I'm looking to build a tuned pipe for my HS-50. I have killed all my brain cells trying to find the specs. for the m48 engine. What I need to find out specifically is the exhaust port angle, the transfer port angle, the exhaust port area (I might be able to find this out if I can ever find my mic.), and the aproximate exhaust gas temp. Nobody, and I mean nobody seems to have this info. I didn't want to leave all this up to you experts (again!!!) but I've run out of rope. Any help???
Richard
I take it you are using the "tuned pipe" program from the MacDizzy site?
(listed on this site as"tuned pipe by Java")
Can you follow the instructions there for measuring port timing?
First make a degree wheel (you can prob photocopy one out of a hotrod car book at the library)... then stick it to a piece of cardboard and put a hole in the middle and attach it to your flywheel and make a pointer out of a coathanger or something.
Then remove the cyl head and measure the "port angle" (its actually called port timing).
Orrr... If you want to make it easier on yourself.. just copy a BiTurbo.
Orrr.. copy the dimensions used by 'Michael' on this site... he put his dimensions on here... only if you do... shorten his middle section and overall length 2 or 3".
I am using a few different sources for getting the pipe length as close to perfect as I can. I've got a line on an extra engine which I'll use as a test bed. I've thought about changing the timing slightly as well as adding the pipe so whatever changes are made, I'll still have a running 'ped. I have though about copying a bi-turbo....I kinda want the satisfaction of building one from scratch (even better if it works!!!) and I hace a great supplier of FREE stainless steel who can even get it chromed for almost nothing. In theory, I could chrome my entire moped for about $40 (cdn)!
I am also tinkering withthe idea of switching from a chain drive to a belt drive to reduce frictional losses. Anyone done this? I REFUSE to do anything that is wholly unreversable just to gain a couple mph. Besides, I love a challenge.
Richard
Well... there is no "perfect" as far as length (and all the other dimensions) goes... there are tradoffs with every change... you gain some of this.. you lose some of that.
And in fact .. to make it easier on yourself.. make the center section with a temporary overlapping "slip joint' so you can change it at will to see what you like best..then when you settle on what you like... chop the extra out and weld it up.
Use a target RPM of 8000 or so.
That is safe enough for a small engine like a ped.. and should still gain you enough top end to make you happy.
Richard,
<Quote> I am also tinkering withthe idea of switching from a chain drive to a belt drive to reduce frictional losses. Anyone done this? I REFUSE to do anything that is wholly unreversable just to gain a couple mph. Besides, I love a challenge. <Quote>
What friction losses have you calculated or do you feel are encountered with a chain drive? The nice thing about chain drive is that it is a solid connection in that you don't have slippage losses like you encounter with a belt drive. The more HP you make the tigher the belt has to be to overcome slippage and then you start putting unneeded stress on your drive train bearings.
Brian
Lamborn's Miniature Engines
I want to reduce any\all mass that I can. I'm 6'4" and 250lbs so any weight saved on the 'ped as a gain for acceleration. If the engine doen't have to work so hard to move that extra weight from the steel chain and sprockets....Bob's yer uncle. I figure I'll use aluminium pullies and I can get a good toothed belt easily enough. I am mostly curious about how well it'll work.
Richard
Without extending your shafts... you increase the overhung load on the bearings because the pulleys are wider... a belt and pulleys of equivalent strength weigh only a fractional amount different than a chain.. and might even be heavier.. moped chains and sprockets are tiny... and light.
The belt will be wider and you might not have room with a R shock or frame in the way.
Then there is the money... 2 pulleys and a belt... $100 minimum.. not including the machining to mount them.
About the only thing toothed belts are.. is quieter and cleaner.
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