Yes, I realize there are definitely some applications where an AL rod is a must, such as Nitro fuel, heavy N2O use, etc.
Not even talking TS/TD, but for a regular bracket racing BBC, (think typical S/P, SC/SG build, 555-582 CI), why would anyone use aluminum rods?
(Again, not saying there are no good reasons, but if there are, I'd like to hear them).
I am asking, because a friend of mine had another engine let go a couple weeks ago.
An aluminum rod broke, (again - 2nd time for him in a few years).
It was a build by one of the premier (top 5) sportsman engine builders in the country. Not going to name them, because the buyer specified AL rods in the build. The resulting carnage at 7,000 RPM is predictably catastrophic - He might be able to save the heads, the intake, and rockers. Not much else.
Which is why I am asking the question. Unless you are pushing your engine into the detonation zone routinely, or running heavy Nitro/Nitrous through her, why aluminum rods? (Go easy, I am trying to learn something here).

You answered your own question by asking it, no reason, no mind good reason to be running aluminum rods in a bracket engine or throttle stop engine, NONE!

Can't disagree with above. Anyone running aluminum rods should expect to change them as routine maintenance, and should have the cost of rods included in their "freshen" budget.

Also, as a side note, you'll never get a straight answer out of an aluminum rod manufacturer for when you should change them.

An aluminum rod broke, (again - 2nd time for him in a few years).. First what is the analogy of the builder to go Aluminum. As with Aluminum rods, it basic heat cycles. Where exactly did the rod break at? Bolt issue?. Well maybe if your throwing 3 kits at it ya. Otherwise Steel...

Because they're purdy?

^^^ Lol
Or because the guy read some magazine article 35 years ago saying that an aluminum rod is more "forgiving" if your engine is detonating and you can't tell. (Seriously).
Can't blame the builder, if the customer says he wants rods made of butter, and is willing to pay the tab and understands there is no warranty.
Maybe he will learn this time. Maybe not. He has the funds to buy another bullet. At some point if it bites him in a Semi or Final, he will see he light. (Not the daylight shining through those new "ports" in his 2 year old block).

Older and wiser as I have run aluminum rods in the past. 86,87,88,90 then in 1991 new motor steel rods. I ran Bill Miller rods, and freshend motor every winter and just put a new set every year as part of the freshen up. Now this was a 468BBC that maybe made 700?. It was enough to get my altered to run 8.30s. No problems maybe 250 passes a year. Rods were close in weight so just a touch up rebalance. But then steel rods for me ever since. As 1320racer said no need as we are bracket racing. I think at the time the Bill Miller rods were like 750-800 bucks (I do not know how much they are now) and income was up so I never really gave it a second thought as having to replace rods every year. Now I run the steel rods for years. Calies,Oliver,Eagle,and for the daughter's small blocks Crower in one and eagle in the other

Aluminum rods because my cranks are setup for aluminum rods when balanced, Plus aluminum rod does cause less damage to rest of engine most of the time it rod breaks. Both my motors are TFX aluminum blocks.

Out of 5 motors we had blow when TA/FC and TA/D. none where because rod broke. Except one. BME rods cracked at bolt on rod ,because too thin. Unless you asked Boll Miller his BS line was. Well if you left them torques in motor then the oil cause a catalyst that caused the aluminum to crack.We found 4 rods cracked in backup engine we runner upped with that weekend. Never had issue with Brooks Delta 88 rods. damn shame not available.
Three had bolt break. One had 4 wrist pins break first 60 feet they ran. Now under the conditions they where ran we swapped rods every 15 to 20 runs. 7000 stage and 10k shifts.
They where 600 per set in mid 90's. MGp or GRP are about $1100 now, but they have higher priced ones for fuel.
Three had bolt break.

I know of quite a few who run aluminum rods in motors that are bracket or equal type racing engines. Plus have had quite a few tell me 400 runs in something like bracket engine is common. Thats only about $2.75 per run

I would not run steel rods in my aluminum blocks if they where free. I will how ever take all you want to give. Hey sale them and buy new set of GRP or MGP rods.

Aluminum rods are better with blower combos with high boost levels. Also better in injected nitro engines.

I agree most bracket engine will not benefit one bit from aluminum rods.

You don’t have a bracket engine, you don’t have a bracket car and you don’t bracket race! Again, aluminum rods have no place in bracket engines.

I will not use aluminum rods in my bracket motors. You may run what ever you want just make sure you have a good diaper so you do not oil the track too bad when it does what they do. And as for doing less damage when aluminum rods let go I do not know about that I have seen them really destroy some stuff.

I understand if you have 2500 Horsepower and a big blower sure but other wise you have a ticking time bomb and you have already lit the fuse.

As for the original question When and Why? I would say anything over 2000 Hp and change every 75 runs.

5" stroke in mine. Aluminum rods. Steel would be so heavy that I'd need POUNDS of mallory metal to balance my rotator.....running MGP and will stick with them. With that much stroke and at my power level, pistons, rings, cylinder bores and rods don't last long anyway. I have considered steel though, and still am....but $1400 for custom rods in aluminum vs. $2800-3000 in steel is a pretty significant difference. MGP told me 250-300 runs, send them in to be inspected. About half way there now, should finish out this season with them before I send them in. I've already had steel rods break on me, and they create some serious carnage when they do. I know I'm not gaining anything with them, but at almost half the weight of a steel rod in the same length, I'll take what I can get...

One thing, aluminum rods these days are NOT the same as aluminum rods from a few years back. Better material and process and much better bolts. They aren't as "throw away" as they used to be. A fellow racer here ran a set for just under 500 runs. Sent them in, they got a clean bill of health, but he replaced them anyway for peace of mind....He runs three classes with his car and makes tons of passes. Top Sportsman, Super Comp, and Super Pro. He won't run steel rods if you gave them to him....

I think one of the issues with aluminum rods that nobody ever talks about is heat. Aluminum gets softer at relatively low temperatures like 250*-300* of course it does not melt until over 1260* depending on the alloys. At 650* it has lost over half its strength. Noticeable at low temperatures like 250*-300* at those temperatures you can bend it much easier. Another reason it is not best material for most bracket engines.

It MAY be possible to extend the life of aluminum rods another 25% or so if you keep your oil, water and motor cool but even IF that is possible we are talking what from 75 runs to possible 100 safe runs? Lower RPM, lower heat you may be able to get more runs but who knows how many more before it goes?

This also applies to the Brake calipers in another thread. The Aluminum heats up faster, it expands more when it does heat up and both of those are not good things for brakes.

quote:

Plus have had quite a few tell me 400 runs in something like bracket engine is common

i call bs
i ran al rods once in a bracket motor ,never again
i have al rods now,blown

I used to want a set for a SBC small journal 283/Just to run for fun and some small bracket races.

I swap my aluminum rods out every season or 75 runs whichever occurs first. Top Dragster is bracket racing isn't it?

Aluminum rods no big deal. I raced with a old school drag racer every Friday night who wouldn't run anything but aluminum rods. He was good at it, never broke one. He'd drop the crank out of it, in the car every 120 140 runs, and switch em out.

Mopar guy of course. 400 block 440 crank

Aluminum blocks, Aluminum rods, you throw everything in play, in a oven. Heat to operating temp, in order to come up with your clearances, tight clearances.

I wouldn't be afraid to run aluminum rods in my sbc, if I do the clearances.

its not that you cant run them,its just not practical.most weekly run motors need to last longer than 100 runs.then what is to gain, not much et in my experience.like i sid i ran,wont do it again in a bracket motor.have also considered not in blown deal

I ran aluminum rods in my 565 years ago. Had a couple stretch on me because I didn't know about the heat cycle thing. Once I learned about that they were good to me but like everyone else said you had to change them out regularly and I ain't bout that life lol.

quote:

Originally posted by Mike Rietow:


I wouldn't be afraid to run aluminum rods in my sbc, if I do the clearances.

That is awesome that you have figured out how to make them last and nobody else could!

So why don't you run aluminum rods? Hmmmm.