Liquid-cooled conversions for Lycomings

[rogerbacon]

http://www.liquidcooledairpower.com/products.shtml

 

Has anyone heard about this? They claim a 38% fuel savings with their conversion (based, I assume on leaning a lot more since the engien temperature is so much lower).

Are those kinds of fuel savings seen in auto conversions that are liquid cooled? Sounds way too good to be believable. Oh yeah, they also claim TBO would go to 3000.

[Edge 513]

I saw this a while ago and was amazed that they wanted 15grand for a 4 cyl Lycoming setup. A LOT of petrol gotta be saved to warrant this as a cost saver...but I am too lazy to math out the break even point.

Now Jack M. has a liquid system on his 540 and he uses it at altitude. He uses alcohol as well, and although his bird flys a little swervingly up there when its on this juice. I would say theres no sky-cops yet to pull him over, so he's in the clear.

I just read this back to myself and it bears pointing out that the bird is using the alcohol at altitude- not Jack.

[Lynn Erickson]

http://www.liquidcooledairpower.com/products.shtml

 

Has anyone heard about this? They claim a 38% fuel savings with their conversion (based, I assume on leaning a lot more since the engien temperature is so much lower).

Are those kinds of fuel savings seen in auto conversions that are liquid cooled? Sounds way too good to be believable. Oh yeah, they also claim TBO would go to 3000.

when you lean an air cooled lyc. and go lean of peek the temps go way down anyway until they get a little to cold for my liking. when at altitude I can lean to 6.5 gal/hr and still have a ground speed of 200. I doubt liquid cooling is going to be 38% better then that. besides at altitude the temps are almost to cool

[Waiter]

I think Voyager used something similiar (or attempted to use them) on its "Around the World Flight".

 

I our air cooled engines, Fuel not only makes things go, BUT, is some situations, it provides additional cooling to the cylinders. This happens anytime the mixture is set richer than "Lean Of Peak". The excess fuel that enters the combustion chamber helps cool the cylinder.

 

Theres a good discussion of this on the CAFE foundation web site.

 

Under these conditions, I could easily see a reduction in fuel burn by using the water jackets. But only if its accompinied by always running the engine lean. (No need to run rich because the water jackets are providing cooling.)

 

Normally, once your cruising, you lean anyway, so you won't recognize any fuel saving in this mode.

 

As far as lower drag - Maybe, the heat from the engine has to go somewhere, and that somwhere is ultimately in the surrounding air.

 

The only advantage that I see to the jackets is the ability to more precisly control WHERE that cooling drag will be placed on the airframe.

 

The only time I provide full rich is at takeoff. Otherwise I constantly lean to get the best lean of peak. MOST IMPORTANT while on the ground.

 

Waiter

[argoldman]

I think Voyager used something similiar (or attempted to use them) on its "Around the World Flight".

 

I our air cooled engines, Fuel not only makes things go, BUT, is some situations, it provides additional cooling to the cylinders. This happens anytime the mixture is set richer than "Lean Of Peak". The excess fuel that enters the combustion chamber helps cool the cylinder.

 

Theres a good discussion of this on the CAFE foundation web site.

 

Under these conditions, I could easily see a reduction in fuel burn by using the water jackets. But only if its accompinied by always running the engine lean. (No need to run rich because the water jackets are providing cooling.)

 

Normally, once your cruising, you lean anyway, so you won't recognize any fuel saving in this mode.

 

As far as lower drag - Maybe, the heat from the engine has to go somewhere, and that somewhere is ultimately in the surrounding air.

 

The only advantage that I see to the jackets is the ability to more precisly control WHERE that cooling drag will be placed on the airframe.

 

The only time I provide full rich is at takeoff. Otherwise I constantly lean to get the best lean of peak. MOST IMPORTANT while on the ground.

 

Waiter

Waiter,

 

I must protest! (probably just a typo-- but I am going to have my say anyway)

 

Actually, the fuel cooling happens when we run rich, not lean of peak. The cool fuel blowing on the intake valves and entering the combustion chamber and hopefully evaporating, reduces the temps. This is used on all air cooled aircraft engines at take-off power. The injectors, or carburetors are set for this at full throttle. This is one of the reason that you should always take off with full power. as you do, even though the aircraft can, many times, easily take off with less than full throttle.

 

That being said, there is a cooling effect when running lean of peak but that is because the "fire" is not as hot as it would be at stoichiometric air/fuel mixture

 

I believe that the engine (rear if I remember) on the Voyager was a continental with water jackets. I seem to remember that somebody tried to market these cylinders, but I haven't seen them around for a while.

 

Water cooling does offer certain fuel advantages in that an air cooled engine must operate well(?) at various temperatures ie TO, Cruise, Descent etc. Because of this, an air cooled engine has much looser fits to enable the various differential rates of expansion/contraction of the different metals that compose the "top" end to work together, without destroying themselves. The liquid cooled engine, on the other cylinder, operates in a narrow band of temperatures and thus everything is made with closer fitting tolerances which increases fuel efficiency.

 

If you want the best of both worlds, install a water resivoir, a windshield washer pump and spray heads over your cylinders. When you CHT gets to the warm side, give it a shpritz!

 

I say that in jest, but I think that with the original 747 engines, which were so unreliable that some of the 747 aircraft were outfitted with a hanger so that they could hang another engine under the wing for transporting, one of the things that they did was to use the above concept to spray and cool some of their turbines, until they came up with a more sophisticated fix:(

[Waiter]

This happens anytime the mixture is set richer than "Lean Of Peak".

I thought thats what I said?? Anytime the mixture is "Richer" than LOP, i.e rich.

 

Waiter

[argoldman]

I thought thats what I said?? Anytime the mixture is "Richer" than LOP, i.e rich.

 

Waiter

 

That's what happens when I read these things right after I wake up.

 

You are indeed correct you did say that. I missed the word Richer and my eyes nailed the "Lean of Peak":o

 

Many mixture related apologies. Thanks for keeping me honest! (and waking me up)

[Waiter]

Hey, no problem, I wrote it right after I woke up, so I had to double check to make sure it said what I thought it said, I think. :D

 

Waiter

[mfryer]

If you want the best of both worlds, install a water resivoir, a windshield washer pump and spray heads over your head. When your brain gets to the groggy side, give it a shpritz!

 

Sorry, couldn't help myself...