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Xtra Pistons

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george.mueller(at)aurora.
Guest

Posted: Tue Mar 10, 2009 5:58 am Post subject: Xtra Pistons

Has anyone tried the Xtra pistons which supposedly increase the horsepower of a Rotax 912 80 hp up to 95 hp?  Did they work?  Any problems with them? 

 

 

 

George in Milwaukee

  [quote][b]

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Fox5flyer
Guest

Posted: Tue Mar 10, 2009 8:05 am Post subject: Xtra Pistons

I recall that a member of this list reported that he installed the piston  kit and was pleased with the results.  I don't know if he's with us still,  but there may be others.

 Deke Morisse

Mikado Michigan

S5/Subaru/CAP  402+ TT

"The aim of an argument or discussion should not be victory, but  progress."

- Joseph Joubert

  

 [quote]

Has anyone tried the Xtra pistons which supposedly    increase the horsepower of a Rotax 912 80 hp up to 95 hp?  Did they work?     Any problems with them? 



George in Milwaukee

 	  Quote: 	
		  

	
[b]

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JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Tue Mar 10, 2009 9:44 am Post subject: Re: Xtra Pistons

I don't know anything about those pistons, but when you start increasing compression to increase horsepower, you can run into detonation and reliability problems.   Many times a short term increase in HP is most definitely not worth sacrificing reliability and having a engine prone to detonation.



I am not saying this is the case here with the 912, but I have see this type of thing do bad things to other engines so many times that I would sure do a lot of research on it.  Again, most of these things turn out badly, Rotax knew what they were doing when they designed the engine for a certain HP and also temps, detonation, and running characteristics.  You also have a gearbox to worry about if you have stronger power pulses with higher compression pistons.  If it were me, I would not risk messing up a very good running engine like the Rotax 912 it for a few more HP.



Mike

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_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

rjdaugh

Joined: 30 Aug 2006
Posts: 195

Posted: Tue Mar 10, 2009 10:26 am Post subject: Xtra Pistons

I have flown in a fox with these pistons.  It may belong to the guy that

Deke mentioned - the barefoot pilot.  He was real happy with the pistons.  I

agree with what Mike says, but in the case of the barefoot pilot, his home

field was over 4600' elevation.  At 4000' engines produce only 80% of the

horsepower they produce at sea level, so he figured that he was just getting

back some of that power.  He did fly to Leadville Colorado at 11,000' (?).

He did switch to premium gas due to the increase in compression ratio.



I don't think that George can rationalize his choice on this basis.



Randy - a 912S that produces 80 hp where I fly...



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_________________
Randy
Kitfox 5/7 912S
Black Hills, South Dakota

Michael Logan

Joined: 10 Jan 2006
Posts: 82

Posted: Tue Mar 10, 2009 12:42 pm Post subject: Xtra Pistons

George,

  

 I know the guy that paid for the development of the Xtra  pistons.  He flies a Pulsar behind his Xtra engine and he runs it very hard  and has many hours on it.  There has never been any sort of problem or  hiccups in the engine.  With the higher compression, he actually gets a  lower fuel burn.  After he developed the pistons, Rotax did virtually the  same thing with the 912S.  

  

 I am not saying this because he is a friend of mine, I  actually think he is a bit of a you know what but the fact is, the pistons work  well.

  

 Mike Logan



   From: owner-kitfox-list-server(at)matronics.com  [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of  george.mueller(at)aurora.org

Sent: Tuesday, March 10, 2009 9:53  AM

To: kitfox-list(at)matronics.com

Subject: Xtra  Pistons

 



Has anyone tried the Xtra pistons  which supposedly increase the horsepower of a Rotax 912 80 hp up to 95 hp?   Did they work?  Any problems with them? 



George in Milwaukee

[quote]



href="http://www.matronics.com/Navigator?Kitfox-List">http://www.matronhref="http://forums.matronics.com">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/c

[b]

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_________________
Mike Logan
Fredericksburg, VA

Paul A. Franz, P.E.

Joined: 02 Dec 2008
Posts: 280
Location: Bellevue WA

Posted: Tue Mar 10, 2009 2:09 pm Post subject: Xtra Pistons

On Tue, March 10, 2009 12:42 pm, Michael Logan wrote:



 	  Quote: 	
		   I know the guy that paid for the development of the Xtra pistons.  He flies

 a Pulsar behind his Xtra engine and he runs it very hard and has many hours

 on it.  There has never been any sort of problem or hiccups in the engine.

 With the higher compression, he actually gets a lower fuel burn.  After he

 developed the pistons, Rotax did virtually the same thing with the 912S.


	


Apparently the company is:



Craftmasters, Inc.  Woodbridge, VA.  22191

FOR  ORDER INFORMATION CALL (703) 652-9480

OR e-mail jerry(at)craftworks.biz



A circa 2004 advertisement quotes the conversion for $800.

<http://www.masterkraft.com/>



Here's the simple looking installation instructions and a new price of $850.

<http://www.craftworks.biz/pistonsite/6318.htm>



In step 21 it says;



"You will also need to run high octane fuel, 92, 93 from your auto gas station or

100LL from your airport".



Getting gasoline with an octane rating of higher than 91 is maybe a little difficult,

at least around here. Interesting too it says "The pistons will raise your compression

ratio up to 10.5 to 1 the same as the new Rotax912S" in their sales page:

<http://www.craftworks.biz/pistonsite/912sales.htm>



They also say the pistons are forged. Another company who makes replacement pistons

including the 912S pistons is JP Associates. The claim the stock Rotax pistons are

cast and not forged. They also say their forged sets come with new rings and wrist

pins. They explain what they think are the advantages and possible disadvantages to

using forged pistons.

<http://www.experimentalfuelinjection.com/wst_page9.php>



I don't know if what they say is true but I do know that the best way to increase the

thermal efficiency of the Otto Cycle Engine (spark ignition) is to increase the

compression ratio. I think 10.5:1 compression ratio is being used in real hot car

engines now but I don't know if their owners have detonation problems with 91 Octane

that's prevalent at the pumps.



 	  Quote: 	
		   I am not saying this because he is a friend of mine, I actually think he is

 a bit of a you know what but the fact is, the pistons work well.


	


Could that person be jerry(at)craftworks.biz ?



-- 

Paul A. Franz

Registration/Aircraft - N14UW/Merlin GT

Engine/Prop - Rotax 914/NSI CAP

Bellevue WA

425.241.1618 Cell

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_________________
Paul A. Franz, P.E.
Registration/Aircraft - N14UW/Merlin GT
Engine/Prop - Rotax 914/NSI CAP
Bellevue WA
425.241.1618 Cell
425.440.9505 Office

pwmac(at)sisna.com
Guest

Posted: Tue Mar 10, 2009 2:18 pm Post subject: Xtra Pistons

Correct Mike,

The only one I am familiar with was a guy near Denver. The hi 

compression pistons resulted in sea level Hp at 5k'. No issues with 

the engine at that altitude.

Paul\===========

At 09:44 AM 3/10/2009, you wrote:

 	  Quote: 	
		  



I don't know anything about those pistons, but when you start 

increasing compression to increase horsepower, you can run into 

detonation and reliability problems.   Many times a short term 

increase in HP is most definitely not worth sacrificing reliability 

and having a engine prone to detonation.



I am not saying this is the case here with the 912, but I have see 

this type of thing do bad things to other engines so many times that 

I would sure do a lot of research on it.  Again, most of these 

things turn out badly, Rotax knew what they were doing when they 

designed the engine for a certain HP and also temps, detonation, and 

running characteristics.  You also have a gearbox to worry about if 

you have stronger power pulses with higher compression pistons.  If 

it were me, I would not risk messing up a very good running engine 

like the Rotax 912 it for a few more HP.



Mike



--------

&quot;NO FEAR&quot; -  If you have no fear you did not go as fast as 

you could have !!!



Kolb MK-III Xtra, 912-S





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Michael Logan

Joined: 10 Jan 2006
Posts: 82

Posted: Tue Mar 10, 2009 3:26 pm Post subject: Xtra Pistons

That would be him. 



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_________________
Mike Logan
Fredericksburg, VA

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Tue Mar 10, 2009 8:22 pm Post subject: Re: Xtra Pistons

Interesting stuff, it sounds like it may be a very good way to get rated HP at higher altitudes.  Just keeping rated HP, and not using it to overstress the engine makes this mod sound a lot more attractive.  Here in Florida, I never have to worry about that losing power with altitude     I cant remember the last time I flew my 912-S over 1000 feet, and all the airports within 150 miles of me are at 10 feet MSL. 



Mike

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_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

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