A

Aden Rich

Well Known Member
This thread is two parts.
Anyone used the Sabre C/S prop extension for the Sam James cowling installation? What's your thoughts/reservations.

Now that AVgas is more than $5/gal in PA, I'm strongly considering using autogas in my new RV-6. Since I'm building this from the ground up, what does it take to use autogas in the RV. I know a cooling shroud around the fuel pump is a must. Anything else to prevent vapor lock. APF system compatible with the fuels containing ethanol.

Thanks, Aden Rich.
 
I would suggest asking the manufacturer of your relevant systems to get their take on it.
 
1. I wouldn't hesitate to use a prop extension with a C/S prop. I know of a few RV's with Sabre extensions with Hartzell's, they work fine. A friend gave me an extension for my Rocket that flew for 15+ years on his Rocket. If I didn't get this extension which is a machined work of art, I would have purchased a Sabre extension.

2. I've been running over 700+ hours now on 87 octane pump gas in my RV, and I'm a big advocate for it, as long as the fuel is alcohol-free. In the past eight months I've only had two fillups of the blue stuff. My engine is an O-360/Hartzell. The main thing is to route lines as short as possible, and minimize the use of 90 degree fittings. The only time I've had any problems is with gas with ethanol, and those problems were vapor lock on the ground. Boost pump usually takes care of it.

I get my mogas from the local farm bureau, and my supplier does not blend ethanol in their fuel.
 
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Sabre Ext

I have a 2 1/4 in. Sabre Extension on my RV-8 with a Sam James cowl. Absolutely top quality item with no issues. I only do "gentlemans acro" with my -8 so I'm not worried about excessive gyro twisting on the crankshaft.

On the -8 the extension doesn't help with the forward CG, but everything is well within range. It might help with the side by side RV's though.
 
gar gas

Rocketbob
What type of plumbing installations to you have. Any return lines to the gas tanks? Thanks, Aden.
 
rocketbob said:
1. I wouldn't hesitate to use a prop extension with a C/S prop. I know of a few RV's with Sabre extensions with Hartzell's, they work fine. A friend gave me an extension for my Rocket that flew for 15+ years on his Rocket. If I didn't get this extension which is a machined work of art, I would have purchased a Sabre extension.

2. I've been running over 700+ hours now on 87 octane pump gas in my RV, and I'm a big advocate for it, as long as the fuel is alcohol-free. In the past eight months I've only had two fillups of the blue stuff. My engine is an O-360/Hartzell. The main thing is to route lines as short as possible, and minimize the use of 90 degree fittings. The only time I've had any problems is with gas with ethanol, and those problems were vapor lock on the ground. Boost pump usually takes care of it.

I get my mogas from the local farm bureau, and my supplier does not blend ethanol in their fuel.
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RocketBob,

The ethanol may not have been the cause of the vapor lock on the ground. I've tested E85 vapor pressure and it comes in almost as good as 100LL. My last 93 mogas purchase from Wal-Mart tested at 60 kPa's (100LL usually comes in at 62) and it had "up to 10%" ethanol.

I've been using ethanol laced mogas for some time and do not believe it is a problem except there may be some loss of power. It would not seem unreasonable to conclude that if aircraft engines were upgraded with seals and o-rings not incompatible with alcohol, the ethanol boogy man would go away. The engines would burn it and probably couldn't care less.

The other issue with ethanol is water absorption the theory being it can hide the stuff until you get to altitude and then will come out of solution due to lower pressure and temperatures. An interesting theory but I've not read a report of it happening or even testing to prove it.

I am not a fan of the politics behind the rise of ethanol. It is a gold mine for those on government agriculture subsidies but some of the myths about it are just that, myths.

The local price of 93 mogas is $3.62 vrs. $5.65 for 100 LL. That do make a difference, ethanol or not.

As a side note, I have pulled an ad to sell the Subaru. After due reflection, it sunk in that the engine is running fine and the hassle and cost of changing out to a different engine simply is not worth it. There are always things that could be better not matter what engine you have and at the moment I am not having magneto problems at all. :)


 
Aden Rich said:
Rocketbob
What type of plumbing installations to you have. Any return lines to the gas tanks? Thanks, Aden.
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Hi Aden, its stock. No vapor return.

I question the usefulness of a vapor return line on a carb'ed engine, since fuel can be boiling in the bowl and there's no way to get it out. A have two friends each with Rockets that run mogas with AFP injection, no problems either. All stock.
 
David-aviator said:
RocketBob,
I've been using ethanol laced mogas for some time and do not believe it is a problem except there may be some loss of power. It would not seem unreasonable to conclude that if aircraft engines were upgraded with seals and o-rings not incompatible with alcohol, the ethanol boogy man would go away. The engines would burn it and probably couldn't care less.
Click to expand...

The only time ethanol fuel has been a problem for me is on the ground with the boost pump off, or a short turn-around where the engine sits for 15-30 minutes and the carb heat soaks. That has happened exactly two times to me in seven years. Its only happened when I used a different source of mogas than normal.

A line with a remote valve to the bowl drain would allow one to purge the carb of hot fuel, but for me I don't see it as something I need to do right now. Unless all fuel has to be ethanol-blended in our state...
 
Prop extension

I would consult Hartzell about using an extension on their propeller. If the extension you are using is not used on a production aircraft with the same engine and prop then you may encounter some vibratory stress issues. When I say vibratory stress issues, please don't misunderstand and think I mean cockpit vibration. Propellers can vibrate in a manner/frequency which is not felt in the cockpit, but can be very bad on propeller wear. Prop extensions tend to increase the magnitude of these vibrations. If there are other people out there with high time props with the same setup you've got, then you should be okay, but better safe than sorry.

Mike
 
I don't think the ethanol is that big a thing either. Did anyone ever find the conclusions with that seal test that was being done earlier last year? I'd be more than happy to buy some engine seals (MS o-rings, Bendix FI orings (carb doesn't have any!), and pushrod tube seals and the like) to see if those are effected by alcohol/ethanol. I've got a feeling it'll be fine. Also proseal... yeah, need to test that.

Either way, on the Saber extensions, plenty of people use them, I've only used them with FP props, but they are beefy.
 
osxuser said:
I don't think the ethanol is that big a thing either. Did anyone ever find the conclusions with that seal test that was being done earlier last year? I'd be more than happy to buy some engine seals (MS o-rings, Bendix FI orings (carb doesn't have any!), and pushrod tube seals and the like) to see if those are effected by alcohol/ethanol. I've got a feeling it'll be fine. Also proseal... yeah, need to test that.
.
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I would seriously, honestly like to see some testing like this! Include the interior of fuel hoses as well.....that should cover most of the worries about ethanol damaging the systems.....
 
I just happen to have some of that stuff laying around my hanger. Now to actually do it.
 
Ken said:
Peterson Aviation has a lot of valuable information including a section on homebuilts.

http://www.autofuelstc.com/autofuelstc/pa/PetersenAviation.html

Ken
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I've spoken with Mr. Petersen as that is where I bought a Hodges vapor pressure tester.

The device is made of plastic and ethanol was destroying it after a few months use. He sent replacement parts free of charge and said they would look into the issue although they do not recommend using ethanol. Good guy to do business with.
 
Interior of hoses

Should be teflon...Ethanol won't touch that

AFP system is completely compatible with Ethanol

Saturation of ethanol with water is my big concern..Should be measurable with a hygrometer...I doubt its a real issue unless going up high, but I don't know for sure

I have not yet confirmed Proseal is completely compatible with Ethanol

All my aerobatics are done with a sabre 2.25" extension and a Hartzel C/S prop..

see http://youtube.com/user/frankhinde

Have oulled +5 and -ve 2.3 G's.

Hartzell will never endorse an extension..officially i asked them

Mahlon is not concerned with a short extension with miled aerobatics.

Thats what I know so far....

Frank
 
Ethanol-Free MoGas?

Relatively new to the Portland Oregon/Vancouver WA area. Haven't been able to find any ethanol-free MoGas. Anyone point me in the right direction?

Keith
RV9A
N355RV (flying x2 years) yep! I built it!
 
It's ironic, but try a place that sells to farmers.
Older gas powered tractors have the same
troubles and don't like ethanol either.
Tom
 
Mogas in OR

ksouthar said:
Relatively new to the Portland Oregon/Vancouver WA area. Haven't been able to find any ethanol-free MoGas. Anyone point me in the right direction?

Keith
RV9A
N355RV (flying x2 years) yep! I built it!
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Lebanon, OR airport (S30) has ethanol-free 91 Oct. Mogas. Where are you hangared? I'm at Newberg, 2S6, and Lebanon is about 20 min down the valley for me.

Jerry
 
yes and it WAS 3.37 a gallon

About to go to nearly $4 when I spoke to them on Saturday
 
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