E.T.W. Phoenix

[John PurdyParticipant @johnpurdy78347]

Twenty five or so years ago I acquired a part finished Phoeinix IC engine by E T Westbury and have been working on it off and on since. It’s almost finished and I have a question for the IC grus. In his description, he states that the driving coupling can be fitted to either end of the crankshaft provided that the engine is arranged for the appropriate direction of rotation, which should always be with the crank pin moving upwards on the transfer port side. My question is why is this?

The only reason I can think of is for an unimpeded flow of crankcase charge through the transfer port up into the cylinder, as if rotation is the other way the con rod would be moving down through the transfer port as the piston descends pushing the crankcase charge up through the transfer port into the cylinder. Any ideas?

[JasonBModerator @jasonb]

I thought it was so that the coupling is not unscrewed by the crankshaft rotation so engine rotation needs to be arranged so crankshaft is always being screwed into the coupling when under load.

[Perko7Participant @perko7]

It could be to do with the way the centreline of the cylinder is offset from the crankshaft (the Desaxe Principle) which I understand helps with improved efficiency and operation of 2-stroke engines. To run the engine in the opposite direction without a corresponding alteration to the crankshaft location would negate these benefits.

[bernard towersParticipant @bernardtowers37738]

Exactly, well done Perko you beat me to it!

[John PurdyParticipant @johnpurdy78347]

I just realized I think it is as, Perko says, because the cylinder is offset away from the transfer port. But I think the reason might be more to do with the angularity of the con rod to crank pin being less on the downward power stroke with the crank pin going down opposite the transfer port as opposed to going down on the transfer port side. Thus less stress on the con rod and crank pin.

John

[John PurdyParticipant @johnpurdy78347]

The Pheonix is finally finished! It might have been started circa 1969 by a Mr. W. Coubrey in Victoria BC (then again, he might have got it part built as I did!). Haven’t tried to run it yet, have to dig out my old “Sparky” model aircraft ignition coil and rig up some sort of test stand.

John

[bernard towersParticipant @bernardtowers37738]

Looks good ,you could try glow Plug start with to see if timing etc is close.

[John PurdyParticipant @johnpurdy78347]

But where do you get a glow plug with a 3/8-24 thread, all I have ever seen are 1/4-32?

John

[HopperParticipant @hopper]

Not enough “meat” to make a threaded plug adaptor?

It sure is a handsome looking engine, and you have made a lovely job of it. A real olde worlde look to it. Shame the castings are no longer available. Looks like a fun project.

Re the earlier posts about the offset cylinder, the offset “Desaxe” cylinder is usually used for two reasons. One is the offset provides greater leverage on the crankpin on the power stroke, thus increasing power, while at the same time reducing side-thrust on the piston, thus reducing friction.  Was used for this reason as far back as steam engine days, then by Henry Ford on his sidevalve (flathead) V8s, and now by Yamaha on their latest high-performance sport motorbikes. I believe the Norton Commando in the 1970s used it too.

The other reason is the offset means the downstroke is longer than the upstroke, in degrees, due to the geometry. Very counterintuitive but a well established principal in engine building circles. So on a two stroke, you get asymmetric port timing, allowing the transfer port and exhaust to stay open longer on the down stroke than the upstroke, which supposedly aids cylinder filling and boosts performance.

Old ET was a cunning operator.

[JasonBModerator @jasonb]

Looks Good, the only bit that detracts from my eye is the machined square where the cylinder mounts to the case but probably done before you got hold of it.

I’d just dig out your ignition box and try it at least then you have the ability to adjust the ignition timing with the bracket.

I suppose if somebody wanted to build one enough then there are a few routes to go down, cut crankcase from solid, cylinder a steel fabrication as it has an iron liner, head again from solid, manual or CNC for the cutting. Or of you are into home casting then 3D printed patterns and cast in aluminium. Deep pockets may think about 3D metal printing. I keep looking at Westbury’s Apex Minor as a possible but its just one on a long list😉

I know someone who did have dies for some of the older engine designs as well as a lot of raw castings but he is not in good health and would not know which engines he has them for now.

[Ches Green UKParticipant @chesgreenuk]

As Hopper notes, Offset Cylinders have some very interesting characteristics.

By coincidence, I was watching this informative video (24 mins) on the subject the other day … Cylinder Offset Changes Everything – https://www.youtube.com/watch?v=gwtZkHoVMso

Ches

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