5000rpm will. (Basing it on HP vs. Revs with no extenuating circumstances ie. oiling issues, tuning issues etc.)

Or am I by myself with this one.
Wasn't trying to start arguments guys lol

 

[Reaper]

Where did I say rod failure was the main cause of engine failure? :S I said they wern't to healthy, if anything, the fact they held together should be a testament to their durability.

The words you used eluded to rod failure being a major cause.

All I was saying is there should be no concrete HP rating on a set of rods. A 400HP engine revving to 8000rpm will damage a rod long before a 400hp engine revving to 5000rpm will. (Basing it on HP vs. Revs with no extenuating circumstances ie. oiling issues, tuning issues etc.)

Why not? Surely it would be an ideal indicator for the application. I think it is fair to require that the other systems on the motor are functioning correctly. It is a bit much for a manufacturer to accept liability if his component was an innocent casualty of war.

Reaper

 

[dons vs]

Where did I say rod failure was the main cause of engine failure? :S I said they wern't to healthy, if anything, the fact they held together should be a testament to their durability.

All I was saying is there should be no concrete HP rating on a set of rods. A 400HP engine revving to 8000rpm will damage a rod long before a 400hp engine revving to 5000rpm will. (Basing it on HP vs. Revs with no extenuating circumstances ie. oiling issues, tuning issues etc.)

Or am I by myself with this one.
Wasn't trying to start arguments guys lol

Ok in your same argument then with a different scenario.

2 engines both have same rods in them
both revving to 8k
ones making 200hp stocko
the other is a supercharged engine making 500hp

which ones going to **** its self first?

Of course rods have a hp and rpm rating, its not all about revs, outright cylinder pressure and hp will effect the life of a rod no doubt about it.
40psi into a squared chamber running alot of advance timing will bend a rod no worries even if its only doing 4-5k if it pre dets.

 

[SilverVH]

Your bringing external influences into the equation. Outright HP has nothing to do with those external influences. Timing, pre-detonation, lean AFR of course will factor into rod longitivity (or lack of) regardless if it is a 300hp streeter or a 1000hp screamer.

I'm not saying that manufacturers don't brand rods by hp rating (simply because its easier to rate and simplier to compare) yes they do. Do I agree with this form of measurement to rate rods? No. There is to many varying factors in every combination, that you can't just say, these rods are rated to 500hp. Sure it may be an "ideal indicator" to base stength on, but it is simply false. HP does not affect torsion strength, casting quality, material grading of a rod, shock rating, yield strength, stretch, it has absolutely nothing to do with it but yes cylinder pressure can play a part. How fast a motor is revolving is the relevant and contributing factor.

When is cylinder pressure at its highest?
What factors contribute to cylinder pressure?
How does cylinder pressure relate to the peak HP of an engine?

 

[pumba]

Your bringing external influences into the equation. Outright HP has nothing to do with those external influences. Timing, pre-detonation, lean AFR of course will factor into rod longitivity (or lack of) regardless if it is a 300hp streeter or a 1000hp screamer.

I'm not saying that manufacturers don't brand rods by hp rating (simply because its easier to rate and simplier to compare) yes they do. Do I agree with this form of measurement to rate rods? No. There is to many varying factors in every combination, that you can't just say, these rods are rated to 500hp. Sure it may be an "ideal indicator" to base stength on, but it is simply false. HP does not affect torsion strength, casting quality, material grading of a rod, shock rating, yield strength, stretch, it has absolutely nothing to do with it but yes cylinder pressure can play a part. How fast a motor is revolving is the relevant and contributing factor.

When is cylinder pressure at its highest?
What factors contribute to cylinder pressure?
How does cylinder pressure relate to the peak HP of an engine?

how will my Procomp H-beam rods go when i am revving my motor to 7500rpm? they told me it will be fine at those revs. I am hoping to make at least 600hp

 

[vt1538]

how will my Procomp H-beam rods go when i am revving my motor to 7500rpm? they told me it will be fine at those revs. I am hoping to make at least 600hp

Good luck.

 

[vyjess]

they will end up in ya sump!

 

[pumba]

^^^ I was hoping they would give me a new glory hole in the side of my block... It would be handy to be able to see inside the running motor

Just for your info, im not actually building up a Procomp motor... I just know how much 'SilverVH' likes Procomp gear