| Yes the NA engine has a smaller wrist pin. Racer has asserted that the wrist pin failure was due to boost. This is obviously false. Wrist pins failures are almost exclusively RPM related. Why? Because the max shear load on the wrist pin is when it is decelerating (stopping, holding onto however you want to look at it) the piston from smashing into the cylinder head or through the oil pan. The force associated with this deceleration varies with the square of RPM while the force associated with increased boost is "relatively" linear as boost increases. (so I guess it could have been a high boost low RPM failure but that is extremely unlikely given the boost that he was running). Racers engine was a high miler. He ran the crap out of it. He did NOT tune it properly at first at all. And he might have overreved it while racing it either before or after it was turbocharged. Who knows HOW it actually happenned, but Math and Physics tell me what happenned. All that said, if I was going to dissamble and build an NA motor, would I use a stronger wrist pin? Of course I would, because your builiding the motor to drive it, which means more time in the higher RPM ranges. Am I worried about the wrist pins in my two NATTs? Not at all.
 CLOSED For The SEASON :-( |
