BellevilleMXZ
08-09-2004, 10:31 PM
Bit of info from DynoTech on a 04 600sdi. Not putting all the info up, you'll have to spend the money for the goodies :)
Flaked rings did little to hurt the power much, just as I have thought for years.Not saying they arn't a problem, but not as big a deal as some make it out to be.
This 2004 600SDI was brought to us by Matt Kelchlin of Ken’s Service and Sales (SkiDoo dealer) in Elma, N.Y. (716-683-1155). We knew ahead of time that though it had only 2600 miles, it had worn rings, which have plagued some SkiDoo twins (leakdown was 50% and 30%). This sled has not had a life of abuse; Matt’s computer read the sled’s ECU—it showed only 71 minutes at full throttle, and max RPM attained was 8300. Big Brother is watching you. Ken and I thought it would be interesting to see what actual power improvement would result from freshening this engine up. So, we connected the sled to our Superflow dyno for baseline numbers. Note that at 70 degrees F the ECU allows us mid .70’s BSFC. Usually, we warm up the engine, engine coolant and pipe(s) and do two or three 10-12 second dyno runs, and expect the engine to repeat within a few tenths of a HP. But even with very constant tuned pipe and coolant temp this engine exhibited an unusually wide nearly one percent HP variation from run to run. One percent variation in HP might not seem like much but it makes looking for minute gains and losses difficult. So, we ran seven dyno runs and used SuperFlow’s averaging program to give us our whipped-ring baseline.+++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++We were surprised that more was not gained by replacing the rings in this engine. Blowby in a two-cycle should be doubly bad since one would assume that it would contaminate the incoming charge. Bender Racing’s Terry Paine predicted correctly during our predyno coffee hour that little would be gained. They had worked for a week with one of their ProStock engines to improve leakdown from 20% to about 3% (special gapless rings, diamond honing, etc) and gained zero HP on their SuperFlow dyno.
114hp stock, at 7900-----after they got done, with a few simple mods, 124 at 7900
Flaked rings did little to hurt the power much, just as I have thought for years.Not saying they arn't a problem, but not as big a deal as some make it out to be.
This 2004 600SDI was brought to us by Matt Kelchlin of Ken’s Service and Sales (SkiDoo dealer) in Elma, N.Y. (716-683-1155). We knew ahead of time that though it had only 2600 miles, it had worn rings, which have plagued some SkiDoo twins (leakdown was 50% and 30%). This sled has not had a life of abuse; Matt’s computer read the sled’s ECU—it showed only 71 minutes at full throttle, and max RPM attained was 8300. Big Brother is watching you. Ken and I thought it would be interesting to see what actual power improvement would result from freshening this engine up. So, we connected the sled to our Superflow dyno for baseline numbers. Note that at 70 degrees F the ECU allows us mid .70’s BSFC. Usually, we warm up the engine, engine coolant and pipe(s) and do two or three 10-12 second dyno runs, and expect the engine to repeat within a few tenths of a HP. But even with very constant tuned pipe and coolant temp this engine exhibited an unusually wide nearly one percent HP variation from run to run. One percent variation in HP might not seem like much but it makes looking for minute gains and losses difficult. So, we ran seven dyno runs and used SuperFlow’s averaging program to give us our whipped-ring baseline.+++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++We were surprised that more was not gained by replacing the rings in this engine. Blowby in a two-cycle should be doubly bad since one would assume that it would contaminate the incoming charge. Bender Racing’s Terry Paine predicted correctly during our predyno coffee hour that little would be gained. They had worked for a week with one of their ProStock engines to improve leakdown from 20% to about 3% (special gapless rings, diamond honing, etc) and gained zero HP on their SuperFlow dyno.
114hp stock, at 7900-----after they got done, with a few simple mods, 124 at 7900