How to mix a fuel for mpg?
 

Let me explain,

Oh hi, I am new here. I've lurked and read here and there for a few years but finally signed up today as I have an experiment I want to try.

I have a Honda Super Cub with a 90cc (84) motor. On hypermiling trips 25 mph "cruise" I have managed to get it up to 350 mpg. The bike is bone stock and has about 179k miles on it (so it's getting very old).

Now I'm interested in mixing a fuel that has a little more BTU and also one that would allow me to run leaner without overcooking anything. I'm toying around with the idea of mixing some petrol and diesel together but am wondering if anyone has tried that, and also if it's possible to try mixing a tiny amount of meth/water in with the petrol to create a possible detonation suppressant so I can run the bike leaner than normal. I know it's risky, but I am interested PURELY for the fun aspect of things and seeing how high I can get the mpg figure.

P.S. I know that to gain a greater efficiency out of the bike I need to mechanically change things like the compression ratio, intake manifold and ports, exhaust baffles, etc. I am looking for a "pour and play" solution. Thanks!

Diesel will make your bike stink to anyone that's behind. It also may make your engine knock. It will also make it run leans since the viscosity is higher than gas, less will flow through the carburator jets. A fairing would help your mpg, if it doesn't have one already. Maybe a front sprocket with another tooth or riding with a big tail wind or pushing it up hills.

http://craigvetter.com/pages/470MPG/470MPG%20Main.html

I would suggest looking into adding a specific type of ash-less two stroke oil ("TC-W3") as a gasoline additive. The ratio varies from 1oz TC-W3 to 4 gallons of gasoline to 1oz TC-W3 to 5 gallons of gasoline; I use the 1 to 5 ratio (a 1 to 640 ratio). This will not increase BTU (it will probably reduce it very, very slightly), but it will increase lubricity and act as a top end lubricant. I use this in my own car, and yes -- I have seen increases in mileage.

methanol does have a relatively high octane rating, however it's energy content is also pretty low, along with a REALLY low stoich AFR are not going to help at all.... without rejetting, you would be running dangerously lean.

Directory:Acetone:Rumbolt's 2-Stroke - PESWiki

This corresponds to 3oz/10 gal.

The first thing I noticed was an immediate increase in idle rpm by 1000rpm! I had to reset the idle screw. I also noticed that the mixture screw had to be reset for max rpm. I had to close it a bit.

I have now had a half dozen flights with acetone in the fuel. Further, the fuel has been allowed to sit in the plastic tank for 3 weeks with no apparent degradation.

My paramotor typically uses about 1 gal of fuel per hour of flight. Last night I flew for 0.9 hr and used only 1/2 gal of fuel! (90% gain?) I have also noticed a 1000rpm increase in max rpm while flying. This means more power!

Usually after a flight, I have to wipe the oil off the prop. (The unburned exhaust goes thru the prop.) I have seen a dramatic decrease in oil on the prop, indicating better burning of the fuel.

The spark plug is showing a good brown coloring, and I have seen no carbon buildup on the piston. Carbon buildup is typical of these engines.

In short, I have found acetone to be beneficial in small 2 stroke engines too!



GP-7 2-stroke racing oil

GP7 has PIB which has been documented to increase mpg for 2 strokes. Not cheap though.

PIB = polyisobutylene?

....

Thanks for the replies so far,

I've tried 2 stroke oil at a 1:100 ratio and have seen a small increase (10% ish) due to the the fuel mixture leaning out. I am not entirely convinced it's due to it being a top end lube though, seems how the mixed in oil only comes in contact with the piston crown and the tops of the valves and everything else is lube via the oil pump. Smells great though!

The bike runs a bit too hot though so I that's why I was looking for a detonation suppressant and something to cool the operating temps in general so I could run it a bit leaner and get a gain that way.

Oh, and I already have a taller ratio setup on the bike, and it's kind of a pig now to be honest. Gears are way too far apart for the measly 7 bhp motor.

Just don't cheap out and use too little oil or borrow your parents regular motor oil. If you try the acetone...find a Sally's Beauty Supply and buy a quart there...even KleanStrip acetone may be adulterated.

Try the 1 to 640 ratio I mentioned; it works very well.

I still have yet to burn off the current tank..:D I'll give it a shot when I run out of petrol.

Petrol and diesel together.

I have tried it in my engine and found that the timing needs to be retarded a bit and the diesel will settle to bottom of the tank and get picked up first.
I did also notice that after running it for a short time there was a bit of carbon build up on the pistons eg it permanently raised the compression when I went back to straight fuel.