What is a few percent between friends
rv6ejguy said:
Here is an interesting discussion of different gearsets, advantages, strength comparisons etc. They list efficiencies of helical gearsets at 95-98%. This is dependent on ratio of course. The typical low ratios around 2 to 1 used in aircraft should be in the upper end of that range.
http://www.automation.com/sitepages/pid1906.php
The Konus Konex site lists HTD belt efficiencies at 98-99%.
The fact that the oil temp on my Marcotte (internal helical type) never exceeds 65C with no cooler and no insulating layer between drive and crankcase, clearly shows that it is quite efficient. Contrast this to hypoid gearsets used in car differentials where in race trim, external coolers are usually required for road racing. I measured oil temp on my Toyota diff at 325F with no cooler! A cooler was quickly installed and the oil would last one season between changes rather than one race.
99%! 
That is what you get when you let a sales man write the sales brochure. No need to quibble about a few percent but 98-99% sounds kind of tight. There are TOO many variables, like pulley size, length, width, reduction ration and power transferred. I guess it is 100% standing still, but I think the gate numbers I stated before 95% to 98% are realistic. 99% with no specifics is meaningless.
I spent a whole semester in Machine Elements, learning every detail you could imagine about gears, belts, threaded fasteners, springs and and a long list of mechanical elements. Good times. This is what engineers do in the most basic sense, design gears. Like a belt and another machine elements, there is no free lunch. They all have pros and cons.
Bottom line you guys can rest assure that a Belt is not going to be a huge power robber, but 95% is not unrealistic but think it will be between 95-98%. No one knows until you dyno it. You have to be realistic, when you transfer power there are losses. That is OK, it is just part of the deal.
Gear vs. Belt? Long list of pros and cons, but the belt has some clear advantages, so I would not be to concerned with what Eggenfellner is doing.
He just got caught up in his own sales pitch for the "gear reduction".
The belt may be 1% less efficient than a perfect gear reduction, but who knows? No body dynos there engines. Eggenfellner thinks there is no loss based on his sales brochures. I don't get all the belts, I guess one is not strong enough or its for redundancy. If done for redundancy I would say a belt operated within the manufactures limits should be very reliable. I don't have any specs or manufacture design guides for large cog belts, but usually the manufacture has design equations to help engineers size the belt for an application in the back of their catalogs.
Belted Power has long successes with their V6 conversion using a cogged belt. You don't hear of them breaking. Also belts today are better than they where just 15 years or so ago. I think you can thank all those rubber belted OH cams for that became popular in the 80's, Gates and other rubber companies. (my '88 acura legend V6 has OH cams, at 225k I am only on my second belt with no problems.) V-belts are not efficient; That is the reason all belts on cars (including accessories) are now flat.
George
PS I asked about the H6 and he says it will add 40 lb over the 2.5L 4 banger. I am sorry but I don't believe that, I think it will be 60 lbs or more. It will be interesting to see what kind of performance a RV-10 gets with it. It will be at least 50 hp under a (I)O540.
