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When are aluminum rods required
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DRR Pro
Picture of Bruce Williams
posted
Looking for opinions on aluminum rods pro and con. At what HP level and RPM is the time to change from a steel rod to an aluminum rod.
Blown alcohol 30 psi boost 8000 rpm.
Any thoughts on billet VS forged.
Both steel and aluminum.


Bruce Lee Cool

Experience is what you get when you don't get what you want.
 
Posts: 2040 | Location: Chandler Arizona | Registered: August 11, 2005Reply With QuoteReport This Post
DRR Top Comp
Picture of wideopen231
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Not sure there is required at set HP. Morfe of choice when. Now with the boost you are running, I would run them, but in all fairness, I am running them now with inject motor.

Cons are they help absorb some of the hammering. help with fast crank speed acceleration with quick revs. Also, less destruction if breaking a rod. With newer stuff like MGP or GRP break one is rarer than used to be. Keep a check on bolt length.A simple check with the mic tells you if the bolt is stretched. My ARPs are 2.210 and if read other than .010 at quick glance I know either bolt of mic operator has an issue.

Now the weight deal depends on what you are running and the rod you use. Most of time not a lot there. Doubt you ever see on et slip.

Now billet or forged. Billet wins if you can afford any day of the week. A good new set will run 1500 or so. yes you probably will need to replace more frequently depending on rpm. Not to scare you but in top alcohol cars 15 runs are normal. We are talking 10,000 plus shifts and mid 50's boost. Lots of guys with milder setups will for 200 runs. I know in A/fuel we have no issue with 100 runs and that we are around 7000 hp, but we almost never see 6800 rpm max.

By the way, prepare for the bs to start. Some good points some never ran aluminum rods.

I do not run anything else in my aluminum motor. Oh yea even with dial in it is not a bracket car according to some here. Not that will stop the comment. Guessing that's an insult to some.Not one of them.

Have fun and enjoy replies.




America home of free. Brought to you by 2nd amendment.
 
Posts: 4236 | Location: Greensboro NC | Registered: May 24, 2011Reply With QuoteReport This Post
DRR S/Pro
Picture of Big Steve
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Bruce I dont know if there is a magic HP number when Aluminum rods are required. What I can say is it is common knowlege that the aluminum rod will act like a shock absorber to the crank. When running a steel rod and your tune up is over center and you have detonation it will beat on the upper bearing and crank harder.
That being said I know someone who has been running a blown TD for several years that runs 6.0x at over 230 mph and has never ever ran aluminum rods has not broke a steel rod or crankshaft. Your results may vary lol.
Bottom line its a personal choice, I have always ran MGP aluminum rods and I put in a new set every off season, the way I look at it is they are much cheaper to replace if they are not broke
 
Posts: 2447 | Location: Moving back to the door side | Registered: April 30, 2010Reply With QuoteReport This Post
DRR S/Pro
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I ran steel with my procharger for the first 4 years... same set of rods and bolts


J.R. Baxter

""Fathom the hypocrisy of a Government that requires every citizen to prove they are insured ..but not everyone must prove they are a citizen."

2024 Miller
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Posts: 1529 | Location: Waxahachie | Registered: July 04, 2005Reply With QuoteReport This Post
DRR S/Pro
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Cost verses runs then replace every year? We saw a max of 65 then boom. 1400 hp N/A. 84-8500. Both motors have in excess of 500 each now with steel Carrillo. Rods get checked by Carrillo at 200 runs or so with bolts replaced. Are we on borrowed time?? I don’t think so. Our new 781 is steel also.

Works for us..


Raceless in California!
 
Posts: 4534 | Location: Vacaville  | Registered: January 07, 2004Reply With QuoteReport This Post
DRR Pro
Picture of Alaskaracer
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I ran my first and last set of aluminum rods in my last build. Less than 100 N/A passes, 6 mild niitrous passes and rod broke below the pin boss. Never again. My former engine builder in Denver (Dave Slatten, recently passed from cancer) used to run aluminum rods in the majority of his high HP builds. Last time I talked to him, he had since stopped and had gone back to steel with zero failures, using Crower billets. Dave built many top sportsman and top dragster engines with numerous wins and championships to his credit. The last few years he raced before cancer got him he ran pretty much all supercharged combos, all with steel rods. Dave did tell me he saw no difference in bearing wear or life, or any issues with crankshaft wear or life after going back to steel. I've also seen several builds now approaching and a couple hitting the 3000hp mark with steel rods and not having issues. In my opinion, I think it has more to do with the tune up than the actual rod material on how hard the bearings and crank get beat up, as I've seen plenty of aluminum rod engines tearing bearings up after just a few passes. I also know of another builder who used mostly steel now as well after having been on the aluminum rod bandwagon for years.....


Mark Goulette
Owner/Driver of the Livin' The Dream Racing dragster
www.livinthedreamracing.com
"Speed kills but it's better than going slow!"
Authorized Amsoil Retailer
 
Posts: 1503 | Location: Back home in Alaska! | Registered: February 13, 2011Reply With QuoteReport This Post
DRR S/Pro
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quote:
Originally posted by BP758:
Cost verses runs then replace every year? We saw a max of 65 then boom. 1400 hp N/A. 84-8500. Both motors have in excess of 500 each now with steel Carrillo. Rods get checked by Carrillo at 200 runs or so with bolts replaced. Are we on borrowed time?? I don’t think so. Our new 781 is steel also.

Works for us..


All else equal,,, Forced induction combo's are easier on rods than NA combo's (assuming properly tuned). NA combo's try to stretch the rods on every intake stoke, force induction forces air/fuel in the cylinder and therefore reduce the rod tension developed, this also helps the bolts too!
 
Posts: 2161 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post



DRR S/Pro
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I do agree. Today we were talking ( if we had too) build another combo would it be Brads best or a pro charged unit?
But then we’d have to sell three bullets and start over…
It’s a little late in the game for that!


Raceless in California!
 
Posts: 4534 | Location: Vacaville  | Registered: January 07, 2004Reply With QuoteReport This Post
DRR S/Pro
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Having broken several sets of aluminum rods I'm sort of biased. I can understand the reason for running them in a blown nitro engine but for the life don't see the reason to use them in a normally aspirated engine. The singular exception might be a nitros application. 99% of us either bracket racing (in one form or another) or compete in Index events, therefore I feel steel rods are a better choice.

Bob
 
Posts: 3098 | Location: Lakeside, Ca | Registered: February 15, 2003Reply With QuoteReport This Post
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