Aluminum rods

We just blew up the 545 in my brothers Fox body after over ten years of use. If the block is ok I am thinking of putting in a new set of aluminum rods in place of the H beams that are in it now. Will they make more hp and what are the minuses and pluses in this change for me as I have never used aluminum rods before?

When I was pulling, I was told to stay away from aluminum because they stretch, but when I talked with GRP at the PRI show a couple years ago, they said that is a myth now days. I also heard you have to replace them more often then steel, but I have since learned life is application dependent. One thing everyone seems to agree on is that they are more forgiving then steel if there is a failure.

Here is an informative article that you should read while waiting on more knowledgeable guys to comment.

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

Aluminum has limits and particular characteristics different than steel

Aluminum rods make LESS power as the power transfer through them is "dampened " by the aluminum itself. That dampening effect is used by nitro racers to slow crankshaft failure. On the other hand Pro Stock racers went back to steel rods for the power gain.

I'd put a fresh set of steel rods back in it.

Unless you’re turning extremely high rpm or a ton of spray I’d stick with steel rods.

^^^^^^^^^^^^^^^^^^^^^^^^^^what he said.

cool40 wrote:Unless you’re turning extremely high rpm or a ton of spray I’d stick with steel rods.

Lem Evans wrote:^^^^^^^^^^^^^^^^^^^^^^^^^^what he said.

What would you call extremely high RPM? Or what RPM would you consider running an aluminum rod in a NA setup?

If I was going to frequent 8500+ in a maximum effort deal it would have MGP or BME aluminum rods in it. I use MGP in the pulling truck and it’s been happy so far @ 9200. I’ve never had issues with Oliver steel rods in my other stuff under 8000.

The Oliver billet steels in my puller saw 8400 to 9400 on a regular basis but it was a little 470 with no expense spared.

Most NHRA prostock engines have steel rods so, rpm in and of it's self is not the issue.

If one has to run a smaller c.i.d. engine...like the 470-485" puller engines... and have the typical bbf deck ht. a steel rod gets long and heavy. The NHRA engines short deck ht. lets the steel rods be short/light/stiff.

My 470” had bearing issues with Oliver steel rods. I think it was more of a crankshaft problem than rod but like Lem said it was a long heavy piece. I repaired it and just a few easy dyno pulls later it was showing signs of problems. Billet Crower crank and MGP rods are working good now. Others results may vary lol.

My crank was a 429 truck crank that Adney worked over heavily. I ran a stock stroke with .060 over pistons. Probably could have done things different but it worked. Never had a bearing issue.

Mine was also a truck crank prepped by Bullet and heat treated. I had some detonation that contributed to the bearing problem but I still wouldn’t run a steel rod again.

rmcomprandy wrote:

EverySparePenny wrote:

cool40 wrote:Unless you’re turning extremely high rpm or a ton of spray I’d stick with steel rods.

Lem Evans wrote:^^^^^^^^^^^^^^^^^^^^^^^^^^what he said.

What would you call extremely high RPM?  

Depending upon the stroke, HIGH RPM meaning is pretty much dictated by mean piston speed ... about 90 feet per second and over gets into the HIGH range.

cool40 wrote:If I was going to frequent 8500+ in a maximum effort deal it would have MGP or BME aluminum rods in it. I use MGP in the pulling truck and it’s been happy so far @ 9200. I’ve never had issues with Oliver steel rods in my other stuff under 8000.

HorsinAround wrote:The Oliver billet steels in my puller saw 8400 to 9400 on a regular basis but it was a little 470 with no expense spared.

Lem Evans wrote:Most NHRA prostock  engines have steel rods so, rpm in and of it's self is not the issue.

If one has to run a smaller c.i.d. engine...like the 470-485" puller engines... and have the typical bbf deck ht. a steel rod gets long and heavy. The NHRA engines short deck ht. lets the steel rods be short/light/stiff.  

Thank you Gents

What kind of oil temps do you see?