Anyone use Aviation fuel in their Ferrari?

Just to confuse the issue, I used to mix Avgas, with a 20% Toluene mix as a cheap replacement on practice days for VP C14 leaded race fuel in a TZ250 GP bike.

 

doesn't AVGAS damage the O2 sensors???

i don't know why but i've seen it happen before with normal fuel injected cars

 

Vern,

You are gernerally correct about Octane. However, the slower, more stable, burn will allow you to advance the timing to gain back the power plus some.



Ken,

I run a mix of AV and super in my 330. The car runs well on it, it's good for the motor, if used on a long roadtrip, it lead-coats my exhaust system and I love the smell of the exhaust. There is one final benefit: AVgas does not have many aditives, therefore it is much more stable over time. So if you use 3 tanks per year, the gas will not go bad and you will not get varnish in the fuel lines.


Regards,

Art S.

 

From a forum I regularly read with plenty of engineers and auto/race industry people and that bans numbskulls at the drop of a hat. I have seen a couple of f-chatters over there, right MarkPDX?
The author below currently work for SWRI in SA.
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Damn, mentioned twice in one thread. Where did I put my princess hat?

OK, we're gonna start out with a little gasoline talk. Gasoline is blended from as many as 15-20 refinery streams to meet a set of target specifications. Specs like a distillation curve (D86), Reid Vapor Pressure (RVP), octane, and a host of others that I listed a long time ago in another thread when I was trying to be thorough. Some of these factors, like RVP, change with the season. The gasoline blend changes to meet those different targets. RVP could be as high as 11-13 psi in summer, and as low as 5-6 in winter, while most racing fuels are around 4-5. So it would a fallacy to think of "87 Octane gasoline" as a specific thing- it, and every other level of gasoline, change all the time.

Why does this matter? Because it leads into the next great myth that needs to be debunked. Here's the real truth- OCTANE AND "ENERGY CONTENT" DO NOT CORRELATE. They just don't. That doesn't mean that if you have one gallon of 87 (R+M/2) and one gallon of 93 that the heat of combustion won't be different between them. It just won't vary the same way the next time you try the test. Maybe in the winter the 93 octane will have a higher energy content, and maybe in the summer the 87 will be higher. I always see all these internet generalizations regarding octane and energy- how higher octane fuel burns slower and thus makes less power if you don't need it. Bull****. SOME significantly higher octane fuels are blended in such a fashion as the heat of combustion of the mixture ends up being lower, but its not because of the higher octane. Some non-leaded racing fuel blends fit this bill- their reliance on aromatics and a few other components over branched chain paraffins caused the heat of combustion of the total mixture to be lower vs. a standard gasoline fuel. Because of some data they've seen with very high octane unleaded race fuel, people tend to get this idea that higher octane equals less energy.


Quote:
The reason you can run more timing w/92 is it takes longer for the flame front to propogate therefore decreasing the chance it will collide with the piston while on it's upward stroke.



Wrong. Next myth out the door- OCTANE DOES NOT CORRELATE WITH FLAME FRONT SPEED. This is another convenient explanation for some people, but it doesn't fly either. I'll offer an example. Two chemicals were originally used to define the octane standard back in the day. Normal heptane (octane 0) and 2,2,4-trimethylpentane (also called iso-octane, with a definition of octane 100). These two chemicals are similarly sized, and also have nearly identical flame front speeds, but one has an octane of 0 and the other an octane of 100.

So what is octane, and why does it confuse so many people? The simple reason for the confusion is that octane is really a chemical property, and people have a hard time understanding that. So they try to equate it with some physical property that they can understand, and are inevitably wrong in doing so. Octane has a lot more to do with the bonds of a particular molecule, and how prone they are generating radical alkyl groups during the heat of the compression stroke. These radical carbons on the hydrocarbon chain are quite prone to preignition under that heat, and can ignite other molecules around them as well, leading to the common detonation from overly advanced spark timing, or the less common pre-ignition purely from the heat/pressure of something like a forced induction vehicle.

Back to your original question- better to run 93 with advanced timing or 87 with stock timing. Even with a 9:1 compression ratio, there is still power to be gained by advancing the timing and running a higher octane fuel to ward off detonation. As BK mentioned, it's a law of diminishing returns kinda thing, so your gains are really gonna plateau off if you try to keep running even higher octane fuel and advance the timing further. If you manage to run a blend with less energy and aren't getting anything from your additional advance, you could actually make less power farther up the ladder.

For anyone who doesn't know me, or wonders what separates me from the 1000 other jackasses posting about this type of stuff on the internet, I have a Chemical Engineering degree and used to work for BP as a refinery process engineer making gasoline. I now do engine and vehicle tuning for emissions reduction at a major research institute in San Antonio.

Hope that helps, jimbo.

 

Yes Rolo, tetraethyl lead in avgas coats the O2 sensor. After a couple of tanks it's done. You have to replace it. There is no way to clean the lead off.

Avgas also has a very different distillation curve. It lacks the "light ends" that street or race gasolines have. For example, in a carburated engine if you are running at WOT you won't notice. But if you are driving where you have to accelerate through the gears (S turns, hills, etc.) the avgas has worse throttle response (sluggishness). It lacks the "light ends" or more easily atomized curve of the fuel because in an airplane you don't want vapor lock at 30,000 ft. Remember these aircraft engines don't turn more that 3000 RPM and under cruise only operate in a narrow RPM band.

 

To really take advantage of the higher octane Av gas, you need to advance the timing a little. (assuming no cats)
Back in the 70's, I think Sonoco 260 was 102 octane at the neighborhood pump (used it in my 70' Vette)- really miss those days- about 75 cents/gal too, I think.
I'm glad my Ferrari is low compression though, it can run on anything, if it has to.

 

Just curious, could you run such a blend (1gal to a full tank) in a Daytona?

 

JCR,

Thanks, nice write-up. My knowledge had been diluted with some of these myths.

I agree with the comments about 'light ends' however, when running a half AVgas / half super blend, there are enough 'light ends' in the blend from the super to compensate. I do not see this sluggishness when I drive (however, I rarely drive 10/10ths so i just might not be perceiving it).


Evan,

I prefer to run a blend of about half and half (see above), I have seen no ill effects in my 330. I don't think the Ferrari Daytona has any sensors that mine doesn't, so you should be fine. The one exception to this is plug fouling. I've been told that the plugs can be more likely to foul with AVgas. I personally have not had any significant issues with this.

Regards,

Art S.

 

Agreed Art, I really meant those racers who use 100% avgas because they are too cheap to buy race fuel. Using 50/50 is no problem other than the legality of it (taxes, lead).

 

JCR,

Franky, I just like driving down the flightline to the tanker truck to fill up .

Regards,

Art S.

 

Why not just toss a box of mothballs in the tank and be done with it?