Rod alignment

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Steve.k
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Re: Rod alignment

Post by Steve.k »

They were not molnar they were dirt track racers. They were running 800hp dirt track engines who tried this system. They reported they're findings back when engine was dynoed. 3-5% on 800hp. You do math. Seems logical now with LSP's findings.Theres hp to be found no one even talks about yet. Theres some smart guys out there for sure.
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Re: Rod alignment

Post by blykins »

That's not what my sales rep told me. I was told 15 hp. 15 hp on an 800 hp engine is not even 2%, which could be a day-to-day difference in weather conditions, dyno room conditions, or practically anything else.

3% is 24 hp.

5% is 40 hp.

You do the math. Which is it?

If it's that important to have a rod perfectly centered under a piston, then by all means, we all need to run piston guided rods. Other than that, no matter what rod you put in there, it's gonna move with a running engine and it's not going to be centered.
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Steve.k
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Re: Rod alignment

Post by Steve.k »

3-5% is what i heard. Maybe they built a few.Even 15 hp is a good deal at no extra costs im thinking :D Ah yes piston guiding even better by looks of it. If anyone going to test the limits NASCAR definitely push them!
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Re: Rod alignment

Post by blykins »

Either way, I'm not one to put my eggs in the basket of a hear-say and exaggerated marketing diagrams.

Yes, 15 hp is good, but 40 hp from an aluminum block to iron block is even better.........and that one is not hear-say, but documented by several engine builders that I can give names for.
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Steve.k
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Re: Rod alignment

Post by Steve.k »

LSP can you run the centered pistons with the standard big end rod layout? Or does it have to be the narrow style?
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Re: Rod alignment

Post by LSP »

Steve.k wrote: Wed Mar 21, 2018 12:02 pm LSP can you run the centered pistons with the standard big end rod layout? Or does it have to be the narrow style?
If the bores & rod throws are exactly where they should be, yes, you can double guide, crank better be sturdy.
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Re: Rod alignment

Post by elwood »

Steve.k wrote: Wed Mar 21, 2018 10:46 am There's HP to be found no one even talks about yet. There's some smart guys out there for sure.
fixed it for ya

i'm going to shim, torrington and bellville the small ends
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Re: Rod alignment

Post by fdicrasto »

So if I use some lightweight spacer/washer shim setup to position the rod perfectly centered in the piston and make sure that there is no binding or misalignment at crank pin end then I could benefit from whatever hp gain this is worth and not necessarily have to purchase a new set of pistons ? Does .005"-.010" seem a good rod to piston end play clearance if this was attempted ? Just curious as to any opinions; sbc engine.
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Re: Rod alignment

Post by Kevin Johnson »

Steve.k wrote: Fri Jan 19, 2018 2:23 pm
IMG_2193.PNG
This is the theory we talking about. Some independent testing reported gains of 2-3% on 800hp engines. Mostly due to more stable piston and ring seal in their view.Note the diagram maybe slight exaggeration but have heard where some rods were out close to this much.
My Porsche 928 connecting-rod/paper-weight is designed following their theory. The Porsche rod (made by GKN) was the first commercial use of sinter-forged rods so this goes back about 45 years or so. I can guarantee that Porsche did that for a good reason particularly since they could have saved money by using the same offset rods in the 944 but they didn't.

Just something to consider.
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Steve.k
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Re: Rod alignment

Post by Steve.k »

Ahh yes the boys in Stuttgart. Did a tour of factory and museum there!!!WoW is a understatement!!! Yes im thinking this centra-lign design is very smart idea!! Porsche know for high hp per cc and longevity!!
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Re: Rod alignment

Post by blykins »

SBF blocks, Scat cranks (and a Callies), with Scat (and Compstar) rods. Both are my engines. The rods are centered on the cylinders you can see.

Image

Image

One I found on the internet:

Cleveland block with what looks to be an RPM crankshaft.

Image

Again, not that it matters, because a dynamic situation will find the rods going everywhere, but someone explain what "Centralign" rods would do for me in these cases where the rods are centered on the pins.
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Re: Rod alignment

Post by Steve.k »

?
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Re: Rod alignment

Post by blykins »

My point exactly.
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Re: Rod alignment

Post by Steve.k »

blykins wrote: Wed Mar 21, 2018 7:12 pm My point exactly.
Brent maybe you found some anomalies! My own 438 is off by fair bit. Most are off. If you got two thats great.However if Porsche spends time to do this, LSP pointedwhy nascar goes the extra step theres a reason. If you got some straight thats good. Chances are next ones wont be. One less headache in my view.
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Re: Rod alignment

Post by blykins »

This is more of a commonality for me than an oddball situation. You have to remember that I specialize in building SBF engines. These are not the only two that I have built.........

It’s going to be a 50/50 shot on whether the Centralign rods fix anything at all. So do I order a set of regular rods and a set of Centraligns at the same time?

This is getting ridiculous.

IMO, if it’s such an important thing to have a perfectly centered rod on the pin, then you need to go to a piston guided rod. Otherwise, the little end will never be centered in a running engine. To me, it’s not even that important and no one has been able to prove otherwise. The true benefit of a piston guided rod is to reduce friction at the big end.
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