Titan 409+EFII

I suspect detonation testing is well within the capability of Airmotive Engineering, an ECI sister company. If not, I'm sure Andy Higgs has the necessary contacts to bring things up to speed.

Heck, there are universities who would do it as a class project. The engines we fly now were certified with using vacuum tube equipment.

http://www.astm.org/Standards/D6424.htm

http://www.faa.gov/documentLibrary/media/Advisory_Circular/ac33.47-1.pdf

rv6ejguy said:

I might add with the EFI/EI there is a lot more flexibility in mapping the fuel and spark to avoid detonation than using mechanical systems.

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Which should be the focus in discussions of EFI/EI on aircraft engines.

Dan, I do not know for sure, but you suspect it is within their capability? Sure, it is within many facilities capability, and why not, its only money and desire. But how many do?

I might add the old vacuum tube days were not as sub standard as the inference suggests.

As Ross points out

I might add with the EFI/EI there is a lot more flexibility in mapping the fuel and spark to avoid detonation than using mechanical systems.

Click to expand...

there is a lot of dynamic ability within an ECU, but what is the one part that seems to hold things back on an air cooled aircraft engine? Acoustic knock sensors.

There needs to be a closed loop system (acoustic or ICP), and without that we really have not gone forward at all by any significant amount. It also needs to be redundant or have a failure modes where "limp home" works.

As an example, if you have a fuel pressure sensor connector that is flaky, does your IO390 stop or your EMS tell you to land immediately like it does in a Diamond?

The air cooled piston aero engine is a remarkably simple and safe device, but making improvements to it, which are all possible as we all see here, come with numerous compounding challenges. Every improvement has to come with no ill side effects. It must pass the "does everything it should and nothing it shouldn't" test.

I believe that should be the focus. Otherwise it is just another auto engine and they have been around a long time too.

RV10inOz said:

Dan, I do not know for sure, but you suspect it is within their capability? Sure, it is within many facilities capability, and why not, its only money and desire. But how many do?

I might add the old vacuum tube days were not as sub standard as the inference suggests.

As Ross points out
there is a lot of dynamic ability within an ECU, but what is the one part that seems to hold things back on an air cooled aircraft engine? Acoustic knock sensors.

There needs to be a closed loop system (acoustic or ICP), and without that we really have not gone forward at all by any significant amount. It also needs to be redundant or have a failure modes where "limp home" works.

As an example, if you have a fuel pressure sensor connector that is flaky, does your IO390 stop or your EMS tell you to land immediately like it does in a Diamond?

The air cooled piston aero engine is a remarkably simple and safe device, but making improvements to it, which are all possible as we all see here, come with numerous compounding challenges. Every improvement has to come with no ill side effects. It must pass the "does everything it should and nothing it shouldn't" test.

I believe that should be the focus. Otherwise it is just another auto engine and they have been around a long time too.

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Even without closed loop knock sensing, modern EFI/EI systems allow you to get closer to knock margins without stepping over them than mechanical systems.

Piezo knock sensors work fine on air cooled engines. We've used them on Porsche and Corvair engines, just have to be set up carefully. Lycoming has had them on the IE2 for a number of years now. The point of knock mapping on the dyno though is to give an open loop solution here. When you know what combinations of IAT, CHT, AFR, timing, rpm etc. result in knock, you can avoid that corner by changing timing and AFR. It's worked for me for the last 30 years on engines with much, much higher specific outputs than atmo Lycomings.

Redundant systems generate lots of debate. If you want this, install 2 systems. Close to 250,000 flight hours over 20 years says the electronics are more reliable than the engines they are attached to, however, the pilot should be comfortable with the choice I believe.

We don't measure fuel pressure since it's a non-critical parameter as far as the EMS is concerned. Flip pump #2 on if the engine stops, use both for takeoff and landing. Most other engine sensors are non-critical as well with defaults entered in the mapping. Limp mode is an invalid concept in aviation EMSs. Sensor failures should not affect power available to any great degree in this application.

DanH said:

Nice job Tom. I check your website from time to time. You've put a boatload of work into your Lancair.

Does Dave Morss also runs a 4-cyl? The two of you were the fastest "little motor" guys?

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Sorry for the slow reply.. Nope, he has a Continental IO-550N. I was able to beat all the rockets, 2 Glasair's with IO-540's, and the Super Six. Pretty sure I have the fastest 4 cylinder average race speed at Reno, ever. Would have had qualifying also but Tom Aberle went way faster this year. I guess they changed how the measure the biplane course because others said he was doing the same lap times.

Either way, I'm happy to go as fast as it does.