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E15 Vs. E10 Mogas for 912ULS

Piper J3

Well Known Member
I thought I'd start a thread on this subject now that<SNIP> 15% alcohol blend <will be required> in auto fuels. <edited per posting rules>

From SERVICE INSTRUCTION SELECTION OF SUITABLE OPERATING FLUIDS FOR ROTAX® ENGINE TYPE 912 AND 914 (SERIES)E10 (Unleaded gasoline blended with 10 % ethanol)... In addition to AVGAS and unleaded automotive fuel (Mogas) the ROTAX® 912/914 series of engines are now approved for use with E10. Fuels that contain more than 10% ethanol blend have not been tested by BRP-Powertrain and are not permitted for use.

I sent an email to Rotax Technical Support telling them the United States will will soon be switching to year-round E15 auto fuels. I will report soonest when I hear back from Rotax. I also sent an email to Lockwood Aviation asking same question.

I also wonder what Van's has to say regarding increased ethanol in the RV-12 fuel system. I believe Van's runs E10 Mogas in the RV-12 demo plane. This will also be a concern with the new RV-12iS.

Aside from compatibility, the increase in ethanol will reduce engine power slightly and also increase fuel consumption slightly as energy content (BTU) for alcohol is less than that of gasoline. On a positive note, added alcohol will increase fuel octane rating.

Other concerns include long-term storage and vapor lock.

Just some thoughts to get the discussion going...
 
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I thought I'd start a thread on this subject now that <SNIP> 15% alcohol blend in auto fuels will be required. <edited>

From SERVICE INSTRUCTION SELECTION OF SUITABLE OPERATING FLUIDS FOR ROTAX® ENGINE TYPE 912 AND 914 (SERIES)E10 (Unleaded gasoline blended with 10 % ethanol)... In addition to AVGAS and unleaded automotive fuel (Mogas) the ROTAX® 912/914 series of engines are now approved for use with E10. Fuels that contain more than 10% ethanol blend have not been tested by BRP-Powertrain and are not permitted for use.

I sent an email to Rotax Technical Support telling them the United States will will soon be switching to year-round E15 auto fuels. I will report soonest when I hear back from Rotax. I also sent an email to Lockwood Aviation asking same question.

I also wonder what Van's has to say regarding increased ethanol in the RV-12 fuel system. I believe Van's runs E10 Mogas in the RV-12 demo plane. This will also be a concern with the new RV-12iS.

Aside from compatibility, the increase in ethanol will reduce engine power slightly and also increase fuel consumption slightly as energy content (BTU) for alcohol is less than that of gasoline. On a positive note, added alcohol will increase fuel octane rating.

Other concerns include long-term storage and vapor lock.

Just some thoughts to get the discussion going...

Good discussion topic Jim. I cringe at the thought of being forced to use ethanol in gas, mostly for the loss of efficiency and the increased corrosive effect of it with aluminum. While it does increase specific fuel consumption (meaning more fuel burned per hour for the same power setting), it increases engine power, which is an effect of the increased oxygenation of the fuel during combustion and contributes to the increased octane, which you noted.

A good read on all of this is INFLUENCE OF COMPOSITION OF GASOLINE – ETHANOL BLENDS ON PARAMETERS OF INTERNAL COMBUSTION ENGINES.

<SNIP>I'm disappointed the FAA's PAFI has been now pushed out until 2020. I was very hopeful to have unleaded avgas in the 100 octane range.

For us UL Power engine users, the engines are good for 15% ethanol, so I guess I'll just grin and bear it.

One last thing to consider, just because the EPA has been ordered to raise the limit from 10% to 15%, and from winter months to all year, does not mean all states will move to it. I highly doubt that the California Air Research Board will go for it, most notably due to the increase smog in the summer months in the already smoggy valleys out here.
 
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....For us UL Power engine users, the engines are good for 15% ethanol, so I guess I'll just grin and bear it......

Hey Ron, this is a total thread drift, but how do you like your UL Power engine? Have you ever had a Rotax that you can compare and contrast it to? If you'd like to just send me a PM or even start a new thread on the subject, that'll be fine.

Thanks,
Mark
 
First of all, could we maybe, pretty please, have just one forum where we don't have a political spin on topics? It gets really, really tiresome. [Agreed, Dale. Rather than delete this entire thread due to rules violation, the thread has been edited to remove the political comments. ]

Second, considering that I can still buy 93 octane unleaded alcohol-free gas at the pump 1/2 mile from the airport, I'm not particularly worried about everything going to E15. There's no requirement that all gasoline will be blended with ethanol at all, let alone 15%.
 
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Considering that I can still buy 93 octane unleaded alcohol-free gas at the pump 1/2 mile from the airport, I'm not particularly worried about everything going to E15.

Unfortunately, 93 octane unleaded alcohol-free gas isn't readily available in all parts of the country.
 
Unfortunately, 93 octane unleaded alcohol-free gas isn't readily available in all parts of the country.
Granted, and it's far from universally available here. There's one gas station chain that I know of that sells it (and my mistake, it's 91 not 93). But I don't think ethanol is required by law or regulation, existing or proposed, in all gasoline in any amount.
 
I thought I'd start a thread on this subject now that <SNIP> 15% alcohol blend <will be required> in auto fuels. ...

As I understood the announcement, E-15 is not mandatory or replacing E-10, it will just be available nationwide. There are a lot of vehicles on the road that were not designed for E-15.
 
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As I understood the announcement, E85 is not mandatory or replacing E-10, it will just be available nationwide. There are a lot of vehicles on the road that were not designed for E85.

I think the debate here is between E-10 and E-15, not E-85.
 
Other concerns include long-term storage and vapor lock.

Ethanol is added to reduce evaporative HC emissions. It has a lower vapor pressure. Stability is another matter as auto gas is not very stable as it is. Vodka seems to last pretty well.

Combustion, power, bsfc, starting and ability to fumigate the intake charge (cold weather starting) would certainly expected to be part of the test protocols.

Elastomers should not be an issue, unless the gasoline side of the formulation changes oddly.

It would have better water tolerance as there is more ethanol to hold it.
 
I think the debate here is between E-10 and E-15, not E-85.

You are correct, I typed E85 when I intended E15. Thank you for the correction, my post has been amended.

I think the main point of my post is still valid, E10 is not going away. The announcement was to permit E15 to be sold year-round instead of seasonally. Several trade groups are already gearing up to block the move to year-round E15.
 
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First of all, could we maybe, pretty please, have just one forum where we don't have a political spin on topics? It gets really, really tiresome.

Hallelujah to that!! Could we please refrain from the Trump (or Clinton) bashing on VAF. I have VERY STRONG opinions to one side, but I refuse to blatantly or covertly inject them into my VAF posts. I am assuming we are all fans of airplanes and Van's Aircraft here....why alienate half of your friends with a subtle (or not) political jab :)

[Agreed. The original post has been edited to remove the political comments.]
 
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Amen! Public discourse has become too polarized.

Original post has been edited...one of the moderators.
 
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As mentioned in first post, I sent an email to Rotax Technical Support.

Here is response...

Dear Sir

The fuel issue is not as simple as elected officials lead you to believe. Increasing the fuel from 10 to 15% would radically increase NO x emissions into the atmosphere. For that reason there will be no allowable increase in our recommendation based on testing of the fuels and emissions. If only 10% auto fuels are used this is manageable but at 15% there must be some consideration for carburetor fitted vehicles, both aircraft and automobiles, to do so without substantial emissions into the environment.

Best regards
Technical support
 
Interesting.

E10 is only "up to 10%" ethanol and as I understand varies a bit but is usually somewhere between 6%-8%. E15 is "between 10.5% to 15%" according to the Alternative Fuels Data Center.

So you can jump from E10 to E15 with only a 0.5% increase in ethanol, presuming E10 is max and E15 min. And this supposedly would "radically increase... emissions into the atmosphere". That sounds.... unjustified.


https://www.afdc.energy.gov/fuels/ethanol_blends.html

When concentrations vary so much it's difficult to see how positive folks can be that "5%" would make that much of a difference.
 
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I found it interesting that the only issue mentioned in the email from Rotax support is emissions. I saw no mention of performance, reliability or other operational issues. I don't know what the limits are on nitrogen oxides from small piston aircraft, let alone experimental aircraft, but I suspect it's not a show-stopping issue for those of us in the US.

Of course there's always 100LL, which eliminates the ethanol issue altogether.
 
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