Well no one would argue with your first sentence, however... There are soooooo many variables that dictate what the life of these tiny engines will be, based on what I have seen, I can't call the use of 30 over 20% a serious contributor.

A friend of mine (who is now my roommate) got an evader about 2 years ago as his first truck and went through 3 of these engines pretty quickly. The sleeves are garbage, hands down. His first engine was run for it's first 7 tanks with no oil in the dry foam air filter. The instructions with his truck and the video it comes with said nothing of oil. The truck that was "ready to run" from the box included no filter oil either. I discovered this on his tank 8 of breakin. I stripped it down and cleaned it thoroughly but it only lasted about a gallon. Engine number 2 had a text book heat cycle breakin. It was set very rich with the head and crank case wrapped in a gym sock to get the temps up quickly, and cooled at BDC for a huge number of cycles. He had learned a good bit and kept a religously cleaned element and ARO'd after each day. It made ok power and was not abused or run lean. This engine saw a sport type (18%oil) fuel of 20% with a hot plug. At about 2 to 2 1/4 gallons this engine would run hot quickly, had lost compression, and was hard to start. The sleeve looked like engine number 1. After some forum digging (places besides here!) it seems that this is not uncommon at all for that mill. Warranty engine number 3 was broken in the same way and spent it's life on 30% race fuel and a medium plug. Careful inspection for the first several tanks after switch-over showed no signs of detonation. This engine was pulled at about 2.5 gallons for something non-OE, and was still running well. This is not offered as any type of counter argument, just an experience.

I have yet to come across a BB or SB car/truck engine that doesn't run better and cooler with 30% and a medium to cold plug. I have many stock and worked engines. I'm not a blind cutter, or uninformed. I use a homemade degree wheel to measure port timing and know what there is to be gained at 1-1.3mm of the right part of the exhaust port. The same goes for the intake (to a lesser extent). I have had a number of engines to cut up. I have passed along to others four or five ported engines that are alive and strong (at this moment) at 3-7 gallons and have been run hard with 30%. A buddy of mine got just over 8 gallons out of a Picco 26 that I worked and reworked, and ran for 2 gallons myself!! This engine was beat on with 30% too. Many people see tired engines that aren't little RTRs at 4-6 gallons on 20% "sport" fuels like BT. Again, this is no counter argument, just experience.

I'm sure it's a variable that contributes to wear, but my experience tells me that it must not be a large contributor. I have seen breakin to be a large contributor to life, especially in my airplane engines that are somewhat comparable to these. I have seen tunes that always run the line of lean, and commonly fall over here and there for the whole life of the engine (about 2 gallons, and not an RTR engine). It had a rebuild that lasted over 3 times as long (now just over 6 gallons on new piston/sleeve/rod) and is still going on a more conservative tune. I like the speed, that's why I'm into this. I've never had an engine that made more power with 20%, and it doesn't seem like a large detriment, so I run 30.


/endlongwindedness