Xtreme Performance Dyno has been simply removing the Tstats from last year’s RMK800 and this years Dragon 800s. This allows unrestricted coolant flow in parallel through front and rear heat exchangers. Bill Davis reports that this drops coolant temp to max of 100-110 deg F on hard running, albeit with way less HP (high altitude) creating engine heat. It’s been suggested by Polaris techs that plumbing the heat exchangers in series like the SnowX racers (as the following link shows) might cause coolant flow to be restictive, lower than the 22 gal/ minute flow they say is necessary to do the job. The easiest thing to do is pop the Tstat out, just run the oring gasket. Check coolant temp and we’re hoping that in reasonable snow it will run 100ish. But if on hard pack, high speeds if it climbs to 125+ you will just lose HP from the hotter coolant/ lower airflow and the increased liklihood of knock that will result in less timing/ richer fuel flow. Surely some are doing the series plumbing like the similarly powerful 600 SnowX mods, that run on-off-on throttle but never see much over 80 degrees F. We can report how this does work out.
Dragon owner Doug Meyers (thanks Doug) sent us this link to show how to put D8
heat exchangers into series.This is how the new IQ race sleds are
plumbed:
http://parts.polarisind.com/PrintAssembly.asp?assemblyID=38095&AssemblyName=ENGINE,
COOLING SYSTEM – S09MX6JS/JE
&ModelYear=2009&LineName=SNO&Print=Yes&ModelName=600 IQ RACER/EURO
– S09MX6JS/JE