Jconard said:
Actually, I believe the comment was that NO Subaru would ever match a Lycoming in speed. A silly comment since it is obvious that several Subaru engines put out more than 180hp stock. I'd venture that a properly prepped turbo EG33 would make more power, longer than even a turbocharged 720 Lycoming.
I think realistic comparisons at least for RVs comes down to engines with similar fuel flow, power and weight to the standard O-360.
I think you miss the point about the whole discussion. It is not what is better as there are winners and losers in that discussion, it is that fact that hundreds of people obviously don't think that the Lycoming is the wonder engine that many here think it is. It does have issues and problems and disadvantages in real life. Eggenfellner would not be in business otherwise and 700-800 gyros would not have Subaru power. People are looking for an engine which is smooth, cheap to operate, cheap to overhaul, reliable and fuel efficient. The Sube seems to fit the bill for many. it is an ALTERNATIVE to the Lycoming. It does not beat it in every category.
Actually I don't agree with your assessment of fuel flow vs. engine speed on geared engines. This does not happen at torque peak, it happens where the point of max VE and lowest frictional losses merge, typically about 400-500 rpm below torque peak. I have never been an advocate of heavily cammed atmo engines spinning way up there to make power for aircraft use, exactly why my engines are both turboed and I raced turbocharged cars very successfully for many years.
I do agree that having to spin a geared atmo engine well above torque peak to make competitive power is a losing situation with regards to SFCs.
Finally, Rotax shows that a well designed, high revving, geared, liquid/ air cooled engine is far lighter and gives better SFCs than a direct drive, air cooled engine. This is a purpose designed engine which is not the same as an auto engine like the Subaru which is bound to be heavier.
People are seduced by the cheap, reliable, mass produced Subaru longblock. It is the total package that can use more refinement, study and testing to improve power, fuel flow and weight. The Egg packages are not optimal today but fit many people's needs despite some disadvantages.
If people ignored the marketing and just looked at the facts about Subaru performance to date and applied a bit of logic, it has been pretty clear that measured performance has not been what Subaru converters claim. Conspiracy? No. The facts have been there to see for some time. If you believe stuff like 200 mph Glastars and 50% lower fuel flow and hp claims at 1000 rpm less than stock power peak rpms, you are not using your noggin'. We see lots of this stuff in aviation, no different in the engine conversion world.
You should have read the mud slung back and forth between the Sube converters on E-Subie forum a few years back. It was ugly with lots of personal attacks, finger pointing, the call for dyno tests, fictional hp figures, fictional speeds, on and on. I left after it just got too ridiculous to stand and Jan left to work on his products while the others withered away in red ink and broken promises.
I just question the anger than some people seem to have about auto engines in aircraft and that they believe people are stupid and foolhardy to install them. Why be so angry about it? Fly a Lycoming if that is your desire. I just don't see the opposite side of the coin where Subaru people are saying Lycoming users are a bunch of mindless idiots. This is simply a choice, a choice based on different criteria. I've stated for some considerable time that if your criteria is best speed vs. fuel flow vs. weight, the Lycoming is the clear choice at this time for your RV.
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