Mandic 0 Posted September 4, 2006 Hi, Can anyone confirm, what's the max constant force Mi16 piston can be exposed to? Thanks Cheers Ziga Share this post Link to post Share on other sites
petert 586 Posted September 4, 2006 That's a bit like saying how long is a piece of string - there's too many variables. ie CR, depth of pockets decreasing crown thickness etc. I've used them at 11.4:1 without problems however. RPM is less of an issue. The reality is you probably won't make enough hp with the std. piston to go much past 7500. Share this post Link to post Share on other sites
Miles 331 1 Cars Posted September 5, 2006 With my old very quick build Race engine (Std build) I was running to 8500rpm without any problems with the Pistons until the big end bolt sheared Share this post Link to post Share on other sites
PumaRacing 2 Posted September 5, 2006 Hi, Can anyone confirm, what's the max constant force Mi16 piston can be exposed to? Thanks Cheers Ziga There is no such thing as a maximum constant anything that mechanical parts can be exposed to. They have a fatigue limit which gets used up more quickly the harder you use them. A piston/bolt/conrod/crank might last 1000 cycles at 10k rpm, 10000 cycles at 9k rpm, 10 million cycles at 8k rpm, 10 billion cycles at 6k rpm. People (well my customers anyway) always seem to think that things either break instantly at X rpm or last for ever at X-1 rpm. I'm forever being asked what's the rev limit on this bolt, rod, piston etc. The question has no answer other than one of probabilities for which you'd need to build 1000 engines and log their failure rates to have any chance of knowing. I remember a drag race customer with a Golf Gti 16v who changed from 2nd to 1st instead of 3rd at peak rpm part way down the strip. The engine died immediately and had to be towed back to the pits. They calculated from the gearing that it had gone to nearly 11k rpm as the clutch banged in and he assumed that something major in the bottom end must have broken. Turned out that the rotor arm in the distributor had flown apart from the centrifugal forces. With a new one fitted it ran fine again. How many times you could get away with doing that is another matter. Share this post Link to post Share on other sites
Mandic 0 Posted September 5, 2006 Thanks to all 3! I do understanad that it's down to cicles, but surely there must be a point where it breaks. Or is it true that brand new Mi16 piston would withstand xxx cycles at 12k RPM? Cheers Ziga Share this post Link to post Share on other sites
camgti 56 Posted September 5, 2006 Thanks to all 3! I do understanad that it's down to cicles, but surely there must be a point where it breaks. Or is it true that brand new Mi16 piston would withstand xxx cycles at 12k RPM? Cheers Ziga I dont think they would last long at 12k. Besides there is no point reving that high. As has been said there is no real figure. Maby tell us what it is your wanting to do and we may be able to point you in the right direction.... Cam Share this post Link to post Share on other sites
Mandic 0 Posted September 5, 2006 Hehe, I'm not aiming to rev my engine to 12k or anywhere near, I'm just interested in things like this. But at the end of the day, it's good to know how much Nm or force can certain things take in case I'll need this info sometime. Cheers Ziga Share this post Link to post Share on other sites
