Frog 150 R diesel

Hi fellow aeromodeller,

Cannot find a dedicated engines section, perhaps admin could create one ?

Anyways, might anyone have a parts exploded view of a frog 150 R MK2 diesel engine please, or have one of these engines fitted with a silencer ?

I have checked on sceptre site, a very usefull engine test site, but it does not answer my query, but does show detail of the engine, but no silencer.

This frog appears to be unmolested and states that it comes with silencer fitted, presumably factory fitted.

I noticed that the back plate was fitted upsidedown, the "step" being at the bottom instead of at the top, which is the norm.

I removed the cylinder head cooling fin jacket which accomadates the compression adjust screw.

The cylinder screws into the crank case, having a large diameter.

The cooling fins jacket screws onto the cylinder, having a smaller diameter compared to the cylinder/ crank case size.

The silencer is a 3 part component, the spring steel "C" clip to close off the silencer outlet port or window, the alloy exhaust gas collector, and the thin spring steel cover plate, a washer.

This washer at the moment is between the crank case and cylinder base. The cylinder would have to be removed ( something I don't really want to do, needing a purpose made c spanner ) to remove this washer.

The alloy exhaust collected "open end" has a register to accept the thin cover plate washer.

The cooling fin jacket base has a small register, being rather thin in depth and diameter, to hold the alloy exhaust collected on. The jacket register does not fit in the exhaust collector "hole".

Since the backplate was upside down, and does not appear to have been removed before as there are no witness marks in the two screws and nuts, is the exhaust collector fitted in the wrong place, or is there a washer missing that fits the cooling fin jacket register, fitting between the jacket and collector ?

I will see if I have a thin washer to fit the register, and of a suitable diameter to fit/nip the collector in place.

Maybe I have answered my own question but if you don't ask, you don't know...

Thanks, rich.

Not sure frog 150's ever came with a silencer? If the back plate was upside down the engine wouldn't turn over as the internal step is there to give clearance to the piston at the end of its stroke.
As Eric said a picture would help.

Yep, picture equals 1000 words, pictures to follow, just waiting for phone to charge, need to take pictures to sell this 47 inch huntsman, sea commander, sea rider and Enya 15rc marine engine...

Pictures




You should be able to make out the cooling jacket register, the shiny thin ring.

The register will not enter the exhaust collector ring centre hole. The register presents a narrow area to nip down on the exhaust ring.

The back plate fitted upside down did not foul the cylinder bottom or piston skirt.

Sceptre mentions a lightened short skirt piston...

Anyway, will either make a cylinder c spanner or/and a suitable washer for register to sit in and washer nipping the exhaust collecter.

Not run this engine since I have had it, 30 years ownership probably , must be a pre decimal currance engine as it's priced £2/19/6p.

P. Should be. d.

Guarantee slip in box says bought from the model shop, 13 Bootle st., Manchester, but is not dated.

Also says engine number which tallies, with silencer.

Here you go Rich, Can't see any washer??

Think it's for the fuel tank Eric?

Nice drawing, some colour to.

I cannot see stuff on the RHS on this phone.

Removable "bush" to fill void between bearings, held in by the vertical single screw under the engine snout.

Contra piston just below the coloured cylinder head in drawing.

A clear plastic tank was available for DC model diesels held in place by the horizontal back plate cover screws and nuts. Some other models had similar, some made from ally.

On my frog which came with a muffler/silencer, there are some tell tale marks, some the same size/imprint of the fin jacket, some of a larger diameter.

Will check and measure later. Perhaps the silencer is up side down, the back plate cover was...

Spent 4 hours + yesterday looking for specific exhaust silencer info and pictures to show exhaust position, no joy.

So, gunna measure tell tale marks and make a washer that fits register them final clean and test run.

Snow on mountain across the valley and much colder today, brrrrr gunna be cold in the shed...

Had another look at your picture Rich, I don't believe that silencer is a frog part, Can't find any info that they ever came with one, looks suspiciously like a Cox part...I stand to be corrected.

Hi Paul, yes that was my initial thought, quite Cox like.

The outer diameters are identical give or take a few thou, but other dimensions are different.

Even thought maybe frog bought them in from Cox, the exchange rate at the time would have been favourable, but differing dimensions suggest not.

Cox td09 ( very interesting threads by Sosam on coxengineforum using/adapting Enya carbs and exhausts, well worth a look see, done without the aid of a milling machine . Some more info needed then ordering parts from ken Enya in japan, to RC and silence the pair of angry hornets these TD's are, they can really "sting" if your not careful ) for comparison, one piece alloy, similar spring steel washer.

Having seen a few unsilenced 150 r pictures, the lower cylinder thread diameter which screws into crank case, seems much larger than the upper cylinder thread, where the cooling jacket screws on.

Doubt the hole in the alloy collector is large enough to accomadate the lower thread diameter, and the washer hole probably too big to accomadate the cooling jacket.

Don't really want to remove the cylinder to find out.

This engine was quite powerful for its time.

Anyways, one book to look at....

The box, label and paperwork suggest the exhaust was factory fitted. Can't see a model shop stripping the engine to fit the exhaust, but it is possible I suppose.

According to this article it does seem unlikely that the Frog 150 R would ever have had a factory fitted exhaust ring.
The 150 R was specifically intended for CL team racing where absolute power was required. The 150 R being the last in a line of developments to extract more power from the same basic 1.5 cc engine to keep up the engine competition.

To give an idea of the 'request for power' Frog subsequently produced the Frog 100. A 1 cc engine that was the same size and weight as the 150 but it did have a higher specific power output. This was to match the performance of the AM10.
Incidentally Allen Mercury did the same thing, but the other way round, as their AM15 had exactly the same dimensions as the AM10.

That my take on a Frog 150 R exhaust.