Interesting. I guess I've been listening too long to Tracy's lectures. Estimated/extrapolated TBO 2400 hours.
This was based on some 875 hours on his first engine. However, it may be reasonable to expect that the groove "wear" may not be linear - the closer they get to limits the faster they "wear". An accelerated or exponential wear curve.

Another point, I think Tracy did not run those 875 hours anywhere near full power on average.

Now, with cooling problems solved and the new 2.85 :1 PSRU you're probably running at higher power levels.

So, maybe we're looking at something like 500 hours TBO at 200 HP continuous, 1000 hours TBO at 150 HP continuous and 2000 at 75 HP continuous. By "continuous" I mean the HP range the engine runs at the vast majority of the time.

But I guess we're waiting for data regarding groove "wear" from the car racers. Lynn? Leon?

Finn

Ed Anderson wrote:

Finn, regarding the possibility of the apex seal simply shattering rather than FOD.  I also found in the overhaul supplemental instructions about the parts in the basic overhaul kit this sentence from Bruce:

 

".... The apex seal will rock in their grooves, wearing the groove to a V and eventually shatter due to the excessive clearance...."

 

Sooooo, I am more convinced than ever that I did not encounter a necessarily rare condition - that excessive seal clearance and shatter seals do happen.  Does not take a foreign object.  I strongly suspect that there are probably several conditions that play a role in when the seal shatters (if ever) and if they all play the wrong way at the same time, the seal shatters sooner.  On the otherhand, the engine might possibly wear out before the seal shatters if those factors never converge.

 

 

Ed

 

Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com