Practical applications for Model ICs?

[VMacKenzie]

I'm new to this forum, and starting the learning curve for this "hobby."

I stumbled onto this when searching Google to see if anything existed in terms of small-displacement, multi-cylinder IC engines. One of the little recreation activities this 36-year old enjoys is go-karting with his brothers. I have often wished my kart was powered by something other than the coarse 6.5hp Briggs.

I first stumbled onto Ken's IC model page and was enraptured by his 4 and V8 engines. Those are trick! I could only envision throwing a Challenger V8 onto my cart!

Which sort of brings this newbee to these questions:

1) How often are mutli-cylinder IC engines built for practical applications such as lawnmowers, snowblowers, karts, gensets, tillers, etc.?

2) Are most ICs built primarily from scratch? I have searched and not found any ready-to-build kits which you would basically assemble as a model.

3) Lubrication and cooling systems, I have been unable to find details about these. Do ICs have pressure-fed lubrication with filters? Do liquid cooled ICs use water pumps for circulation, or thermal convection?

4) What RPM do your multi-cyl ICs generally operate at? What displacement would I need to generate approx 8 HP?

If I were to build what I wanted, it would probably be a 3 cylinder, preferably a inline 4 or 6, with a target of 8 hp. I would lean toward something that is durable with a long stroke, torquey, not a high RPM screamer.

Thank you everyone,

Vaughn

[Doug_C]

Welcome VMac,

The thing about miniature engines is they rarely have a practical purpose. The ones I like to get involved with are for R/C aircraft use. Most of the others model engines are primarily just for show. Although I have seen a couple of the V8's used as trolling motors in boats. I would doubt they would put out much raw sustained HP.

Folks in this hobby are not always interested in spending time making an engine to do work with. Commercial engines are readily available and cheap to free as beasts of burden. Narrowing the field of use to a specific purpose brings the cost up to meet the demand.

I would say most models are made from scratch or at minimum someone elses prints. Check out the price of the casting kit of the V8's. I think they run around a grand plus and you still take the risk of scrapping out parts inadvertantly. Not to mention the hrs and equipment involved in getting one finished and running. As most of the folks in this hobby tend to have more time on their hands than money. Coming up with material is much easier to carve a block out of barstock, than purchasing castings. Practicality in terms of machining time and weight saved is inconsequential. We are willing to make do.

Lubrication is based on scale, desired service life and either simplicity of complexity of the skills each individual may have. It is what ever one can get away with, I'd imagine.

Small displacement engines will need to turn some pretty high RPM's in order to make HP to sustain instant torque without being lugged below the power band. Although I think torque is more important that HP. The output will be based on the efficiency of whatever displacement chosen. Lower RPM's go with bigger displacement which translates to lower piston speed, greater low end torque etc. Those attributes go hand in hand. A condition where you usually can't get something for nothing in the natural order of things.

I thought the 2 and 4 stroke motorcycle engines and tranny's were what the kart crowd was using these days.

DC

[Grue]

Most IC engine builders spend many hours making an engine that is primarily used as a "display" The fact that it runs is importanat to the model's authenticity.

Most builders would never consider using one in a go cart!

There is a supplier in Florida that has a 1/5 scale V8 that he uses in a scale dragster. The plans and castings for this only run to $100 and its a suitable job for the first time (novice) builder. The engine produces 3.2Hp and is only a fraction of the size of the 6.5 briggs. This engine uses glo plugs and the fuel is a nitro - oil mixture for lubrication.

If you are looking to build your own engine this one would be a good starting point for you. You'll learn about the machining skills necessary and have fun with the project while learning. Its low cost and simplicity will probably get you hooked to venture further into a more precise engine.

Details and pics are on my web page.

Glenn

[Bryan]

Glenn, do you have a point of contact for this guy?

[Al_Messer]

Coles' Power Models has a casting kit for an in-line 4 cylinder spark ignition engine, water cooled, pressure lubed.

[ronm]

RE: RPM-I just read the other day about a 1/4 scale small-block Chevy in "Strictly IC". The builder had a 10,000 RPM tach on it, & when asked "how fast will it turn", he said, "I don't know, it pegs the tach when I just blip the throttle..." He used Corvette cam specs to grind the cam... Amazing...

[Grue]

Hi Bryan,

Mark Miller is the guys name, email him - Castvee8 at aol.com (fix the space @ space).

Glenn

[Grue]

There's another guy in Florida, Ted, who sells a V8 - uncleted at cfl.rr.com (fix the space @ space). Ted's a ham, his call is K5AAV.

The picture shows another jewel that Ted sells. It is a V8 with a total
displacement of 4cc! It is $2500. Ted also has a "A" Model ford he sells.

Glenn

[VMacKenzie]

Thank you all for your input, it was helpful. I will check out the links and sources. I figured with the expense and time commitment to build an engine a modeler would not want to subject the engine to anything that may damage it, and I certainly understand the challenges of getting a small displacement engine to run, and to run smoothly.

The reason I am looking into this is the desire to build a cart with more refinement than your typical "Fun Kart" with a Briggs. Basically a kid's toy for an adult. Refinements such as working suspension, disc brakes, 3 or 4 speed transmission, multi-cylinder engine, all built with reliable and smooth operation. Yes a far-fetched and quite atypical goal, but from what I see many modeling ideas don't exactly follow mainstream thinking [img]/ubb/images/graemlins/smile.gif"%20alt="[/img]

If I want a project, I thought of building an engine with as many available parts as possible. For example I can use the piston & rod assemblies from the Tecumseh 3hp engine which is 2.25" bore and 1.84" stroke yielding 9.06 CID per cylinder. These parts would make a great inline 3 for a 27.2 CID engine (444cc) which should yield about 10hp, and make for a fun kart! That would put me where I'd want for displacement and power and all I'd have to come up with is the block, head, cam and crank. It would still be a project but should not be monumental. [img]/ubb/images/graemlins/smile.gif"%20alt="[/img]

Vaughn

[Al_Messer]

My word, Glenn, Ted must be a watchmaker! Beautiful little job!

[millman5]

Once upon a time & long ago I designed & built a cart utilizing a 197(?) Kawasaiki
350CC street bike 2 stroke 3 cylinder engine. Boy did that thing ever seem rocket powered!!!

What details I remember about it now is I used the front hydraulic disk brake on the rear live axle. Had to play with the tire size quite a bit to get enough traction to eliminate wheel spin but still be able to turn the thing. Designed in clutch, brake & throttle pedals, & ran the shifter up the left side for left hand shifting. The only thing I never fully worked out was the expansion chambers for the exhaust. My first attempt was a headder design like a 4 cycle engine would use. Had a very unique sound but didn't work well. My guess now is, it was presurizing the scavenger ports on the 2 stroke engine. Ran ok but just didn't have that screaming power band that those triples were known for.

I constructed the frame from round tubing not much thicker than EMT electrical conduit. I never weighed it but I could load it on my pickup truck by lifting the rear wheels to the tail gate then picking up the other end & rolling it in.

Not knowing how unstable this thing might be I designed a roll cage around myself too. Used a fiberglass racing seat & 5 point harness also.

It was a fun project to build. Even more fun to take to the track & watch the masses OOh & Ahhh over it. Of course there wasn't any lind of open class racing so was run exhibition only. Wish I had taken pictures of it to share with others now. Oh well!!

[Grue]

There's a lot of interest in small engines from military sources. If you look at the success of the latest Middle east conflicts, pilotless drone aircraft were used to flush out the defender's radar.

I am aware of a lot of research into this field including micro remote control of cameras on pilotless drones.

Computer "nerds" look like being the frot line troops in any future conflicts, flying and controlling small pilotless aircraft.

Glenn