Stock main caps ?

Paul Kane wrote:

richter69 wrote:those pics Nick put up, that was an aluminum rod deal.

And how did it compare when the engine had steel rods in it?

I already posted about those pics on page 3...

Don't know, you have a steel rod D9 block with a 4.300 RPM Steel crank and steel rods with Eddy Heads running a few hundred shot out there running?

I can say my 528" A460 headed DOVE Block motor was walking the hell out of them at 905 HP and 13:1, scat steel 4.3 and Oliver Billet Rods.

14:1 466 @ about 625hp with a D1 block and CJ Rods walked them a little.

11.5:1 750 hp 466 w/Scat Hbeams we did for EMC walked them slightly, but in fairness we ran the shit out of it on pump gas and hard dyno pulls, I'm supprised that one wasn't worse.

My old 521 with the DOVE block 10.5:1 and Eagle Hbeams, Never Dyno'd never notice any walk.

Haven't noticed any A460 blocks moving them around with steel rods, nore any stock / slightly modified 429 or 460 i've owned over the years have I noticed any cap walk.

A bad tune up will make about anything....walk. Sometimes into the oil pan.

As Hp goes up, the more the engine is trying to force the crank out the bottom of the block. Also as stroke goes up with the same amount of cylinder pressure the more force the crank sees.

The crank is balanced, so as the crank pin goes around the center line of the crank the counter weight is off setting that force.

The aluminum rod is still transferring the forces trying to exit the crank out the bottom of the engine. While aluminum rods will act as a shock absorber the cushion the effects of detonation I don't understand how it could effect the total load or force of the crank being pushed down in the block, It may slow it to some degree but the total force still gets there.

Lem Evans wrote:

Paul Kane wrote:In this case, "shock" is a kind of "force." So same page there; again me being more general and you being more specific.

So you don't believe aluminum rods can reduce cap walk? And/or, you believe they will measurabley and substantially hurt overall engine output compared to the steel rods?

Or...are you saying that you'd take the cap walk (etc) over the "substantial" power loss? And if so, where would you draw the line (how much cap walk (etc) does it take for you to eventually opt for the aluminum rods)?

1] I do not believe aluminium rods reduce cap walk.
2] I believe force makes the crank rotate.
3] I never said that I'd 'take' cap walk "substantial" or otherwise...do not put words in my mouth.
4] I draw no lines.
5] I do know that the high end aluminium rods cost about 1/2 as an A460 block.

Lem, I'm not putting words in your mouth; I'm asking you a question, your perspective. I asked you an either/or kind of question, and based on your point "1" it looks to me like you chose the "either" (the former, not the latter of the two scenarios I proposed).

Also, the price of the aluminum rods was not part of the question. The question is simply whether aluminum rods can reduce the possibiliy of main cap walk. And it looks like you feel the answer is a flat "no."

And I think they can.

But I also think that no-one here (or anywhere of which I am aware) has ever done the back-to-back test.

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dfree383 wrote:Don't know, you have a steel rod D9 block with a 4.300 RPM Steel crank and steel rods with Eddy Heads running a few hundred shot out there running?

I can say my 528" A460 headed DOVE Block motor was walking the hell out of them at 905 HP and 13:1, scat steel 4.3 and Oliver Billet Rods.

14:1 466 @ about 625hp with a D1 block and CJ Rods walked them a little.

11.5:1 750 hp 466 w/Scat Hbeams we did for EMC walked them slightly, but in fairness we ran the shit out of it on pump gas and hard dyno pulls, I'm supprised that one wasn't worse.

My old 521 with the DOVE block 10.5:1 and Eagle Hbeams, Never Dyno'd never notice any walk.

Haven't noticed any A460 blocks moving them around with steel rods, nore any stock / slightly modified 429 or 460 i've owned over the years have I noticed any cap walk.

All steel rods.

Again, I think about the only way to scientifically deduce a final conclusion is to build an engine, for example first with steel rods, dyno it at 3000, 4000, 5000, 6000, etc, all the while checking the caps at each rpm range to see where cap walk first shows up. Then, replace the steel rods with aluminum rods and rebalance, dress the caps, and repeat the test and see if the cap walk appears under the same circumstances/same rpm. And even then, is that a measure of the forces transmitted through the typical rotating assembly...or only a single, real-world scenario--one scenario of possibly endless engine combos-- where that specific combo will walk only with steel rods while another combo might walk with either aluminum or steel at that horsepower level? And does one induce more walk than the other? Such a test is absurdly impractical, let alone painstaking. And depending on the power levels we're presumably talking about, it might very well be a waste of time relative to the severity of the cap walk in question.

I realize this next example is removed from the original question, but for the sake of exaggerating my perspective: I would think that a 750 hp 521 with steel rods is more likely to show cap walk than a 750 hp 466 with aluminum rods. My point is that the steel has more mass swinging around, is transmitting more shock to the crank and main caps, etc. Why woudn't that be true (between the two types of rods in question) if both engines were otherwise identical except for the rod selection (less exaggerated but technically one rod type causing more walk than the other)? And if they are both walking, then wouldn't the rod with less mass be better suited under the circumstances? I'm pretty sure it would be, but I don't know it to have been proven with any isolated testing.

So I still think that the aluminum rod has it's advantages in the area of cap walk. Sure it comes at a price, dollar-wise, lifespan-wise, etc. Or one could choose less expensive, longer lasting steel rods...and have greater risk (or greater amount) of cap walk. Or not? I just tend to think the aluminum has an advantage here. That being said, I'm also beginning to suspect that if anyone went thorugh the trouble of proving one way over the other that the difference might not be that noteworthy afterall.

Paul

Lem Evans wrote:A bad tune up will make about anything....walk. Sometimes into the oil pan.

Ha! Tune obviously should be more of a concern, and understandably so.

IDT-572 wrote:As Hp goes up, the more the engine is trying to force the crank out the bottom of the block. Also as stroke goes up with the same amount of cylinder pressure the more force the crank sees.

The crank is balanced, so as the crank pin goes around the center line of the crank the counter weight is off setting that force.

This is only partially true; the reciprocating mass is factored into the balance, but the power generated/transmitted by the combustion process is not fully accounted for in the balance.

IDT-572 wrote:The aluminum rod is still transferring the forces trying to exit the crank out the bottom of the engine. While aluminum rods will act as a shock absorber the cushion the effects of detonation I don't understand how it could effect the total load or force of the crank being pushed down in the block, It may slow it to some degree but the total force still gets there.

Thats kind of my point: it changes when it gets there and how it is delivered.

Paul

Lem Evans wrote:
"2-bolt, filled block , girdle ......about 750 plus 150 of nitrous"......Like has been said....'how many passes?'
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I would not call be bearing "good" although it's not in trouble yet. The front part of the bearing shows a good deal of wear and the rear about none. Taper in the block's housing bore or taper at the rod journal....flexing of the block or crankshaft.

Improper seal "crush"