Good plans for a "modern" single cylinder?

[apullin]

Hey folks. I am currently hunting around for plans for a small engine to build, something 4-stroke, air cooled, gasoline fueled, ring seals, and as many ball/needle bearings as possible. Something around 35-50 cc's would be great, but I should be able to scale to that fairly easily.

And as far as the "modern" part, well, it would be ideal if it was an overhead cam design. I think the model agricultural and tractor engines, while nice, aren't quite what I'm looking for.

Thus the search for plans, rather than designing from scratch myself: I'd like to start with something that's already been proven to work, and had some debugging.

A single or boxer twin configuration would probably be "best", since I think those are the easiest to make?
Jerry Howell's V-twin engine looked interesting, but I would like to elide the complex gear train for driving the valves, and there's the extra complexity of the oddly shaped crank-case.

Here's a couple that I've been looking at:
http://www.cad-modelltechnik-jung.de/baumotor/1_zy_vier.htm (higher displacement would be better)
http://www.cad-modelltechnik-jung.de/baumotor/4_zy_box.htm (pushrod)
http://hamiltonupshur.tripod.com/ (#2 and #4, pushrod )

Advice? Recommendations? It's all welcome. I will have access to CNC machines for most/all of this work, and I'm a CAD wizard, so none of that should be a hang-up.

 

[John S]

Nemitt ?

http://modelenginenews.org/cardfile/ne15s.html

 

[Mosey]

What would you think of a scaled-down version of a Ducati desmodromic single?
There are abundant drawings of those engines around. Shop manuals and parts books are readily accessible, too.

 

[apullin]

That Nemitt engine does look fairly neat, I'll have to email the guy to ask about getting plans...

I think desmo valves would probably be *super* difficult to get working. I've heard that getting them dialed in on a real bike is hard enough, so coupling that with designing & manufacturing them ... phew. Although it would be quite well suited to the application of this engine: a high mileage competition vehicle.

Although, I would certainly take a look if the plans already existed.... you say drawings do exist?

 

[John S]

Andy,
Unfortunately Malcolm Stride the author is dead but there are plans out there and it was covered in Model engineer in 2006 or such like.
I have some plans but at the moment I'm sorting out 4 big boxes of books and drawings from a guy who recently died, not Malcolm, and there are some drawing in there for this engine plus at least 4 copies of the build book.

 

[apullin]

Hrm, interesting. There's so many stories of these old guys making this amazing stuff, and by the time I've learned about it, they've passed on. A guy names Henry Parohl made a Wankel style rotary engine that I'd *love* to build, but unfortunately, there were no plans for it. Oh well.

So, would it then be considered "OK" to ask someone to photocopy the plans and mail them to me? Or scan? Or is there a better way to track them down? It looks like there are some back issues available via Ebay ...

 

[bearcar1]

What is it exactly you are looking to do with this said "already engineered" engine if I may ask? For someone that is a wizard at CAD with access to CNC machines, I would not think that they would find complex shapes any problem at all. Just curious. Have you ever built any type of engines before and what types/sizes. An introduction would be nice too as long as we are asking for things.


BC1
Jim

 

[steamer]

Hrm, interesting. There's so many stories of these old guys making this amazing stuff, and by the time I've learned about it, they've passed on. A guy names Henry Parohl made a Wankel style rotary engine that I'd *love* to build, but unfortunately, there were no plans for it. Oh well.

So, would it then be considered "OK" to ask someone to photocopy the plans and mail them to me? Or scan? Or is there a better way to track them down? It looks like there are some back issues available via Ebay ...

NO actually it's not OK. We take copywrite material laws rather seriously on this board.
If you google model engine you will find many perveyors of plans to chose from by Model Engineer, Model Engine Builder, ect, whom I am sure would be glad to sell you a copy for a modest price.

Please tell us how you make out with your search.

Dave

PS I would be remiss if I didn't point out that your expected to post in the welcome section and tell us about yourself. We like to know whom we are inviting into our home.

Thanks

 

[apullin]

What is it exactly you are looking to do with this said "already engineered" engine if I may ask?

Sure you can ask. I'd like to put together an engine platform for a student high mileage vehicle competition. That is, the engine will actually be used to provide traction power to a lightweight "vehicle (pretty much an aluminum ladder with wheels on it). A lot of engines in this application are Honda GX35's and such that are extensively modified, and I thought to perhaps approach it from the other end: a 'custom' engine. Strip out what isn't needed, and build in the pieces that would need to be added anyway.

And, yes, you're right, that the level of complexity of the parts in one of these engines is not particularly high, and shouldn't be too much CAD work to generate. And as for the CNC part, well, I hope that that will just make the goal of a custom engine that much more achievable: instead of needing a year of special setups and such, I can reduce several hours of, say, using a boring head into just a scant few minutes on the CNC.

But if I do just generate a design from nothing ... there is an 'X' factor there. That is, I might need to work through issues (rings? oiling? etc) that others have collectively resolved with decades of experience.
And, really, as I've started to see, there's not *that* much difference in all the designs for these really simple, unconstrained engines, not mimicking something else that already exists.
I will be adding computer controlled EFI and spark ignition, but those are systems that I know how to adapt, and already have the hardware for.

copywrite material

Ah, sure, ok. The question was motivated from learning that the designer has passed away, and thus the plans can't be bought first hand anymore, so it potentially mightn't be a copyright issue. Consider the seemingly difficulty in sourcing this particular set of plans, I'll likely have to discount the NE15S as a posibility, and go with something that's still available.

 

[steamer]

Check with model engineer. They have back issues of the Nemitt

Dave

 

[bearcar1]

If it is a student competition, what engineering ideas have they (the students) come up with in order to meet any criteria set down in the project? Seems a shame to have such events and merely bastardize a design that has already been proven or modified from something else.


Jim B.

 

[Mosey]

That Nemitt engine does look fairly neat, I'll have to email the guy to ask about getting plans...

I think desmo valves would probably be *super* difficult to get working. I've heard that getting them dialed in on a real bike is hard enough, so coupling that with designing & manufacturing them ... phew. Although it would be quite well suited to the application of this engine: a high mileage competition vehicle.

Although, I would certainly take a look if the plans already existed.... you say drawings do exist?
Yes, I will dig up something, but it may take a few days, then I will post what I can of the full-scale engine.
Mosey

 

[Jasonb]

The basic Nemett design can also be adapted, something like this will get you closer to the 35cc you wanted though the blower may not do much for economy

Also take a look at the various engines in Model Engine Builer Mag, for the price of a back issue or two you will get the plans and description of the build.

J

 

[Mosey]

Here are several shots from the Work Shop Manual suggesting what the Ducati engine entails. Looks like it would be more than a weekend's work!
If there is interest, I will look for engineering drawings, but this would be an epic project.

 

[apullin]

Here are several shots from the Work Shop Manual suggesting what the Ducati engine entails. Looks like it would be more than a weekend's work!
If there is interest, I will look for engineering drawings, but this would be an epic project.

Ha, yeah. Although, I don't need the integral transmission. It's really just the head. Doing the cam geometry should be pretty straightforward in Mathematica, but it's all the small parts ... the springs, washers, bumpers, seals, etc. Hence the hunt for an existing design, so I could build and be running withing a couple of months, so I can get right into drivetrain adaptation, EFI, tuning, etc.

 

[gbritnell]

I could build and be running withing a couple of months, so I can get right into drivetrain adaptation, EFI, tuning, etc.

Whoa there friend!!! Methinks you think this is a lot more simple than it is. First off in this world of 'model engineering' there's not much in the way of EFI. The subject has been tossed around but at present there isn't much out there for us.
Second, unless you have studied camshaft design that subject alone can get pretty deep, engine working rpm, torque ranges, manifold designs, etc. Then there's the question of how you're going to heat treat and grind it.
I don't think there are many of us on this or other model engineering forums who have designed and built 'working engines'.
I would suggest that you start with a small motorcycle engine and make performance modifications to it. That way you have a good base to do your experimenting and beside that there are parts available should something go wrong.
gbritnell

 

[Mosey]

Amen!
And just a bit of information to share...my 50 year old Ducati engine still goes together without crankcase gaskets, just metal to metal castings, and doesn't leak a drop. Awsome.

 

[mu38&Bg#]

Other university teams have managed to come up with engines from scratch. It didn't happen in one year however. There is plenty of info on the web. Some detailed, some not. Cam design is not a trivial task, fortunately it won't be critical in the application you're looking at. Making a few parts on CNC is no faster than doing it manually. The actual cutting time is small, it's the setup that adds up. None of the model engines are designed to be efficient. No model engine has your concerns about rings, oiling, etc. sorted for efficiency. While every engine has a crank, piston, and head, the resulting operating efficiency is all over the map. Set your goals at 200g/kWh and see how close you can get. Designing an engine from scratch take quite a bit of effort. Producing one to meet specific goals, takes development. Even if you take an existing design your needs are so different from a basic engine that I doubt it will save any time. There is a reason many engines are based on the Honda's design. EFI is standard for this application, it doesn't seem to be optional anymore.

If this is for the Shell Eco Marathon you have your work cut out. Based on the work I've seen on past teams websites, it takes an ongoing effort to be near the top.

BTW, if I remember correctly past rules required the use of a certain make of engine block and/or head. In recent years the engine design has been opened to scratch built engines.

 

[apullin]

Whoa there friend!!! Methinks you think this is a lot more simple than it is. First off in this world of 'model engineering' there's not much in the way of EFI.

Yes, I do know that. But EFI system is completely done already, as a separate thing. That is, the pressure source, low flow injectors, electronics, code, etc, is already done. That's the easy part.

Now, as far as a desmodromic valve configuration and such, that was just a pipe dream suggestion that someone else fielded, and since there are no existing plans, it's not really an option.

Other university teams have managed to come up with engines from scratch.

Ah, I knew I'd drum up someone who was familiar with the competitions
Teams don't seem to put too much effort into their websites, so the information isn't always there. There's plenty to be learned at the competition itself, as people share quite openly on-site.

Shell eco-marathon is open engine design. SAE Supermileage requires the use of a Briggs & Stratton block. I am targeting my efforts just to the former.
I consider a lot of the engine designs a little bit "silly", since many of them now use essentially every part from a Honda XR50 engine, and it's just physically supported by the aluminum crankcase of the B&S engine. Just trying to think laterally.

Designing an engine from scratch take quite a bit of effort.

That's why I'm looking for some initial plans, a 'bootstrap'. I mean, I could just show up on a riding lawnmower; that'd be the least amount of development hours ;D

 

[steamer]

I could suggest a Dale Carnige book.... :

Apullin....have you built an engine before?

I ask that question quite earnestly...

Dave


PS We're still waiting for the message from you in the Welcome section.