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rparigoris
Joined: 24 Nov 2009
Posts: 796
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 Posted: Tue Dec 16, 2014 3:25 pm Post subject: Engine boosting |
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Hi Group
I have a 914. The Garett Air Cooled Turbo that the 914 uses has been around for some time (I think it is very close to the one on my 1983 GLT50 (245) Volvo Turbo Wagon).
Curiosity question:
Can a "much more better" designed air pump reduce heating of air?
I was at the New York Bike show over the weekend. One bike really caught my eye:
A Kawasaki H2(R).
It's a track bike with a H2 model that will be street legal (I'm sure less powerful). Anyway the H2R has a 1,000cc Super Charged engine that is claimed to produce 300hp. 300hp per liter, quite impressive. Specifications are still a bit vague, but 14K may be close to redline?
Anyway supposedly Kawasaki did their homework (drawing from their affiliates that know about turbine design) and their H2R design uses ~ a 2.5" diameter centrifugal compressor with the larger stage being an 18 blade design. It is driven from the crankshaft via chain off crank, then planetary gears that can spin turbine up to 140,000rpm, spewing out air centrifugally at up to a little more than 1,000mph. Just a note, the bike I saw (and heard run) had single speed gearing, but patent Kawasaki has is for 1,2 or 3 speed. 3 speed would make for a lot of air at lower rpms (or high altitude!). The gearing on the single speed was a little under 10 to 1 of crank speed.
The interesting thing is it doesn't have an inter-cooler. Kawasaki mentions it doesn't need an inter-cooler because the "miracle shaped blades) make less heat than if it were traditionally shaped (whatever that means".
The super-charger is at the rear of the engine and it has an aluminium combiner/air-box sitting on top of the engine.
I don't know much about fluid dynamics. Can anyone shed some light:
If a more efficient design is had for a compressor that compresses air to boost intake pressure to an engine, give me an idea of how much less heat might be produced.
I know on my 1983 Volvo, it had a 4 cylinder engine with a 2,300cc displacement. Stock out of the factory without an inter-cooler the turbo would raise air temp as much as 145 degrees F. If you installed the factory offered inter-cooler, instead of raising the air temp going into your engine 145F, it would only raise the air temp 45F. The inter-cooler came with a device that would wait until you got to 3,750rpm, then it would increase boost.
Sincerely
Ron Parigoris
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rob(at)hyperion-ef.com
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| Posted: Tue Dec 16, 2014 4:45 pm Post subject: Engine boosting |
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According to the "ideal gas law" (which is a pretty good approximation for
air at the pressure in the intake manifold) PV = nRT so no matter what kind
of compressor/turbo is used, for a given amount of compression there is a
predictable change in temperature. Of course, if there is a difference in
the inefficiency of the turbos being compared that could make a difference
but I suspect that the differences will be minor compared to the theoretical
temperature change.
Best regards,
Rob Housman
Irvine, California
Europa XS
Rotax 914
S/N A070
Airframe complete
Avionics in progress
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ch701builder(at)yahoo.com
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| Posted: Tue Dec 16, 2014 7:06 pm Post subject: Engine boosting |
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Rob,
Just FYI.
Here is a link to a company that is using a 912 and 912S, a centrifugal blower, and getting around 25hp to 45hp extra.
http://www.flygas.info/en/news-en.html
Keith
**********************************************************************************
--------------------------------------------
On Tue, 12/16/14, Rob Housman <rob(at)hyperion-ef.com> wrote:
Subject: RE: Engine boosting
To: rotaxengines-list(at)matronics.com
Date: Tuesday, December 16, 2014, 5:44 PM
--> RotaxEngines-List message
posted by: "Rob Housman" <rob(at)hyperion-ef.com>
According to the "ideal gas law" (which is a pretty good
approximation for
air at the pressure in the intake manifold) PV = nRT so no
matter what kind
of compressor/turbo is used, for a given amount of
compression there is a
predictable change in temperature. Of course, if there is a
difference in
the inefficiency of the turbos being compared that could
make a difference
but I suspect that the differences will be minor compared to
the theoretical
temperature change.
Best regards,
Rob Housman
Irvine, California
Europa XS
Rotax 914
S/N A070
Airframe complete
Avionics in progress
--
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rampil
Joined: 04 May 2007
Posts: 870
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| Posted: Thu Dec 25, 2014 7:43 am Post subject: Re: Engine boosting |
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Rob is exactly correct. Compression always increases energy, in this
case heat. For a given compression ratio, there will always be the same
increase in heat energy and if starting from the same temperature,
always ending at the same higher temperature irrespective of fan blade design.
As for "Flygas", not in my airplane! There's something reassuring about
ground up system design and review of all affected parts in terms of
flight reliability.
Happy Holidays and Safe Flight!
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Ira N224XS |
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wdaniell.longport(at)gmai
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| Posted: Thu Dec 25, 2014 9:52 am Post subject: Engine boosting |
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Where I live in Colombia they developed a turbo for the stock 912 before the 914 came out. It uses a Mitsubishi turbo with the standard carbs albeit adjusted. I hear that you can get 39" but I only use 33" but given that I fly out of SKGY MSL 8500 this gives 500' minute performance with two adults aboard my ICPStol.
The system is pretty much what you would imagine with the four exhausts feeding the turbo which has the standard vehicle blow off valve but with a weaker spring than the vehicle one. I had manual adjustment with a vernier for a while which also worked fine but added work. The cold side feeds an airbox which feeds the carbs. I like this set up and I have flow nearly 500 hours on it without a problem except once when I fitted normal paper carb bowl gaskets which let in air and high MP. Cork gaskets solved the problem.
I had an engine tear down by a rotax certified mechanic at 500 hours and all tolerances where within spec.
A lot of people use this set up here and I have never heard of any problems except when the boost is set too high 40" +. In fact due to the complexity of the 914 in many ways it seems a more reliable option.
Will
William Daniell
LONGPORT
+57 310 295 0744
On Thu, Dec 25, 2014 at 10:43 AM, rampil <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)> wrote:
[quote]--> RotaxEngines-List message posted by: "rampil" <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)>
Rob is exactly correct. Compression always increases energy, in this
case heat. For a given compression ratio, there will always be the same
increase in heat energy and if starting from the same temperature,
always ending at the same higher temperature irrespective of fan blade design.
As for "Flygas", not in my airplane! There's something reassuring about
ground up system design and review of all affected parts in terms of
flight reliability.
Happy Holidays and Safe Flight!
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=436250#436250
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rampil
Joined: 04 May 2007
Posts: 870
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| Posted: Fri Dec 26, 2014 7:16 am Post subject: Re: Engine boosting |
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William - Merry Christmas!
It is not wear on moving parts that would be of concern, it is instead
the added stress on the crank, the rods, the pistons and the cylinders/heads.
Remember the rotax gets its performance from light weight alloys which are
designed to just meet expected stress, not the added stress of running at
an MP 10 - 30% higher than design.
The 914 is not just a 912 with a blower bolted on, some moving parts were
also upgraded.
In experimental aviation fooling around with your engine is certainly
permissible, even encouraged, if you know what you are doing. There is
even a Rotax-designated service center in Mississippi that does all
kinds of mods to stock engines for the Highlander / SuperSTOL crowd.
All I said in my initial comments is that for my aircraft, I would not markedly
diminish the reliability of my engine for a small gain in power and an even
smaller gain in speed. Your mileage will vary. I use my 912s Europa for 1000 nm cross country trips from 0 - 1000' MSL airports. I like a reliable engine!
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wdaniell.longport(at)gmai
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| Posted: Fri Dec 26, 2014 7:41 am Post subject: Engine boosting |
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Ira likewise Merry Christmas.
Yes I had the same thoughts about stress hence keeping the boost to 33" and reduce power to 30" within 3 minutes of take off. I cruise at 27". Also I suppose my need taking off at 8500' is slightly out of the normal operating range and requires extraordinary measures! However the local mechanics tell me that the internals of the 914 are the same as the 912 and certainly the anecdotal reliability "stats" would suggest that the mod doesn't over stress the engine. At 27" I am burning 4 gals and hour.
The downside of the mod in my opinion  is weight, complexity and heat albeit this is less complex than a 914. If I were flying at sea level I would choose a 912s as an excellent balance weight simplicity and power.
Interestingly enough the only major issue that I have heard of with rotax here was a 912s on mogas. Even the premium mogas here is of very poor quality and in a friend's aircraft this caused detonation which cracked a piston. Quality gas is a must in high compression engines.
Will
William Daniell
LONGPORT
+57 310 295 0744
On Fri, Dec 26, 2014 at 10:16 AM, rampil <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)> wrote:
[quote]--> RotaxEngines-List message posted by: "rampil" <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)>
William - Merry Christmas!
It is not wear on moving parts that would be of concern, it is instead
the added stress on the crank, the rods, the pistons and the cylinders/heads.
Remember the rotax gets its performance from light weight alloys which are
designed to just meet expected stress, not the added stress of running at
an MP 10 - 30% higher than design.
The 914 is not just a 912 with a blower bolted on, some moving parts were
also upgraded.
In experimental aviation fooling around with your engine is certainly
permissible, even encouraged, if you know what you are doing. There is
even a Rotax-designated service center in Mississippi that does all
kinds of mods to stock engines for the Highlander / SuperSTOL crowd.
All I said in my initial comments is that for my aircraft, I would not markedly
diminish the reliability of my engine for a small gain in power and an even
smaller gain in speed. Your mileage will vary. I use my 912s Europa for 1000 nm cross country trips from 0 - 1000' MSL airports. I like a reliable engine!
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=436284#436284
===========
br> fts!)
r> > com" target="_blank">www.aeroelectric.com
w.buildersbooks.com" target="_blank">www.buildersbooks.com
p.com" target="_blank">www.homebuilthelp.com
e.com" target="_blank">www.mypilotstore.com
" target="_blank">www.mrrace.com
target="_blank">http://www.matronics.com/contribution
     -Matt Dralle, List Admin.
===========
-
xEngines-List" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
===========
FORUMS -
_blank">http://forums.matronics.com
===========
[b]
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