At the PSMCDR we do allow aftermarket forged steel rods. We can’t police or control what’s inside and hidden in the blocks, but we know most engines have Eagle, Scat, and we’re sure Molnar rods as well. Pistons go the same route, most use modern forgings that are lighter with the 1/16” ring packs. We allow what NHRA Stock class rules allow for the bottom end for the most part. As Formulajones said, we encourage stronger rotating assemblies for safety and longevity. Yes, it is a lighter rotating assembly and allows 2 to 3 tenths quicker et’s, but we don’t want any catastrophic destruction of any racer’s engines due to old connecting rod or cast piston failure in the name of “factory original parts.”
We are more concerned with the proper block (displacement), heads, cam, valve train, intakes, carbs, transmissions, rear ends, and, to a lesser extent, distributors being factory stock. We, personally, use forged aftermarket rods and pistons in the pure stock builds we do. We’ve had 2 Pontiac engines with cast rods fail on the dyno (fortunately our own engines and caught before breaking), even after careful resizing with ARP fasteners! That convinced us that we’re always going to use forged rods in every build we do…no if’s, and’s, or but’s. It's no more expensive to do so and well worth the peace of mind! We have had no failures/issues with Eagle or Scat H-beam & I-beam rods since the switch (20+ years).
We allow mini-domes on pistons in order to preserve original blocks from being decked to their limits as long as compression is no greater than 1.5 points above advertised. You might lose a little hp from the minor obstruction of the flame front, but it’s minimal. We’ve used Icon, DSS, Diamond, and Ross forged pistons with full floating pins.
We’re leery using 50-60 year old connecting rods and cast pistons anymore. We recognize we need to adapt by allowing better components for the race participants, or the race will end if we’re too idealistic.
Anyone that wants to run cast rods and pistons (or TRW/Sealed Power forgings), that is fine with us. I do see we need to update the rules to allow forged steel rods (still not allowing aluminum rods). Also, as ‘stock’ replacement cams become harder to find, we’ve implemented the 16” of vacuum at 1200 rpm minimum rule for most engines (RAII/RAIV, W30 stick, W31, DZ 302, L88, R/W Code 427 Ford, etc. that are ‘big’ cammed from the factory are exceptions and consider 12” an achievable minimum at 1200 rpm).
Granted, there are participants/racers that spend more money than I care to think about on their cars to nudge the 11.50 mark, but more power to them…as long as it’s legal by our rules…and the only thing you can win is bragging rights at our little race. The guys that have the most fun are in the slower cars (13.00 and higher). They don’t break parts and are reliable run after run.
Dennis
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