Interesting find

ACLR · Post by **ACLR** » Wed Jan 30, 2008 6:30 am

well I found something very interesting on the weekend. our MSS loco was running realy great with the upgraded piston kit but there was no chuff chuff like the sl1k. the sl1k wasnt as good a runner as the mss loco either. so decided to investigate and found that the exhaust pipe on the mss had the end crimped over and a small slot cut into the pipe just under the crimp. I hadnt realy noticed that before and the sl1k the pipe was cut off clean no crimp.
I decided to make the pipe on the mss the same and cut the end off but bad mistake nice chuff chuff but runs like a dog. im assuming this crimp and slot provides back pressure so making the engine run better. im going to put the original pipe back and compare again. marvin (MSS) has always been a great runner so maybe this has been the reason . not sure but will let you know when Ive fixed the exhaust pipe.

Chris Cairns · Post by **Chris Cairns** » Wed Jan 30, 2008 1:42 pm

I think we touched on this subject when discussing the exhaust regulator.

So it is interesting to read that it actually works on at least one loco.

So far I've just put a piece of silicone tubing onto the exhaust pipe of my Mamods & MSS locos, primarly to bring the steam exhaust towards the top of the chimney, and also to back inject some steam oil into the cylinders.

It is interesting to hear that it does make a difference to your MSS loco which is fitted with all the upgrades. Wonder what it is actually controlling then, as I would have thought that the regulator kit was all that was required?

steamyjim · Post by **steamyjim** » Wed Jan 30, 2008 4:23 pm

I beleive exhaust regulators make an engine more efficiant. Something to do with steam consumption

mhlr · Post by **mhlr** » Wed Jan 30, 2008 10:13 pm

CCairns, I have a piece of silicon tubing on Columbine's exhaust, it gives quite a nice chuff. Perhaps that's the answer ACLR, but I have also seen people just dropping a largish piece of copper tubing over the exhaust to amplify the chuff...

ACLR · Post by **ACLR** » Wed Jan 30, 2008 10:36 pm

Im going to experiment a bit if I find time this weekend

grumpfuttock · Post by **grumpfuttock** » Thu Jan 31, 2008 1:05 am

ACLR wrote:Im going to experiment a bit if I find time this weekend

It will be interesting to hear the result of you experiments ACLR. I have always been told that the less back pressure in the exhaust part of the system would mean greater power from the piston, as it has no pressure working against it. As I understand it the exhaust regulator was designed to keep Mamods and other "tear away" locomotives better under control as the back pressure reduced the power to a certain extent, keeping the loco more docile, and reducing the speed at which the piston could travel in the cylinder due to the reduced speed at which the steam can exit the system.

One thing I have noticed after buying some replacement cylinders for my Mamod SL1's from both PPS and also IP engineering, was that the inlet holes to the cylinder and also the port face, are smaller than the original Mamod design, and since replacing the original cylinders on one of the loco's, it is now incapable of pulling the skin off a rice pudding

I had originally enlarged the exhaust port on the reversing valve and added a larger bore exhaust pipe ( with the end of the pipe open) to reduce any back pressure and that made a great improvement to the power of the loco (originally) and also the chuff was good, but maybe you have hit on something, maybe the MSS cylinders work better with back pressure, although I am puzzled as to why.

ACLR · Post by **ACLR** » Fri Feb 01, 2008 11:08 am

Here is a vid of my mss running with the exhaust pipe narroed down to about 1/16th of an inch.
its still a bit chunky on blocks havent run it on the track yet.
but its 100% better than without the restriction.
all I did was mold over the end of the pipe to still keeping it round but narrowing the hole.
I also added about 35mm of 1/8th id brass pipe to it whish sits inside the chimney.

sorry about the light quality as the kitchen lighting isnt the best at night

Chris Cairns · Post by **Chris Cairns** » Fri Feb 01, 2008 11:27 am

Interesting video Graham.

Has your oil consumption changed at all, as that clunkiness sounds a bit like my IP Jane when it has not been lubricated properly. On my running last night I found it ran best whilst under load with 4 wagons on the test track, sucking the oil through better than running on blocks.

ACLR · Post by **ACLR** » Fri Feb 01, 2008 11:31 am

I didnt check the consumption Chris
I filled it up before running it water consumtion is down still have heaps left after the meths has exhausted
will see how it runs on the track over the weekend

ACLR · Post by **ACLR** » Sat Feb 02, 2008 7:06 am

Here is marvin on the track
http://www.youtube.com/watch?v=WRjZ9HprpyI

grumpfuttock · Post by **grumpfuttock** » Fri Feb 15, 2008 11:16 pm

Graham, you certainly got a good chuff from the loco. I love that sound, just like my old Mamods. Have you noticed any change in power? It certainly seems to be good at self starting after a stall, and wow did it sound good as it pulled away.

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