# It is a start...



## MrBaz (Dec 3, 2012)

So, as my intro post explains, I have no experience making model engines.  I'm working on my BS as a MechE, so I have no problems diving in head first.  I'm making all the parts in Inventor first.  I'm posting my work/thoughts here for constructive criticism.  I will warn you ahead of time, many of my ideas/plans may seem odd or uncomon for what I'm building first.  Just give me the pros/cons instead of turning it into a flame war.

The Idea:
I eventually want to work on making a supercharged V12 (similar to the Artus V12 from Germany).  For now, I'm going to make a 4-stroke, 2-cylinder opposed engine.  The idea is to actually use this on a scale model aircraft (so it has to work).  I'll be experimenting on production techniques on this 2-cylinder for experience/ideas on the much bigger V12.

The plan is to run pure methanol with a manual mix of pure nitromethane (not the mixed 'nitro' from hobby shops).  Oil control is separate, and pressurized/forced/whatever-have-you.  This should allow me to run high compression with slight supercharging.

So first up, the piston design.  So far, 1in diameter dished piston.  Two rings (will be fine-grained iron - Tremble method).  I'm still debating on an oil control ring.











Thoughts?


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## Cogsy (Dec 3, 2012)

I'm too new at this to be able to offer any thoughts, but I can tell you that we don't do 'flame wars' here. I'm sure you'll get lots of feedback and help though Thm:

Good luck with your build!


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## trumpy81 (Dec 3, 2012)

MrBaz, two things, why the dished piston? and is the wrist pin location correct? It seems a little low to me.

I'm no expert mind you, I'm asking for my own knowledge as much as anything else.

Other than that, it's a very nice Inventor model. What version of Inventor are you using? I have 2013 Pro.


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## Minerjim (Dec 3, 2012)

MrBaz,
Nice rendering. i can use the AutoCAD, but i like to revert back to the paper and pencil i was originally taught with. if you are schooling to become an ME, you are smart to try and balance all that book learning with hands on experience building things, you will find it will help you become a much better engineer over the long run.( has worked for me for over 35 years inthe business)  Have always thought my machinist friends have had it over me because they could design *and *build their designs. Look forward to seeing more of your renderings, and hopefully pix of your model.


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## kuhncw (Dec 3, 2012)

Nice looking piston, though the ring grooves look rather wide for a 1 inch bore.  I'd expect the Trimble method to specify a pretty narrow ring, perhaps 0.040 or so.

Good luck and please keep us up to date on your project.

Chuck


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## MrBaz (Dec 4, 2012)

trumpy81 said:


> MrBaz, two things, why the dished piston? and is the wrist pin location correct? It seems a little low to me.
> 
> I'm no expert mind you, I'm asking for my own knowledge as much as anything else.
> 
> Other than that, it's a very nice Inventor model. What version of Inventor are you using? I have 2013 Pro.


 

It will be a semi-high compression setup that will eventually get supercharged.  I'm controlling the compression and piston-to-deck travel with the dish in the piston, just like how they do it on the full-size boosted conterparts.

The wrist pin could possibly use a little more meat on the bottom.  Otherwise, I'm not sure what you mean by its location.  I've been using JE and Weiso performance pistons as a guide -- they have short piston skirts.


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## MrBaz (Dec 4, 2012)

kuhncw said:


> Nice looking piston, though the ring grooves look rather wide for a 1 inch bore. I'd expect the Trimble method to specify a pretty narrow ring, perhaps 0.040 or so.
> 
> Good luck and please keep us up to date on your project.
> 
> Chuck


 
I was wondering about that.  I believe I have the grooves set for a 1/16" (.063in) thick ring.  I wasn't sure if I could safely go thinner.  Keep in mind that this will be a high compression, supercharged engine.

I forgot to mention a few things:
rings - fine grained cast iron (Durabar 6000 maybe?)
sleeves - cast iron
pistons - 4032 aluminum


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## trumpy81 (Dec 4, 2012)

MrBaz, normal practise is for the wristpin to be located at the midpoint between the piston crown and the bottom of the skirt. It may be parallax error and or the picture, but your wristpin location looks lower than that midpoint.


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## MrBaz (Dec 4, 2012)

trumpy81 said:


> MrBaz, normal practise is for the wristpin to be located at the midpoint between the piston crown and the bottom of the skirt. It may be parallax error and or the picture, but your wristpin location looks lower than that midpoint.


 

I see what you mean.  Like I said, I was just trying to model off of a typical performance piston from JE, Weisco, etc.  If midpoint is preferrable for small scale engines, I'm more than happy to change the design.  I do want this to work after all!  

Attached is an example of what I'm talking about.  You can see how the wrist pin is darn near dead-bottom.


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## trumpy81 (Dec 5, 2012)

MrBaz, wow, they are really nice pistons!! Now if you could just use those it'd be great ... lol

I'm wondering if using such a piston in a model engine, what effects it would have. Would there be too much pressure on the skirts or too much expansion of the crown, given the reduced size for model use?

I have often wondered why modern piston design is not used in model engines. They obviously work in full size engines so why not model engines?

Will your engine be glow or spark ignition?


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## MrBaz (Dec 5, 2012)

trumpy81 said:


> MrBaz, wow, they are really nice pistons!! Now if you could just use those it'd be great ... lol
> 
> I'm wondering if using such a piston in a model engine, what effects it would have. Would there be too much pressure on the skirts or too much expansion of the crown, given the reduced size for model use?
> 
> ...


 

I wonder the same thing.  Maybe I'll just build a 2-cylinder with such pistons and see? :hDe:

I'm planning on spark ignition using a custom solid state system, including spark advance.


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## MrBaz (Dec 5, 2012)

trumpy81 said:


> MrBaz, two things, why the dished piston? and is the wrist pin location correct? It seems a little low to me.
> 
> I'm no expert mind you, I'm asking for my own knowledge as much as anything else.
> 
> Other than that, it's a very nice Inventor model. What version of Inventor are you using? I have 2013 Pro.


 

I forgot to answer your other question; I'm using Inventor Pro 2013.


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## MrBaz (Dec 5, 2012)

Update:  0.04" ring gap.  Distance from crown to wrist pin hole midpoint is 0.735".  Piston is a total of 1.088" long.  Still debating the oil control ring.  How does one make one?


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## trumpy81 (Dec 6, 2012)

MrBaz, There are several techniques for making oil control rings. The one that sticks in my mind is to use a jewelers saw to cut small slots in the periphery of the ring. Another method of oil control is to drill a few holes aligned with the fore/aft piston skirts (where the most friction occurs) and that are tangent to the top of the ring groove but may extend past the bottom of the ring groove depending on the diameter of the hole. For a .040 ring groove an .080 drill bit would be used. It's easier to model than it is to describe .... lol

Love that Inventor!! (Hate the new materials and appearances though


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## Leucetius (Dec 6, 2012)

trumpy81 said:


> Another method of oil control is to drill a few holes aligned with the fore/aft piston skirts (where the most friction occurs) and that are tangent to the top of the ring groove but may extend past the bottom of the ring groove depending on the diameter of the hole.(



Which is the same method used in the pictured pistons, if I'm not mistaken.

Inventor 2013 is a neat piece of software indeed, but I'm most sure, that in 2012/11 it was possible to place a hole on a round surface ... this is gone.


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## trumpy81 (Dec 6, 2012)

Leucetius, the second picture of a piston is mine and yes it is still possible to place a hole on a round surface in 2013 ... maybe a different technique is needed than what you were used to?

That piston was drawn in 2013 Pro.


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## MrBaz (Dec 6, 2012)

trumpy81 said:


> ... Another method of oil control is to drill a few holes aligned with the fore/aft piston skirts (where the most friction occurs) and that are tangent to the top of the ring groove but may extend past the bottom of the ring groove depending on the diameter of the hole. For a .040 ring groove an .080 drill bit would be used. It's easier to model than it is to describe .... lol
> 
> Love that Inventor!! (Hate the new materials and appearances though


 

So, would it be possible to use the second ring as a dual-use friction and oil control ring?  I was thinking about doing something exactly as you described, but wasn't sure.


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## Leucetius (Dec 6, 2012)

I think so. The picture I meant was  this: (posted by yourself). You can see that the holes overlap the lowest ring groove other than emerge fully in it. (sorry for bad english)

Leuc


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## MrBaz (Dec 6, 2012)

Like so?  3 on each side.  Should they be farther apart?  A hole is then drilled through the underside of the piston until I hit the oil passageways.  Is this the correct method?  Oil scraped from the cylinder wall flows through the oil passageways into the center hole 'in' the piston so the oil then 'drips' onto the small end of the connecting rod, right?


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## trumpy81 (Dec 7, 2012)

MrBaz, Not quite, but that is one way of doing it. My piston crown bisects the oil holes at about the midpoint of the hole so they are open to the bottom of the piston crown. The holes would be drilled before the interior of the piston is milled out.


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## trumpy81 (Dec 7, 2012)

Leucetius said:


> I think so. The picture I meant was  this: (posted by yourself). You can see that the holes overlap the lowest ring groove other than emerge fully in it. (sorry for bad english)
> 
> Leuc



Leucetius, that picture is from MrBaz, but now I understand what you were saying.

Don't feel bad about your English ... mine's just as bad sometimes ... lol


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## MrBaz (Dec 10, 2012)

An update.  I've been working on the cylinder.  The pictures below are of the assembled set, obviously.  The iron sleeve is approximately 1/8" thick.  The 'bulk' of the aluminum running the length of the cylinder stays a minimum of 1/8" thick as well.  I've been debating on whether the cylinder should be made of 6061 or 7075.

Are 4 bolts enough to hold the head on to the cylinder?  I'll be using a copper gasket (0.01" thick).  This will be a high compression engine (maybe supercharged).
Is the iron sleeve too thick?


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## Dinkum (Dec 11, 2012)

G'Day Mr Baz,

I like this project.  Thm:    Would high compression with forced induction cause knocking though?  And don't copper gaskets corrode alumiminium kinda quickly?  Just a couple of thoughts.   Keep up the good work - would love to do this myself.   

Regards,
Dinkum


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## MrBaz (Dec 11, 2012)

Dinkum said:


> G'Day Mr Baz,
> 
> I like this project.  Thm:    Would high compression with forced induction cause knocking though?  And don't copper gaskets corrode alumiminium kinda quickly?  Just a couple of thoughts.   Keep up the good work - would love to do this myself.
> 
> ...


 

I would alter the compression a little if I know for SURE I'm going to supercharge it, but it would still be pretty high.  This engine will run off of 99.9% pure methanol (maybe nitromethane added in later) which has an octane rating around 115 if I recall correctly.  Plus, methanol has the added benefit of cooling the intake charge.

I picked copper just because I've seen many other RC engines use copper gaskets.  Should I not?  I honestly don't know.  I could annodize the alumnium to prevent any corrosion or reactions between the copper and the fuels.


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## trumpy81 (Dec 11, 2012)

As far as copper gaskets on aluminium go, there's no problem with them. Old Triumphs use copper head gaskets to no ill effect, in fact I find the copper gaskets slightly better than the fibre gaskets on my 72 Trophy. The Rocket III is a different horse altogether though ... lol

The trick to using copper gaskets is that they have to be annealed directly before fitting and torquing down the head. Annealing is simple, heat to cherry red and dunk in water. This softens the copper and allows it to 'flow' into the contours of the sealing areas. A quick soft wire brushing helps to clean off the scale left from the heating/quenching process.

Although that is my personal choice, there is no reason you cannot use paper, cardboard, teflon/nylon or just about any other material for a head gasket. Some things will work and some wont, it depends on a lot of factors like how true the mating surfaces are, how much compression, the total area of the sealing surface, placement of retaining bolts etc... etc...

For your cylinder liner, I would recommend a wall thickness closer to 1/16 inch  and only slightly larger for the cylinder, around .080 inch should do. You have to take the thermal properties and expansion rates into consideration. Of course it really depends on what sort of usage this engine will see as to how thick the wall needs to be. 

Running pure methanol can make it hard to start, adding 5% Nitro will help. You should aim for a compression ratio around 8:1, that way you have a bit of wiggle room if you want to supercharge at a later date and it shouldn't detonate with normal aspiration.

Four head bolts should be sufficient but try to keep the bolt pattern as tight as possible. It's the distance between each bolt that makes the difference between success and failure. More bolts is good, but not always practical or possible depending on the physical constraints of your design.


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## trumpy81 (Dec 11, 2012)

MrBaz, just another small note, the mounting flange at the base of your cylinder, it looks great, but can you actually get a screw and a screwdriver in there?? 

Just food for thought and yet another thing you have to consider when designing an engine


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## mu38&Bg# (Dec 11, 2012)

Methanol with spark ignition easily will run at 15:1 in cylinders larger than this. You can probably run pump gas at 15:1 in a 1" bore without issue. If you're thinking glow plug ignition ~8:1 would be normal, but up to 15:1 has been used in production model four strokes. 8:1 with a supercharger will be OK with glow ignition. Mode airplane engines almost universally use 1mm (.040") rings. Head gaskets are usually aluminum, but copper or what looks like brass is sometimes used. Corrosion from methanol will be a much bigger problem than the gasket.

The piston will work fine as is. Placing the wrist pin that low only makes the cylinder taller. The length of the skirt is really dependent on the bore. Extremely short piston skirts like the Wiseco pictured are only for racing applications. Anything with a long expected service life will have a much longer skirt. Your piston has plenty of skirt area. I wouldn't bother with dish, but if you take head geometry into account to get a decent squish area it will be fine. Dishing at this scale has a large impact on compression ratio. What is the volume of the dish and cylinder displacement?

Engine design is all about compromise.

Greg


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## Leucetius (Dec 11, 2012)

Full-scale engine construction rules ask for a compression height (distance from center wrist pin to top of piston) of 36% to 45% of bore diameter. For skirt length (center wrist pin to bottom of piston) 40% to 50% of bore diameter are asked. Shorter skirt length are for racing engines, as stated by dieselpilot.

Source: Verbrennungsmotoren - Motormechanik, Berechnung und Auslegung des Hubkolbenmotors (ISBN-10: 3-528-43108-3)


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## MrBaz (Dec 11, 2012)

trumpy81 said:


> As far as copper gaskets on aluminium go, there's no problem with them. Old Triumphs use copper head gaskets to no ill effect, in fact I find the copper gaskets slightly better than the fibre gaskets on my 72 Trophy. The Rocket III is a different horse altogether though ... lol
> 
> The trick to using copper gaskets is that they have to be annealed directly before fitting and torquing down the head. Annealing is simple, heat to cherry red and dunk in water. This softens the copper and allows it to 'flow' into the contours of the sealing areas. A quick soft wire brushing helps to clean off the scale left from the heating/quenching process.
> 
> ...


 
Annealing copper is no problem.  I've worked with copper before.  Work-hardening metals are a pain to work with.  I was actually thinking about annealing the copper just the other day.  You've confirmed it.  Thm:

I'll shrink the sizes of the sleeve and cylinder a bit.  

I'm still wanting to retain high compression since this will be specifically only run with methanol/nitro.  Even gas engines start at 8.5:1.  Oh, and this will be 4-cycle.

Head bolts are 0.15" from edge of bore.

If this thing actually works, I'm planning on putting it on an RC plane where it could see 15 minute run times.




trumpy81 said:


> MrBaz, just another small note, the mounting flange at the base of your cylinder, it looks great, but can you actually get a screw and a screwdriver in there??
> 
> Just food for thought and yet another thing you have to consider when designing an engine


 
I haven't edited the inventor part for it yet, but I will mill the fins over the holes so that it is easily accessible.



dieselpilot said:


> Methanol with spark ignition easily will run at 15:1 in cylinders larger than this. You can probably run pump gas at 15:1 in a 1" bore without issue. If you're thinking glow plug ignition ~8:1 would be normal, but up to 15:1 has been used in production model four strokes. 8:1 with a supercharger will be OK with glow ignition. Mode airplane engines almost universally use 1mm (.040") rings. Head gaskets are usually aluminum, but copper or what looks like brass is sometimes used. Corrosion from methanol will be a much bigger problem than the gasket.
> 
> The piston will work fine as is. Placing the wrist pin that low only makes the cylinder taller. The length of the skirt is really dependent on the bore. Extremely short piston skirts like the Wiseco pictured are only for racing applications. Anything with a long expected service life will have a much longer skirt. Your piston has plenty of skirt area. I wouldn't bother with dish, but if you take head geometry into account to get a decent squish area it will be fine. Dishing at this scale has a large impact on compression ratio. What is the volume of the dish and cylinder displacement?
> 
> ...


 
I've been looking at everything corrosion/methanol related.  It seems that the methanol isn't really the problem, but the water content it can carry.  Many people have no problem with corrosion.  Maybe I'll idle some nitro with oil in it when I'm done with it to coat everything with a little oil.  Like I mentioned earlier, I could also annodize everything to add some corrosion resistance.
The oil system will be separate from the fuel, so that will help as well.

Dish volume is .524cc.



Leucetius said:


> Full-scale engine construction rules ask for a compression height (distance from center wrist pin to top of piston) of 36% to 45% of bore diameter. For skirt length (center wrist pin to bottom of piston) 40% to 50% of bore diameter are asked. Shorter skirt length are for racing engines, as stated by dieselpilot.
> 
> Source: Verbrennungsmotoren - Motormechanik, Berechnung und Auslegung des Hubkolbenmotors (ISBN-10: 3-528-43108-3)


 
Interesting.  Time to crunch some numbers.


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## MrBaz (Dec 11, 2012)

Here is some info: (All measurements are in inches)

Enter Cylinder Bore Size:   1   
Enter Piston Stroke Length:  1      
Enter Head Gasket Bore Diameter:  1.004  
Enter Compressed Head Gasket Thickness:   .01
Enter Combustion Chamber Volume In CCs:  0  
Enter Piston Dome Volume In CCs Negative For Dished Pistons:  -.524    
Enter Piston Deck Clearance Negative If ABOVE Deck (Use '-'):  .06   

Calculated Engine Compression Ratio:   10.03:1  
Total Displacement Volume:  1.425957499409645 cc

For simplicity sake, I was planning on going with a flat head.  Any reason not to?


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## Dinkum (Dec 11, 2012)

Wow, it always amazes me how much knowledge and experience is found  on this site.  
I've heard that copper gaskests are known to cause galvanic corrosion on "real" engines with aluminium heads but it seems that that doesn't apply to model  engines.  I think that must be because they don't use coolant and therefore there isn't an electrolyte.    So I guess I better just sit back and learn.    :hDe:


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## mu38&Bg# (Dec 12, 2012)

I didn't see if you'll be using spark or glow ignition. Glow ignition and straight methanol can have problems with detonation at relatively low compression ratios. I was running an FS-40S this year on methanol (no nitromethane in the fuel) and was very surprised when it threw a prop due to detonation. I had not read about it before, but I was trying for the most power and that meant as lean as possible. The FS-40S is only 8:1 or so. The big bore engine was much more forgiving in that regard even though compression ratio should have been a touch greater. I think the slightly larger squish area made a difference.

If you make a flat combustion chamber, that will give you a workable compression ratio. If you haven't designed the head yet, you might check that everything fits in the head the way you want before deciding on the flush combustion chamber. .060" for squish clearance is tremendous in an engine this size and would seem to be non-functional, but is common of many model airplane four strokes. Two stroke glow competition engines can have squish clereance on the order of .005-.010" but .020 is very common for OEM. Unless valves are sized to clear the inside bowl area, you won't see valve clearance issues until the head is designed and the cam added to the model. Mostly, the intake valve can interfere as it opens BTDC as the piston is still traveling upward. While your' designing consider how this will be made. I see a rectangular relief with small corner radii in the bottom of the piston. Unless you intend to, or can, machine with a extra long and tiny endmill (100+USD+) this will be impractical. Assume you'll be using a standard endmill, maybe a 1/4" or an 3/16" XL.

I agree that methanol isn't a big issue for corrosion. Methanol fuel should also be used with a compatible oil in the crankcase, but I think the old Kavans with an oil sump used regular motor oil with glow fuel. Blowby is a reality and you will have fuel, water, and byproducts in the crankcase.

I've attached a drawing of the O.S. Engines FS-48/52 piston. Virtually all of their four stroke pistons look like this except in larger sizes the skirt is relieved. Some of the newer engines use shorter pistons. Anyway, the inside of the piston is forged so my drawing is simplified here. The 20.8mm counter bore in the bottom of the piston facilitates machining of the external features. The piston is put on a mandrel fixture with a pin through the wrist pin holes. The fixture pulls the piston back and holds it.

I think the design belongs to the designer. So the above is just some rambling about things stored in my head. I don't think any of it is a show stopper. 

View attachment 45803200.PDF


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## MrBaz (Dec 12, 2012)

I'll be using spark ignition.  After studying quench and squish, I'm going to redesign the piston and I have an idea for the combustion chamber shape for the head.  Something like a wedge design.  Either that or create a greater dish in the piston and minimize the deck height (quench distance of the 'rim' around the dish) to something nearer 0.03".


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## petertha (Dec 12, 2012)

MrBaz said:


> ... eventually want to work on making a supercharged V12... plan is to run pure methanol with a manual mix of pure nitromethane (not the mixed 'nitro' from hobby shops).  Oil control is separate, and pressurized/forced/whatever-have-you.  This should allow me to run high compression with slight supercharging...


 
I used to run YS 4-strokes when I flew RC pattern, then got into pylon (2-stroke HP engines). So I have a bit of hands on experience. Since the 140 4S generation, they have increased in complexity & power. Now direct injection (vs pseudo induction boost) & electronic ignition (vs glow). I would google & study engines like these for sizing & materials etc, because if anything they are probably conservative to what you are embarking on.

http://www.ysengines.net/dz170-cdi/
http://www.gbrcaa.org/smf/index.php?topic=1440.0

On one hand, ignition system is more sophisticated vs glow, but I think net better decision. Varying nitro content in methanol inherantly affects glow plug ignition timing, and sometimes in a not-good way. We typically play with plug selection (varying heat settings) & alter head shims (compression alteration) not just for power, but prevent destructive detonation. And these tweaks are required when the fuel (%nitro) is fully known beforehand. I can tell you that a setup suitable for stock 15% nitro is completely different than 45%, probably the max I ever ran. But at these compression levels, a couple thou thickness in shims is actually pretty noticeable. Some of the HP boaters would run higher nitro, but they had water cooling & even then melted a few along the way. Altering nitro on the fly introduces more variables, least of which will be ignition timing. So I suspect you will likely require a way advance/retard that on the fly as well?

Heat starts to become a lot more problematic at these levels, so that will tax the lube system. The alloys used in pistons, heads, chromed liners etc is pretty sophisticated stuff. Not taking anything away from your exciting project, but I would try & sponge as much information from existing engines as you can.


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## MrBaz (Dec 12, 2012)

petertha said:


> I used to run YS 4-strokes when I flew RC pattern, then got into pylon (2-stroke HP engines). So I have a bit of hands on experience. Since the 140 4S generation, they have increased in complexity & power. Now direct injection (vs pseudo induction boost) & electronic ignition (vs glow). I would google & study engines like these for sizing & materials etc, because if anything they are probably conservative to what you are embarking on.
> 
> http://www.ysengines.net/dz170-cdi/
> http://www.gbrcaa.org/smf/index.php?topic=1440.0
> ...



Thanks for the links.

I found a place that I can source copper sheet from below 0.01" to 0.05" and more if I need to alter the compression ration.

Using spark ignition, I could have a iginition table for straight methanol and build some others based off of tuning done beforehand.  Like you said, I would have to know exactly what I'm running BEFORE and load the correct timing table to the ignition accordingly.

This project is a learning experience in so many different ways than I even imagined before I set out on it.  I've learned SO much so far in just engine design, let alone honing my skills in Inventor.  This forum has been just fantastic so far.  I never thought I would get so much excellent feedback from so many knowledgeable people.


After studying quench and squish more, it seems that a wedge head isn't really a good design to help reduce the chances of detonation/preignition.  A dish design is supposedly GREAT for high compression engines -- as long as the rest of the design is adequate.  I can get great quench distance with a dish if I rely on the piston design to set the combustion chamber.  My worry is that a large dish might induce TOO much heat into the piston.  

If I go with a flat top piston and match the combustion chamber in the head, I can get better quench/squish.  This will allow me to deposit more heat into the head instead of the piston.


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## mu38&Bg# (Dec 12, 2012)

With spark ignition in a 1" bore, detonation will not be an issue. I run kerosene in ~23mm bore engines with spark and they do not detonate. If you were using glow ignition it would be a much greater concern.

Greg


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## petertha (Dec 12, 2012)

Probably jumping ahead a bit, but you might also want to check this old post I started on 4S valve timing re metahnol based model engines. I noticed a lot of variation amongst designs (particularly the YS-4S). Your project will likely be on the bleeding edge.
http://www.homemodelenginemachinist.com/f26/valve-timing-4-stroke-glow-17093/


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## trumpy81 (Dec 13, 2012)

Dinkum said:


> Wow, it always amazes me how much knowledge and experience is found  on this site.
> I've heard that copper gaskests are known to cause galvanic corrosion on "real" engines with aluminium heads but it seems that that doesn't apply to model  engines.  I think that must be because they don't use coolant and therefore there isn't an electrolyte.    So I guess I better just sit back and learn.    :hDe:



This is false as far as I can tell Dinkum. I have two old Triumphs, a 1972 Trophy and a 1976 Bonneville and both run copper head gaskets with aluminium heads and no ill effects.

Also, Top Fuel Dragsters run copper head gaskets and most teams use a VHT product made for copper head gaskets. It's a spray on copper coloured glue for want of a better term. I have some somewhere because I have used it on my Triumphs a few times, but in all honesty it is not really needed on them.

When I crewed for Peter Gratz (Top Doorslammer) he also used copper head gaskets on his aluminium KB block and heads. No ill effects were observed at all on this engine either.

Copper is a fairly inert metal and it takes a long time for copper to corrode under normal atmospheric conditions. It has even been used for roofing in Europe in past centuries.


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## MrBaz (Dec 13, 2012)

dieselpilot said:


> With spark ignition in a 1" bore, detonation will not be an issue. I run kerosene in ~23mm bore engines with spark and they do not detonate. If you were using glow ignition it would be a much greater concern.
> 
> Greg



Good to know.



petertha said:


> Probably jumping ahead a bit, but you might also want to check this old post I started on 4S valve timing re metahnol based model engines. I noticed a lot of variation amongst designs (particularly the YS-4S). Your project will likely be on the bleeding edge.
> http://www.homemodelenginemachinist.com/f26/valve-timing-4-stroke-glow-17093/



Thank You!  This is GREAT info.  I will definitely be using this later. Thm:



trumpy81 said:


> This is false as far as I can tell Dinkum. I have two old Triumphs, a 1972 Trophy and a 1976 Bonneville and both run copper head gaskets with aluminium heads and no ill effects.
> 
> Also, Top Fuel Dragsters run copper head gaskets and most teams use a VHT product made for copper head gaskets. It's a spray on copper coloured glue for want of a better term. I have some somewhere because I have used it on my Triumphs a few times, but in all honesty it is not really needed on them.
> 
> ...



Even more excellent information/assurance.


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## MrBaz (Dec 13, 2012)

Here is a updated rendering of the cylinder using the new dimensions.


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## trumpy81 (Dec 13, 2012)

MrBaz, that's looking pretty sweet.  I'd be interested in seeing the rest of it when you have finished modelling it. It would be nice if you made it 4 valves per cylinder, just so I could get some feedback on the 4 valve performance as there doesn't seem to be too many people out there building those. It is of course much easier, cheaper, quicker, to build 2 valve heads so that's probably why there are so few 4 valve designs floating around. Just thought I'd throw that in ... lol

How long have you been using Inventor?

Have you tried out stress analysis in Inventor yet?


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## Dinkum (Dec 13, 2012)

trumpy81 said:


> This is false as far as I can tell Dinkum. I have two old Triumphs, a 1972 Trophy and a 1976 Bonneville and both run copper head gaskets with aluminium heads and no ill effects.
> 
> Also, Top Fuel Dragsters run copper head gaskets and most teams use a VHT product made for copper head gaskets. It's a spray on copper coloured glue for want of a better term. I have some somewhere because I have used it on my Triumphs a few times, but in all honesty it is not really needed on them.
> 
> ...



Hi Andy,

Interesting stuff.

Maybe it's because of the spray on stuff that corrosion doesn't occur - it creates a layer of insulation between the two metals.  Have a look here: http://en.wikipedia.org/wiki/Copper_in_architecture#Galvanic_corrosion

Do you use a spray on coating for model engines?

Regards,
Dinkum


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## AussieJimG (Dec 13, 2012)

I run copper head gaskets with aluminium head on my 64 Triumph with no problems

Jim


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## trumpy81 (Dec 14, 2012)

Dinkum said:


> Hi Andy,
> 
> Interesting stuff.
> 
> ...



Dinkum, I suspect that if the copper/aluminium surfaces were in contact with an acid (EG: Battery Acid) it would expedite the corrosion process somewhat. Likewise if either were in contact with salt water, but when used as a gasket it doesn't suffer much exposure because there is no way for the air, or anything else, to contaminate it and there is definitely no galvanic reaction between the copper and the cast aluminium.

Another possible reason why the Triumphs don't have any problems is because they use a Positive Ground electrical system.


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## trumpy81 (Dec 14, 2012)

AussieJimG said:


> I run copper head gaskets with aluminium head on my 64 Triumph with no problems
> 
> Jim



Jim, I like the 60's Triumphs, I have a 65 frame that I am going to put the 72 Trophy motor (only usable part left) into and create a bobber if I ever get around to it ... lol

Is yours stock, restored or ???


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## MrBaz (Dec 14, 2012)

trumpy81 said:


> MrBaz, that's looking pretty sweet.  I'd be interested in seeing the rest of it when you have finished modelling it. It would be nice if you made it 4 valves per cylinder, just so I could get some feedback on the 4 valve performance as there doesn't seem to be too many people out there building those. It is of course much easier, cheaper, quicker, to build 2 valve heads so that's probably why there are so few 4 valve designs floating around. Just thought I'd throw that in ... lol
> 
> How long have you been using Inventor?
> 
> Have you tried out stress analysis in Inventor yet?



4 valves would be interesting, but I'm afraid the valves would just be too small at that point.

I haven't been using Inventor for very long.  About a year.  I used Solidworks for a little bit before that.  This project is helping me learn Inventor as well as other skills.  I have not run any stress analysis on anything yet.

Here is an updated rendering showing the niftier milling in the fins for bolt access.


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## trumpy81 (Dec 15, 2012)

MrBaz, that's looking really good. I've been using Inventor on/off for about 10 years now. I played with stress analysis once or twice but I'd be lying if I said I understood it all ... lol

If you need any help with Inventor just holler, I'm no expert but I'm willing to help out if you need it.


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## MrBaz (Dec 21, 2012)

Sorry I haven't posted anything in a while. I've been busy.  I've changed to a 1.5" bore.  I've been slowly working on the cylinder head.  Here is what I have so far.  Don't mind the squareness or thickness.  I've got quite a bit of work before it is done.  These are just screenshots, not renderings.

15* angle on intake/exhaust ports.  Still trying to work out the spark plug angle.  I changed from 6 smaller bolts to 4 larger ones to make for easier spaces for spark plugs/ports/etc.

Debating whether to go with a full valve cage, or separate seats/guides/valves.


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## vederstein (Dec 21, 2012)

MrBaz:

You mentioned you're a BSME student.  So I assume you're about 20 years of age.  I also assume you plan on making these components yourself?

If you're outsourcing them to a shop, then forge ahead.  A professional machinist can make these parts.  If not, think of the complexity of what you're trying to accomplish.

I too have a BSME (Class of '96) and have been designing machines as a profession for over 15 years.  Let me tell you something:  it's much much easier to design a part than make it.  I'm currently making my 13th engine.  It was about after my 6th that I started to get the hang of machining.  And my 8th was my first engine from castings (and in any way presentable to show people).

Please don't take this the wrong way, but if you have limited experience with machine tools and you're going to make the parts yourself, I believe your design is too complex.  Every detail is a cut, and sometimes a whole different setup.  Each time a cut or setup is needed, there is a source of error.   Multiply the number of cuts & setups by 12 (for twelve cylinders) and you'll quickly have hundreds of ways to make scrap.

CNC machining certainly helps doing multiple copies if you have CNC availability.  Just remember, CNC is like any other computer program: garbage in = garbage out.

Just some food for thought...

Ved...


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## MrBaz (Dec 21, 2012)

vederstein said:


> MrBaz:
> 
> You mentioned you're a BSME student.  So I assume you're about 20 years of age.  I also assume you plan on making these components yourself?
> 
> ...



Understood, but that still doesn't stand a chance holding me back from doing it.   I have some machining experience.  I'm keeping the design going with machinability in mind.  I believe I can make every one of these cuts.


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## trumpy81 (Dec 21, 2012)

MrBaz, It's not the cut that's the problem, it's the tolerances involved. Tight tolerances are extremely difficult to obtain even for professional machinists and I can attest to that with my own bumblings ... lol
The plan may call for a 15mm hole for example, but I guarantee that only the best of the best will actually get a 15mm hole. For me, it would be more like 16mm ... lol

The heads are looking good thus far 

Wouldn't it be nice if we could use a spark plug exactly the size we need. I'd have 2mm diameter spark plugs everywhere ... lol

Unfortunately, they would be extremely difficult to make at that size 

Try offsetting the plug to one side or the other, sometimes you can squeeze it in that way. You can sometimes get away with the plug in a small pocket also.


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