It was fun to dig in and work it out, and satisfying to calculate fuel consumption of a Babe Bee and get close to reality with a bunch of assumptions and not too much work. I left out some details in between numbers, but all the density and stoichiometry figures are readily available on the internet. I'll go one step further, maybe this evening, and generate a table of fuel blends and graph total combustibles intake per stroke for a range of fuel blends. The plan is to keep a consistent volumetric (not mass) ratio of methanol to nitromethane of 3:1 and start at zero oil up to 50%. This sounds like a lot of work but with Excel all it takes is getting the initial math right then it does the slug work. I'll plot oil content on the xaxis and total mass of air/fuel mixture (sans oil) on the yaxis, and post it here. That will paint what I hope is an interesting picture of theoretical power loss versus oil content. It may put some to sleep but I find it interesting.ORIGINAL: combatpigg
I think 2 stroke model glow engines are roughly 2/3rds as fuel efficient as the same size 4 stroke..?.
Some highly tuned engines can exceed the 100% volumetric efficiency mark. I wouldn't be surprised to hear that piped 2 strokes are right at the top.
Your mathematical breakdown was an excellent read, thanks for taking the time to post that here...!
There's a typo in my post: "0.8cc x 16,000rpm x 0.9 = 10,880cc/minute of mixture"
It says 0.9 but I actually used 0.85 for 85% VE. Should read "0.8cc x 16,000rpm x 0.85 = 10,880cc/minute of mixture"
Now I know nobody is reading that closely..











