Van's Air Force
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Electronic ignition on 0-320 running Mogas
- Thread starter Chunky
- Start date
What compression ratio is your engine?
There seems to be a lot of evidence that if your compression ratio is 8.5:1 or less and you use 92 octane fuel you will be ok. If you are worried, you can retard the base timing by a few degrees (say, 22-23 instead of 25 BTDC).
I ran a LS II on my O-235L2C 118hp (8.5:1) set to stock 25 BTDC and, frankly, ran the pants off of it at all altitudes and power settings lean of peak on Premium with no troubles for 4 years / 550 hours. Ran smooth and true, but that is no guarantee you will have the same experience.
There seems to be a lot of evidence that if your compression ratio is 8.5:1 or less and you use 92 octane fuel you will be ok. If you are worried, you can retard the base timing by a few degrees (say, 22-23 instead of 25 BTDC).
I ran a LS II on my O-235L2C 118hp (8.5:1) set to stock 25 BTDC and, frankly, ran the pants off of it at all altitudes and power settings lean of peak on Premium with no troubles for 4 years / 550 hours. Ran smooth and true, but that is no guarantee you will have the same experience.
rocketbob
Well Known Member
What evidence?
I've been running 87 mogas for almost 1000 hours now, O-360 std. comp. and an Electroair/mag setup.
What base timing setting are you using? Do you ever run lean of peak?
Most of the "evidence" seems to be theoretical, with one or two people having reported detonation under certain circumstances. With carburated engines it is harder to flow match, so running lean of peak stands a greater risk of detonation in one cylinder - but that too seems to depend on the airplane.
Build9A
Well Known Member
E I Confused
I know that this has been hashed over here but I can't seem to locate what I need.
I have 2 traditional mags. They have been trouble free and are currently undergoing 500 hr. maintenance. Plan to keep running them for another 500 hrs. However, maybe change after the next 500 hrs. I hope to learn more about the emag/pmag performance and related issues. I have read what I can find on the site search but I'm still less than knowlegable.
I have read that the 0-320 D1A can run mogas with emags/pmags. Are 0-320 D1As with EI and 8:50:1 compression ratio running mogas without any other mods and with carb.? Most of what I have read previously before i heard of pmags was DON't run mogas in this type engine for a variety of reasons.
If other mods are needed; what are they?
If someone has a website or document that can help me around the learning curve, please post the link or just answer here. thanks
I know that this has been hashed over here but I can't seem to locate what I need.
I have 2 traditional mags. They have been trouble free and are currently undergoing 500 hr. maintenance. Plan to keep running them for another 500 hrs. However, maybe change after the next 500 hrs. I hope to learn more about the emag/pmag performance and related issues. I have read what I can find on the site search but I'm still less than knowlegable.
I have read that the 0-320 D1A can run mogas with emags/pmags. Are 0-320 D1As with EI and 8:50:1 compression ratio running mogas without any other mods and with carb.? Most of what I have read previously before i heard of pmags was DON't run mogas in this type engine for a variety of reasons.
If other mods are needed; what are they?
If someone has a website or document that can help me around the learning curve, please post the link or just answer here. thanks
N941WR
Legacy Member
Where have you read this? I follow E/P-mags fairly closely and haven't don't recall seeing a thread on this?
Build9A
Well Known Member
question follow-up
Keep in mind that I know little or nothing about this issue. Here are several issues that I have questions about:
1. What are the differences among the various installations? P/mag, E/mag, Lasar, etc. That has been touched on here briefly, but mainly quotes like "I have this or a combo of that, etc."
2. Do you have to have a fuel return for auto fuel or does an 0-320 D1A with pmags just fly away with mogas? without fuel injection - with just a carb?
3. Lycoming says no auto fuel in 8:50:1 ratio compression engines.
4. What other changes are needed, different hardware or fuel lines or gaskets or changes to the standard Vans fuel pump, etc.?
I don't really expect you to answer every question here, although I am looking for sources to learn more before my mags wear out. I have read through other posts by you and others, but sometimes the posts seem to expect a higher level of knowledge than I have right now. Thank you for taking an interest in my questions and would appreciate any reference material you could provide links to. Since my last post I have found a couple of articles regarding LASAR. But other than suppliers websites, that's about it. thanks
Keep in mind that I know little or nothing about this issue. Here are several issues that I have questions about:
1. What are the differences among the various installations? P/mag, E/mag, Lasar, etc. That has been touched on here briefly, but mainly quotes like "I have this or a combo of that, etc."
2. Do you have to have a fuel return for auto fuel or does an 0-320 D1A with pmags just fly away with mogas? without fuel injection - with just a carb?
3. Lycoming says no auto fuel in 8:50:1 ratio compression engines.
4. What other changes are needed, different hardware or fuel lines or gaskets or changes to the standard Vans fuel pump, etc.?
I don't really expect you to answer every question here, although I am looking for sources to learn more before my mags wear out. I have read through other posts by you and others, but sometimes the posts seem to expect a higher level of knowledge than I have right now. Thank you for taking an interest in my questions and would appreciate any reference material you could provide links to. Since my last post I have found a couple of articles regarding LASAR. But other than suppliers websites, that's about it. thanks
rocketbob
Well Known Member
Stock timing, 25 deg. I have a timing advance meter, and at the altitudes I usually fly it stays at 25-26 deg. Carb setup so I can't consistently run LOP. When leaned I usually run 8.5 GPH on 87 mogas.
Sid Lambert
Well Known Member
0-320 8.5:1 with 1 Electoair EI for 648.0 house and not a single problem. Auto fuel about 99% of the time. I do have a switch to turn off the advance and I leave it off unless I'm in a high altitude cruise. That's the only time it advances anyway.
David-aviator
Well Known Member
The issue with any engine and octane is detonation, the lower the octane the more advanced the spark, the more likely it will occur.
The EI systems used with the Lycoming are mapped to advance spark based on manifold pressure and rpm. There is no provision for knock sensing. At idle after start the system I had would be running at 32 degrees. At take off it would drop back to 25 and after take off with climb power set it would advance depending on rpm and manifold pressure. It is simple, straight forward and works quite well.
Obviously fuel octane has to enter the picture, the lower the rating the greater the risk of knock. When I was running the Subby with an A/F ratio meter for a few tests, it did retard timing somewhat when burning 83 mogas verses 94 mogas. The system had a knock sensor.
With Lycoming, there is no knock sensing. The system does no know when it occurs so the pilot must be aware that running at 35 degrees advance at altitude LOP with 83 mogas may not be a good idea.
I also believe the EI systems were developed based on 100LL fuel, not mogas, no matter what they say or have not said on the subject.
The EI systems used with the Lycoming are mapped to advance spark based on manifold pressure and rpm. There is no provision for knock sensing. At idle after start the system I had would be running at 32 degrees. At take off it would drop back to 25 and after take off with climb power set it would advance depending on rpm and manifold pressure. It is simple, straight forward and works quite well.
Obviously fuel octane has to enter the picture, the lower the rating the greater the risk of knock. When I was running the Subby with an A/F ratio meter for a few tests, it did retard timing somewhat when burning 83 mogas verses 94 mogas. The system had a knock sensor.
With Lycoming, there is no knock sensing. The system does no know when it occurs so the pilot must be aware that running at 35 degrees advance at altitude LOP with 83 mogas may not be a good idea.
I also believe the EI systems were developed based on 100LL fuel, not mogas, no matter what they say or have not said on the subject.
N941WR
Legacy Member
There is a good bit of difference between the installation of the E/P-mags and Laser system. The E/P-mag installation is simple as they just plug in like a mag, wires run, and they are timed. The difference between the two is the P-mag has an internal generator that allows the unit to power itself, if your electrical system goes out. The Laser is a bit more complex in its installation as you have to mount a brain box, coil packs, and trigger. Most people run one Laser and one traditional mag, just incase their ship?s electrical system dies. That or they have an extra battery wired in just to power their ignitions. The functional operation of these units is about the same.
Fueling (not the type of fuel) has little to do with the ignition. The need for a fuel return line has to do with the type of fueling system you run. A carb does not need a fuel return line and neither do some FI systems.
See this thread.
RocketBob,
Do you run mogas w/ ethanol? If you do, what modification is necessary for your carb to make it compatible with ethanol?
Thanks,
Robin Hou
rocketbob
Well Known Member
The mogas we get at our airport doesn't have ethanol, but I have run mogas with ethanol and the only issue has been hot starts after quick turnarounds. I had the carb apart over the summer and there was no sign of any detrimental effects.
