Quote:
Originally Posted by Jakobi
It's kind of the same story though.
All to do with tolerances, operating temps, and thermal expansion. Generally speaking bigger parts require bigger tolerances to allow for greater variations. In a race engine with tighter tolerances you need to remove some of the variables.. thus specific start up/warm up procedures.
From my research, it seems to be the same with most of the 2T reading about heat cycles. Usually bigger bores (think jet skis/snow sleds, etc), moving from a cast piston to a forged. Forged by nature expands more and needs more tolerance. Add to that the bathtub curve and infant mortality, and odds are that when you make significant mechanical changes, that if it's going to fail it's going to do so sooner rather than later. If you're going to have a big piston nip up due to thermal expansion you're best chance of avoiding is a slow warm up, and in the event that it does nip it's best on a low load slow idle than wide open down the track.
Factories probably tend to stick to a certain procedure for consistency and fault finding. The less variables you are dealing with the better.
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Yes, that sounds very plausible to me. The BMW engineer (it was a BMW with a Judd V8 engine) I talked too said the engine would be destroyed when its started cold and this is due to the very close tolerances. They had a specially designed external pump with a heater unit connected to the car. One tube was lead through the oil pan to warm up the oil.
Here is a little video of the car
https://www.youtube.com/watch?v=84rE2LcwHIw
Unfortunately Georg, the driver died in a horrible accident at a hillclimb race in 2011. It was a great honor for me to know him.