Ex.Chamber Science

[Tomtall]

Gotta thank Jeff Lytle for finding this one.Cool site Jeff! http://kawtriple.com/mraxl/expansionchambers.htm

[Seagull 170]

But I can't work out why his reeds are chuffing at the end of the inlet stroke, give me that M6 spanner I want to have a look at them.

[kws]

somethings just make you hmmm
makes me wonder why they called them expansion chambers and not a packing chambers

[Mark75H]

The term "expansion chamber" actually pre-dates the late 1950's MZ tuned pipes. I was quite stunned to see it in literature from the early 1950's. At that time it simply refered to a closed area for exhaust gases to expand in. It would be very interesting to learn how the phrase "expansion chamber" came to be associated with tuned pipes .... could have been a misnomer by some boat racer or perhaps Carl Kiekhaefer himself. I think a query to Mssrs. Strang and Rose is in order.

The first outboard I've seen with closed end pipes is the 1961 Carniti V-4 500cc racer, followed by Königs a year or so later .... after 2 years of the Carniti dominating 500cc racing in Europe. I think Carniti took the 500cc World championship 2 years in a row before König switched to loop charging and expansion chambers. König's switch to loop charging is what drove Christner to produce the Quincy Looper. You have to fight fire with fire sometimes.

[kws]

i think i read somewere the germans played with expansion chambers in the 20's. but i could be very wrong lol have slept many times since i read that.
but one thing is for sure that is a great illiustration
if a picture is worth a thousand words, a moving colorized picture might be worth 10,000 words lol

[Mark75H]

A German developed loop charging in the 20's. Expansion chambers were also invented by a German, but it was the late 1950's.

[OUTBOARDER]

But I can't work out why his reeds are chuffing at the end of the inlet stroke, give me that M6 spanner I want to have a look at them.

As the piston is on it's way down the pressure in the crankcase builds up and at some point overcomes the inlet pressure wave thru the carb and the reeds slam shut. The air/wave that was flowing thru carb rebounds of off closed reeds back out of carb as a result. "Chuffing"
Happens more at certain rpms than others, typically at lower rpms.

After getting on plane the 45ss the engine has fuel puddled in lower pan from this.

Can cause a 2-stroke engine to load up with gas mixture from picking up fuel twice thru carb.

Ideally the over rich condition can help with engine accelerating, like what a accelerater pump does in a automotive carb. The rich condition also lowers egt temp and lowers tuned rpms of the pipe which helps with making effective rpm range larger.

[Powerabout]

they all do the reverse fuel thing
Get an engine in a test tank and use a timing light just in front of each barrel of the carbs.
There is always fuel in front of them
( try it at night!)