Jump to content

MOGAS and UL98 in Rotax 912 - Real experiences?


Recommended Posts

It's on the wane only because of the toxicity of lead and that's fair enough too if the concentration in the area is high enough to be a problem. I agree that avgas is not for the Rotax as it can cause compression loss. I've seen that and it came good after returning to Mogas in both cases..but that is not assured. There's a reason for that .The Rotax 9 series runs too cool on the valve seats for the lead to Lubricate the seats and it instead forms a build up and some of it can detach and poor valve seating results. The makers of aero engines recommend what fuel (and oils) to use and I don't  depart from that.   I've put plenty of time into research on fuels and oils and working on engines and don't rely on websites that say the makers know nothing and aero  engine oil is 'Hinge" oil. I think you run a pretty good ship from your posts but I consider Motors that recommend 100 LL use it still something else replaces it that is approved.. Nev.

.

  • Informative 1
Link to post
Share on other sites
  • Replies 56
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

The debate on what fuel to use in aero engines has been going on for years and an numerous threads on this forum and it seems to come down to    a) The devil you know and don't know. b)

Rotax has a current Service instruction - SI-912 i-001 that details what is required. Anything else, including web posts is hearsay and possibly out of date or just plain wrong - and that comes from a

Not picky at all: Some months ago I met someone who was waiting for a replacement set of wings for their Jab. They had been unwittingly using fuel with ethanol, causing the wings to start delam

Posted Images

KGW Just one point on "shelf life"  of 98 RON  - the reserch has consistently shown that 98 is good for at least 6 months IN A SEALED CONTAINER filled to 75 % capacity or above .  Also  a good dollop of fresh 98, added to your possibly stale fuel (in tank) will restore almost all the  good attributes lost due to volatilisation. So instead of filling your tank, when you return from a days flying, consider doing so just befor you fly next.

  • Like 1
Link to post
Share on other sites

I ran 250 hours on a Rotax 912 with unleaded, and occasional Avagas, or mixtures. I run my Lycoming O360 on avgas with occasional unleaded or mixtures. Neither have given  any problems. I use Mr Funnel with Jerry can fuel. The O360 has an STC for unleaded.

  • Like 1
Link to post
Share on other sites
11 hours ago, skippydiesel said:

KGW Just one point on "shelf life"  of 98 RON  - the reserch has consistently shown that 98 is good for at least 6 months IN A SEALED CONTAINER filled to 75 % capacity or above .  Also  a good dollop of fresh 98, added to your possibly stale fuel (in tank) will restore almost all the  good attributes lost due to volatilisation. So instead of filling your tank, when you return from a days flying, consider doing so just befor you fly next.

I never refill until I am ready to fly again. If you do not give the aromatics a chance to evaporate then they won't. Partly filled plastic jerrycans will blow up like a balloon if left around for weeks in hot weather. Fill them right up & there is little expansion. My 20 litre plastic jerrycans hold 24 litres to the brim & that's how I fill and store them.

  • Like 2
  • Agree 1
Link to post
Share on other sites
14 hours ago, facthunter said:

The makers of aero engines recommend what fuel (and oils) to use and I don't  depart from that.

Running mogas doesn't necessarily depart from the recommendations of the manufacturer. There are a number of older and newer engines from Lycoming which run fine on Mogas the link below provides a from the horse's mouth view.

https://www.lycoming.com/sites/default/files/SI1070AB Specified Fuels.pdf Note that Mogas is included.

 

From a technical point of view the majority of GA aircraft will run on Mogas without an issue. There are some higher compression and turbocharged aircraft which currently require Avgas however these aircraft are in the minority. Essentially the GA industry has been subsidizing those aircraft for decades at enormous cost. If there is a significant swing towards using mogas the whole economics of the avgas industry will collapse.

 

The problems with all of the replacement AVgas fuels is that they're more expensive and consumers don't want that.

 

  • Like 2
Link to post
Share on other sites

If  your motor is OK for Mogas you still have cut your detonation and vapourisation margins. The Octane figures for Mogas and Avgas have a different base, usiually about 5 points LOWER for Mogas and they give two figures for lean  and rich'.  Permitted to use doesn't mean equal performance. They are nowhere near equal in quality control either. Aviation fuels have a release note.. Nev

Link to post
Share on other sites

I think I can summarize :

1) Vapour lock should not be an issue if the aircraft airframe is serious about MOGAS and has a FUEL RETURN  to ensure the fuel is getting circulated around. Most of them. 

2) AVGAS is fine in rotax with fuel additive (Decalin etc)  and more frequent oil changes

3) 98 has a higher volume of volatiles and doesnt have the same shelf life in an unsealed tank . should be better than 95 when is new.

4) Degree of ethanol compatiiblity with fuel system components varies amongst airframes.

 

Edited by RFguy
  • Agree 1
Link to post
Share on other sites

RFguy

Number four ETHANOL !

If leaving any engine for extended periods, the ethanol will separate from it,s parent chemical,  petrol or diesel, 

Not good at all, l need to know how to over come this problem, with my car Unused for nearly a year now. 

Could be Next year these unused vehicles, may explode the first time driveing .

My oil is two years out of date, but no kilometers driven, do l change the oil per p o h,.  ( 12 month ).

spacesailor

 

 

 

 

 

Link to post
Share on other sites
3 hours ago, spacesailor said:

RFguy

Number four ETHANOL !

If leaving any engine for extended periods, the ethanol will separate from it,s parent chemical,  petrol or diesel, 

Not good at all, l need to know how to over come this problem, with my car Unused for nearly a year now. 

Could be Next year these unused vehicles, may explode the first time driveing .

My oil is two years out of date, but no kilometers driven, do l change the oil per p o h,.  ( 12 month ).

spacesailor

Check engine/filters for nesting creatures  & remove, charge or replace battery - inflate tyres to correct pressure (consider replacement ASAP) - drain as much old fuel as you can - refill with fresh - start engine - drive to get engine up to even running temperature (minimum 20 minutes longer better) - drain engine oil and replace with fresh - also replace break fluid at earliest opportunity.

Link to post
Share on other sites

That ! 

Replace the vehicle when the pandemic is over.

Is my thinking! .

Logbook records :  15/2/21 last driven.

Previously : 12/ 6/ 20. After fitting a new battery.

Milage  12/6/20 : 218,638

Now,   219,675

spacesailor

Link to post
Share on other sites
3 hours ago, turboplanner said:

RFguy I know you like to do theoretical sums, so I'd recommend you think about my deadly serious post.

To what/which post are you referring? 

Link to post
Share on other sites

You can get jerry cans that you tip upside down, and the weight of the fuel opens the tap. Very little spilling. This one is called a Tough Jug. I can’t vouch for the quality. I was looking for a pic because people were mentioning jerry cans and electric pumps. This is an alternative to a normal jerry can. One advantage of this is that the aircraft supports the weight of the jerry can while the fuel flows.

9B798695-C36E-4B7A-B0D3-EF7A8BE9C75F.jpeg

Edited by APenNameAndThatA
  • Informative 1
Link to post
Share on other sites

I have finally formed a plan for refuelling my high wing aircraft: 

 

1. Insert AN6 dry break socket in fuel line between tank and shutoff valve.

 

2.  Bosch 044 electric pump or equivalent with suitable fuel hose attached.

 

3 Dry break plugs on either end of hoses, also a 100 micron or less filter with dry break coupling.

 

‘’To refuel - insert suction end with filter into jerry can and pump.

 

‘’To defuel reverse direction of hoses and suck.

 

‘’Pump can be powered either from jumper pack or aircraft battery.

 

No mess, reduced fuel spillage opportunities. I have big vents on the tanks that will handle an overfilling incident.

 

No step ladders, climbing, balancing, funnels, etc.

 

What is not to like?

  • Like 2
Link to post
Share on other sites

sounds great.

 

Ensure that the power connectors and/or pump power switches are intrinsically safe (to avoid explosion) (or the switches/connectors can be nowhere near vapour).

something like this walrus ?

https://www.efisolutions.com.au/straight-aluminium-quick-release-dry-break-an6

 

Edited by RFguy
  • Like 1
Link to post
Share on other sites

RF, yes, something like that but with an important addition......... Where I need to place the fitting in the fuel line, I cannot absolutely guarantee that there will never be negative pressure (ie a  little vacuum) in the line. Its a gravity feed to the fuel pumps but they are EFI pumps and they suck, if you know what I mean. I have yet to find a dry break coupling that will guarantee that it remains leak proof under vacuum. As you can guess, I don't want any air to leak into the fuel system ever! The solution, I think, is a mini ball valve behind the dry break fitting that remains closed unless the fitting is in use.

  • Like 1
Link to post
Share on other sites
On 18/01/2022 at 7:09 AM, walrus said:

I have finally formed a plan for refuelling my high wing aircraft: 

 

1. Insert AN6 dry break socket in fuel line between tank and shutoff valve.

 

2.  Bosch 044 electric pump or equivalent with suitable fuel hose attached.

 

3 Dry break plugs on either end of hoses, also a 100 micron or less filter with dry break coupling.

 

‘’To refuel - insert suction end with filter into jerry can and pump.

 

‘’To defuel reverse direction of hoses and suck.

 

‘’Pump can be powered either from jumper pack or aircraft battery.

 

No mess, reduced fuel spillage opportunities. I have big vents on the tanks that will handle an overfilling incident.

 

No step ladders, climbing, balancing, funnels, etc.

 

What is not to like?

Sounds great.

Questions/thoughts

All those couplings must cost a bit

With all those connections, the potential for a fuel  leak has  risen significantly

The pump cost $200-400 is way over the top for an on ground transfer pump - get a Chines knock off for under $100

The flow rate of the pump isn't bad - you will take about 4 minutes to deliver 20L (under ideal conditions)

What sort of pump is the Bosh? - if its centrifugal its ability to self prime will be marginal and any "head" will have a dramatic impact on flow rate 

You may want to think twice about the filter - it will cause a significant restriction, slowing fuel delivery

If refuelling from a drum/can, a rigid tube/spike on one end of the pump is the safest and easiest way to go.

  • Like 1
Link to post
Share on other sites
On 17/01/2022 at 10:57 PM, APenNameAndThatA said:

You can get jerry cans that you tip upside down, and the weight of the fuel opens the tap. Very little spilling. This one is called a Tough Jug. I can’t vouch for the quality. I was looking for a pic because people were mentioning jerry cans and electric pumps. This is an alternative to a normal jerry can. One advantage of this is that the aircraft supports the weight of the jerry can while the fuel flows.

9B798695-C36E-4B7A-B0D3-EF7A8BE9C75F.jpeg

Certainly reduces the chance of spillage.

At near $100 you could have an electric pump.

Resembles the 10L 2/ can I have for our chainsaws etc

If only 10L its going to take a lot of cans to do the job

If 20L still have the problem of lifting (especially for high wings)

Not so good on (near) vertical fill points

Wouldn't want to carry fuel in the aircraft - likely to vent at altitude and may not be 100% spill proof if falls over

Edited by skippydiesel
  • Like 1
Link to post
Share on other sites

So far, I've found that this EF-01A transfer pump ($80 from easyflow) works well and has simplified the fuelling process. 

But I still prefer lifting 10L jerry's rather than 20L ones up onto the turtle deck.

(this small battery powered pump is not designed to push fuel from ground level up to wing tank height) 

Anyway the chap at Easyflow is good to talk to and to do business with.

EasyFlo Pumps

0408336816

04083368160408336816

https://easyflo.com.au/

 

(Click on this image for higher rez or see the pdf below:

 

219536509_easyflowpump.thumb.png.4a03feb3176c5a29950411083f12016b.png

 

 

FUEL TRANSFER PUMP.pdf

 

 

 

 

 

Edited by Garfly
  • Like 1
Link to post
Share on other sites

No offence Garfly but these sort of "pumps" are, in reality, not so much better than a syphon.

 

For similar cash outlay, you can have a petrol rated, positive displacement, 12v, fuel transfer pump that will easily deliver 20 L in about 3 minutes, from the can on the ground, even up to high wing tanks.

  • Like 1
  • Agree 1
Link to post
Share on other sites

That may be a better solution (any links, suggestions?) but I still like this pump for easily moving fuel around minus a 12V source.

I'd be concerned fuelling up from ships power that I'd deplete the battery.

  • Like 1
  • Agree 1
Link to post
Share on other sites

That's the most expensive poly jerrycan and hand pump I've ever seen! Are they gold-plated and built from aerospace materials?

I think Skippys on the right track, a standard petrol engine, electric fuel pump with a simple pump wiring arrangement (that has to be explosion-proof, of course) is a better way to go. 

  • Like 1
Link to post
Share on other sites
1 hour ago, Garfly said:

That may be a better solution (any links, suggestions?) but I still like this pump for easily moving fuel around minus a 12V source.

I'd be concerned fuelling up from ships power that I'd deplete the battery.

Well I have been using my Holly (Chines knock off) for about 6 years now. Anderson plug Under panel,direct to "ship" battery, pump up to 70L in one filling, and so far not a problem.

  • Like 1
  • Informative 1
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...