can i run aluminum rods on the street????

Dear Aluminum Rod owner,
Take a course in Metalurgy and go work in the industry for 35 years. Fact: All aluminum alloys lose 80% of their tensile strength @ 300 F. What is your oil temperature...around 250 F on a hot day. 250 F will anneal all aluminum alloys after a few hours... They work well in engines that undergo severe detonation such as TF.
Some aluminum alloys actually improve tensile properties with age.
Using old used rods in a street engine comes very close to Grenade time.
Not a good idea unless you like to replace engine parts. Made sense to use them when parts were cheap in "The Good Old Days" Saw many Ohio gassers grenade them in the 60's. Have never lost a forged steel rod even when a crankshaft failed....Respectfully Submitted, X-Jet Boat Bill

 

I've run aluminum rods on the street in a big block Chevy engine but they were new. I would never run a used set. Sell them and the pistons you got to get your money back.

 

A Triumph 650 rod length is 6.50" with a stroke of just under 3.25", not exactly a short rod. Not to mention that this is an 8000 rpm engine, which is air cooled (tends to run hotter than a typical water cooled car engine).

It annoys me that people say the well known "canned" answer to questions here very often, with no real backup. Has anyone run aluminum rods in a street car, disassembled it after x miles, checked the length, and needed to replace the rods because they were stretched?

I've run many MC's with aluminum rods and not had an issue (and have rebuilt the engines with no issues on rod length). Also, there is a high temp AL that is strong over 300 F (2618). In my previous employment I used it for high temperature centrifugal compressor impellers. I'm not sure what typical rods are made of, I think pistons are sometimes made from 2618 but I'm not sure.

 

I normally raced a manx. But I worked on anything that came into Haps shop. The thing that one has to bear in mind is that even a TT has a lot less reciprocating mass than even your smallest V-8. Rod stretch is caused by a change in inertia and the more mass you have the greater the effect. The other thing to remember is that the loads on a V application are different than the loads in an inline application.

I am not against running aluminum rods on the street and some like outlaw have had good luck with them, there are obviously brands that are going to hold up better than other brands and the type of rod is also a factor. I personally would not do it with a street motor the benefits don't out way the deficits in the majority of applications.

 

A manx norton is a really nice looking motorcycle.

I think that is a reasonable point. If it was me and I had a motor that was together or near-together and had aluminum rods, I wouldn't hesitate to run it, but I would measure the rod length at final assembly and remove and disassemble it occasionally to see if the rods stretched (I like working on cars more than most...). If the OP wants an engine that he can stick in a car and not worry about, then he should buy a steel set of rods.

 

Um yes I have. Rod stretch is a common thing to check if you are a mechanic and not a parts replacer.

I am amazed that you being the big assed expert that you are would compair an impellar to a connecting rod.

Had nothing to do with looks and had everything to do with how hard it would come out of the corner. I would have raced a matchless if it would have pulled that hard.

 

Think about your time. Do you want to waste time and money replacing parts that you wouldn't necessarily have to replace if you had run good steel rods!

 

All things wear/fatigue/deteriorate over time. Aluminum just does those things faster than steel. While people get by with running GOOD aluminum rods is street cars, those are hobby cars. Aluminum rods are not a good choice for a car that will be driven the 10,000, 12,000, or 15,000 miles per year, or the 100,000 miles plus, that "real" street cars are.

The following is real-life evidence of what I said : There are racing classes that allow aluminum rods, yet steel is used instead. There are no heavy duty industrial engines that have aluminum rods. Car manufacturers would love to use aluminum rods, but none do.

 

Less mass is the key. Aluminum rods and pistons = less reciprocating mass. You guys better check your late model D/D autos.
Unless you are driving something built in the last century there is a good chance it has aluminum rods. Todays cars see 300K without a rebuild.

 

Modern street car rods are mostly powdered/sintered metal. Although it's possible to make aluminum powdered/sintered metal parts, the rods you are talking about are a good grade of powdered/sintered STEEL. They are not as good as a decent steel rod, but they are better than the iron rods most engines had before the switch to powdered/sintered ones. That same material is now used to make cam sprockets, oil pump gears, cam followers, all sorts of things.

 

Here's a good read on alum rods.

http://www.dragzine.com/tech-stories/engine/debunking-aluminum-rod-myths-with-grp/

 

This subject has been beaten to death a bunch of times. Friend who had more money than sense had a dirt track car, found an engine out of a drag car that had aluminum rods. We all told him it wouldn't hold up to the accel/deccel cycles of a flat quarter mile track, but he bought it and had his mech. install it. Ran like Jack the Bear, but blew all to Hell in the first race.
Another friend more recently had a 434 cid sbc with special tall deck, big bore block and aluminum rods and all sorts of trick stuff in a Camaro that turned sub 5 sec. 1/8 miles. Kept saying it was time to change rods, but kept putting it off.
Two weeks ago one of the rods broke and it destroyed a $3000 blosk.
It just ain't worth it.
Dave

 

Al,
I would just about bet that a dart with a blown 392 that isn't going to get raced is a hobby car. '

1939 street rod this is not a slam jyst an observation. There is a '58 Chevy in one of my hot rod magazines that was built in that time period, it has a blown 348 full of all the really neat stuff, it has never been started in all these years but was very successful on thre show circuite, it has been garage kept and the opriginal extreme paint job and interior is still intact. Not all rods get beat like rented mules, it is just a fact of life.

 

Bill Miller claims his rods will go 100,000 miles on the street

 

Good article-

Ive "compressed" aluminum rods a time or two:

 

on reading thru this ....noone has pointed out that he is asking about using rods from back in the day the alum used then is not as good as what is being used now..........used a set alum rods&pistons in my 327 that came out of a old jr fuel car..........run it hard &on the street until recent rebuild
sold them on ebay .........

 

A good forged rod will last and last and last under normal street use. We're not talking about some of the stuff that was available in the 60s and 70s here folks. Cryogenically treated, forged rods have come a long way in the last 20 yrs. If they need to be changed as a safety precaution at 100 quarter mile passes at 3,500hp and 10k rpm, how long will they last cruising at 2,500 rpm, with an occasional 450 hp/6500 rpm blast? I agree with Bill Miller, a long time.

 

Good info, but not unbiased. I agree that GOOD modern rods don't need to be changed routinely like the old ones did. The superior strength and durability of steel rods is mentioned, but minimized. The down sides of aluminum rods were not really discussed. If one's entire knowledge of aluminum rods was that article you would wonder why they aren't used in recip airplane engines and Caterpillar diesels.

 

I am no wizbang but I do know alum.has a finite legnth of time before breakage.They give no warning just break! Put steel rods in it and forget about it! If the cost of new steel rods upsets you,then there is no reason for you to be building/driving a hotrod,much less one with a blown Hemi! The price of a good set of rods compared to the carnage of a broken Alum. rod is miniscule! jmho...R~R

 

Well put!

 

OK, I GOT THE SKINNY ON THESE RODS STRAIGHT FROM BOB AT HOWARDS - THESE ARE NOS 'OLD' RODS - THAT IS, THEY ARE 2014 ALUMINUM AND ARE NOT SUBJECT TO CYCLING LIKE THE NEWER 7178 ALUMINUM RODS - A BIG FAT "YES" THEY CAN BE USED ON THE STREET! - HOWEVER, THERE ARE SOME TEMPERATURE LIMITS - CANNOT BE USED UNDER ABOUT 45 DEGREES TEMP...NEED SPECIFIC MINIMUM BEARING AND SIDE-TO-SIDE CLEARANCES...ALSO, > .050 PISTON TOP - TO- HEAD CLEARANCE (INCLUDING GASKET)....Many thanks to bob at howards.....when the build is complete and engine running, i will post more - next spring i think as other projects are first - got my trans for it today too - 727 all done up - need to get the $$ hemi-to-sm blk 727 adapter next tne build!...thanks for all the help and advice - if you are gonna do this too, check your alloy first!

 

absolutely a hobby car, but also a short drive car...we will see next year if it can keep together...i am doing this cause i have most all the stuff for this build left over from other builds - no more work and living on SS limits what i can and cannot buy now so trying to use what i do have ....after speaking to bob at howards, i am more confident than ever that these particular rods WILL work and for a while too....we'll see....thx...johnnyB

 

these are all NOS - never used - it's a toss up......looking amybe to trade them to my friend with an old front engine hemi dragster for some steel H rods....

 

If you're going to run these on the street, don't downshift if at all possible. Ask me how I know. If you can minimize stretch load it will give the rods a better chance of lasting. As said try not to downshift, minimize coasting with it in gear and clutch engaged, etc. Hopefully you will have a long and lasting relationship with your rods! Mine broke up with me pun intended

 

Ongoing interesting conversation!




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After 3 pages of banter this is the best idea I have heard........ And no, I would never use aluminum rods in a street engine. Period.

.

 

If that's the car your building it will need a built Hemi just to pull that beast around

 

JohnnyB,
I get the impression that you do intend to use the rods and that you don't intend for the car to be a long mile car. One thing to remember and this is coming from a fella that does occasionally build pieces for things that go fast and show is that everything that I build is the absolute best on the market. If you catch my drift.

I grooved a pair of M&H Racemasters and ran them on the street once. They did not have a long life but that was what I had and so I got by. If aluminum rods are what you got and money is not what you got then you do what you got to do.

I hope that it holds together well for you and that you don't end up destroying a rather rare block to save a buck. It doesn't sound like you will have a problem as long as you set it up correctly, and it never gets cold where you live.

 

SCREW IT...THE RODS MUST GO - TOO MUCH ALREADY INVESTED - IT MAY PUSH MY DATE OFF A BIT, BUT THIS IS NOT WORTH THE CRAP I COULD GET IN THE END - THANKS FOR ALL THE COMMENTS....johnnyB - JOEY - THIS CAR WILL WEIGH ABOUT 3200 POUNDS WHEN I GET THRU WITH IT - MAY HAVE TO DO THE STRAIGHT AXLE FRONT END TOO SINCE I WILL PUSH MY DUE DATE BACK A BUNCH - IT LOOKS LIKE 'CHRISTINE' LOOMING OUT IN THE BACK SHED!

 

JB you will get it I am sure patience grasshopper patience..... Now in the mean time stop by and see these doors I did I have to install them Friday they love em and I am very happy even if my arms and hands hurt from all the hammering on them...lol