marcboy62 Posted March 23, 2011 Report Share Posted March 23, 2011 is there a big difference between these two setup?? Quote Link to comment Share on other sites More sharing options...
Hilarious Posted March 23, 2011 Report Share Posted March 23, 2011 is there a big difference between these two setup?? There is 4mm of stroke difference... You beat the shit out of either and not take care of them, neither will last very long. I have had great service out of both. Quote Link to comment Share on other sites More sharing options...
marcboy62 Posted March 23, 2011 Author Report Share Posted March 23, 2011 ahaha okk loll thank you! Quote Link to comment Share on other sites More sharing options...
SlowMoe Posted March 23, 2011 Report Share Posted March 23, 2011 Obviously the more power you have the faster certain things like bearings and clutches will wear. Not to mention faster piston speed with the 4mill engine for a given rpm meaning shorter ring life. Theoredically of course Quote Link to comment Share on other sites More sharing options...
Hilarious Posted March 23, 2011 Report Share Posted March 23, 2011 Not to mention faster piston speed with the 4mill engine for a given rpm meaning shorter ring life. How does adding 4mm or any addition of piston travel amount to faster piston speed at a given rpm? Quote Link to comment Share on other sites More sharing options...
SlowMoe Posted March 23, 2011 Report Share Posted March 23, 2011 (edited) How does adding 4mm or any addition of piston travel amount to faster piston speed at a given rpm? Picture a piston with 10 feet of stroke inside a cylinder. Now, imagine how fast that piston would be travelling at 60 rpm (1 trip down and back up in one second). Picture how fast it would be moving. 10 feet of stroke one way. Now imagine a cylinder with one mile of stroke at the same rpm (1 trip down and back up in 1 second) The second piston would be moving like ten thousand miles per hour to complete that trip in one second. The first only 20 feet per second average. Piston speed is a big factor that limits high rpm operation in large engines. I think there is a set limit of like 3,000 feet per second maybe that you shouldn't go over. Something like that. Edited March 23, 2011 by SlowMoe Quote Link to comment Share on other sites More sharing options...
Burt Reynolds Posted March 23, 2011 Report Share Posted March 23, 2011 (edited) With a 4mil your going to wear some things out faster,like clutches/clutch baskets/chains/sprokets,but they are reliable as long as you take care of them. I did a dune 4mil and destroyed the stock clutch and basket in just a couple months. Edited March 23, 2011 by Burt Reynolds Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted March 24, 2011 Report Share Posted March 24, 2011 3000 fpm is not much for piston speed. Sleds are around 3400 stock or so. IMO you could safely go to 3500-3600 w/o issues. My sled engine I think was around 3600 fpm or so and I don't ave issues. Quote Link to comment Share on other sites More sharing options...
DieHard2Smoker Posted March 24, 2011 Report Share Posted March 24, 2011 There is a limit as far as how many feet per second (FPS) a piston can travel without destruction. [Please note that this should be FPM feet per minute - Rick] This limit has been established at (an average) of about 4000 FPS for high output motors - 5000 FPS for short drag racing (rare indeed) - even more rare are the to fuelers who go as high as 6000 FPS. Increases in the stroke make the limit closer and have to be compensated for in other ways. - macdizzy.com (site about 2 strokes) I've read thost same #s somewhere else as well I think its correct. But some other of there stuff about port work makes me think there not all too knowledgeable. Quote Link to comment Share on other sites More sharing options...
RadarRacing Posted March 24, 2011 Report Share Posted March 24, 2011 They are both about the same honestly. I feel if the 4 mil will pull my fat ass around at 6000 rpms but I'd have to rev the stock stroke more then the piston wear will be no more or less with the 4 mil. If you are going into the motor to do a crank absolutely do a 4 mil. Your new welded crank and bearings will be better than the stock crank you take out of it anyway. As far as wear on components a 4 mil isn't a crazy build its just going to be maybe 10% more HP. Quote Link to comment Share on other sites More sharing options...
SlowMoe Posted March 24, 2011 Report Share Posted March 24, 2011 They are both about the same honestly. I feel if the 4 mil will pull my fat ass around at 6000 rpms but I'd have to rev the stock stroke more then the piston wear will be no more or less with the 4 mil. If you are going into the motor to do a crank absolutely do a 4 mil. Your new welded crank and bearings will be better than the stock crank you take out of it anyway. As far as wear on components a 4 mil isn't a crazy build its just going to be maybe 10% more HP. That sums it up well. Quote Link to comment Share on other sites More sharing options...
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