Mixing fuels

[martyf]

Ok here my question about mixing, blending octanes

I'm an aircraft mech and often we have to defuel aircraft with aviation gas, this is av gas not jet fuel. It's 100 oct low lead.

Now i know if I ran this straight in my ride it would eventually burn valves and pistons BUT what about mixing it with say 87oct 50/50 would that essentially make it 93 oct and be Good to go for running in my street eng??

What do you guys think??

 

[26Troadster]

the av fuel is ment to be used at altitude. ok that being said mix away it has been done for many a year, we use high oct. premium when mixing. it will drop the oct. some but it still works.

 

[Old Iron]

Yes, it can be mixed to any ratio you are wanting.
50/50 would get you in the 93 to 93.5 range.
There's a misconception, in most peoples minds, about higher octane giving you more power.
If the compression ratio, in the engine you're running, is 9.5 to 1 or less you don't need anything higher than 87 octane.
If you run 91, 93, 100, 110 etc. all that will happen is the engine will not burn all the fuel and the excess gas will be burnt in the exhaust manifolds and exhaust pipes, causing excess heat.
The compression ratio has to be raised in conjunction with running higher octane fuels so, the fuel is bunt in the combustion chamber of the engine where it makes the power.
I used to run the highest octane fuel I could find in my latemodel circle track car where we were limited to 11 to 1 compression and flat top pistons.
I read an article on fuel ratios and started mixing my fuels and ended up with a mixture that gave me 97 octane for the best torque and horsepower.
It took me from where I was to where I wanted to be and started winning races.
I can go on for a long time explaining fuels, propylene oxide, nitrous oxide (I know it's not a fuel), nitro methane, alcohol but, this should give you the info you need.

 

[Torch]

What makes you think it will burn valves?

 

[HOT40ROD]

We use to run the purple stuff 100% in the race car with no issues. also used it in my car on the street at the end of the season and never had any issues. Back in the 70's you could buy 100 oct at the pump

 

[maverickmk]

Running higher octane will give you more power - if your motor is pulling timing out to compensate for knock. Computerized motors of course.

 

[sgtpontiac]

Since I do fly I can tell you that 100 low lead aircraft fuel

has been used for years in HP street cars.....without any neg. affects....including some of my own.....true the fuel is blended so as to work well in low temp / altitudes but most small aircraft don't fly much over 8 to 10 thousand feet unless they have oxygen or are pressureized..... that being said, you can mix it with any of the current fuels and as said, the octane levels will drop.....remember, it is LOW Lead, not unleaded and if you put this stuff thru a catylitic converter you will destroy it.....

 

[Bamamav]

We used to run it back in the 80's in a 383 stroker street/strip car, usually mixed it 50/50 with premium, then added a can of Moroso octane booster, never had any ill effects except on the pocket book......

 

[GJunktionMike]

Like all the above pointed out. been done for years, so mix away.

 

[gold03]

Interesting... You really don't want it. I happen to know a guy who takes care of problems just like the one you are facing. What to do with high octane fuel? [ddd

Kidding... Sorta

My understanding is that higher octane fuel burns slower. Think of diesel. Higher octane than gasoline. Slower burn gives more control in combustion chamber. Slower burn is like pushing down real hard on the piston instead of hitting it with a real big hammer.

I used to mix regular and premium when I was racing my 1970 Malibu. 50/50. Worked great! Would love to have been able to play with aviation gas back then. When I was a kid my old man had aircraft and his own fuel supply. Tried it in my old maverick with poor results. Would love to do it again with what I learned from drag racing.


Gold03

 

[R Pope]

More octane than the engine needs actually costs a bit of power, but there will be no other side effects like burning valves and pistons.
Av gas is formulated to be less volatile to prevent rapid evaporation at high altitude, so it might lean out the mix a bit. I suppose if your engine was already a bit lean, it might have a hot burn problem, but you likely already had one anyway!