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Discussion Starter #1
which company offers the lightest aftermarket rods?

blueprint i beams weight?
manley i beams weight?
carillo weight?
crower weight?

just want to know which one is the strongest yet the lightest?
 

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It will be a custom rod from Cunningham, Carrillo or Manley.
They will need a lot of info from you to determine the requirements.
You can spend more than 1500 per rod if you go all out.
 

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A much better question, and what you should really be concerned with, is which aftermarket companies use the best aerospace quality material, the best bolts (not ARP), forgings with the correct grain structure in both the beam and the cap, and refuse to buy or sell Chinese products. None of the companies you mentioned fulfill all of those criteria. In fact most of them don't make the cut on ANY of the imporatnt issues.
Unless you're someone who's drag racing at the apex of the game, and you're magnafluxing and refreshing your parts on a regular basis, the lightest rods shouldn't even be a consideration to you. The strongest rods you can find are what you need to be looking for.
The lightest rods are made of Aluminum.
The strongest rods are made of Steel.
The strongest light rods are made of Titanium.
The strongest bolts are around 300,000 psi tensile strength.
 

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A much better question, and what you should really be concerned with, is which aftermarket companies use the best aerospace quality material, the best bolts (not ARP), forgings with the correct grain structure in both the beam and the cap, and refuse to buy or sell Chinese products. None of the companies you mentioned fulfill all of those criteria. In fact most of them don't make the cut on ANY of the imporatnt issues.
Unless you're someone who's drag racing at the apex of the game, and you're magnafluxing and refreshing your parts on a regular basis, the lightest rods shouldn't even be a consideration to you. The strongest rods you can find are what you need to be looking for.
The lightest rods are made of Aluminum.
The strongest rods are made of Steel.
The strongest light rods are made of Titanium.
The strongest bolts are around 300,000 psi tensile strength.
So what would be the strongest rod (Company) u know of?
 

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which company offers the lightest aftermarket rods?

blueprint i beams weight?
manley i beams weight?
carillo weight?
crower weight?

just want to know which one is the strongest yet the lightest?
Just curious, why aren't OEM tsx rods a choice?
 

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I gotta disagree on some of this. Steel is not the strongest and no where close.

Take a 400 gram 6 inch rod and put 500hp through it and its over. I don't care what company made it. Most of the big names in rods won't even build a rod that light, and the rods in the 425-475 gram range aren't even rated over 300hp in most cases. This is why the steel turbo rods that have been proven to not deform after extensive use and big hp are all huge 550-650 gram rods. It takes a lot more material to make them strong. I can't tell you how many steel rods under 475 grams I have seen bend or break at 300hp level and some were very high $ talked about here. Probably the lightest off the shelf rod is the Saenz at around 395g and its stronger than a lot of the others that are heavier.

Compare that to a 6 inch 350-370 gram aluminum turbo rod and you can put 3-4 times the power through it no sweat. 1300hp, all day.

Steel and aluminum both have their place....but steel is NOT as strong in terms of handling hp and rpm.

How long would a steel rod last in an 8000 hp top fuel motor?
 

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Luke, I don't think the majority of people here have the time and patience of a Top Fuel / Top Alcohol pit crew to tear down an engine in 30min after every pass at the strip. :emsmilep: I see where you are going, but it isn't relevant here. Joe was making a broad generalization for the materials most widely used in smaller motor applications.

The stock rods can handle 600 whp as has been proven time and again. If whp was the measurement for what the rods are rated at, we would all be recommending the factory rods for almost every application on this forum.

Al, like Ti, requires different considerations during the build. How many people spend the money on Ti stuff, and then pay to have it fluxed at the cyclic intervals as per the manufacturer's recommendation?

OP, more discussions and user feedback on the different rods is available in these threads:
http://www.k20a.org/forum/showthread.php?t=83115
http://www.k20a.org/forum/showthread.php?t=93072
http://www.k20a.org/forum/showthread.php?t=95338

Your budget will likely be the largest consideration. Shop around, and contact the companies that actually make rods.
 

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Stock Honda rods are stronger than a lot of the cheap aftermarket rods, and the biggest question you have to ask yourself is how high are you going to rev the motor, because piston speed is the critical thing here. As long as you're being reasonable with your rev limit, and that depends on the length of the stroke so we're talking about 4,900 ft/min, then stock Honda rods have proven to be strong enough even in endurance road racing.
Luke,
The HP an engine makes has absolutely nothing to do with how strong the rods need to be. The #1 determining factor is the piston speed, which is directly related to rpm. The type of racing is another important consideration, especially in road racing where the engine gets used for braking and is held at high rpm at light load. Those conditions require stronger rods and bolts than in an application where you're just accelerating from one rpm to another. The expected lifespan of the rod and the temperature its going to operate in determines whether or not you'd consider using Aluminum. Even 7068 Aluminum, which is the alloy all Aluminum rods are made from, gets weaker the hotter it gets and only has a tensile strength of 103,000 psi at 68 F. Top Fuel guys use Aluminum rods because they're cheap and get thrown away after every pass. They use what's OK for one pass and nothing more because they don't have time between rounds to put new pistons on stronger steel or Titanium rods.
4340 steel can have a tensile strength up to about 340,000 psi, but at that point it'd be too brittle so its generally heat treated to about 260,000 psi where it has the best cyclic load fatigue lifespan of ANY metal. EN30B is an English steel alloy that works quite well in the same applications, but heat treating it is an extremely complex process and one not known to most heat treating companies in the USA. Steel is at its strongest at 400 F.
Titanium (6Al4V) isn't as strong as 4340 steel, only about 200,000 psi tensile strength, so to use Ti6Al4V the rod needs to be made beefier to be as strong. At the same strength it'll be lighter, but about 4 times the cost. It also doesn't have the cyclic load fatigue strength of 4340, so at the same overall strength it won't live as long. Normal engine temps have very little effect on the strength of 6Al4V.
The rods in the picture are 6Al4V Titanium and were made by Cunningham, who use only the best bolts in the industry (A1).
 

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Well I just lost all that post..stupid phone.

Long story short...I disagree based on the original question and the fact that it does not specify application of endurance racing. Ounce for ounce, size for size, a steel rod can not handle the abuse aluminum can. Metallurgy aside, a light weight steel rod can't handle the power or rpm without deforming...usually at the cap.

And top fuel does not throw away Rods every round. They can be used over and over. It's the only material that can take the abuse.
 

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Discussion Starter #17
i was discussing the lightest rod for drag purpose,which can be "light,yet strong and reliable" so i dont have to worry about it like lets say a person would worry about an alluminum rod maybe :blur:
 

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Luke,
Its the metallurgy of the materials that's at the very heart of the matter, so as long as you're willing to put "Metallurgy aside" (your words) then you must be basing your opinion on something else. Blind faith... Voodoo... Hero worship... Some rumor you heard... who knows?
Aluminum is without question the weakest of the 3 materials under discussion and that's not an opinion, that's a well tested and documented scientific fact. Top Fuel teams go through pallet-loads of pistons and rods every season. They're considered to be cheap consumable items and certainly not worth using more than once when there's BIG money at stake on every pass. The standard material in most forms of motorsport is steel, unless the budget is big enough and then it's Titanium.
N2O,
Back to the original question, huh?
If you want "light, yet strong and reliable" as you've stated, then Titanium meets all of those criteria quite nicely. If you can't afford Titanium then that leaves you with 2 choices, and as long as you're willing to forget about "reliability" and replace your rods on a regular basis (if they stretch .0015" or don't pass a Zyglo test throw them away) then Aluminum is fine. But you began by asking about steel rods, so talk with Jim at Cunningham once you know exactly what you want and what all the dimensions are, and you'll be set. Plan on ordering the rods about 3 months in advance because Cunningham doesn't mass produce generic shelf rods, every one of them is custom built specifically to the customer's needs.
 

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How about real world experience and trial and error? I'm not sure if that kind of stuff holds water anymore with all the information online, but it should. There are many other considerations and what Actually happens goes beyond looking at the tensil strength of materials. Top fuel does not run alum strictly for cost purposes. Those rods are a shock absorber, can move without breaking, and are MUCH lighter. I have no idea what a steel rod built for that power level would look like or what actual material would be...but it wouldn't be small or light and that weight thrown around would probably break the crank.

You could talk me under the table on metallurgy. And yes steel is "stronger" metal, but if we start pushing the hp and rpm limit on Rods in the same weight class I guarantee that aluminum will be the last standing. If we had to make something drive around a road course for a few hours I'd be using steel also, but the size and weight would depend on a lot more things than piston speed alone.
Cunningham is top of the line no doubt, but build one within 100g of aluminum and we will stretch that cap into a football at less than half the power level of aluminum. I didn't look in a book to find that out.


i was discussing the lightest rod for drag purpose,which can be "light,yet strong and reliable" so i dont have to worry about it like lets say a person would worry about an alluminum rod maybe :blur:
The lightest Readily available to you steel rod in our market is the Saenz that Jeremy sells. It's under 400g and there are guys out there racing on it every weekend. There are other high end rod builders that can make something like that and Cunningham is one of them...but tell them you need 10,500 rpm on over a 4 inch stroke and you need it at 400g and they probably aren't willing to put their name on it. Much lighter aluminum pushed past that rpm level...over 11k at times and we have had 0 failures and don't even replace them. Now that the turbo street cars are pushing Over 1300hp and 11k Rpm thy are all on aluminum...not because it's cool, it's because they don't bend or break. The steel Rods that have held up to that abuse are big and heavy, and weight matters. Maybe not so much for horsepower as you may think, but for crank flex at high rpm. Heavy stuff thrown around breaks cranks.

If I was you I would go with what is proven and being raced on every weekend. Some of the steel rods you listed may be past their intended design at only 300hp @ the Rpm level we need to run these.


:popcorn: good info!
Where? Lol

"enlightened trial and error prevails over the planning of flawless intellect"
 
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