[Zeke]

Add one ounce to one gallon propylene oxide and a few ounces of nitropropane. Increase the overall blend percentages until you see too much change in spark plug color, engine knock or mixture problems.

The propylene oxide boiling point is about 90ºF so I kept it in a cooler. The cetane value of PO is higher than gas so works better in lower compression (stock) engines. Nitropropane mixes with gas whereas nitromethane does not and separates floating to the top.

This will add not only HP but hundreds of dollars to the cost of your fuel bill in the quantities you need. I ran this stuff in karts where we didn't use much more than a pint in a short sprint race. Maybe a quart in the main. If there were post race fuel tests you fail.

At a low compression of 7:1 in a 2-stroke the PO was an 'exciter' and the burn rate was increased using a 50/50 mixture of the 2 for total of 10% mixture overall. IDT that 50/50 will work in a 4-cycle motor but the methane will definitely increase the torque and HP.

Legend has it that circle track cars running gas would use PO as it evaporated before the finish of the race and was therefore undetectable in a post race test. That is not the case with NP.

Toluene works too but it burns hot. Not good for air cooled engines.