Zpat

My Feedback: (2)

I have a Moki 1.80 w/an APC 18x8W prop running on a 20% castor mix of FAI fuel. It runs, throttles and idles well.
It's hauling a 17# Pits M12 w/a 60" wing.
I'd like a little more performance out of this engine.
Clarence Lee states he can turn an 18x8 undisclosed prop 8650 rpm on 5% nitro.
My APC 18x8W turns 7500 rpm and when I attempted to run a 5% nitro mixture in it it seized.
According to my trusty prop-power calculator, Mr. Lee is getting almost another .5 hp from his engine.

I'd like to know about other experiences with this engine.
Has anyone experienced Mr. Lee's findings with an 18x8 prop?

Thanks Guys!

j.duncker

My Feedback: (2)

What kind of silencer have you got on it. If it is a Pitts type it may be restrictive. try another less restrictive silencer and see what happens.

You should be able to run 5% nitro even in a hot conditions. It is only when you get above 10% that they need a head shim or two.

If you really want more power shim the head run 20% nitro [may need 1 step cooler plug ] and fit a tuned pipe. See [link=http://www.justengines.unseen.org/acatalog/Tuned_Pipes.html]CLICKY[/link]

w8ye

My Feedback: (16)

I think it was in the late 90's when he ran the test on the 180?

Seems he used Zinger's back then?

A APC 18 X 8W is not exactly going to be a RPM demon.

Try a Vess 18 X 8 Sport?

Your Moki most likely seized because of oil or mixture or it got too hot? They should handle 5% nitro OK if the mixture is adjusted and they are kept cool?

earlwb

There are a number of factors that come into play that can affect the performance.
One is there are quite a few different 18x8 props out there. I suspect Clarence lee used a narrow prop not a wide. Very likely a wood prop.
I would expect it to be a Zinger or a Xoar wood prop. the Zinger actually has two different 18x8 props a regular and a Pro version.  The APC prop you used is very efficient and probably loaded the engine more. I guess a Master Airscrew 18x8 wood prop is a possibility too.

Then temperature and humidity can affect the performance a lot in some cases. a really hot humid day can really rob the power from a engine, so much so you may not be able to even get the needle valve to run at anything near optimum and you have to leave it real rich for the engine.

Zpat

My Feedback: (2)

The muffler came with it and I believe it's homemade.

I guess I'll try a wood sport propeller.

Thanks for the info guys!

earlwb

In this article http://www.justengines.unseen.org/ac..._Magazine.html
they mentioned they used Zinger props, but they didn't state if it was the regular or pro. But I would assume regular props.
are you sure you have a 1.80 and not a 1.50 engine?

mk1spitfire

I popped a apc16x12 on my moki 1.80 with good speed results, 132mph using the F1 sundowner 80inch. FAI fuel

Here

[youtube]http://www.youtube.com/watch?v=15stDdjUuIQ[/youtube]


[youtube]http://www.youtube.com/watch?v=kZTLrzRzURs[/youtube]

Zpat

My Feedback: (2)

I don't know what rpm your turning, but it sounds like a lot more than I'm getting.

I've never taken into the consideration of the engine actually being a 1.80, except for the obvious number on the case, is there a way to identify?

w8ye

My Feedback: (16)

The marking on the side is a pretty good indication

j.duncker

My Feedback: (2)

That silencer is going to be restrictive. Anything with a flat face that close to the exhaust port is going to bounce the gas pulse right back at the post.

But I guess you want to keep it inside the cowl.

captinjohn

Put a good pipe on it & let it rip!!!!!!!! Capt,n

totius

After +- year of being on the shelf i started get my katana with 210 moki ready for our yearly scale meet at Oudtshoor . This motor not run alot say +- 20 flights , And i was not very please with it from the start , I have never removed the head nore checked if it was tight . What was my supprice to find all the bolts loose. Have any of you had the cylinder head bolts go loose

I will see if this improves the motors performance. I am going to change this motor to gas with electronic ignition just waiting on the spares bought from just engines.