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4 stroke versus 2 stroke engines - Which is more reliable?

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John H Murphy

Joined: 03 Jan 2007
Posts: 78
Location: Henderson, NV

Posted: Thu Mar 08, 2007 7:31 am Post subject: 4 stroke versus 2 stroke engines - Which is more reliable?

I've heard people talk about how much more reliable 4 stroke engines are versus the 2 stroke variety. Any truth to this? I understand the Rotax 912 engines are very reliable. Why not more affordable 4 stroke engines on the market?

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Thu Mar 08, 2007 8:26 am Post subject: 4 stroke versus 2 stroke engines - Which is more reliable?

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

Richard Pike

MKIII N420P (420ldPoops)

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Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

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JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Fri Mar 09, 2007 11:36 am Post subject: Re: 4 stroke versus 2 stroke engines - Which is more reliabl

The 4 stroke engine is MUCH more reliable than a 2 stroke.   Every certified airplane in the world uses 4 stroke, every car in the world uses 4 stroke.  Even most dirt bikes and motorcycles are now 4 stroke.  There is a really good reason for this.



Some people that have 2 stroke engines live in a state of denail and will try to convince you otherwise with all sorts of different "reasons".   



Bottom line is, when all is said and done, 2 stroke engines have many more fialures, problems, etc. than 4 strokes.



Mike Bigelow

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Steve Boetto

Joined: 11 Jan 2006
Posts: 365

Posted: Fri Mar 09, 2007 11:52 am Post subject: 4 stroke versus 2 stroke engines - Which is more reliable?

In a message dated 3/9/2007 2:37:38 P.M. Eastern Standard Time,  orcabonita(at)hotmail.com writes:

  	  Quote: 	
		  

Some    people that have 2 stroke engines live in a state of denail and will try to    convince you otherwise with all sorts of different "reasons".      



Bottom line is, when all is said and done, 2 stroke engines have many    more fialures, problems, etc. than 4 strokes.



Mike    Bigelow



	


 

 Hi Mike, have to disagree with ya here.  "Reasons"   Build  me a 4 stroke engine that produces 40 hp at or near the weight of a 2 stroke for  my Legal UL and I will be first in line.

  

 Steve

 FF #007 on Floats



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David.Lehman

Joined: 10 Jan 2006
Posts: 265
Location: "Lovely" Fresno CA

Posted: Fri Mar 09, 2007 11:54 am Post subject: 4 stroke versus 2 stroke engines - Which is more reliable?

Wow, I'm impressed!...  I've never met someone who was such an expert on four-stroke vs. two-stroke engines...

  

 I live in California and operate a two-stroke so I'm not in the State of Denail, but I am interested in where you got your facts on "more fialures (sic), problems, etc,"...  Hearsay/rumors are one thing, cold hard facts are another... 

  

 DVD

  

 do not archive

 



 

 On 3/9/07, JetPilot <orcabonita(at)hotmail.com (orcabonita(at)hotmail.com)> wrote: [quote]--> Kolb-List message posted by: "JetPilot" <orcabonita(at)hotmail.com  (orcabonita(at)hotmail.com)>



The 4 stroke engine is MUCH more reliable than a 2 stroke.   Every certified airplane in the world uses 4 stroke, every car in the world uses 4 stroke.  Even most dirt bikes and motorcycles are now 4 stroke.  There is a really good reason for this. 



Some people that have 2 stroke engines live in a state of denail and will try to convince you otherwise with all sorts of different "reasons".



Bottom line is, when all is said and done, 2 stroke engines have many more fialures, problems, etc. than 4 strokes. 



Mike Bigelow



--------

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





Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=99677#99677

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WhiskeyVictor36(at)AOL.CO
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Posted: Fri Mar 09, 2007 3:02 pm Post subject: 4 stroke versus 2 stroke engines - Which is more reliable?

In a message dated 3/9/2007 2:37:37 P.M. Eastern Standard Time,  orcabonita(at)hotmail.com writes:

  	  Quote: 	
		  Even    most dirt bikes and motorcycles are now 4 stroke.  There is a really good    reason for this.

	


 

  

 For street bikes it was due to Environmental Regulations.  The only  2-strokes on the street any more are the little 49 cc. scooters, or  antiques.

  

 For off road use and MX racing, the 2-stroke still provides the best power  to weight ratio, but the 4-strokes are gaining in popularity.   

 Bill  Varnes

Original Kolb FireStar now - but long ago I was a motorcycle  man.

Audubon NJ

Do Not Archive





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kfackler(at)ameritech.net
Guest

Posted: Fri Mar 09, 2007 3:41 pm Post subject: 4 stroke versus 2 stroke engines - Which is more reliable?

David Lehman wrote:

 >>I am interested in where you got your facts on "more fialures  (sic), problems, etc"

 >>Hearsay/rumors are one thing, cold hard facts are  another.

 Well said, sir, well said! Alas, in my life I've found that those who are  willing to spout such assertions are also unwilling to change their minds to  operate on a more rational basis. In other words, you're probably "flattening  your own forehead" when you try and get them to cite (let alone produce)  verifiable evidence. As the bard said, "What fools these mortals be!"

 But it is nice to see that critical, rational,. data-based thinking is  still alive out there! Good on you.

 -Ken Fackler

 Kolb Mark II / N722KM

 Rochester MI

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Steve Boetto

Joined: 11 Jan 2006
Posts: 365

Posted: Fri Mar 09, 2007 7:08 pm Post subject: 4 stroke versus 2 stroke engines - Which is more reliable?

In a message dated 3/9/2007 6:03:04 P.M. Eastern Standard Time,  WhiskeyVictor36(at)aol.com writes:

  	  Quote: 	
		     For street bikes it was due to Environmental Regulations.  The only    2-strokes on the street any more are the little 49 cc. scooters, or    antiques.

    

   For off road use and MX racing, the 2-stroke still provides the best    power to weight ratio, but the 4-strokes are gaining in popularity.     

   Bill    Varnes

	


 

 Good point Bill, I own an older 2 stroke Vespa Scooter (Germans call them  Rollers) and a  newer 4 stroke. The 2 stroke is lighter, Quicker and more  nimble. It also gets better mileage. all this on 50 cc vs 150cc.

 What is interesting is the fact that the transmission is a constant speed  type that tends to focus the rpm in a tight range. Makes you consider the idea  of running your 447 in that 5600 to 6100 range doesn't it?  Over 6000 miles  at 30 mph and no problems. Not bad for one cylinder the size of your  thumb.

  

 steve

 strokin 2 at a time



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Don G

Joined: 10 Jan 2006
Posts: 156
Location: Central Illinois

Posted: Fri Mar 09, 2007 8:19 pm Post subject: Re: 4 stroke versus 2 stroke engines - Which is more reliabl

Mr. Murphy,



Let me reply to your question with a terribly long but pertinent discorse on the 2 cycle/4 cycle subject.



This question cannot truly be answered because it does not have enough parameters. It is kind of like asking iwhich is better a Ford or Chevy. When a person eliminates brand loyalty and gets down to the details..not enough parameters. For instance..which is better, a Corvette, or a Pinto? And what features weigh the most in your desires? GAs milage?, or life? or maybe 1/4 mile speed...or top speed possibly, or cost.

The issue of reliablility needs more details too. like "Reliable for how long?

So which 2 stroke vs which 4 stroke?

And for how long. Detroit deisel makes 2 cycle engines which are reliable for many more hours of service than , say..a Rotax 912 or a Lycoming IO-360

Tecumseh makes a small 2 cycle engine that is very reliable for about 50 hours..then it is wore out and will become unreliable. IT does very well in its intended market.



One can look at the content of Brother Steve B's answer and determine that Steve's priority characteristic is power to weight ratio, and it is very hard to create a 4 cycle engine that can beat a 2 cycle in this arena, so he is right according to his highest priority.



But if longevity of service is a higher priority, then a 4 cycle might be the winning choice, but which particular ones?  As the above examples indicate, more specifics are needed.

And of course, how about cost...a factor that certainly might play highly to one list of "preferred characteristics".

When we isolate our choices to engines suitable and commonly used on aircraft,  which undoubtedly you are thinking. There still needs to be more parameters for an accurate analysis. Which specific engines and what lifespan is desired or determined "acceptable " in terms of hours of service before the lack of reliablility due to excessive wear is discounted as "expected".

Generally 2 cycles run at a higher rpm so they wear faster..But really fast 4 cycles will wear at near the same rate. Ring/cylinder/skirt wear is a function of piston speed first...other factors second. This generally gives faster engines less service lifespan. It DOES NOT necesssarily make them less reliable.



 WIth IC Engines, Like with different designs of aircraft, features of performance are generally all compromises with other features. Fast wings vs low stall wings. High wing loading vs low wing loading..neither is better than the other generally, but there are obvious winners when more parameters are given and priorities arranged by either mission requirements, or other desires deemed most important.



So in a nutshell, the definition of "reliability" needs an expected service life parameter to start an accurate....errr..debate!!!

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Central Illinois
Kitfox IV Speedster
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WhiskeyVictor36(at)aol.co
Guest

Posted: Sat Mar 10, 2007 8:54 pm Post subject: 4 stroke versus 2 stroke engines - Which is more reliable?

In a message dated 3/9/2007 10:09:12 P.M. Eastern Standard Time,  N27SB(at)aol.com writes:

  	  Quote: 	
		  I own an    older 2 stroke Vespa Scooter 	


 

 Steve,

  

 By golly, I do believe you may have an antique there!   

 Bill  Varnes

Original Kolb FireStar

Audubon NJ

Do Not  Archive





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NeilsenRM(at)comcast.net
Guest

Posted: Sun Mar 11, 2007 1:05 pm Post subject: 4 stroke versus 2 stroke engines - Which is more reliable?

John



This is a rather sensitive subject, so I will try to tread very carefully. 

Two stroke airplane engines that are currently on the market aren't as 

reliable as four strokes. I don't have any hard data to prove this comment 

but if I did I'm not sure those are so adamant would believe it. Just 

looking at the rebuild schedule for Rotax two strokes and Rotax four strokes 

has to be close to hard data but....



Granted there is a place for 2 strokes. They provide much better power to 

weight than four strokes. They also are much less expensive than a four 

stroke from the same manufacturer and the are less expensive to fix. But are 

the less expensive in the long run????



Why aren't there more four strokes out there? The market is too small and 

too dangerous from a liability stand point.



There is the VW engine which can be purchased new with all accessories for 

around $4,000.00 to $6,500.00 depending on how much you build and who you 

buy it from. There is still not a ideal reduction drive for the engine but 

the Valley redrive is serviceable. Over the last few years there have been 

two new products that have reduced the weight of the VW engine down to the 

weight of a 912 rotax. The new nikasil cylinders cut 10lbs and the new light 

weight geared starter cuts two pounds. For those that want more power there 

are the new water cooled heads that will stay cool while producing 100HP. 

 	  Quote: 	
		  From first hand experience these engines can be rebuilt for $1800.00 all 

moving parts, parts and labor. This results in a 4 stroke engine that costs 
	


about what a 2 stroke costs (maybe less) to buy and rebuild. Is it as 

reliable as a two stroke... I think it is much more so. Is it as reliable as 

a Rotax 912... I don't think so.



There are also a number of other engines out there that people are working 

on. Seems like there are GEOs, BMWs, Jabirus, and others. Are they less 

expensive and reliable as a 912 rotax??? Also do they produce the thrust 

that a 912 produces????



My $.02 worth



Rick Neilsen

Redrive VW powered MKIIIc

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planecrazzzy
Guest

Posted: Sun Mar 11, 2007 3:02 pm Post subject: Re: 4 stroke versus 2 stroke engines - Which is more reliabl

Hey Don,

               Good explination....you should send it to KITPLANES or EAA for a coulum in their Magazine....



 Gotta Fly...

Mike in MN / Rotax 503





 	  Don G wrote: 	
		  Mr. Murphy,



Let me reply to your question with a terribly long but pertinent discorse on the 2 cycle/4 cycle subject.



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