anybody with aluminum rods run them on the street? Thinking of building a 10.80's motor and was thinking about using small journey aluminum GRP rods? Street Duty 50% of the time? Anybody doing it? Let me know why I shouldn't. If I shouldn't where would I get the baddest small journal 4340 rods around in 6.7" length and built to last forever? Thanks, JP
I have seen guys run alum rods on the street for Many years... they don't last forever though. Don't use your motor to engine brake! Oliver makes one of the best 4340 rods.. not sure if they have yours though.
The pushing of the rods os not the problem, the pulling is? Is that why engine breaking is a problem?
Higher RPM is what kills Al rods, especially if used with heavier pistons. Tensile (stretch) is the enemy while compression is of little issue. The good news is that the typical sub-7000 rpm operation of the BBB lends itself nicely to long rod life. Devon
During acceleration, you're compressing the rod. On deceleration in gear(engine braking) the rod is stretching. The rod cap has less material than the rod itself so it will stretch eventually oblonging the big end or snapping over a long period of time. Heat cycling the aluminum doesn't help either, it adds to the problem. I talked to GRP about a set on the street and he told me that a few employees have them in their daily driver. He had seen them go as much as 40,000 miles before needing replacement. The more abuse you put them thru the less they'll live.
My buddy has been running AL rods in his street engine going on 4 years now, manley 6.8" rods, no issues. We did send them to 300 below for cyro treatment before assembly. HTH Rob Ross
