RUMCars Forum
General Category => Unusual Microcar Discussion => Topic started by: adi on March 05, 2009, 06:14:01 PM
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Sorry another tech question from me...
I need a new exhaust!
I removed the exhaust collar, and took the exhaust system off, to be faced with this abortion:
(http://img.photobucket.com/albums/v405/adibrook/DSC00216.jpg)
As you see, it is what i would guess to be the stock villiers downpipe (?), which is then attached to a smaller pipe by means of bird droppings. This pipe is then attached, again by means of adhesion by bird droppings ( :P) to what i assume to be a stock exhaust pipe from some British bike.
That thing in the middle looks like just an expansion bottle. It has no baffles, neither is it a glass pack, its just pipe.
The exhaust is no doubt well-flowing (or it would be if it was welded properly :P), and is no doubt a period acessory/bodge, and therefore deserves some kind of recognition as a historic period mod, but it is STUPID loud.
Like, when it first sprung into life with an almighty noise, it actually sounded silly. My beetle dont have much in the way of an exhaust, and is loud, but its not a whiny two stroke, this just sounds absolutely silly. Also my beetle has the acceleration and power to justify the noise...the bubble car im afraid may look just a little silly. Although, being slow but outrageously noisy, im sure the kids at the local matalan car park will instantly love it, but appart from that i see no reason for this exhaust.
I think a proportion of this has to do with the fact that its leaking badly through the exhaust flange, since it was attached as i later found out with no gasket at all, or anything, just flare to flange.
But even that kind of appreciable leak wouldnt cause SUCH a nasty noise. At least i dont think so.
Im gonna try and get the appropriate gasket for it (some kind person has offered to send me one), and try this exhaust with a gasket, just for the sake of seeing what its like, but i have a feeling that it will still be silly loud, having no baffles or anything.
Also, having no baffles or expansion bubble at all can be bad for a 2 stroke, but i doubt such a slow agricultural-looking no-reed-valve engine such as this would actually care what its exhaust is like, it probably is way too crude to see any difference in exhaust.
So...how do i go about getting something with a little less noise. I know they wernt wisper quiet fron the factory, but at least they are possible to run for a few mins in a residential area without bothering the whole street.
I assume new exhausts are unobtainable, but im not so bad at welding and fabrication, so im sure knocking up a new one would be easy if i knew what its actually supposed to look like and function like.
Any ideas?
Thanks in advance.
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What i would be particularly curious about is the design of the muffler. I assume there is only one, but would be cool to find out how many stages of baffling i has, what sort of baffles, and wether it has any kind of dimension critical expansion cavities etc. And of course size of outlet pipe.
i dont suppose that kind of detailed info is obtainable, but it would be cool to find out something at least.
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Also...supposedly thers a HEATING SYSTEM???
How does that work?
Anyone?
The car is rolling now by the way and all gears and clutch work etc...just need to sort the exhaust out and then i can think about cleaning it all up, refitting everything, and then it should be road worthy.
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Don't know anything about this myself, but good to hear of your progress
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Hmm...it seems generally very hard to find any info at all on these.
They must have made a workshop manual of some kind for these...right? Even simple diagrams of the exhaust system would be cool, as i really CANT imagine what it would have looked like, or how this supposed rudimentary heating system would have worked.
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Adi,
Go to the Scootacar Register, I'm sure they can help you out.
Rob D.
Contact Details
Stephen Boyd.
Email: scootacar@btinternet.com
Tel: (01263) 733861
Address: Scootacar Register
18 Holman Close
Aylsham
Norwich
Norfolk
NR11 6DD
UNITED KINGDOM
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http://www.flickr.com/photos/maicomobils/530240920
gives you some idea. Will try and get a photo of mine for you.
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Hmm...so the muffler is that thing riding up under the back schassis leg thing, at an angle?
That seems pretty self explanatory. The muffler is gonna be hard to get as i assume being 2 stroke its different to other more common 4 stroke mufflers.
Although...perhaps a muffler from some little old British car which have pathetically small tailpipes and exhaust systems might do. Of course it would be 4 stroke specific, but im sure it would still kind of work alright with such a basic engine.
But im still baffled by the 'heating system'. There is a hole in the floor near the drivers left foot, which apparinty is a heating vent, but i cant see where it would get its hot air from.
If its a heat exhanger system, like beetles 2cvs trabbis etc, it would need an output from the engines cooling cowl so leech some engine cooling air pressure for the heating system. But i see no such ports on this engine at all.
So...how exactly does the 'heating system' work on these?
Thanks
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heating is very basic. it just takes heat from the exhaust....
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(http://i30.photobucket.com/albums/c315/philfiestasi/DSC00194.jpg)
Here is a pic of an exhaust. Note the box on the right hand side is where the heat from the exhaust comes from (not the fumes - just heat from the pipe itself). There is a hole in the chassis and the heat travels along the chassis box section to the hole you mentioned. There should be a flap in the hole you have mentioned inside the car.
My father is in process of getting diagrams and measurements of the exhaust for you.
Hope this helps
Phil
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OOOH, this is cool, thanks very much.
So the heat exchanger is just a hollow box around a portion of the exhaust system?
In other aircoold cars, beetles of course, 2cvs, trabbis, etc, have alloy finns on the exhaust pipe to aid heat exchange, and a separate hollow jacket around it for the heated air to go into.
But this just looks like liturally just a box, right? Should be pretty easy to make.
One thing im curious about, where does the heating air come from originally? It must have a source of air, other aircooled cars use a connection to the cooling fan shroud to get some air pressure from the engines cooling fan. How is it done on these?
Also, does the heating box line up with and connect directly to the hole on the schassis memeber? Or is there like a flexible duct for example in between?
Thanks
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Ok i think i got an idea...dont laugh.
I was at the parts store looking at various exhaust systems they had, to hack up and use the muffler, and i came up with one that looked nearly exactly the right shape to fit in there. Its a Reliant Robin backbox.
So i came up with this idea. Fabricate the front section from pipe and a heater box from sheet steel (should be reasonably easy).
Then connect that to the reliant robin backbox. The mount is omitted for clarity.
Then crimp the original reliant robin tailpipe, and weld a smaller diameter tailpipe into the side of whats left of the robin tailpipe, and bend it as shown here.
That would give a reasonably standard appearence, and would hopefully be pretty functional.
(http://img.photobucket.com/albums/v405/adibrook/bubbleaus.gif)
What do you guys think?
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Well, hers todays progress
(http://img.photobucket.com/albums/v405/adibrook/ausi.jpg)
(http://img.photobucket.com/albums/v405/adibrook/ausii.jpg)
I tried it on the engine itself, and it seems to fit very nicely.
Tomorrow will sort out the heater box, and then can think about the backbox.
Still would be cool to find out where the air supply for the heater box originally comes from. Anyone know?
Thanks
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There is no air supply...its just heat from the exhaust pipe ::)
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I don't know them, but from pix it just looks like a box fits around the exhaust pipe, the air in the box warms up, and moves into a tube and thence into the cabin...as simple as that? Must be about as effective as a person breathing in the Albert Hall ! You probably get more heat transmitted through the engine mounts, to the chassis, then to the cabin, as well as general warmth from the engine bay.
Mind you in very small cars in winter you dress as for outside, the engine and your own warmth keeps the car toasty
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Hmm...this is the thing i dont understand.
The air has to come from somewhere, to blow through the heater box, and then into the schassis.
Otherwise there would be no air flow, because as hot air rises from the heater box, where would the new cold air come from to replace it?
In every other aircooled engine set up iv seen, there is air being forced into the heater box from the engine cooling fan, and therefore blows out of the other side.
Hot air in itself DOES rise, but if the the heater box only has that one stub of pipe on one side, i fail to see how there is anything more then a neglegeble amount of airflow.
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How many 1950/60s microcars had/have a heating system?
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Heinkel/Trojans do, but I heard you can get fumes from them, and when I bought my car those bits were missing, so I never bothered to obtain any. I have been out many times in almost freezing weather, and appropriately dressed, I was fine, and within 10 mins the car is adequately warm.
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Don't forget Fram King Fuldas.
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Don't forget that the Messerschmitt had a fan assisted heater and the early cars had a separate take pipe for the passenger.
The heater pipe can be deflected on to the windsreen for a demister and it is realy cold you could shove it up your trouser leg!