SINGLE RING VS. DUAL RING

 
 
The heat energy in the piston is absorbed by the rings. The rings then transfer this heat into the cylinder walls and eventually into the engine coolant or into the surrounding air (air-cooled engine). The table shown below provides data on this heat dissipation and transfer phenomenon under different engine operating conditions.

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Since the piston rings are in firm contact with both the piston and cylinder wall, they can 'take' heat energy from the piston and transfer this heat into the cylinder. The graph above shows that approx. 70% of the piston's heat is carried away by the piston rings, under both unloaded and loaded engine operation conditions, at 1,500 and 3,000 rpms


Above from Riken Ring.. One of, if not the, largest ring producer in the world.

There are many reasons why , I THINK, BRP uses a single ring on the 800

1)When you have less heat transfer with a single ring, the ring gets over-loaded and ring seal fades and with fading you get combustion blow-by... With blow-by you get power LOSS.. So, if you have blow-by (which you do) and you Lose power (which happens with blow-by) then you will now be over-fueling the cylinder, contaminating the intake charge (due the blow-by) which, in turn, lowers charge purity, which in turn, lowers power... So, now you have made your engine make less power BUT you are still feeding it with the same fuel (via carb jets) for the stock power.. So, now you have created a over-fueling (rich) condition inside the engine.. Rich conditions COOL the piston which is needed because of the ring over-load, and this same rich condition also aids in the power LOSS.. you can not make power with an overly rich condition...
So, it is a cycle that repeats over and over.. ring over-loads, charge density lessens, rich conditions occurs, power ouput is dimished, piston cools, ring seals normal again, back to stock power (or close to it) rinse, wash, and repeat..

It is VERY hard to seize an engine with a very rich condition... This is a very good reason for BRP to use a single ring. Less engine failure due to over-fueling.

2) DETONATION.. there is that "buzz word" again.. One of the MAIN signs of detonation is hammering between the rings (2).. Deto if left untreated will hammer out the piston area between the upper and lower rings.. This area will crack and eventually break off causing some good engine damage.. VERY COMMON with Detonation.. Well.. with 1 ring.. it is impossible to hammer out the small area between the 2 rings because there is no second ring... ANOTHER good reason for BRP to use a single ring..

3) HORSEPOWER (DYNO POWER): single ring pistons WILL have less drag then a double ring Epsecially when the dual rings are quite thick.. and you are comparing them to a thinner single ring.. So, on short pulls (LIKE DYNO PULLS) before #1(above) occurs, the dyno run is over and the output power is up a few HP due to the shortness of the dyno pull..

ANOTHER good reason for BRP to use a single ring...>>>> MORE DYNO POWER! = Better advertising and better sales..

NOTE: as this single ring gets thicker and thicker (like it is) the difference in drag between 2 thin rings and 1 thick ring become less and less..


NOTE#2: Thicker rings HATE higher rpms.. You get what is called ring flutter with high rpms and thick rings.. Thinner rings are a standard cure for ring flutter... Also the Dykes (L ring) used on the 670 engine was designed just to combat ring flutter.. However, the Dykes rings has other negatives that accompany it which is why it was abandoned for standard key stone rings.

NOTE.. The RK Tek Drop in Kit for the Series III Engine uses 2 very thin rings... Just some FYI..

Anyway.. the above is only some technical info based on KNOWN data on how rings function . it is not speculation on the part of what happens with single rings, thick rings, thin rings, ring flutter dual rings.. etc. etc.. It is known facts that can be backed up with SAE papers and just common knowledge..

What IS speculation , on my part, is the added verbage about "WHY" BRP uses a single ring.. I have no inside info on why they do it.. I just know what happens internally with the engine and piston and SPECULATED and Formed a THEORY as to Why BRP MAY have went this route.





 

 

 

 
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Copyright 2006. 2StrokeHeads.com    Disclaimer

Website updated by Urban Plains Web Design