Billet aluminum connecting rods

[Jason84NA2T]

[quote]SATAN wrote:

After reading a couple articles like this one, I'll stick with steel.

http://www.rrconnectingrods.com/choosing.htm
That was a good explanation as to why an aluminum rod CAN break sooner than a steel rod.
It has some good information, and is very well written. Thanks for posting that...

just one thing:

Aluminum has a fixed fatigue life. Well, what’s that you might ask? Every material can be deformed to a certain extent and only a certain number of times before it breaks.

All materials have a fixed fatigue life, including every alloy of steel. In a rod application if I'm not mistaken it would be directly related the the modulus of elasticity of the alloy in question. IE you could make a steel rod more or less "springy".

I guess it's still boiling down to one phrase:
"Can they fail sooner than steel rods?...... Maybe."

Just like with other things, I try not to be a parrot with information. If I or anyone else has not tried it, then everything is simply speculation.

[G-E]

I used to know someone who was really into metallurgy, not specifically engine stuff but in general like welded parts and heat tempering and all that, and I've made many of my own tools in a forge and treated them myself and when you get it right the strength can be phenomenally better than when you get it wrong

anyway from all I've chatted about aluminum and everything I know first hand leads me to believe that while pistons are alright, I wouldn't trust the rods

and yes suzuki and a few other small engine makers do use factory aluminum pistons and I have never seen aluminum rods - except in hobby motors

[SATAN]

So Jason, is this an engine that you are planning on building someday or is this just for learning perposes?

You said you can get the rods for a good deal but what are your goals with the alluminum rods? Higher redline faster rev? Are you trying to build an engine that is really smooth for somewhat cheap?(arent we all) gernerally only the race engines use these that are tore down regularly(you already know this) So you are hoping to get roughly 40-50k on aluminum rods at what 450-550whp? That doesnt seem to far fetched, now getting 40-50k on say 750-850whp, obviously might reduce the life of the engine, BUT... like people are saying isnt the hardest stress point on a rod when the rod is coming down without combustion? in which case you could have an engine that is making 100whp and revs to 8k that is just as stressed as the 600whp engine that revs to 8k. sorry I'm ramblin

[Jason84NA2T]

Just a learning experience. If I did it, it would be for tehpopas car which would be driven 50K in maybe the next 10 years, have a built auto and make 550whp.... at 7K, run 10's on the weekends etc etc. [/dream] The real benefit to the lighter assembly with the right gearing will show up on the ET's the car runs pretty quick.

No I understand what you're saying pefectly... but remember that:

1. lots of the inertial loading done on a rod is from the weight of rod itself
2. lots of weight can be removed from most pistons without losing strength.

[Taris Blue]

It's deffinitly something I will think about going with when I do eventually build a motor for my car, since by that time I will probably have another DD to use in case of any problems. As it stands now however, any failures of any kind can put me out of action for weeks at a time; (see Cam Install figure 1 for reference) and I really need my engine to last a long time.

[Firehawk]

For under $1k, I would be interested in a set for my next motor buildup, but that won't be until next year unless a customer wants to try it.