How does it work ??

[renevanl]

Hello, i am Rene from the Netherlands, i am 42 years old and i am looking for sometime for information on this very nice site.

Now i have a question about the foto of the v6 2 stroke engine.
How does it work?

I want to build a 2 stroke v4, v6 ore v8 engine and use it in a r/c model boat.

Rene

[vulcom1]

Rene,
Very nice work from somewhere. If you had more pictures it would help. There are several possibilities and from what I can see it has a pull starter on the rear which makes me think of magneto or cdi ignition. Without seeing the inside I suspect it is a 2 stroke as there are 3 carb/injectors, 2 cylinders for each one and could be port intake and exhaust timed on the cylinder's. This would get it away from having each cylinder sealed in the case. Looks water cooled as there looks like hose fittings on the heads. Not sure if I am even close but as I said I would like to see more or where you got the picture from.
I am an ex HD mech. medically retired and would like to do a project like this. Although I am not cnc but do everything manually but I am learning a lot from being on here. Somebody else may have more idea's on this one. I have converted small air cooled gas(chainsaw/weedies) engines and at this time making a 2 cylinder(60 cc's) horizontally opposed engine for my RC model.
John

[renevanl]

Hi John, i only have 1 more picture of that engine. As far as i know its a glowplug engine running on methanol.There is no ignition. On the rear there is a toothbelt that is driving something below the carbs. That must be the intake timing "something". So what i want to know is; how do you get the cilinder filled and lubricate de crancshaft in a 2 stroke V engine without a blower.

I also converted small gas engines, i used 2 aircooled zenoah car engines and made it in to 1 watercooled 2 cylinder boatengine. This was my first engine project. And now i want more.

Please don't look at my english, it is not my native language. I can read and speak it, but writing is something else.

René

[renevanl]

Hi,

is it posseble that this 6 cylinder engine actualy is a 4 stroke engine, because the thing under the carbs is "geared", looks like 2:1.

René

[Bajaman]

This engine looks to have a rotory intake valve system with a side port
exhaust opening.
This can make an engine very high reving like a two stroke!
This can also be an easy engine to design and build.

[itsme]

Hi there,

After a quick Google search, I managed to find the MHZ-Engines website.

http://www.mhz-engines.com/

They don't provide very much information on this engine, but I think it is a 2 stroke. Here's why:

From looking at the photos, I suspect they use a rotary valve to control the intake into the crankcase (a bit like a disk valve on some other 2 stroke engines). If this rotary valve were to look like a common model engine's carburetor barrel (ie. a ground piece of bar with a single hole in the case of a single cylinder engine; or three in this case; cross-drilled through it), then there would be a requirement for this valve to rotate at half the crankshaft speed (hence the 2:1 belt drive). If the valve were to rotate at the same speed as the crankshaft, then it would be opened twice in 360 degrees of crankshaft movement (or one cycle), which would not work - it would merely allow the fresh charge to 'pushed' out again on the downstroke of the piston(s).

I would think that it would also be possible in the case of these 'vee' engines, that each pair of cylinders in the 'vee' could share a common crankcase volume as well as a common crankpin. Although one piston will always arrive at BDC or TDC a few degrees later than the other cylinder (depending on the 'vee' angle), it should still allow the common 2 stroke principles to work reasonably well for both cylinders.

I hope this makes sense and helps in some way.

Regards
Warren

[NC Cams]

Has anyone dropped a note to MHZ yet???

I cruised thru their site and didn't find anything on it.

2:1 drive could be for a water pump - not having fins, it will NOT live long unless you pump coolant thru it.

2 strokes can be rotary valved or even simply piston ported ala most model aircraft two strokes. As low on the bore as the exhaust ports seem to be, I'd suspect conventional piston porting with loop scavenge.

IT is probably an adaptation of a water cooled model boat engine that they they fitted to a common crankcase.

Work of art no matter what they did or how they did it.

[ger21]

http://www.mhz-engines.com/index.php?cas=1161530527&X[strana]=test6&X[lng]=3&X[par3]=Sextett2_2.jpg&X[par4]=1&X[par5]=1&X[par6]=test5%09%2A%095%091

The link doesn't save right. Copy the whole line into the address bar above to get to the picture

[NC Cams]

My bet:

Water cooled V-6 with piston porting, loop scavenging and glow plug ignition (no rotary valve to save cost and reduce complexity)

[vulcom1]

Water cooled V6 with glow ignition and I think the carb induction has the rotary shaft to separate the intake ports from each other in the pair configuration. As mentioned also the shaft looks like 1 to 2 ratio which may get away from the regular 2 stroke as it might not fire on every stroke. I know the 4 stroke RC engines use the F type plug which will glow longer because of the deep chamber in the glow plug. Very interesting with all the comments and actually would be nice to see the parts layout. Was on the site and could not find that engine but there is a 4 cly. in line engine which looks like the same setup.
For lubrication it may have the old style splash system with no pump or oil mix in the fuel. For cooling in a boat and used for racing which the company is
advertising for It may be by pressure from a scoop on the hull. Most of the model glow engines water cooled in high speed boats are that way.
Your english is great wish I could do the same in another language.
John

[MrWild]

My bet is a rotary valve intake. Most model engines are not piston port timed alone. The crankshhaft is hollow and a port aligns with the carb opening before BDC. This fills the crankcase on the upstroke allowing some compression of the charge on the downstroke after the crankshaft opening closes off the carb port.

Because of the way a twin fills the crankcase as both pistons rise, the charge could go to the first piston to open it's intake port causing a rich/lean condition beteen the two cylinders on that v section (if crankcase charged induction was used).

My bet is that the geared 1/2 to 1 shaft is an intake port timing device. The engine is a blend of two stroke and four stroke technology. It is hard to understand why they don't run the valve shaft at one to one as a 1/2 to one means that one full revolution will be used for nothing more than to make a piston go up and down. The shaft valve may help keep the charges seperate so both sides see equal burn, but this engine really needs a blower like a detroit two stroke desiel in design.

[itsme]

Hello again,

As mentioned earlier I think that the 2:1 geared shaft is a rotary valve used to time the intake into the crankcase of this engine. I also still think this engine is pure 2 stroke - not a combination of 2 and 4 stroke. Let me try and explain my reasoning again (perhaps my last attempt was poor)...

If the rotary valve were to be a piece of bar that is cross-drilled, then the periphery of the bar will have 2 openings on it that are set 180 degrees apart. The fact that it would have 2 openings that are set 180 degrees apart, is the reason why the 2:1 gearing would be needed. If you look at any model engine that uses a rotary valve in the front of the crankshaft, you'll notice that it has only one opening on the periphery of the shaft and that it also (quite obviously) rotates at crankshaft speed. The best direct comparison that I can think of at the moment would be to put two holes/ports into the disk valve on a 2 stroke engine that uses a disk valve. If these 2 ports were to be 180 degrees apart, then the disk valve would have to rotate at half crankshaft speed.

As for the rich/lean problem on a pair of cylinders in the 'vee', would it not be possible to adjust the transfer ports so that they are biased towards a cylinder?

I hope this makes more sense than my last attempt.

Regards
Warren