Questions and Answers If you have general RC questions or answers discuss it here.

2 stroke vs 4 stroke

Reply

Old 06-23-2007, 01:27 PM
  #1  
edaf1246
Junior Member
Thread Starter
 
Join Date: May 2006
Location: Williamsburg, VA
Posts: 2
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default 2 stroke vs 4 stroke

I am getting ready to start building my third airplane. My initial instructior has recommended that I use an OS 90 4 stroke engine, in lieu of the OS 55AX I was planning to use. I keep hearing that the sound is better with a 4 stroke, and that they are more fuel efficieint, but is that really worth over $100 more for the engine? The kit manufacturer suggests a .40 to .60 2 stroke or a .60 to .90 4 stroke, so both are within the suggested limits. If I go with the 4 stroke, what are the differences I should expect from my previous experience with 2 storke engines? Thanks.[sm=50_50.gif][sm=50_50.gif]
edaf1246 is offline  
Reply With Quote
Old 06-23-2007, 02:37 PM
  #2  
bbbair
Senior Member
 
Join Date: Jan 2003
Location: Belleville, ON, CANADA
Posts: 963
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: 2 stroke vs 4 stroke

A Four stroke engine is a great piece of Kit!

But... []

Like all things there are trade offs, when all is said and done it's up to you to make a decision... [&o]

Four stokes have a deep low sound that adds to the authenticity of the moment, they burn less fuel, are more powerful and can swing a bigger prop. therefore folks like them.
BUT
They are a more complicated engine having pushrods, springs and valves which require maintenance from time to time. They are also heavier and more expensive, they usually require a different fuel and a hotter glow plug.

IF you are new to the hobby and still prone to crashing stay with the two stroke as there is less too damage. A Bent push rod on a 4 Stroke is expensive and usually writes off the engine.

Like I said; it's up to you to make a decision...
bbbair is offline  
Reply With Quote
Old 06-23-2007, 02:43 PM
  #3  
aerowoof
 
Join Date: Jun 2006
Location: pembroke, NH
Posts: 2,949
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: 2 stroke vs 4 stroke

the cost factor is up to you 4 strokes will swing a larger prop than a 2 stroke and due to the firing every other stroke use less fuel.they weigh more than 2 strokes have more parts and some need valves adjusted after so many running hours.to me a 4 stroke and 2 stroke sound the same like a model engine so I use 2 strokes.others use nothing but 4 strokes.again the choice is yours.
aerowoof is offline  
Reply With Quote
Old 06-23-2007, 02:57 PM
  #4  
ChuckW
Senior Member
 
ChuckW's Avatar
 
Join Date: Jun 2006
Location: Clovis, CA
Posts: 5,165
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: 2 stroke vs 4 stroke

What kit is it? Your .55-AX is an EXCELLENT engine. For a 2-stroke, it is basically trouble free with plenty of power. The .91 4-stroke is great too. So it really just depends on the application it is going in.
ChuckW is offline  
Reply With Quote
Old 06-23-2007, 04:40 PM
  #5  
edaf1246
Junior Member
Thread Starter
 
Join Date: May 2006
Location: Williamsburg, VA
Posts: 2
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: 2 stroke vs 4 stroke

I am planning to put the engine I pick on a Goldberg Super Chipmunk. I am probably leaning to the 55AX, since while I don't crash (too hard!!) often, I am not at all sure of my ability to recognize when an engine really needs adjustment. I am just getting to the point where I can make appropriate, though minor, adjustments on the .46LA on my Avistar. It sounds like there is a lot more to know and adjust on a 4 stroke. Is that right?
edaf1246 is offline  
Reply With Quote
Old 06-23-2007, 06:15 PM
  #6  
PMAXX
Member
My Feedback: (5)
 
Join Date: Apr 2005
Location: ISLAND PARK, NY
Posts: 60
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: 2 stroke vs 4 stroke

I have the WM super chipmunk which is pretty close in size. I have a O.S. 61 FX and it flys pretty well but I wouldn't go any smaller. I would definately consider the 90 4C if I were to build a new one. The magnum 91 is only $169.99 at tower.
PMAXX is offline  
Reply With Quote
Old 06-23-2007, 06:46 PM
  #7  
da Rock
Senior Member
 
Join Date: Oct 2005
Location: Near Pfafftown NC
Posts: 11,511
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: 2 stroke vs 4 stroke


ORIGINAL: edaf1246

I am getting ready to start building my third airplane. My initial instructior has recommended that I use an OS 90 4 stroke engine, in lieu of the OS 55AX I was planning to use. I keep hearing that the sound is better with a 4 stroke, and that they are more fuel efficieint, but is that really worth over $100 more for the engine? The kit manufacturer suggests a .40 to .60 2 stroke or a .60 to .90 4 stroke, so both are within the suggested limits. If I go with the 4 stroke, what are the differences I should expect from my previous experience with 2 storke engines? Thanks.[sm=50_50.gif][sm=50_50.gif]

You need to compare more than just price and sound. And the difference in fuel efficiency isn't even noticed by most.

The FS91 is listed as 24 ounces.
The 55AX is listed as 14 ounces.

They both list basically the same horsepower.

There is $105 difference in the price.

My first experience with 4strokes was using an OS71 FS in an airplane that wound up with a 46AX 2S in it's place. I discovered that the FS was a b****h to start in that airplane. I discovered that the FS really didn't like my 10% fuel. All the FS guys told me right away that FSs take more nitro to run good. So I bought some more expensive fuel and discovered that b***h still didn't like to start in that airplane. I discovered that the airplane flew almost exactly the same with either. The FS used a bigger diameter prop doing basically what the 2S did with a smaller prop. That didn't strike me as mattering at all. After running the FS awhile in another plane, I was told by a FS expert that I really ought to adjust the valves and I'd get more power. I did. And I didn't. I adjusted them and I didn't see any difference. The guy says I didn't waste my time because you need to learn how to adjust valves anyway. Yeah?

If I sum up what I got out of the FS experience, I'd say.......... I got part of a gallon of more expensive fuel. The backfiring FS ruined a couple of plastic spinners that would have lasted on the 2Ss for years. I've got some nice big props now. I've learned how to adjust FS model engine valves (I enjoy adjusting automobile valves lots more.). I've got some spare FS plugs that cost me way more than 2S plugs cost. I've got a spare FS that I might someday use if I find a model that needs more noseweight than expected, but doesn't need any extra power to go with the weight.

Ask yourself if the model you're considering is probably going to need 10 ounces of nose weight?
da Rock is offline  
Reply With Quote
Old 06-23-2007, 08:38 PM
  #8  
warhwk
My Feedback: (3)
 
Join Date: Dec 2001
Location: Knoxville, TN
Posts: 667
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: 2 stroke vs 4 stroke

I've had three Chipmunks. I would not go lower than a .61 two stroke. On the other hand, the Chipmunk seems to be a perfect match to a 91 four-stroke. A match made in heaven!! I had a YS 1.20 on one as well. It didn't fly nearly as well. Your instructor knows what he is talking about.
warhwk is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service