G100UL - Martin Pauly YouTube video

[M20F]

1 hour ago, N201MKTurbo said:

Any of our engines can be modified to run on auto fuel. But there would be a performance or reliability issue. 

Getting most of our engines to run on car gas would only require a reduction in spark advance. Some may also require a reduction in compression. This will decrease its max power output. The only way to recover the lost power is more displacement or higher RPM. Our propellers limit our RPM, so to get higher engine RPM and keep the propeller from overspeeding, we would need a gearbox. Geared engines are generally heavier and less reliable.

Our engines have been optimized for reliability and power to weight ratio. changing them will require compromising on one of the three. There is no modern magic that will change any of this.

It will be interesting to see how the DeltaHawk does in real day to day service. We will probably not know for sure for a decade or two.

I may have flown a AC560 for years on auto fuel and a slight shot of 100LL for the valves.  There are numerous solid low compression engines out there today that can run auto fuel.  This was 1940’s tech, believe we could do better today. 

[N201MKTurbo]

34 minutes ago, M20F said:

I may have flown a AC560 for years on auto fuel and a slight shot of 100LL for the valves.  There are numerous solid low compression engines out there today that can run auto fuel.  This was 1940’s tech, believe we could do better today. 

The GO-480 has 7.5:1 compression. I imagine it requires 80 octane fuel. They are not the most fuel efficient or lightest engine ever made. 

[M20F]

39 minutes ago, N201MKTurbo said:

The GO-480 has 7.5:1 compression. I imagine it requires 80 octane fuel. They are not the most fuel efficient or lightest engine ever made. 

No but with augmenter tubes they really put on a spectacle at nights landing.  That makes up for a lot. 
 
O360 is a decent engine that does mogas. 

 

[Hank]

4 hours ago, M20F said:

O360 is a decent engine that does mogas. 

There is no STC for mogas in my Mooney, but apparently other planes with my engine use it. So all I need is a convenient source of mogas at home and my destinations, and a DER . . . . Oh, and an understanding IA for as long as I want to fly. Because the next IA may disagree, and then where up the creek am I???

[tony]

14 hours ago, Hank said:

There is no STC for mogas in my Mooney, but apparently other planes with my engine use it. So all I need is a convenient source of mogas at home and my destinations, and a DER . . . . Oh, and an understanding IA for as long as I want to fly. Because the next IA may disagree, and then where up the creek am I???

......and test data so the DER can find compliance.  

[Shadrach]

16 hours ago, Hank said:

There is no STC for mogas in my Mooney, but apparently other planes with my engine use it. So all I need is a convenient source of mogas at home and my destinations, and a DER . . . . Oh, and an understanding IA for as long as I want to fly. Because the next IA may disagree, and then where up the creek am I???

Unlikely that a DER is going to approve a one off Mogas application in a Mooney given that Peterson Aviation has documented why both the M20 and PA-24 airframes failed to meet the STC requirements due to fuel delivery issues.  

[M20F]

21 hours ago, Hank said:

There is no STC for mogas in my Mooney, but apparently other planes with my engine use it. So all I need is a convenient source of mogas at home and my destinations, and a DER . . . . Oh, and an understanding IA for as long as I want to fly. Because the next IA may disagree, and then where up the creek am I???

What does that have to do with an O360 being a decent engine that runs mogas? 

[dkkim73]

On 6/25/2024 at 6:54 AM, N201MKTurbo said:

Any of our engines can be modified to run on auto fuel. But there would be a performance or reliability issue. 

Getting most of our engines to run on car gas would only require a reduction in spark advance. Some may also require a reduction in compression. This will decrease its max power output. The only way to recover the lost power is more displacement or higher RPM.

I wonder if the solution might not be a FADEC retrofit and possible some fancy modern (materials) approach to the valve seats. 

 

Edited June 26 by dkkim73
clarifying materials approach

[Hank]

52 minutes ago, M20F said:

What does that have to do with an O360 being a decent engine that runs mogas? 

Because my C model has an O-360, but no mogas STC is available 

[Shadrach]

1 hour ago, Hank said:

Because my C model has an O-360, but no mogas STC is available 

It’s not an engine issue. The problem is with the fuel system components associated with the airframe. In the case of Peterson they were able to overcome vapor lock issues. However, I suspect they did so by increasing the fuel pressure. This caused problems at the carburetor.

Peterson explored an STC for both the M20 and the PA24. At the end of the day, they could not make mogas meet the performance requirements in those applications.

[hammdo]

Article on Swift 100R and info on drop in UL100E

https://aviationweek.com/business-aviation/safety-ops-regulation/faa-approves-100r-avgas-cessna-172s

-Don