AV - Gas?

[WillySteve]

PowerTec will build what you need! I had to overprop the 25 Merc by 4" to keep rpm's reasonable on the bottle!

[FMP]

Which year 25?

[FMP]

I can't stop laughing!!!!

Yup, I mean nope. Lol

[olboatman]

If your askin me Frank....mine is a 88.

[FMP]

Good years, the Merc?

[WillySteve]

Good years, the Merc?

84 mercosil.

[FMP]

I have an 86, was running in the snow this morning

[Mark75H]

Unless my memory is way off, Mr Smith drove a delivery truck for the gas company, so yes he worked for a gas company and was involved in predelivery mixing.

Like Royal Purple additive, Klotz octane booster is MTBE. Better than what you can buy at AutoZone, which is ... ethanol.

It is correct that regular grade pump gas has more BTU energy than AV gas ... but so does TNT, but that doesn't make TNT better motor fuel.

Klotz Nitro is mostly nitroparrafin, but its not an octane booster.

The higher octane and longer shelf storage components of AV gas are not "additives", they are the base, its just different, not "juiced up" regular gas.


On 2 strokes with radical exhaust tuning, cranking compression may not be the sole factor in deciding where to start using higher octane fuel. On the other hand, I have several racing outboards that crank 275psi. These motors do require race gas and run fine on AV gas. I occaisionally use it in my standard pleasure motors just to avoid E10

[FMP]

275 is a bunch. Purple is MMT, finally read the can again.

[71V153]

Fwiw you can get 104 at Venice Airport. Credit card and container'n yer good to go.

[FMP]

100LL up here, have to fly down and get some 104 lol

[Michael J Giesler]

100LL up here, have to fly down and get some 104 lol

100LL av is 110 octane

[FMP]

Educate us? Just dragged this over, maybe I read it wrong? I've used it mixed with 93 and even straight 100LL and have noticed a smoother run.

AvGas octane numbers are determined in a different test than motor gasoline octane numbers. Do not be confused by the big numbers from the AvGas test method. They are not comparable to motor gasoline test numbers. The 110 leaded gasoline will test out at about 160 on the AvGas scale.
AvGas is held to tighter requirements than street gasoline, but not nearly as tight as is the entire line of Racing Gasolines. Some racing gasoline blenders us AvGas as a blending component to save money.
AvGas has a lower specific gravity than most racing gasolines. This means that if a racer tries AvGas and has not re-jetted, he can burn a piston because the air-fuel ratio is too lean and/or the engine detonated. To make a good comparison between two gasolines, the air-fuel mixtures must be the same. Even after re-jetting, the racer can experience burned pistons with AvGas if the Motor Octane Number (MON) is lower than what his or her engine needs.
Another potential problem with AvGas is that there are several different octane grades. The 80/87 grade is red in color and can get you in lots of trouble because of its very low octane number. The 100LL is blue and the 100/130 grade is green. Both of these have much lower Motor Octane Numbers (MON) than most racing gasolines and will detonate when the engine octane demand is greater than the octane number of the gasoline.

[WillySteve]

We played with av gas years ago and the very 1st thing you'll notice is the specific gravity.....a carb mota will have gas shooting out the vents if you don't lower the floats.
Cars & Boats don't run at 20,000 feet!!!
If you race, use racing fuel....if you don't race, don't build a mota that takes racing fuel....if you feel the need for more HP then buy a bigger mota!!!!
js

[FMP]

93,94 octane pump with 20% total volume Toluene gets you there, add a can of purple on that. I think I might mix that and try it, works to about 101. 91 non ethanol with 20% gets about 96.