# Cylinder, piston and fuel for  internal combustion engines !



## minh-thanh (Jun 21, 2017)

I'm starting the internal combustion engine mini (2,4 stroke)
I have 3 questions:
* 1 / Cylinder made of steel, piston made of aluminum / brass, is it ok ??
  2 / Piston ringless , is it ok?
  3 / What is the fuel use for internal combustion engines?
Thanks for help !!!


----------



## Cogsy (Jun 21, 2017)

Steel cylinder is fine (12L14 has been used by many with success) although cast iron is somewhat favoured. Aluminium is better than brass for the piston to reduce the weight of the piston. Ringless can work, depending on the engine type and size, but for most rings are better. You can make your own from cast iron or many use O-rings (normally viton) but the bore has to be very smooth.
For fuel I use regular petrol/gasoline, with about 5% lubrication in it, either a splash of 2 stroke oil or WD-40.


----------



## minh-thanh (Jun 22, 2017)

Thanks Cogsy ! 
I use  the old cycle telescopic front forks of motorbike make cylinder for internal combustion engine, make rings  from cast iron is best but I do not have method to do it! Maybe with homemade lathe is difficult to make rings , I'm researching how to do it.


----------



## Cogsy (Jun 22, 2017)

Hi Minh. You can make rings on your homemade lathe, they're not difficult to make really. There are many methods described online, from very simple to very involved, I tend to make mine very simply. They don't seal perfectly at first, but good enough to get the engine started. Then over the first 10 minutes or so of running they wear in (or 'bed in' if you prefer) and compression is very good.

The method I use, just for your reference: Turn the OD of the ring blank to the exact bore size, then bore the inside of the blank to what ever size you've worked out for required ring thickness. Then part off slightly wider (maybe 0.001" or so) - when I part them I have a rod in the tailstock into the bore to catch them as they drop. Rub each side in a figure 8 pattern on some fine sand paper on a flat surface to get to the required width. To snap the ring you can use your finger (but you might break a few until you work it out) or cut through with a saw. Then you need to place a 'wedge' or spacer in the split to spread the ring a little (the width depends on the size) and place the rings on a large washer or something like that - I use a car body washer held horizontally in my vice. Heat the ring with a propane torch evenly to bright red and keep it there for a minute or so, then let it cool naturally. When the spacer is removed the gap should stay the same and the ring now has tension. File down the ends to achieve the required ring gap when it's installed and it's ready to go. I normally make at least twice as many ring blanks as I need and just split and heat treat the ones I need, keeping the others as spares.

For the fuel, I forgot to mention a lot of people use something called Coleman fuel which I'm told burns cleaner and smells nicer than normal petrol. I don't bother as it's hard to get here and I only run my engines outside once they're finished.

Good luck with your build. I'm hoping you'll post a build thread with construction photos as you build it.


----------



## minh-thanh (Jun 22, 2017)

Thanks Cogsy !! 
I will try do it ..


----------



## lohring (Jun 22, 2017)

Cylinder and liner materials depend a lot on bore diameter.  A lot of small (under 25 mm bore) cylinders used cast iron pistons with a lapped fit in a steel cylinder.  Lots of oil (20% castor oil) in the fuel gives a very good seal.  Today's high performance model engines use high silicon aluminum pistons in a chrome plated aluminum or brass cylinder with a carefully tapered bore.  

Glow ignition is a lot simpler than spark ignition and can be used with both two strokes and four strokes.  A methanol based fuel works well with glow ignition.  Straight methanol with a castor/synthetic oil mix will run, but a little nitromethane makes an easier to operate mixture.  There is a lot of information on design and building older style model engines at http://modelenginenews.org/

Lohring Miller


----------



## minh-thanh (Jun 22, 2017)

Thanks lohring !!


----------



## Mechanicboy (Jun 22, 2017)

Hi Minh Thanh..

You can use aluminium from old piston from car since aluminium has alloy inside. Melt down the old piston and pour into the steel pipe. Let it cool down, then you has a piston material to create the piston on lathe. 

Piston ring material is not difficult to find: Old cam shaft or brake disc from car.

The formula of piston ring dimension: 
Thickness of pistonring: Diameter : 25 = Thickness of piston ring. 
Height of piston ring: Thickness = Height. 
Ring gap: Thickness x 4 = Ring gap. (Not mounted in the cylinder bore! When mounted in the cylinder bore, the ring gap is smaller. The rule about ring gap: 0.0889 mm gap per 25,4 mm of cylinder diameter. Example: 101.6 mm (bore) x 0.0889 mm = 0.35 mm minimum gap. )

The important thing to think: The piston diameter must not be same measure as the cylinder diameter. Also the piston diameter is a bit smaller than cylinder diameter when the engine is cold. When the  engine is running, piston will be hot and expanding until near same piston diameter as the cylinder diameter. If the piston has same diameter as cylinder diameter, it will stuck into the cylinder when the engine is hot. The real piston is a bit tapered, also the top of piston is smaller than piston skirt. 

When i created the piston, i took calculation of heat expansion selected by material expansion coefisient. I will set a temperature range between 150-250 degree celsious and calculate to a final diameter of piston when the engine is hot. Then i turn the right diameter when the piston is cold at lathe, some time adjust to right diameter with emery paper. I prefer tapered piston: The piston skirt near same diameter as cylinder bore and the top of piston is in the size of diameter when the piston is cold. When the piston is hot, it will be  "parallel" piston. Google this: How to calculate thermal expansion coefficient. 

The cylinder wall must be honed to cross hatched to have a lot of oil pockets then piston ring/cylinder will last long time.


----------



## Mechanicboy (Jun 22, 2017)

Here is a good start to build the petrol engine, see after this text "download the plans here." in this link -->
http://www.machinistblog.com/free-plan-webster-engine-works-4-cycle-gas-engine/


----------



## minh-thanh (Jun 22, 2017)

Thanks Mechanicboy !!The precious information for me.
I'm starting now. Step by step, hope to have a complete engine to show you!!


----------



## minh-thanh (Jun 26, 2017)

Webster 4Stroke Plans : diameter of cylinder about : 22 mm , stroke of piston : 30 mm 
diameter of my cylinder 19 mm ( I use telescopic front forks on motorbike make for cylinder of engine ) so, how much the piston stroke I can set up ?
Webster 4Stroke Plans is ok-It is a reference for me !! , BUT I want to make use of the available ones !!
Thanks your opinions !!


----------



## Mechanicboy (Jun 27, 2017)

To reduce stroke if bore is known¶---> 30 : 22 = 1,36 - > 1,36 x 19 = 25,84 mm stroke.


----------



## minh-thanh (Jun 27, 2017)

Thanks *Mechanicboy* !!!:thumbup:


----------



## Cogsy (Jun 27, 2017)

I'd be tempted to leave the stroke as it was for ease. You may have to be careful of the conrod potentially contacting the sides of the bore but I'd guess you could open the bottom of the bore slightly and/or modify the conrod to fix that. Apart from that issue I don't see any other problems and I believe it'd run just fine with the longer stroke. Keeping the stroke the same means you don't have to modify the drawings and critical dimensions which makes it far easier to follow plans.


----------



## minh-thanh (Jun 28, 2017)

Thanks Cogsy !
I know, for every job that needs to be plan, it is the best.
Better free plan!
But with the machinery and tools that I have now, I have to adjust to what I can do with those machines.
You have seen and know my workplace and machines, tools.
And I'm doing the cylinder, piston with rings, when done - I hope it's ok - I'll post it for you to watch it.


----------



## Mechanicboy (Jun 28, 2017)

> I'd be tempted to leave the stroke as it was for ease.



In fact it's not possible with same stroke 30 mm with this 19 mm bore in this WEW engine if the engine is in same size overall as in the drawning with 19 mm bore and 30 mm stroke. The connecting rod will hit the edge of cylinder. Also reduce the stroke to 25,8 mm if the cylinder bore is 19 mm

See at my engine how near is the connecting rod to the cylinder edge in the movie.

[ame="https://www.youtube.com/watch?v=vdlAESytmVs"]https://www.youtube.com/watch?v=vdlAESytmVs[/ame]


----------



## minh-thanh (Jun 28, 2017)

Thanks Mechanicboy ! 
I'm trying to do it .. step by step, adjust .. check ..
I hope to ok


----------



## karolh (Jun 28, 2017)

This seems like a very interesting thread.


----------



## Cogsy (Jun 28, 2017)

Mechanicboy said:


> See at my engine how near is the connecting rod to the cylinder edge in the movie.


 
It's very difficult to see the rod clearance while it's running, but I did suggest this may be an issue. 

My fix would be to 'throat' or bevel the bottom of the cylinder to give the required clearance. In fact, thinking about it, simple small slots in the cylinder would allow the rod clearance and would do so without compromising the fit of the piston skirt to the bottom of the cylinder. In theory, as long as the slots do no extend into the area where the rings run, there should be no effect on running at all. It's certainly possible to retain the 30mm stroke with the reduced bore.


----------



## minh-thanh (Jun 28, 2017)

Thanks Mechanicboy, Cogsy !!
Do not worry about the stroke of the piston, I will check it step by step
The same with my flame eater engine, I listen to all your opinions,(my flame eater engine, it has bore of cylinder 18,5 mm and stroke 30 mm )
Now , I has one question : I make rings of piston made of steel - it's not as good like cast iron - your opinions ???Is it durable?


----------



## Cogsy (Jun 29, 2017)

Steel rings running in a steel cylinder is not the best option and could lead to problems. In general you shouldn't run same metals together or it can lead to galling. Maybe viton orings would be a better option if you can't source cast iron? Are they available to you where you are?


----------



## Mechanicboy (Jun 29, 2017)

Con rod clearance..


----------



## minh-thanh (Jun 29, 2017)

What do you think about make rings made of teflon ?


----------



## Mechanicboy (Jun 29, 2017)

Cogsy said:


> Maybe viton orings would be a better option if you can't source cast iron? Are they available to you where you are?



Easy available: Cast iron in brake disc


----------



## Mechanicboy (Jun 29, 2017)

minh-thanh said:


> What do you think about make rings made of teflon ?



No, not good idea.


----------



## minh-thanh (Jun 29, 2017)

What do you think about make rings made of brass ?


----------



## Mechanicboy (Jun 29, 2017)

minh-thanh said:


> What do you think about make rings made of brass ?



Cast iron only, ask the car workshop about they has old  brake disc in trash you can take with to your workshop. It cost nothing.


----------



## minh-thanh (Jun 29, 2017)

I'm looking for cast iron from old motorbike.
Meanwhile, I will try brass, it will help me have more experience


----------



## Mechanicboy (Jun 29, 2017)

Minh Thanh..

Piston ring is too thick and not flexible. 

The right dimension will be calculated when you are use 19 mm bore:

19 mm : 25 = 0,76 mm, round of to nearest 0,8 mm.

19 mm outer diameter and 18,83 mm inner diameter. (The piston ring must be lapped with lapping ring + fine lapping paste and check the ring is snug fitting into the cylinder before parting of the piston ring from workpiece. Snug fitting the piston ring into the cylinder is better because we can not make it better on lathe, the fit of piston ring in the cylinder will be improved by running-in the engine) 

The height of piston ring 0,8 mm (Create piston ring groove in piston and measure with blade feeler gauge 0,8 mm and the height of piston ring must be 0,85-0,9  mm when the piston ring is parted off from work piece. Then grind the piston ring on the fine sandpaper #400-800 on glassplate in "8" form when you are grinding the piston ring (never in one way grinding) and check the height of the piston ring will fit into piston ring groove.)

The ring gap 0,8 mm x 4 = 3,2 mm after the piston ring is heated up to near glowing then let it cool down (do not drop in water or oil!)

Follow this link: http://www.modelenginenews.org/feeney/pg8.html

http://www.modelenginenews.org/cirrus/pistons.html#3


----------



## minh-thanh (Jun 29, 2017)

Thanks Mechanicboy !!The very precious information for me.
I'm doing  again


----------



## minh-thanh (Jun 30, 2017)

While looking for cast iron, I searched on google " how to make gears with lathe "
And :
[ame]https://www.youtube.com/watch?v=A3UBktaprhk[/ame]
[ame]https://www.youtube.com/watch?v=0dMYBFGfFOw[/ame]
[ame]https://www.youtube.com/watch?v=1wBghabUTWs[/ame]

Your comments on these videos ??
Thanks !


----------



## Cogsy (Jun 30, 2017)

Looks good to me. All you need is a cutter and some method of indexing. For the cutter, see this site LINK for details on making your own, simply and from scrap. I've made quite a few timing gears for I.C. engines using this method and they work perfectly.


----------



## minh-thanh (Jul 1, 2017)

Hi Cogsy !
I'm trying to do the same video first.


----------



## minh-thanh (Jul 1, 2017)

step by step..


----------



## minh-thanh (Jul 3, 2017)

step by step..


----------



## Cogsy (Jul 3, 2017)

Is this your gear cutting rig getting set up Minh?


----------



## minh-thanh (Jul 3, 2017)

Yes . But it's not finished yet, the same video first.


----------



## minh-thanh (Aug 28, 2017)

Some pictures of gear cutting tool in progress ...I hope it ok .


----------



## Cogsy (Aug 28, 2017)

Looks good. Have you made any gears yet?


----------



## minh-thanh (Aug 29, 2017)

Hi Cogsy ! 
it's not finished yet, I have to do some details.


----------



## minh-thanh (Aug 29, 2017)

Some pictures of gear cutting tool, FINISH !
During gear cutting, I adjust the height .... so the gear is not good enough. It's just a test gear (gear made of aluminum)


----------



## ShopShoe (Aug 29, 2017)

Very Nice.

Thank You for posting,

--ShopShoe


----------



## Cogsy (Aug 29, 2017)

That gear looks like it might be good enough to use. I've used aluminium for cam/crank gears on hit and miss engines with no problems. Might be a little better to make the crank gear out of brass though.


----------



## minh-thanh (Aug 29, 2017)

Thanks ShopShoe, Cogsy !


----------



## minh-thanh (Aug 31, 2017)

some pictures gears from my gear cutting tool - gear made of brass


----------



## Mechanicboy (Aug 31, 2017)

I recommend locking the shaft instead of locking only with the locking pin on the gearwheel as the indexing disc. This is to prevent the gearwheel from turning out of position during milling. Then you get better teeth profiles on the machined gearwheel.


----------



## Cogsy (Aug 31, 2017)

Nice job - looks like they mesh very well.


----------



## minh-thanh (Aug 31, 2017)

Thanks Cogsy , Mechanicboy !
And  Mechanicboy , I will to do same like your recommend !


----------

