# Long Stroke Engine



## OrangeAlpine (Dec 25, 2012)

I'm looking for a new shop project, leaning toward an I.C. engine.   Requirements are that it has to be interesting, slow running and  something I can build.  Right now, I'm thinking of a long stoke, hit or  miss, horizontal engine with 1" bore.  By long stroke, I mean than four  times the bore.  The idea being that the long stoke would be an  attention getter and make slow running easier.  The engine would have an  auxiliary exhaust to compensate for the necessarily smaller exhaust  valve.

As I search the internet, I find nothing on this subject.  Stroke seems  to be bore size (approximately) up to about 1.5 times bore.  Why is  that?  I posed this question on a site heavy with automotive types, very  smart guys whose normal mode of thinking is out of the box.  Responses  ranged from "Hmmm" to "That's the way we make power".  

Its almost to the point I may have to make one to see what happens.  All input is welcomed.

Bill


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## Tin Falcon (Dec 25, 2012)

Bill look into the designs of Hamilton "Dick" Upshur

http://hamiltonupshur.tripod.com/
these engines are 3/4 bore. 
Tin


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## sssfox (Dec 25, 2012)

Two reasons why you don't see strokes that long.

It only takes the gas so long to expand, so past a certain point, it doesn't help the power generation.

The longer the stroke, the wider the crankshaft needs to be.  So past a certain point, the crankcase becomes too big to be practical.  If you are making a conversation piece, you don't really need a crankcase.  The crankshaft would still be large.  For instance, a 1" bore with a 4" stroke would have a crankshaft a somewhat over 4" in diameter.

The longer the stroke, the lower the top RPM.


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## kf2qd (Dec 25, 2012)

You would have to have a jointed connecting rod like a steam engine.

More complexity, and gas expansion would not help you, and it might even pull a vacuum before it hit bottom dead center.


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## Philjoe5 (Dec 25, 2012)

> Requirements are that it has to be interesting, slow running and   something I can build.  Right now, I'm thinking of a long stoke, hit or   miss, horizontal engine with 1" bore.  By long stroke, I mean than four   times the bore.



Of course, that's exactly why some of us build steam engines that can run at 30 rpm

Phil


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## cfellows (Dec 26, 2012)

Don't know about a 4x stroke, but the Henry Ford engine has a pretty long stroke to bore ratio.  The model I built has a 13/16" bore and a ratio of about 2.25:1

[ame]http://www.youtube.com/watch?v=P_No_FrDhSY[/ame]

The following video is a full size model of the Henry Ford engine.  You can see in the video that it has a large stroke to bore ratio.  The cylinder is made from a 1" pipe nipple which gives it a bore of around 1 5/16".  Plans for this engine are available.

[ame]http://www.youtube.com/watch?v=PDnbtU_1EOA[/ame]

Chuck


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## cfellows (Dec 26, 2012)

Here is some additional information and pictures for the Henry Ford Engine

http://www.nbutterfield.com/Pages/HenryFordfirstengine.aspx

Chuck


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## OrangeAlpine (Dec 26, 2012)

Thanks all, especially Chuck.  I was aware that Henry made a long stroke engine, but was unable to find any specs.  

In general, I understand the comments (sort of) about the power generating ability of the long stroke, but there is one fact that sticks in my mind:  The engine I put in the Alpine has a 3.7" stroke and will rev effectively to 7,000.  Why is the 4.0" stroke restrictive at the 500 (max) rpm I hope to run my engine?

The overall purpose of the engine will be to make an engine that is unusual, so a crosshead and overhung construction was kind of baked into the concept.  

I had considered making a double action engine, but incorporating the auxiliary exhaust with the long stoke would result in an incredibly long piston and engine.  Then this morning, I had a a thought (or possibly a brain fart).  How about a double acting engine and instead of ported auxiliary exhaust, use either a slide or poppet valve?   Each end of the engine would have two exhaust valves, one to serve each combustion chamber.  

Bill


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## Till (Dec 26, 2012)

Hello Bill


OrangeAlpine said:


> The engine I put in the Alpine has a 3.7" stroke and will rev  effectively to 7,000.  Why is the 4.0" stroke restrictive at the 500  (max) rpm I hope to run my engine?


You got the term wrong. Long stroke refers to the ratio of bore and stroke. longstroke = Bigger stroke way  than bore size.
It has nothing to do with the absolute way swept by the piston.


Difficulties with very long stroke engines (=very long stroke compared to bore size):
-inefficient  combustion chamber geometry (this is will be even more important with  very small displacements, as the swept volume rises linear with stroke,  wereas the volume of a hemispherical chamber only rises with third power, which ist  very very small at small sizes!!!)
-small valves = bad gasflow at high rpm = low torque at high rpm = low outputpower
(-huge valve angles)
-difficult balancing for a wide range of rpm

As long as you don't need outputpower or efficiency, a very long stroke isn't a problem for your modell engine.


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## mu38&Bg# (Dec 26, 2012)

When you look at all the variables of engine design, it basically comes  down to "that's how you make power". The obvious point you've already  mentioned is the limited valve area for breathing. Limiting bore  diameter of a four stroke cycle engine makes for small valves. The  extreme oppposite of your design is a Formula 1 engine. where bore  exceeds twice the stroke! F1 engines are designed to operate at 18,000  RPM (well this past season anyway) so they take advantage of the greater  valve area to make power at that speed. An F1 Engine wouldn't be the  ideal engine for highway cruising either, so cars have bore/stroke  ratios that they do.

For display engines, virtually anything  works. Your engine will likely run. Efficiency doesn't matter, so I  wouldn't worry about it. If making a 1" bore over 5" deep isn't a  problem, I'd give it a try


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## aonemarine (Dec 26, 2012)

How about a non compression engine?
[ame]http://www.youtube.com/watch?v=fiVbeyoUmuA[/ame]


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## MuellerNick (Dec 26, 2012)

> In general, I understand the comments (sort of) about the power generating ability of the long stroke,



But you shouldn't understand it, because it is wrong. You won't pull any vacuum.
A bore:stroke ratio of 1:4 is quite uncommon, so you won't find that much real examples.
A ratio of 1:2 is very common on ship Diesels and these are the top notch efficient engines.
There is a valid remark (or drawback) of long strokes that huge as you want it: A huge flywheel (but that looks attractive to me) and a very long pushrod (or it would hit the cylinder walls). So, the longer the stroke, the more you run out of (esthetic) proportions, as this engine will become quite long and skinny.

You could take any design that you like, change bore:stroke as you want and keep the CR and displacement. And it will run.


Nick


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## aonemarine (Dec 26, 2012)

heres a good one too
[ame]http://www.youtube.com/watch?v=9W875WV0v90[/ame]


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## MuellerNick (Dec 26, 2012)

> heres a good one too



The Otto & Langen is a really nice engine. But absolutely nothing for a starter. The ratchet-mechanism is intriguing, and it is really hard to get here running.


Nick


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## cfellows (Dec 26, 2012)

I've really liked the Henry Ford engine from the first time I saw it running.  A fellow had a 1/2 scale version running at the PRIME show a number of years ago and it was a delight to watch, ticking over at around 300 RPM all day long.

Unfortunately, from what I hear, it's a bit tricky to get running as designed.  There is too much space in the combustion chamber so packing material has to be added to get a decent compression ratio.  Also, the exhaust valve assembly is such that it's hard to get a good compression seal.  The drip carburetion is also tricky to get adjusted right.

However, with all that said, it's quite an attention getter.  I've seen it at several different shows.  If you are inclined to incorporate some of your own designs, you can take my appoach and change the things you don't like and make improvements.  As you can see from the videos, my version is quite different than the original.

Chuck


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## cfellows (Dec 26, 2012)

This is another engine I found kind of interesting.

[ame]http://www.youtube.com/watch?v=WFabrN8zT0g[/ame]

Here is the fellow's website.  I believe he has plans and perhaps some rudimentary castings for this engine.

http://rmcscratchbuilt.20megsfree.com/photo.html

Chuck


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## Wagon173 (Dec 26, 2012)

I honestly think it could be done but you would have to find something very very slow, hot and consistantly burning that isn't too thick.  And even then you would have several head scratching sessions trying to get it to run.  And on top of it I doubt it would have enough power to run anything but itself. Unless maybe you had an abnormally large combustion chamber maybe?  If you go forward with this thing I'm very very anxious to see it!  Best of luck!


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## MuellerNick (Dec 26, 2012)

> Unless maybe you had an abnormally large combustion chamber maybe?



Or "maybe" just keep the compression ratio within reasonable limits? 1:6 for a slow running engine, and no wild guesses of maybe abnormal maybes.


Nick


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## OrangeAlpine (Dec 26, 2012)

MuellerNick said:


> Or "maybe" just keep the compression ratio within reasonable limits? 1:6 for a slow running engine, and no wild guesses of maybe abnormal maybes.
> 
> 
> Nick


Nick, that was going to be my next question.  

The number that you have expressed makes me wonder.  1:6  Just what does that mean?  My interpretation is that compression would be less than atmospheric.  I have aways seen compression ratios written just the opposite, or 6:1.  Would you write the ratio for a modern engine as 1:10?

Regardless of the notation employed, I would probably be using Coleman fuel.  Would that ratio be good for that fuel?

Bill


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## MuellerNick (Dec 26, 2012)

> 1:6 Just what does that mean?



Sorry, read it from right to left. 
I always confuse the order of the numbers for CR and scale. It's like being unable to properly use left and right (I can do THAT!).
I meant 6:1


Nick


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## cfellows (Dec 26, 2012)

I actually think engines with compression ratios as little as 4:1 will operate pretty well, although 6:1 seems to be the standard for model engines.

Chuck


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## MuellerNick (Dec 26, 2012)

> I actually think engines with compression ratios as little as 4:1 will operate pretty well



Yes, no complaining about that. I just don't know how tight he will get his piston and valves. 


Nick


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## OrangeAlpine (Dec 26, 2012)

MuellerNick said:


> Yes, no complaining about that. I just don't know how tight he will get his piston and valves.
> 
> 
> Nick


I don't know either.  I'll ask the next time I see him.  It seems another issue is how well the engine breathes, but the auxiliary exhaust should help that issue.  I had been thinking 5:1.  6:1 sounds good.

But first, a mock up and a lot more thinking is in order.

Bill


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## mu38&Bg# (Dec 26, 2012)

What do you mean by auxiliary exhaust? The exhaust gasses will be forced out the exhaust valve on the exhaust stroke. A restrictive valve will only require more power to do so.


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## OrangeAlpine (Dec 26, 2012)

By auxiliary exhaust, I mean ports located at the bottom of the cylinder, as in a 2 stroke engine.  That leaves less exhaust to exit the undersized valve.

Bill


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## MuellerNick (Dec 26, 2012)

> I mean ports located at the bottom of the cylinder



Now that is *really* old-school! 
I have never herded or seen such an engine running. I only know that they did it that way in the early days (and quit it). But I really like that idea!


Nick


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## Wagon173 (Dec 27, 2012)

That's pretty funny nick.  What's the fun in taking maybes and wild guesses out of the equasion?  Isn't that the spice of life?  The CH47 Was nothing but maybes and wild guesses and according to modern aerodynamics, would only fly if someone balled it up and threw it off the drafting board.  But I've ridden one and they are awesome.  So maybe a little imagination is all you need to go beyond your standard 6:1 protocol.


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## OrangeAlpine (Dec 27, 2012)

Wagon173 said:


> That's pretty funny nick.  What's the fun in taking maybes and wild guesses out of the equasion?  Isn't that the spice of life?  The CH47 Was nothing but maybes and wild guesses and according to modern aerodynamics, would only fly if someone balled it up and threw it off the drafting board.  But I've ridden one and they are awesome.  So maybe a little imagination is all you need to go beyond your standard 6:1 protocol.


I not sure (not a clue, really) what you mean.  Are you saying I should have a go at a higher CR?  

Anyone know the octane rating of Coleman fuel?

Bill


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## OrangeAlpine (Dec 27, 2012)

Whoa!  After a short stint on the old Google Machine, I find the octane rating of Coleman fuel is 50-55.  Makes me think that a true CR of 4:1 is about all that stuff can support.  

Bill


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## Till (Dec 27, 2012)

Building the engine with higher compression ratio allows some compensation of bad seals (common error source!).
You can easily decrease the compression ratio afterwards by exchanging the head gasket for a bigger one, if compression ratio turns out to be way to high.


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## OrangeAlpine (Dec 27, 2012)

Speaking of fuels, has anyone tried E85?  I know nothing about the stuff, but it is available to me.  It seems regular gasoline and Coleman fuel are used, but no talk of other fuels.

Bill


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## mu38&Bg# (Dec 27, 2012)

OrangeAlpine said:


> Whoa!  After a short stint on the old Google Machine, I find the octane rating of Coleman fuel is 50-55.  Makes me think that a true CR of 4:1 is about all that stuff can support.
> 
> Bill




Everything else about the engine design also comes into play. I run kerosene in small engines at 8:1 and even higher. Kerosene is closer to diesel fuel than it is gasoline, and you can't even find an octane rating, it has a cetane rating. E85 is fine, but can cause corrosion compared to a petroleum fuel.

The auxiliary exhuast sounds interesting in it's own right, but this was stopped when they figured out to just open the exhaust valve BBDC. Early engine valve timing didn't make too much sense when we know what we do now.


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## Wagon173 (Dec 27, 2012)

OrangeAlpine said:


> I not sure (not a clue, really) what you mean.  Are you saying I should have a go at a higher CR?
> 
> Anyone know the octane rating of Coleman fuel?
> 
> Bill


I'm not saying do or don't.  What I was saying is that I wouldn't not do something the way you want to do it because someone thinks it's against standard practice or has an easier way to do it.  I'm absolutely brand new to this model engine building but for my day job I work on diesel engines with a 23:1 compression ratio.  To achieve that high compression most of our engines use a kerosine based JP8 style of diesel with a cetane number around 35 or so if I remember right.  So unless there is something I'm overlooking here, I just don't see why you couldn't do a longer stroke higher compression engine the way you had originally wanted to.  Good luck to you whichever way you decide to take this project though!


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## OrangeAlpine (Jan 6, 2013)

As promised, I have given this engine quite a bit of thought.  It was obvious it was going to be long and spindly looking.  After much thinking and a couple of nightmares, this is what I came up with:

Gentleman, meet Funky.







A horizontal gasoline beam engine.

A few more photos of the engine as it goes through one rotation.





















The bore is 1 1/8", stroke 3 3/4", crank throw 3/4" (1 1/2" stroke of the connecting rod.  Keep in mind this is the crudest of mock ups, done to get a feel of the concept.  The rest of the engine would be totally conventional, with the exception of the auxiliary exhaust.  Any ideas or comments?

Bill


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## MuellerNick (Jan 7, 2013)

A beam engine, that has fallen over. 
I would limit the tilting of the vertical lever to +/- 30°. Things start to bind if you go higher.

Since long, I like the idea of a super long stroke, but I didn't build anything. I'll watch your progress.


Nick


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## 4ndy (Jan 21, 2013)

Tin Falcon said:


> Bill look into the designs of Hamilton "Dick" Upshur
> 
> http://hamiltonupshur.tripod.com/
> these engines are 3/4 bore.
> Tin



I have mentioned this before on this forum and I am attempting to tie up all the loose ends, but I am the grandson of Hamilton Upshur and I have been working with my Aunt to redo the website where his plans are sold. Tripod is quite dated and the advertisements just make the site unreadable. In the process of fixing this the website has moved locations

UpshurEngineWorks.com

this is the new web address for Upshur Engine Works. you will notice it looks identical to the old site, minus the nasty ads. Hopefully this will continue to suffice as I work as hard as I can to put together a new and improved site.

If anyone knows any other place on the internet where the old web address is still advertised can you please change it or bring it to my attention. I can be emailed directly at [email protected]


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## OrangeAlpine (Jan 26, 2013)

I took Nick's advice and lengthened the lever.  The action was not binding, but was somewhat herky-jerky.  It is now much smoother.





I had an idea that I pursued.  Here it is.





The action is the same.  I like the original because it is somewhat self balancing.  I like the second one because it is more compact.

Opinions?  Keep in mind this is to be built only as an oddball, although I do want to keep it mechanically sound.

Bill


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## OrangeAlpine (Jan 27, 2013)

Hmmm.  Several lookers, no opinions.  

After further cogitation, I really like the idea of balancing the engine using reciprocating weight rather than rotating weight.  How about using the "lever" engine design, but with a counterweight on the end of the beam?

Any thoughts on which design would make the most interesting engine?

Bill


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## MuellerNick (Jan 27, 2013)

> I like the second one because it is more compact.



Looks better to me. With the first setup, the flywheel is quite up in the sky. The second one looks more natural.
As it is now, stop playing around and make chips! 

Just my opinion.


Nick


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## OrangeAlpine (Jan 27, 2013)

MuellerNick said:


> Looks better to me. With the first setup, the flywheel is quite up in the sky. The second one looks more natural.
> As it is now, stop playing around and make chips!
> 
> Just my opinion.
> ...


Thank you Nick.  

There's only one problem with making chips:  I have no idea how I'm actually going to make the thing.  So far, this has been an exercise to determine proof of concept and gain some idea of proportion.  In fact, I'm thinking I will have to pursue a wooden mockup a little further, something that is actually made to predetermined size and conformation!

Unless, or course, someone comes up with drawings.

Bill


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## OrangeAlpine (Jan 29, 2013)

I know that I stated that aside from the bore/stroke ratio, the engine was going to be conventional, but I'm going to renege.  I'm seriously consider making it gearless, using Philip Duclos's Maverick as a model.  Also thinking of using an eccentric to activate the exhaust valve.  Does anyone have any experience doing that?

Wait a minute, why not use the beam to activate the valve?  

Bill


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## el gringo (Jan 29, 2013)

Chuck;
Off topic question...
I am building the Henry Ford engine and saving the fuel system for last. I don't understand the reasoning behind the 'restrictor orifice' reasoning and did you use in your builds? Orifice size?

ray m


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