I have bought several of thease rear induction Russian .15ci. Marz Russian diesels for cheap on ebay.

[link=http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=002&sspagename=STRK%3AME WN%3AIT&viewitem=&item=120114672438&rd=1&rd=1]Marz .15[/link]

I took a OS FP 10 carb and put it in. It fits perfectly with a little file notch to hold it in with the old spray bar. They are about $20 at Tower with the discount.

It didn't throttle well at first.... I looked at it and saw that it had about 1/64" of sub piston induction and I figured that would make the idle unreliable.

So I raised the liner by putting thin copper wire under it's seat and that got rid of the sub piston induction.

It does a nice steady reliable 3,500 rpm idle and 11,000 on a MAS 9x4 on 1/2A Baker Black Brew... That is 1/2 Davis 1/2 my pump diesel base stock.

The other thing I learned about thease is that you have to polish the burrs out of the ports before running it!!!! Whoever was suposed to do that job was probably angry that the government wouldn't let them change jobs so it didn't get done!

For $50 total it is a pretty good deal for a well designed sturdy ball bearing .15.

It weighs 6.8 oz with and exhaust collector ring and the 9x4 prop on it.

They need an exhuast prime to start because the fuel has to go all up hill to get to the cylinder unlike front carb engines...

I'm thinking about building a tri motor[8D]


Treven.

Treven-

I bought one of these cheap off Ebay too. Seems to be a strong runner, havn't put it in a model yet though. You mention an exhaust collector ring - is that some form of a muffler? Where does one find something like that? I know without any muffler it would exceed the noise regs of the club I belong to. I would be interested in trying your carb mod too. Do you have pictures?

Chris

One of the engines I bought has a factory mufler - exhaust collector. I plan to coppy it for my other engines. It is definetly a lahte project.

I don't have digital picture taking abilities at the moment.....

I suggest taking some 400 grit paper and a pencil erasser to rub the paper around all the edges of the ports otherwise your piston may get scratched very soon.

It is pretty neat to have a look in there anyway. You will like how beefy the rod is!

Did you get your Valantine engine that is in your avitar picture to run well? I have one of those on the way too. I hope it runns well 'cause it was pretty expensive.

I have four of these sturdy engines, that I use as test bench for mixes. What is the highest rpm you reached, and what propeller? They say 15.500 rpm but don'n mention the propeller. Maybe eliminating the induction has reduced greatly the speed for sake of flexibility?
A basic difference is in the upper crankase, where the liner fits in it. The oldest I owe has a flat crankase at this point. Other two, more recent ones, have the seats of the screws holding the cylinder that protrude from the crankase until touching the bottom of the aluminium cylinder. The fourth has a muffler, a very simple crown surrounding the exhausts, but the seats of the screws do not protrude until the cylinder. as the first mine. If you want to make a similar muffler the best way is to cut the protruding parts of the seats, if you have them, in this way the muffler is as simple as the original one and fits better in place.
Ugo

It does 11,000+ before and after my mods on a 9x4 MAS. Raising the liner slightly didn't affect it on this prop. Mine also has the aluminum muffler on one engine the rest have the high screw lugs and no muffler.

It will be a bit of machine work to coppy that muffler.........

Pay attention since the mufflerized mine had the crankase too much turned down in a way the liner went too low and that the piston was touching the contrapiston. I had to rise the liner and correspongly the muffler bottom ! Maybe I will make a new taller muffler. Sturdy, but somewhat a rough engine.

Treven, got any pics of it?

No, I need help with digital camera software upgrades.

It looks just like the one in the ebay link.

Treven, I have a Kodak 4320 my daughter got me for Christmas a couple of years ago. Originally I installed the software that came with it, the Kodak software is so propietary it wouldn't let me upload to RCU, it would only let me send it to E-mail addresses. I fixed that, I booted all the Kodak software and now just use the picture software that was already in the computer. It works just fine.

Hi Chevy43

Just a question? Did you get your Ebay Marz 2.5 from a seller called Panaseer?

Ployd

No. I have had good dealing with Burbanks1 and two I bought from blerio11 but he is in the old Soviet Union somewhere and I haven't gotten those two yet.....

There seem to alot of them comming out of the woodwork!

Treven,

Can you give some performance numbers on this engine. Fuel mix and prop size and brand. Can you provide a picture ?

Wow. You renewed an old thread.

I broke in My MARZ 2.5 using Davis or Aerodyne, can't remember which. It had almost zero compression when I started, but developed some as it ran and formed an oil seal on the piston. Here's a couple of pics:

George

Thanks George, it was prompted by a request to sort out throttling problems. Looks like a pretty robust engine. downside for me is no muffler,, not sure I like collector rings. I'm a real fan of muffler pressure to the tank.

Problem here is that the engine is not a real fan of any muffler and you will probably lose about 1 000 rpm or more by using any 'ring' type of muffler bit if noise supression really is required then their is little else you can do.

I wonder if a collector ring with much more volume and an exhaust stub would help. There's lots of room. I'd also have a few cooling fins built in.

My last post assumed that the sub piston induction was still present, which the original post obviously states that it has been eliminated, but most mufflers on 'racing' designs do rob power regardless due to back pressure.

Simply providing a greater volume for the exhaust gases to expand into will help but Ihighly doubt that finning the collector will do much at all.

Try this link for some info - http://modelenginenews.org/ad/marz.html

Exhaust collectors also collect heat and in my experience this can be a problem. But that was on glow and this is diesel which doesn't mind heat as much. Thanks for the link. I searched for Marz and all I could get was Mars.