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Discussion Starter · #1 ·
Anybody ever attempt to lighten a higher end connecting rod like a Crower/Carrillo/Oliver or maybe profile and clean off the excess on roller rockers(pick a brand, nearly all have dead weight on them short of the very top end)? I am just curious how far you can go. I was looking at connecting rods and the weights are all over the place on similar designs. There has to be dead weight on them, just a matter of where.
 

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with those names you mentioned of rod makers id look else where to save weight,or you can go ahead grinding away and tell us how that works out
 

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There is almost certainly dead weight on these items for particular combinations and not others. These manufacturers have to cater to many different applications, and factor in an element of safety as well.

You'd have two options really, grind/run it on repeat until it breaks, or do some FEA analysis of the designs and evaluate/redesign accordingly.
 

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I'd reframe your question - Is there any power to be gained by removing weight from these parts via grinding?

If it is of interest to you, do a search for F1 (Formula 1) connecting rod
 

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Anybody ever attempt to lighten a higher end connecting rod like a Crower/Carrillo/Oliver or maybe profile and clean off the excess on roller rockers(pick a brand, nearly all have dead weight on them short of the very top end)? I am just curious how far you can go. I was looking at connecting rods and the weights are all over the place on similar designs. There has to be dead weight on them, just a matter of where.
Absolutely not. What will you gain? A rocker arm that is designed correctly has a center of gravity specifically located to optimize the weight. There's no dead weight in a connecting rod, worth removing. The gain will be ZERO in hp and acceleration. These are old myths from years back about weight vs acceleration.

In a low power sportsman engine, the benefit of a lighter component with the risk of reducing the strength is a lose lose situation.

In a high power, high rpm engine the benefits of these components listed being heavy(subjective term) is a positive. Weight can be your friend. Every time I add weight to the Crankshaft, Rods, Pins and Rockers my engines make more hp and have more reliability. Weight reduction is mostly limited to Valves, Springs and related hardware and pistons to a degree. Not rods and rockers.
 

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Chris I've heard something like this before. That a heavier Crank/rod combination will hold power better. Just like it's said a Steel flywheel will make/ hold better power than a Aluminum 1.

Sounds like the Objects in Motion Quote, and with Weight it tends to carry more Motion aka Hp.
 

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Discussion Starter · #9 ·
Lol, yeah, that's the answer I expected.
Absolutely not. What will you gain? A rocker arm that is designed correctly has a center of gravity specifically located to optimize the weight. There's no dead weight in a connecting rod, worth removing. The gain will be ZERO in hp and acceleration. These are old myths from years back about weight vs acceleration.

In a low power sportsman engine, the benefit of a lighter component with the risk of reducing the strength is a lose lose situation.

In a high power, high rpm engine the benefits of these components listed being heavy(subjective term) is a positive. Weight can be your friend. Every time I add weight to the Crankshaft, Rods, Pins and Rockers my engines make more hp and have more reliability. Weight reduction is mostly limited to Valves, Springs and related hardware and pistons to a degree. Not rods and rockers.
Thank you, that was a well formed answer. It was an unknown for me as the super highend builders like yourself don't always publicize what happens in the back room. I just didnt know if there was anything there to gain or not. Thanks again and have a great one!
 

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Lol, yeah, that's the answer I expected.

Thank you, that was a well formed answer. It was an unknown for me as the super high end builders like yourself don't always publicize what happens in the back room. I just didn't know if there was anything there to gain or not. Thanks again and have a great one!
The subject of rod weight came up in the Pro Stock Tech thread, Chris's response jogged my memory. As you probably know, there is a minimum weight that is mandated by the NHRA. I think the general consensus was basically all the engines running would have rods heavier than the minimum.
 

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Chris I've heard something like this before. That a heavier Crank/rod combination will hold power better. Just like it's said a Steel flywheel will make/ hold better power than a Aluminum 1.

Sounds like the Objects in Motion Quote, and with Weight it tends to carry more Motion aka Hp.
I can tell you hanging an extra 7 lbs on the back of your crank will slow you down a bunch. When I ran a stick in my car going from a 20 lb steel wheel to a 13 lb aluminum wheel was 2 tenths. Did that back to back. Look at all of the new clutches they are small diameter with very light flywheels. No one runs a 20 lb wheel anymore.
We run pretty light weight pistons in super stock engines. Light pins too. Cranks are as light as we can get them. Small rod journals. Many run the Honda pin size on the rods. Super stock engines are pretty high rpm engines.
 

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I can tell you hanging an extra 7 lbs on the back of your crank will slow you down a bunch. When I ran a stick in my car going from a 20 lb steel wheel to a 13 lb aluminum wheel was 2 tenths. Did that back to back. Look at all of the new clutches they are small diameter with very light flywheels. No one runs a 20 lb wheel anymore.
We run pretty light weight pistons in super stock engines. Light pins too. Cranks are as light as we can get them. Small rod journals. Many run the Honda pin size on the rods. Super stock engines are pretty high rpm engines.
That is specifically because a flywheel has significant weight far out from the crank center. If most of the mass was near the center you would see little to no gain in any weight change.

On super stock pistons and pins..... I will guarantee that if I built an equal super stock engine with robust pins and pistons vs what I have seen in the past with light weight skeleton components..... it would have significant improvements in hp and acceleration.
 

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Thanks for the Clear up Chris..
 

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That is specifically because a flywheel has significant weight far out from the crank center. If most of the mass was near the center you would see little to no gain in any weight change.

On super stock pistons and pins..... I will guarantee that if I built an equal super stock engine with robust pins and pistons vs what I have seen in the past with light weight skeleton components..... it would have significant improvements in hp and acceleration.
Maybe yes maybe no. Have you ever built a competitive super stock engine? I have several that are decent and all have light weight internals. Even the balancers are aluminum I dont know of any engine builders that specialize in stock and super stock engines that use heavy weight internals except for possibly the forced induction combos.
 

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It's best not to try to lighten a component that is already made a certain way. If you need lighter parts, then buy the lighter parts up front! Such as titanium rods and retainers vs. steel, etc.
 

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Maybe yes maybe no. Have you ever built a competitive super stock engine? I have several that are decent and all have light weight internals. Even the balancers are aluminum I dont know of any engine builders that specialize in stock and super stock engines that use heavy weight internals except for possibly the forced induction combos.
It's all relative to the power produced. Light weight is good in everything, until you lose control of the part through deformation. Then you lose both efficiency and power. We experience it in our more restricted combos. Some parts might be lighter than we curenlty run if there wasn't a minimum weight rule for them. Others wouldn't, even in the low 400hp range...
 
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It's best not to try to lighten a component that is already made a certain way. If you need lighter parts, then buy the lighter parts up front! Such as titanium rods and retainers vs. steel, etc.
True, you rarely can make a precision part significantly lighter, and still maintain the "precision" it originally came with! Lol
 
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Maybe yes maybe no. Have you ever built a competitive super stock engine? I have several that are decent and all have light weight internals. Even the balancers are aluminum I dont know of any engine builders that specialize in stock and super stock engines that use heavy weight internals except for possibly the forced induction combos.
I think comparing "heavy" and "light" the way you are is misleading. Point being made is instead of focusing on weight, more focus is being made on strength. Wrist pins are a perfect example. Yes, light is good until, like Warp said, you start losing control of the part. Pushrods are another example. "Intuition" would say lighter is better but in reality, it's the exact opposite. The strength of a bigger pushrod is a welcome trade off for the extra weight. As with almost everything in an engine, it's a matte of compromise. Not necessarily heavy, but "heavi-er" can be a good thing.
 

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I've seen inside a few Aussie Pro Stock engines over the years, I'd say that parts have been designed better these days, rather than have every possible ounce of weight taken out of them.
 
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