Running on Auto...fuel that is

[Ccater]

WAG Seafoam?

[RanRan]

WAG Seafoam?

Nope. But it is about protecting your engine.

Pretend you are an oxygen sensor. (Which you are, by the way, every time you adjust the mixture.) What other sensor would you really, really like to shake hands with?

[Frank]

OX sensor and EGT.......?

[RanRan]

OX sensor and EGT.......?

No, it's a Knock Sensor. They can be attached anywhere on engine and sense a knock on ANY of the cylinders - the sound travels through the metal. You cannot hear it in an airplane.

Thermo probes are essentially switches - measuring resistance. Hook # 5 or 6 probe to the knock sensor - and you will have an on or off signal telling you that the engine is knocking. This is easy to test. Wire a KS to probe terminals and tap on it with a metal object. It should red-line. Try it.

Why is it important? When you lean and then enrichen the mixture to get rid of the roughness - your engine may still be knocking but you have no way of knowing that. Ignorance is not bliss.

Why is this vitally important? Because no matter what fuel you may be burning in the future, you will know that you will not be destroying your engine because you can now sense pre-detonation (knocking) and react to it.

This is the simple solution to the up-coming fuel change-over problem for the fleet. Crude, at best, but workable.

The more elaborate solution involves: OX sensor...KS sensor...Spark Timing...EG Temps...ie. an engine computer. We'll get there...we're only 30 years behind the auto guys. So what's the rush? Simple. New fuel anticipated for the fleet of GA and FUEL MILEAGE.

I've checked for patents - no game - but I have a better idea for solving the EPA - FAA dilemma. But I'm not going to put it here.

Go green!

Ran....from Motown. ;-)

[Frank]

I'm not so concerned with our fuel system materials compatibility, I believe they are, but here's the dealbreaker scenario....

Your plane is filled with mogas/ethanol and sits outside for a month or so. Condensation accumulates every day in your half full tanks as they heat up and cool down. After a month or so a fair amount of water has accumulated. The ethanol absorbs it up to a point and you don't see it when you diligently sump your tanks. But your plane has now passed that point where the ethanol can hold the water and it is separating, "phase separation" it's called. It's 40° outside and you takeoff over the mountains. The OAT quickly falls below freezing and the now-separated water that has now been sucked into the fuel line freezes. Your engine quits over nasty mountains and though you're a superb pilot you just can't make a survivable landing on the side of a mountain and you are killed. The NTSB determines the cause and your widow now sues CC for approving autofuel when this is a known failure mode. We are now out of business, the fleet is orphaned, and we can't make great airplanes anymore. So, where's the upside in CC approving auto fuel in the CC340?

RanRan,
A Knock Sensor would be a plus in the battle of longivity of engine life, but.......Randy still has not had a solution posed for his very valid position which concerns fuel that has yet to enter (and may never enter) the area of engine operation.

[RanRan]

RanRan,
A Knock Sensor would be a plus in the battle of longivity of engine life, but.......Randy still has not had a solution posed for his very valid position which concerns fuel that has yet to enter (and may never enter) the area of engine operation.

Oh, I think a new universal fuel is coming. And it may well contain ethanol - they have to replace the lead with something to control detonation - (and isn't harmful to breath).

Whatever it is, it's going to burn differently than 100LL - hence the need for knock sensing. (I'd like to see Dynon and others develop a dedicated circuit for a KS - complete with adjustments for sensitivity). I could help. A KS is a tiny little thing and weighs about an ounce.

The key word in all this is 'universal.' Once the properties of the new fuel are known, things will get interesting. If they do something esoteric to avoid ethanol - we might see outrageous fuel prices in the future.

Ran

[RanRan]

RanRan,
A Knock Sensor would be a plus in the battle of longivity of engine life, but.......Randy still has not had a solution posed for his very valid position which concerns fuel that has yet to enter (and may never enter) the area of engine operation.

As in real-world valid? I don't see it. Mogas is 90% gasoline and 10% ethanol. RonRico 151 Rum is 75% ethanol and 25% WATER. Both 'fuels' will ignite and burn.

In a 30 gallon fuel tank of mogas - there would be 3 gallons of ethanol. You could add a GALLON of WATER (to make 151 proof ethanol) to the tank and the ethanol (and water) would still burn. I just don't see that amount of condensation occurring within a meaningful time period.

With aircraft vibration that 30 gallon tank becomes a big cocktail shaker - the water will find the ethanol molecules - bond and then burn. So 'phase separation' is a bogeyman. Try this experiment: in a clear glass pour fill it a quarter full of vodka. Hold it up to a light - it's clear. Now add another quarter of water. Hold it up to the light - it will seem to now have a 'texture' - that's phase separation. It will go away as you watch the water and ethanol assimilate, like magic - the mixture is clear again.

Now one more experiment: take a bottle of 70 proof vodka, which is 65% WATER and put it in your freezer overnight. Take it out in the morning and see that it is clear as a bell - no phase separation. Ethanol can assimilate a LOT of water!