# How to design an engine



## Ukko (May 2, 2018)

How to design an engine?


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## Mechanicboy (May 2, 2018)

You need this book.. https://wiganlanebooks.co.uk/books/hobbies/modelling/model-four-stroke-petol-engines-designing-building-running-by-l-c-mason/


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## Anatol (May 2, 2018)

Ukko said:


> How to design an engine?



Jens, generous spirit that he is, has taken your question seriously. 
I guess the majority of readers just rolled their eyes 

How to build an atom bomb? 
How to become a millionaire?
How to play the flute?

Your question is like these. 

The general answer is:  
study hard for many years in relevant fields, 
carefully examine previous successful examples, 
have several hundred design ideas which you then 
build prototypes of and 
carefully study the way they fail, and 
learn from your experience.

Its as easy as that! 

My response is actually very serious. The modern 'maker' culture suggests that making is easy. That's just because they want to sell you junk. 
Thomas Edison said "I haven't failed, I've found 10,000 ways that don't work"
Making new stuff that works is (irreducibly) difficult.
Get ready to fail. Don't give up.


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## Ukko (May 2, 2018)

Is there any free stuff available?


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## Herbiev (May 2, 2018)

Your best shot would be to buy the book suggested by Mechanicboy. As far as I know there is no free stuff available without breaking the forum regulations


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## bobm985 (May 2, 2018)

"Aircraft Engine Design" by Liston is at the "Internet Archive".


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## Anatol (May 2, 2018)

review all the failed designs at the museum of retro technology
http://www.douglas-self.com/MUSEUM/museum.htm
to avoid repeating old mistakes.


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## lohring (May 3, 2018)

Are we talking about model IC engines?  Two stroke or four stroke?  My favorite book on the history of full size engine design and development is Sir Harry Ricardo's The High Speed Internal Combustion Engine.  The paper back edition is much less expensive but lacks the great fold out drawings.  Another definitive work is The Internal Combustion Engine in Theory and Practice.  On models try  http://modelenginenews.org/ for a historical look.  Modern two stroke design is discussed extensively by some world experts on this thread on Kiwi Biker.  Pit lane has even more.  The internet has extensive content but you need to learn to filter out a lot of BS.

Lohring Miller


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## rlukens (May 3, 2018)

Anatol said:


> review all the failed designs at the museum of retro technology
> http://www.douglas-self.com/MUSEUM/museum.htm
> to avoid repeating old mistakes.



Neat stuff there.


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## rlukens (May 3, 2018)

Ukko, I assume you're not wanting to reinvent any engine. 
I like to "design" my own. Of course I'm not inventing anything, but I design builds that utilize my skills, equipment and on-hand materials.  
If that's the case, I suggest you download a basic CAD program and learn how to use it. Draftsight is one such program... easy to use and free.
Russ


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## Mechanicboy (May 3, 2018)

bobm985 said:


> "Aircraft Engine Design" by Liston is at the "Internet Archive".



The book from 1942.. Really old book  

https://archive.org/stream/in.ernet.dli.2015.205331/2015.205331.Aircraft-Engine#page/n1/mode/2up


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## Charles Lamont (May 4, 2018)

Ukko said:


> How to design an engine?



Get a degree in mechanical engineering and then add many years experience!

Sorry, but for once I could not resist.

If you are interested in steam then 'Model Stationary and Marine Steam Engines' by K N Harris remains a very good starting point.

In this world of expecting everything to be available for free on the internet, one of the best things you can still do is to sit down for several hours with a book, printed on paper.


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## XD351 (May 4, 2018)

Before you start to even think about designing an engine regardless of what type you need to understand how it works and then break it down into its basics.
Type of engine - 2or4 cycle internal combustion , rotary , steam or turbine .
What fuel it will use , gasoline , nitro , diesel , lpg etc or steam powered .
Capacity and number of cylinders or rotors .
Form factor , flat or boxer , v type  or radial type  for piston engines .
Air or water cooled .
Pushrod or ohc for four cycle .
From there you really need to gain an understanding on things like bore to stroke ratio , con rod ratio , compression ratio , valve or port timing events , rocker ratios for pushrod four cycle engines .
Many of these things can be learned online or in some  engine blueprinting books and the books mentioned above .

Cad programme would be the ultimate but many an engine has been designed on a piece of paper with basic drawing tools and basic layouts done with cardboard and paper clips ! 
This is where 3d printing really comes into its own as you can design in cad , slice and print prototypes much faster than you can machine them ! 
Asking how to design an engine really doesn't give us much to work with and it is difficult to gauge your  experience with machining or engines and we still don't know what type of engine you are asking about !


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## Ukko (May 4, 2018)

I am designing vertical 1 cylinder 4 stroke pushrod engine.


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## Hopper (May 4, 2018)

This type of engine has been designed many many times before. Look at what has been designed before and proven to work. Build one or two of those proven designs yourself so you can learn for yourself the practical side of construction. Then start your own design by combining what you consider to be the best of  several existing designs. Plenty of free IC engine plans on the net if you trawl around. Look at sites such as Jan Ridders, John-Tom Engine Plans, or google some of the recognised designers of teh past such Edgar Westbury (aka ET Westbury) and LC Mason. Plenty of their plans floating around on the net. 

Best to start with these existing plans because, realistically, if you have to ask "How to design an engine" your are not ready to design an engine yet. You must learn to walk before you can run.


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## Ukko (May 4, 2018)

Can the cylinder be Just 1 piece?


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## stevehuckss396 (May 4, 2018)

Ukko said:


> Can the cylinder be Just 1 piece?



Yes it can


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## XD351 (May 4, 2018)

Ok now you know what you want to design now you need to add a few things like:
Type of fuel and ignition type ( spark or glow ) so you can aim for a compression ratio.
Overhead valve or side valve ?
Is it to be an open or closed crank design ? ( open  has no crank case and is only good for short runs  and closed has a crankcase and oil supply and can be run much longer ) open design is easier to machine .
Does it need to be constrained to a certain set of dimensions ? This will govern engine capacity and thus bore and stroke dimension , also if the engine is big enough you may be able to use commercially available parts like pistons , rings ,conrods and valves  etc.
If i'm guessing correctly when you asked about one piece culynder you mean cylinder and crankcase ?


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## lohring (May 5, 2018)

A two stroke is a much simpler engine to start with.  Below is an engine I built in high school.  It was patterned after a racing engine of the time (1950s) and taught me most of what I know about machining.  You don't need castings.  This is a post on a very simple design and this is a plan book on several very successful, simple designs.

Lohring Miller


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## Ukko (May 12, 2018)

Can i use water pipe as cylinder liner?


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## Mechanicboy (May 12, 2018)

Ukko said:


> Can i use water pipe as cylinder liner?



No, use high tensile steel or cast iron.


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## Cogsy (May 12, 2018)

Ukko said:


> Can i use water pipe as cylinder liner?


 
I've never built one of these aero engines but I can't see why not. 'Normal' 12L14 steel is perfectly fine for liners with cast iron rings and I can't see there being much operational difference between that and mild steel. If you're not going to use rings that might be a different proposition altogether.


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## kadora (May 13, 2018)

Seven years ago I was in your shoes - reading HMEM forum
to soak the knowledge of experienced guys . //thank you guys again//
Then I start to built my first 4 stroke single cylinder from 
junk material. I have found that is not important for first engine perfectly aligned crank shaft , perfectly machined camshaft and its timing and so on.
Important is GOOOOD COMPRESSION + HEAVY FLYWHEEL.
With good compression will run //for short time of course// even badly built engine and you will be so happy to see running your first engine that you will start to build second much much better engine .


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## Mechanicboy (May 13, 2018)

You can use old drive shaft as cylinder, it's high tensile steel in drive shaft for front wheel drive car. Piston ring can you create from old brake disc who are made of cast iron. Piston of cast iron to example from old cam shaft (no cam who are impossible to machine or annealing, between cams is soft enough to machine).

Read this book who are good to have in collection. 

Here is to download the book https://rclibrary.co.uk/download_title.asp?ID=1996


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## Hopper (May 13, 2018)

Mechanicboy said:


> You can use old drive shaft as cylinder, it's high tensile steel in drive shaft for front wheel drive car. Piston ring can you create from old brake disc who are made of cast iron. Piston of cast iron to example from old cam shaft (no cam who are impossible to machine or annealing, between cams is soft enough to machine).
> 
> Read this book who are good to have in collection.
> 
> Here is to download the book https://rclibrary.co.uk/download_title.asp?ID=1996



Thanks for the link. That certainly is an encyclopedia on the subject.


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## Hopper (May 13, 2018)

Re water pipe as a cylinder liner, I would not use it. Water pipe has a welded seam running along its length, visible inside. Makes for difficult machining and inconsistent wear and bearing qualities. Better to use a piece of seamless tubing or machine from solid. Often a liner will not need to be high tensile as it is not under massive load, being surrounded by the shrunk-on cooling jacket or cylinder block or whatever, depending on design. Many liners are cast iron, which is relatively low tensile but self lubricates well.


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## Mechanicboy (May 13, 2018)

Many liners are *cast iron*, which is relatively low tensile but self lubricates well.

It,s in older model engines who are produced 1950 years and before, the problem is brittle when screwing to hard until it break of.

I has used wristpin as cylinder, the wristpin was annealed before machining to a right size and form. No necessary to re-hardening the cylinder. It's alloy inside steel who are good to withstand wearing caused by piston. 

Wristpin is easy to find i all sizes and length.


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## minh-thanh (May 14, 2018)

Hi Ukko ! 
I totally agree with Kadora .



kadora said:


> Seven years ago I was in your shoes - reading HMEM forum
> to soak the knowledge of experienced guys . //thank you guys again//
> Then I start to built my first 4 stroke single cylinder from
> junk material. I have found that is not important for first engine perfectly aligned crank shaft , perfectly machined camshaft and its timing and so on.
> ...



  Instead of asking "How to design an engine"
You should ask: "how to make ring pistons, how to make gear ...."
And you will have a lot of options to do it (sometimes there are different opinions on how to do or material .... BUT it is the experience of the master on the model engine ! )
* I also had the idea of "how to design an engine" before doing the same as you, but I realized that: I designed it but I did not know how to make individual parts, so I chose to learn how to do individual parts. And that combines them together. I just need the engine to run, and now I'm confident I'll design different types based on the parts that I have done. 
http://www.homemodelenginemachinist.com/showthread.php?t=27696


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## Lakc (May 17, 2018)

Mechanicboy said:


> The book from 1942.. Really old book
> 
> https://archive.org/stream/in.ernet.dli.2015.205331/2015.205331.Aircraft-Engine#page/n1/mode/2up



Thanks for that link! I still have photocopies of some of the pages. :thumbup:


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## cliff20 (Jun 2, 2018)

Some "REALLY" good advice here in these posts.  I have been trying to design a small two stroke engine for a special application for several years.  It is more of a challenge than I thought when I started, by far.  There are more good books than mentioned here, though I won't mention them, as apparently their are regulations I'm not aware of on the blog, apparently about free books.  
From what I gather you aren't really designing your own engine, but want a spreadsheet where you fill in the blanks, and POOF, the magic designs dimensions appear.  Actually there are some spreadsheets fairly close to that ideal, but they do not go into the real challenge.  The crankshaft diameter, bearing surface areas, con rod thickness, casing thickness, materials expansion and contraction, how different materials wear and get along together.  And a bunch of other factors that determine how your "design" will run, and if it is worthwhile making or not.  That comes from a lot of experience, or research.  Preferably a lot of both.  
I have yet to run across an "instant gratification" engine design program.  However their are quite a few really good engine designs, radially available, as mention in various posts here, that are designed to be made by limited shop equipment, and at times, effort, that run quite well.  And actually more than several seconds before seizing.  
I am NOT trying to discourage you in the least.  I find the same challenge extremely frustrating at times, yet also intriguing.  As one thing leads to another, and another.  It becomes a game to me, better than any video game, that grows into a much larger knowledge base that can be used, or applied, to many other things.  It is not a wasted effort if it doesn't work out as well as you hoped.  I learn something in the process.  It just means, I overlooked something.  Especially if your pushing the envelope on technology, or you are into uncharted territory.  Keep at it.  It is a battle of Wills and skill.

I might add here, that read up on scaling laws.  Physics changes as fluid flows go below say a 1/16th of an inch, and capillary effects start to appear, along with other Quantum influences coming out of the woodwork.  For example, piston and cylinder gap become more and more critical the smaller you get.  Yet you also have to battle the seizing of the piston in the bore as the engine heats up.  Why Cox .010 is the smallest production model engine ever made that I am aware of, years ago, and nobody made a smaller one, or even another copy of it that size. 

And by the way, lohring if you read this, that is a VERY nice set of casting molds and resulting engine.  ESPECIALLY done in high school.  I'd be proud to have done that workmanship now, let alone back then.  I take it, from the intake ports, this recreation was of a Dooling 2 stroke model aircraft engine.  One HOT engine in its day.


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## goldstar31 (Jun 2, 2018)

One must read 'history' rather the constantly , repeated variations and modifications of someone else has copied!
George Stephenson of the Rocket locomotive fame and his son Robert and all this about 'inventing thing' is probably arrant nonsense.
George was illiterate and couldn't read or write and from what my late father pronounced- who could barely read or write as well, claimed the ideas came from the blacksmith at the local colliery. The railway line was old stuff and can be traced back as far as the Roman chariots that plied along the Roman Wall. Four foot eight and a half inches- and there is no measurement that remotely ties in and I've been back as far as measurement of the Megalithic times and based on the movements of the planet Venus!
I'm always happy to suggest guys like Archimedes, Hero of the Jet engine fame- driven by steam and Pythagoras along with probably dear old Euclid who was probably more than one bloke! I studied Il Principe by Machiavelli - for every aspiring millionaire. You know this Land, Labour and Capital thing to be taken with a large dash of Enterprise.

Unless you have a grounding of Science and Maths with a clear understanding of Chemistry and Physics, you simply tart up what has gone before. 

Always remember  that there is very little that is new as the elements of such things goes back rather a very long way.

Me? Well a few of us were discussing such erudite matter last evening. The malt was coming in neat doubles and  the vino collapso glasses were adding up to more than one bottle a hazy head.  We had one thing in common. We were all retired and apart from one, we had all given up this silly idea of having to work beyond the age of 55.  We's got the Factors of Production sussed out.N

If one doesn't grasp the fundamentals of living, you will be forced as one authority of full size and model engineering said ' You will ask the same silly questions and-- get the same silly answers.

Once, I gave him a rather interesting dissertation of acid erosion in internal combustion engines- and fell asleep listening to his reply.


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## XD351 (Jun 2, 2018)

Are you taking any new medication Norman ???


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## goldstar31 (Jun 2, 2018)

I suggest that you consult the two major pharmaceutical firms of which I continue to be a major shareholder .

My doctor of many years always suggested 'whisky and aspirin and if supplies of aspirin ran out to double the quantities of whisky'

And just for your delectation, my son in law is a senior consultant heart surgeon and his comments to a very aspiring young son, 'Don't fool about with Grandpa. He's Mensa!'  You know the sort. of thing, outside the three standard deviations  from the rather higher end from the Mean!

All to do with genetics, I'm merely lucky.

Norm


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## ShopShoe (Jun 2, 2018)

*Norm,

Whoever, (Where-ever), complained about you not showing pictures is missing the points (many) you make everyday and keep us (some of us, anyway) reading what you post.

You seem to be more than merely lucky to be here after...

And I thank you for more things to think about than machining when your name appears.

Anyway, just felt like putting words out today in a random way.

--ShopShoe*


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## goldstar31 (Jun 2, 2018)

I spend my days 'bean counting' for perhaps the largest charity in the World. It's a wonderful privilege  to  have ben asked and still able to do it.  

Having chipped and grimy finger nails is 'an another bit of mental exercise' that keeps the dreaded dementia more or less at bay.

Thank you

Norm


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## Anatol (Jun 2, 2018)

goldstar31 said:


> son Robert and all this about 'inventing thing' is probably arrant nonsense.
> George was illiterate and couldn't read or write and ... claimed the ideas came from the blacksmith at the local colliery. The railway line was old stuff and can be traced back as far as the Roman chariots that plied along the Roman Wall. Four foot eight and a half inches- and there is no measurement that remotely ties in and I've been back as far as measurement of the Megalithic times and based on the movements of the planet Venus!.



So Norm, 
(if you don't  mind, that's what they're calling you...)

I like a rambling rant and that kind off talk is characteristic of some very smart people I know. But it does require some reverse-engineerring to pick out the gems from the dross. Mind you this is a forum, you're not writing a dissertation and its worth what I paid for it. Enough preamble. To the question of design and invention.

George may have been illiterate but that does not mean he was not smart. It wouldn't have mattered if he was math professor because the discipline of engineering did not yet exist. There was no thermodynamics, no Bernoulli, etc (Well, Stephenson was born about the time Bernoulli died - which, coincidentally, was the same year James Watt made his engine.). But the first professional society of mechanical engineers was not formed  till 1847 in UK  (gotta love wikipedia) - it was another 33 years before ASME was formed in USA. 

My point is, in Stephenson's time, engineering, as a mathematized discipline we know, did not exist. It was all artisanal knowledge, and blacksmiths were often extremely clever and skillful. One does not need math to make strong and ambitious structures. The Gothic cathedrals are still standing, and those master masons used no numbers at all. 

According to my research, the vast majority of novel inventions are made by mavericks, misfits, renegades, left-of field types. (for instance, Henry Morse, inverter of the telegraph, and Daguerre, inventor of photography, were both painters. Edison was a self taught inventor, the Wright brothers were bicycle mechanics, etc etc. I would go out on a limb and say the vast majority of fundamental technologies upon which our technological society is based were not invented by engineers, but they were tested and developed by engineers.

Engineering is a conservative discipline (it has to be and we're glad of it). Engineering tests and refines ideas, but in my experience, invention and creativity are not primary values of the discipline.  

Regarding the railway gauge, the story I've heard is that European carriage makers in preindustrial times made carriages to run in the ruts of roman roads, which were still in use. The ruts were made by roman chariots. When those carriage makers were asked to build railway carriages, they preserved the dimension of  roman chariots. Nothing to do with Venus, afaik.


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## goldstar31 (Jun 2, 2018)

I seriously enjoyed your version of things. However there are a few possible corrections( forgive me, please)
Stephenson's cottage is on the North bank of the River Tyne and opposite, my father was a blacksmith/farrier who came, ironically, from a family of blacksmiths who( coughs discreetly) worked in Shildon, County Durham -for Timothy Hackworth,another engineer.
So they moved a bit further North and Sam, my grandfather was blacksmith and later engine man in one of the collieries in North West Durham.  The three boys( my uncles and father) became blacksmith/farriers at Consett Iron Company and a bit of research will lead to sword making at Shotley Bridge which is a stone's throw from Consett. They were of German Solingen descent.  They made steel so good that a gentleman's sword could be wound safely in a gentleman's top hat. I digress!
During one of the depressions, familiar in coal and other engineering, Dad moved next to Stephenson's Cottage.
So I was born on what was the border of Durham and Northumberland- in a house! Funnier things have happened!
There's another branch of the family but wait awhile.
So eventually I got married. She was the nearest living relative of John Dobson who was the architect along with Robert Stephenson, son of George and  they designed the Railway Station in Newcastle- almost on top of the Roman Wall. John was the son of a gardener  but managed to sort out the family castle of Ravensworth- and politely married one of the daughters. He went on to flying buttresses on Newcastle Cathedral and - I cough discreetly- a gaol and a pile of 'piles'or family seats. Here enters the ancient Liddell family complete with Alice in Wonderland's father who wrote the Lexicon from the Greek and Alice- actually Alice Pleasance Liddell, became famous for Mad Hatters and White Rabbits and Looking Glasses!

So today, we have the 65th Anniversary of the Coronation of - one of the members of the family AKA Elizabeth Alexandra Mary Windsor- or Battenburg and mother of Big Ears. Big Ears is or so it is said great friends with the other branch of MY family- Blackadder or Mr Bean or earlier a graduate in  Electrical Engineering. He was or is quite a famous racing driver!

Me- well, not quite as much notoriety but - still doing well. And . Yes, the masons did measure - and I have funny things on my apron to prove it.


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## XD351 (Jun 2, 2018)

Perhaps you should start your own thread about yourself and put all of your ramblings in there , i'm sure there some on this forum that will enjoy reading it .
Tho OP asked how to design an engine not for a brief history of engineering or of your ancestry .


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## Cogsy (Jun 2, 2018)

I have to agree with XD351 Norm - and I would like to remind you of our brief discussion of 'off-topic' and "glass houses / pots and kettles" from a few days ago as well.


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## goldstar31 (Jun 3, 2018)

391 likes

Thank you for them


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## editor123 (Jun 3, 2018)

Ukko said:


> Can i use water pipe as cylinder liner?


There is so much work that goes into a running engine that using junk metal is not a good idea.


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## pushrod_38- (Jun 3, 2018)

I have been designing and building my own 4 stroke aero engines since 1997 They are of the single crank type with overhead valves (open rockers) and cam gears driven off the crankshaft at rear. My book is not free; but the E version is fairly cheap. 'designing and building a miniature aero engine' Crowood Press. You can get it on Amazon and other places. I have made a lot of mistakes over the years, but my engines fly all my model aircraft and my book may cut some corners for anyone starting out.


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## Tim Wescott (Jun 3, 2018)

A water pipe would be a poor choice for a cylinder lining, because it's soft and poor quality steel.  I suggest that before you design an engine, you build a few from plans, as a walk before you run kind of thing.  If you don't, then when your first own-design engine doesn't work, you won't know if it's from machining errors or design errors.  The next step would be to do what most self-respecting engineers do -- shamelessly copy something that you like, with tweaks here and there that you think will make it better.  Or do a shameless mash-up of design features you've seen in all of the plans that you've studied but haven't built, and see if it'll run.  Note the key word that's repeated there .


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## caribconsult (Jun 4, 2018)

lohring said:


> A two stroke is a much simpler engine to start with.  Below is an engine I built in high school.  It was patterned after a racing engine of the time (1950s) and taught me most of what I know about machining.  You don't need castings.  This is a post on a very simple design and this is a plan book on several very successful, simple designs.
> 
> Lohring Miller
> 
> View attachment 95434


Looks a little like an old Dooling. Remember those?


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