MPS, Maxwell Propulsion

[0591]

Hello to all you lucky Oshkosh visitors

I am wondering if any of you visited MPS/s booth and can give your honest opinion on their FWF package, and in particular their new 205 HP 2.6 liters, NA.

Please post your thoughts


Brian

[rv6ejguy]

There was a discussion on one of the Sube forums about the hp claims made by MPS. It is impossible that this engine can make 205hp at the 4500 rpm they listed. This represents a BMEP of 227 psi.

I suspect they are still using the dyno from the old NSI days which used to give a lot of suspect data. They countered by saying it was recently recalibrated. Hmmm... It might be possible to make 205 hp at 5500-6000 rpm.

Some flight test data (third party) on a Glastar fitted with the MPS package does seem to show comparable performance in cruise to an O-360, suggesting that it may produce around 180hp. Cruise numbers and fuel flows were very good.

One of my friends will be fitting a MPS 2.6 in his 7A shortly. This has already flown with another Sube package so we can compare to that and known Lycoming performance to verify the claims. If it has the goods, MPS sales will certainly pick up.

[breister]

I just looked at their site - they are only advertising 165hp now. That seems more reasonable since my non-turbo 2000 Subaru (car) is rated at 140hp.

As for Subaru engines in general, my aircraft is one row over from a fellow who went through 5 (as I heard it - don't shoot me if I'm off by one) such engines before he gave up. Does that mean they haven't figured it out yet? I don't know, and I'm too chicken to try it myself.

[rv6ejguy]

Originally Posted by breister

I just looked at their site - they are only advertising 165hp now. That seems more reasonable since my non-turbo 2000 Subaru (car) is rated at 140hp.

As for Subaru engines in general, my aircraft is one row over from a fellow who went through 5 (as I heard it - don't shoot me if I'm off by one) such engines before he gave up. Does that mean they haven't figured it out yet? I don't know, and I'm too chicken to try it myself.

This fellow, have these all been MPS engines or were some NSI?

[Randy]

I am the one planning to try a version of this engine on my 7A. After having many problems associated with the supercharger at first, and then a turbocharger setup, I am attracted to the simplicity of the setup and the fact that it will allow me to shed between 40 and 45 lbs from my firewall forward weight.

I think MPS made an error in stating the 205 HP at 4500. It will probably make more than 200 HP at it's take off RPMs of around 5,000, but not down at normal cruise RPMs. I live not far from the MPS shop and have grown to trust that they can build up a quality engine for me. I was and remain pretty skeptical of any one messing around with the insides of an engine I plan to fly behind. I believe MPS is indeed a different company with a very different business model than what it was in the past. I am giving them a chance, but with the old "trust but verify" approach.

The demonstrator did record impressive performance numbers on the trip to and from OSH, and based on those numbers, I think this engine has some great potential to be relatively light Sube RV engine package. No, probably not as light as a Lycoming package.

My engine will be Sube EJ25 based with a billet stroker crankshaft, balanced and blueprinted, stock rods, custom pistons with a compression ratio of 10.4 to 1. The MPS demo plane is running WRX heads, mine will use the dual cam STI heads that should help a little more with the horsepower as they are known to breathe better.

For me this is a natural follow on experiment in trying to get performance as good or better than I could get with a Lyc. but with a smooth running liquid cooled Sube engine. I had great performance with the Turbo STI, but it did suffer some in the reliability area, mostly caused from my own inexperience in turbo installations. I will still have to have a turbo STI again one day. I have tasted what it is like to have control of MAP and will probably not be satisfied until I have it available to me again. It is so fun to be able to keep the power up at high altitudes. I think I am adicted to the experience.

I have been through a tremendous amount of trials in my quest to accomplish the above stated goal. To be honest I have been ready to give it up a few times and put a Lyc. in it and just get in some enjoyable flying hours instead of continuous experimentation, it gets old after a while seeing other RVs rack up the flying hours while I work on mine. I am stoked about this new approach though. The installation may not meet Van's definition of "lighten and simplicate", but from where I have been, that is indeed the direction in which I am heading.

Perhaps in a few months I will be able to report in with some new performance numbers and weights, and hopefully start racking up the flight hours without problems.

Randy C

[breister]

Originally Posted by rv6ejguy

This fellow, have these all been MPS engines or were some NSI?

I believe they were early Eggenfellners, but cannot swear to that. I'm sure things are better today, but also sure that I'm not convinced.

[rv6ejguy]

Originally Posted by breister

I believe they were early Eggenfellners, but cannot swear to that. I'm sure things are better today, but also sure that I'm not convinced.

Lack of adequate flight testing has come back to haunt many engine vendors. MPS has been stating that they don't want to follow that old path as it can only lead to business failure eventually. I hope lessons learned from the past will be applied and that they will offer reliable, comparably priced FF packages with comparable performance to the Lycoming setups. In 3-5 years, perhaps we'll be able to answer that one.

We'll be looking eagerly at Randy's numbers soon!

A word of advice to MPS- if you want to succeed in this market, post real data and have it vetted by a third party. People are very jaded in this market and rightfully so. I'm thinking, do the Van's fly off thing. This will remove any performance doubts and help sales along without much advertising. The rest will come through solid engineering, transparency if there are problems and good customer service.

[L.Adamson]

Originally Posted by breister

I believe they were early Eggenfellners, but cannot swear to that. I'm sure things are better today, but also sure that I'm not convinced.

Not that much better....

A friend of ours has had countless problems with his six cylinder Subie installation, which involves mostly cooling problems with his RV8. He has now spent far more, than a Lyc would have been; and has only got 19 hrs in the last year. Mostly on the ground!

His test pilot at least got some more time in it the other day, without boiling over (after a lot more modifications), but you can still smell the hot antifreeze. Performance isn't as good as a Lyc either. Perhaps it has to loosen up some.

But never the less; a Eggenfeller Sube engine isn't near the advance for aircraft, that one might get from reading the Eggenfeller website. Between cooling problems, less performance, and required upgrades such as swapping $4500 gear boxes........... I'm surprised he hasn't junked it already!

They need a muffler too! The engine runs at an annoyingly high pitch in anything but taxi speeds. It's now become a joke..........that airport residents are going to sign a petition for noise control...

Bottom line............. I wouldn't recommend one to anybody.

L.Adamson ---- RV6A (flying)

[rv6ejguy]

Originally Posted by L.Adamson

They need a muffler too! The engine runs at an annoyingly high pitch in anything but taxi speeds. It's now become a joke..........that airport residents are going to sign a petition for noise control...

Bottom line............. I wouldn't recommend one to anybody.

L.Adamson ---- RV6A (flying)

I agree about the noise. The atmo Subes are raunchy sounding things even with the two types of mufflers tried to date. Someone needs to do some serious testing on a real muffler system. You reach the pain threshold at about 4500 rpm without headphones with the Egg sixes. Quite unpleasant.

Any auto engine conversion should include proper stainless mufflers or a turbo which makes everything sound proper.

Randy is used to that nice mellow, quiet turbo note now. We'll see what he thinks of the MPS 2.6 atmo note.

[Gwen]

Hello folks,

Last week I heard there was a discussion regarding Maxwell Propulsion Systems on this site, so I decided it was time to join the group and with luck, present some of the issues from the MPS perspective.

205+ HP 2.6 L Stroker
Just before the Arlington Show, we put a high performance engine package on N787MX, the MPS Sportsman that we use as our testbed. It has 298 hours since June 26, 2008. The first 240 were flown with the normally aspirated 165 hp system. The package was built using the following components:

• Subaru EJ257 STi Block w/ 2.5 SOHC
• Normally Aspirated 2.6 L Stroker
• Custom Camshafts
• Modified/Polished 10 mm oil pump
• J E Forged Pistons
• K-1 83 mm Billet Crankshaft
• K-1 4340 Forged Rods
• ACL Race Bearings

The engine was blueprinted and balanced prior to installation, however it was not run on the MPS engine dyno. As a result the hp ratings are not fully verified. Having said that, the data from our return flight from Oshkosh to Arlington are shown below. In comparing these to the numbers published in the recent Kitplanes IO 360 and IO 390 Sportsman flyoff the numbers compare favorably with the 390, advertised as 210 hp. (Data from Captain William Graves, retired Continental Airline Pilot.) I will try to post the complete table later, but here is data from the final leg from Bozemen to Arlington:

Performance -BZN TO AWO
Initial Climb -700 fpm
Fuel Burn - 12.1 gph
MAP - 24?
RPM - 5250 rpm
Average Climb - 500 fpm
Speed - 100 kts
Fuel Burn - 10.9
MAP - 24?
RPM - 4700 rpm
Cruise Altitude - 8500 ft
TAS - 138-143 kts
RPM - 4700
Fuel Burn - 8.1 gph
MAP - 21?
STATUTE MPG - 16.5 mpg

MUFFLERS
I can't say that our straight pipes with baffles are up for best sound of the year, but I will try to get some video with sound posted on YouTube of our current muffler package so you can evaluate for yourself. Better yet, we are developing a 4 into 2 tuned exhaust. I am expecting that will be a huge improvement in both sound and increased hp! Short of a turbo that should be pretty nice. A welder is due here this week and when the mockup is complete, we will get if off again to Aircrafters Exhause.

MPS Testing and Analysis

Lack of adequate flight testing has come back to haunt many engine vendors. MPS has been stating that they don't want to follow that old path as it can only lead to business failure eventually. I hope lessons learned from the past will be applied and that they will offer reliable, comparably priced FF packages with comparable performance to the Lycoming setups. In 3-5 years, perhaps we'll be able to answer that one.

Excellent point. I totally agree. In addition to the flight testing noted above, and, in contrast to other engine vendors, we test all of our products on the ground and in the air.

Our propeller and PSRU were subjected to the equivalent of the FAA certification test required for certified engines. The testing protocol used was that included in the FAA regulation 33-2A.

We also performed vibration analysis of our PSRU that was recently published in Contact! Issue 97.

Dominic Acia, has written an article that describes the engine blueprinting and balancing that is part of our build/assembly process, and the rationale behind it. Of note is that the most likely cause of the unfortunate customer who had 4 or 5 engine failures with his Eggenfellner engines is that the Subaru factory clearances are inadequate to support the engines when they are run at high rpms for long periods of time. The article was published in the GlaStar-Sportsman Flyer last January and Marc Cook of Kitplanes tells me that it is scheduled for the November issue of that magazine.

MPS Dynamometer

I suspect they are still using the dyno from the old NSI days which used to give a lot of suspect data. They countered by saying it was recently recalibrated. Hmmm...

Again, you are correct, and I totally understand your concern over the highly suspect data. (You probably don't know the half of it!) So, while it is certainly hard to prove a negative...I can say that getting two SuperFlow Dyno technicians out to Arlington to replace the circuit boards, recalibrate, and install the software upgrades and train the MPS technicians put quite a hole in my checking acount balance! I am unlikely to forget that experience!

Confidence Building
My thanks to Randy for his kind words and confidence in MPS. While I have some RV customers, I would certainly enjoy the opportunity to help others fly behind a Subaru, be it a complete MPS package, a builder-designed system, or an upgrade to another package. I believe the Subaru is an excellent option for the experimental aircraft, it is unfortunate that converting it to a safe, reliable package has been so long in coming, that said, I believe that the products that MPS is has tested and flown meet these criteria ...I am happy to say that having flown behind the MPS package for upwards of 120 hours this year alone, I have complete confidence that it is just about everything that I want...yeah, yeah, yeah, OK, More speed would be nice!

Best Regards,

Gwen Maxwell
Maxwell Propulsion Systems, Inc.
19132 59th Drive NE
Arlington, WA 98223
Phone: 360.474.8118
Fax: 360.474.8299
www.maxwellpropulsion.com