Technical > Matt Shaff's Engine Shop

Aluminum rod lifespan.

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dreracecar:
2 killers of alu rods is heat and frequent teardown. Proper side clearence to keep the oil flowing will draw the heat out of the rod and the bore will stay round. Every time you reset the torque on the aluminum beam you pull the threads more and soon you will pull past yeild and incur rod failure.
Things that help in rod life is to have the big ends re-sized after a few passes when the rod settles in and a purchase of a GO-NO GO thread tool to inspect the rod threads. If the tool does not fit - junk the rod.

masracingtd1167:
I use the MGP rods in mine and change them at around 100 runs . My motor see's about 9400 during a run . Another thing to think about is how much power the motor makes . If it is making over 1000hp and only turning 7500 I would still want to change them around 100 runs .

dusterdave173:
Totally T
With the low RPM you mentioned I think you could use a set for a long time. I have built dozens of Big Block Mopars with BME aluminum rods for bracket racers--before we had aftermarket blocks they helped keep stock blocks from breaking once we had Indy heads etc and started really making some decent HP for stock blocks--We used to get 400-500 runs easy with those turning no more than 7000 RPM.
I have always been of the opinion that aluminum rods need a good warm up before racing. BME says un-torque aluminum rods over the winter or when stored--we Never did this ever and could get 500 plus runs. My experience tells me in your application you could run them a very long time betting you don't get near as many runs as average bracket racer --many will see 300 runs in a year.
Follow the mfg's specs on bearing clearance, warm them up good before racing, torque them with a quality inspected tq wrench using the EXACT lube as outlined by the rod maker and let er rip tater chip--no worry.
Now..If you are turning big RPM and making big HP then you know... that they should be replaced much more often.
BME offers racers inspection, correction, and some piece of mind if you send them in--always better to let THEM do any of that than regular machine shop on alum rods IMO.

MaggiFinn:
Sbc nitrous, ca 900-950hp. Shifts at 7300 traps in 8000. Bought them plenty used from a nitrous formula offroad car. 6years in our engine, street and track use. Manley 6".

wideopen231:

--- Quote from: dusterdave173 on August 04, 2014, 07:06:14 PM ---Totally T
With the low RPM you mentioned I think you could use a set for a long time. I have built dozens of Big Block Mopars with BME aluminum rods for bracket racers--before we had aftermarket blocks they helped keep stock blocks from breaking once we had Indy heads etc and started really making some decent HP for stock blocks--We used to get 400-500 runs easy with those turning no more than 7000 RPM.
I have always been of the opinion that aluminum rods need a good warm up before racing. BME says un-torque aluminum rods over the winter or when stored--we Never did this ever and could get 500 plus runs. My experience tells me in your application you could run them a very long time betting you don't get near as many runs as average bracket racer --many will see 300 runs in a year.
Follow the mfg's specs on bearing clearance, warm them up good before racing, torque them with a quality inspected tq wrench using the EXACT lube as outlined by the rod maker and let er rip tater chip--no worry.
Now..If you are turning big RPM and making big HP then you know... that they should be replaced much more often.
BME offers racers inspection, correction, and some piece of mind if you send them in--always better to let THEM do any of that than regular machine shop on alum rods IMO.

--- End quote ---

Bill Miller swear leaving rods torqued over winter with oil will cause a catlyist  and rods will crack,or so he told me was reason for one blown engine and other had 4 out of 8 with cracks at bolt holes.This was in the last set of BME rods we ever bought. Guess brooksb 88 had different aluminum as it was never issue with their rods.

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