Project engine proposal - your views?

[LongRat]

I've been interested in building an engine for many years now, and I think my skills are at a level where it wouldn't be impossible any more. I build RC cars from scratch, and ultimately I would like to drop in my own powerplant to a home made vehicle.
My wish is to build a multi-cylinder engine with useable power. I don't necessarily want anything that is scale. I am more interested in extracting motive power without too much complexity. The sort of thing I am thinking of would be something like a flat or inline 4, or maybe a straight 6. Something like a shrunken version of a 'modern' Japanese engine (I am thinking of the sort of thing you might find in a tuned MR2, Skyline or Toyota Supra). The small-displacement engines that rev high and make a lot of power for their size. Running the numbers, it seems to me that using an electric-powered supercharger might be possible in small scale. The power of small brushless motors is high enough to deliver the air volumes required at this size, plus I wouldn't mind if the compressor system was close to the same size as the engine which I think it would have to be. I can't see making a turbo work in a model size so this would be a kind of substitute, as the real engines are turbocharged.
Also, the simplicity is important. I like the idea of glow ignition because that is what I have experience with, and it is very simple. But is it compatible with my ideas?

I've never seen anyone model an engine of this type (RB26, 2JZ-GTE, 3SGTE etc) its mostly older stuff and V8s. If anyone has done it I would love to see.
What I would like to understand are the possible show-stopping problems that could present themselves in a project like this.

[D.L]

Keep it modular, existing patterns for plugs, rings, bearings, chains.

Could you post a few pics of your cars please?

Sounds interesting,,,,,

[One of Many]

As far as glow engines go, they do not like low RPM and stay lit. Not a show stopper, but it will require a glow driver to either kick in at low rpm or constant power, which can be hard on the elements and battery charge duration.

Bruce Satra had a 0-440 flat opposed engine in Strictly IC a few years back, that was 25cc.

What size engine are you thinking about?

DC

[LongRat]

Thanks for your input guys, it really helps.
I had not considered the low-RPM glow issue. I'm thinking the smaller the engine, possibly the less this will be a problem as the RPM range would likely be higher. Also, I don't think I would be up for designing something from scratch. More like, take an existing layout and modify it where necessary to get closer to what I would want. The size I am thinking about would be around a 6" long block.. I wouldn't have thought much over 25cc. I am definitely in agreement with keeping everything modular. I would fully expect this to break and require fixing, and ideally that would not be a multi-week exercise.

The last car I built was a 1/8 scale buggy. It is powered by a 5cc glow engine mounted in the rear. Its got a few unique features apart from the drive layout, like the ceramic disc brake system and cable operated steering rack.

[LongRat]

A couple of shots showing more detail under the body. I am not thinking of an engine to fit this car, just possibly something similar but slightly bigger.

[skippy]

Beautiful work!
regarding the engines, yes you are right in that most seems to be modelled on small block chevys and that kind of engine technology. I did see a post here a few weeks in this section (I.C. engines) that had one of the best lists of links I have seen to model engines but unfortunately I didn't save it.
If you are planning on the engine running for more than short runs it will need water cooling and that's what complicates the building of a multicylinder engine and even more if you are going for multivalve engines.
I must admit I love the modern Jap V8s including Nissan's VH41 and VH45

[LongRat]

Thanks Skippy.
I agree although I haven't seen so much of the Japanese V8s. The recent posts about the Schillings V8 engine really sparked my interest as this looks exactly the sort of thing I am interested in. A more modern 'looking' V8 although actual details of the engine I am unsure about. It is glow ignition though, and DOHC. Pretty cool.

[D.L]

Blind freddy could see that buggy rules!

Maybe reverse engineer an OS flat four and sell it afterwards and build a flat six version. Honda make the GX35,45 brush cutter which would be a good baseline.
They have OHC, dry sump, and some have fuel injection.
A GX35 flat four would be 140cc, big enough for a go kart, to big.
Maybe a GX35 Vtwin?

The possibilities are endless.

[One of Many]

Nice pic's LongRat,

I can almost smell the caster and nitro! Very impressive work.

25cc is going to be roughly equal to a single cylinder weedeater/string trimmer motor. I have one(toro) on my Phaeton90 bipe that I converted to glow. Fuel efficient it is NOT and talk about a mess to clean up!

Skippy is correct with the heat issues. Something I don't have concern as much with a prop cooling the cylinders. Your big heatsync times 4 won't be enough with still hot air around them.

I have also wanted to make a flat 4. My plan was to purchase production cylinders and piston assemblies. Then just make the crank, con rods and case to simplify the project.

DC

[LongRat]

I want to get some 4-stroke experience before jumping in trying to build an engine too. I will get hold of a single cyl glow 4 stroke and just get familiar with it soon hopefully. Building a multi-cyl engine out of production 4 stroke nitro parts is definitely a possibility. DC, what was involved in converting a gasoline powered engine to glow? And what about a small multi cylinder engine, I guess if it was spark ignition then gasoline would be an appropriate fuel? I've read about people mixing all sorts of things as fuel but I would want consistency in performance really. Not sure I could handle spraying whole cans of WD40 into a fuel tank!

[One of Many]

I want to get some 4-stroke experience before jumping in trying to build an engine too. I will get hold of a single cyl glow 4 stroke and just get familiar with it soon hopefully. Building a multi-cyl engine out of production 4 stroke nitro parts is definitely a possibility. DC, what was involved in converting a gasoline powered engine to glow? And what about a small multi cylinder engine, I guess if it was spark ignition then gasoline would be an appropriate fuel? I've read about people mixing all sorts of things as fuel but I would want consistency in performance really. Not sure I could handle spraying whole cans of WD40 into a fuel tank!

I have a few Saito 4 strokers. I love the sound of those on a slow fly by. Nice looking too. Set up well, it only take a flick of the prop to start it. The flywheel affect of the prop can help get the idle fairly low you can hear the pluck of the piston on the intake stroke.

The other nice thing about the 4 strokers is they aren't crank case induction. I do have a Fox 1.20 2 stroke twin that is CCI, but still has 2 carbs. The crank is double opposed, so both pistons are moving in or out at the same time. That keeps a negative pressure inside the case to pull in more fuel. otherwise it would just push it from side to side and no change in volume.

DC

[philbur]

You might want to look here:

http://www.modelenginenews.org

Your problem is going to be performance. Getting a high power to weight ratio, similar to commercially available model engines, is not going to be easy. The precision required is going to be extreme.

It can be done but the level of skill required is very, very high. The duration is very long and the necessary commitment is unbelievable. Other than that it's a piece of cake.

Just an opinion or two.
Phil