ESE's works engine tuner

[wobbly]

Sorry, wrong end of the stick re being a 250 cylinder.
Re the 3:1 mill/lathe.
I had a cheaper Smithy for 20 years and it worked really well, but the big issue was that the swing height was " just " too low to machine
twin heads like RZ350/Banshee etc.
So I sold it and got a very similar machine that seems to be copied by various Taiwanese company's that has a much higher swing.
Only issue is I couldnt get one at the time with powered cross feed, big mistake - sure to be one now I would think.

[peewee]

im assuming you were using the lathe function to machine the chambers. the engine head was contacting the mill head ? i know on most of the new smithys the mill head swings 360* so it can be moved out of the way but im wondering if a twin cyl head wouldnt hit at the bottom where the table is. website says they have power feed on x and y axis. i would defintaly have to machine twin cyl heads

anyways one more day of build up and it should be good enough. thinking it would be warped to buggery if i didnt attach the two plates. it broke one of the tack welds and started pulling down. ill probly weld the plates on alittle stronger tomorow

[wobbly]

The Smithy machine you showed has a swing of 12", not enough.
The other machines with greater swing to the bed have 16" - plenty.
Yes you have to be able to center on one spark plug hole, and on a Banshee the head will hit the bed of a 12" swing machine..

[nick gill]

Attachment 313217

Really interesting 'hack' there that I'm going to take to my next dyno session.

A question about the placement of piston windows for cylinder/reed engines:

If flow velocity and mass transfer into the cylinder is maximal at BDC, then does that also mean crankcase induction through the reed is also maximal at BDC, and therefore windows ahould be made to this optimisation ?
It could be the difference between modifying Windows, a Skirt, or both...

[husaberg]

Really interesting 'hack' there that I'm going to take to my next dyno session.

A question about the placement of piston windows for cylinder/reed engines:

If flow velocity and mass transfer into the cylinder is maximal at BDC, then does that also mean crankcase induction through the reed is also maximal at BDC, and therefore windows ahould be made to this optimisation ?
It could be the difference between modifying Windows, a Skirt, or both...

No idea maybe Wob will chime in the Robinson Book has a bit on reed frequency with some dyno results.

[Frits Overmars]

If flow velocity and mass transfer into the cylinder is maximal at BDC, then does that also mean crankcase induction through the reed is also maximal at BDC, and therefore windows should be made to this optimisation ?

The flow velocity from the crankcase to the cylinder will increase as long as the crankcase pressure is higher than the cylinder pressure.
At max.torque rpm the flow velocity reaches its maximum at roughly 10° to 20° after BDC; then the crankcase pressure and the cylinder pressure are equal, and they are also roughly equal to atmospheric pressure. The reed will only start to open when the crankcase pressure drops below atmospheric pressure, so it won't even begin to open until after BDC.

[jasonu]

To anyone, why do Frits' .pnf attachments take forever to load? They take so long that I never have the patience to wait them out. Any way I can speed this up?





No, SOME un-American fools, having been talked into believing the claims of certain socialist pinko bedwetter Europeans that their measurement system is inherently superior, have been messing with our perfectly good system. Why is a decimal system of measurement better than a fractional one that's easily divides into 12, 64, and 360, evenly. Sometimes decimals are more useful, sometimes fractions are, neither is superior all the time. This same bunch of fools convinced automakers that sideways-mounted engines and transaxles with CV joints that soon have an inch (an INCH, dammit!) of accumulated lash is the way to go. Try to swing a wrench in one of these miserable vehicles!! Good old American cars had the engine here, the transmission there, and the differential back there, so you could work on any of them relatively easily.

Metric system, aargh! I learned to work with it fifty years ago when I raced German Konig outboards, but still don't see a reason we should change. Y'all can change!!

There are around 400 million yanks using the standard system. Why should they change?
Mind you, my 1989 Chev pick up (ute) has both standard and metric bolts on it which is a real pain when you crawl under it with a 12mm socket only to find the bolt is 1/2 inch...

[Yow Ling]

There are around 400 million yanks using the standard system. Why should they change?
Mind you, my 1989 Chev pick up (ute) has both standard and metric bolts on it which is a real pain when you crawl under it with a 12mm socket only to find the bolt is 1/2 inch...

population of America is 319 million, I guess you must have included the mexicans

[jasonu]

population of America is 319 million, I guess you must have included the mexicans

It is hard not to...

HAPPY INDEPENDENCE DAY TO ALL THE SEPTIC TANKS THAT LURK AROUND KB!!!

[wobbly]

The reeds opening and thus initiating case inflow is as Frits detailed, dependent upon the pressure differential
across them.
In this typical example that does have critical intake tuning - ie where the intake length is arranged such that as the case goes negative,the bounced off atmosphere
intake wave is arriving as a coincident + wave that opens the petals quickly, there is no significant reed inflow till the transfers are starting to close.
There is certainly no flow around BDC, so this will obviously affect your thinking as to what will be important re shaping the rear of
the liner and piston cutaways etc that are in the way ie the position of the bottom timing edge of the piston has alot more affect on power than do skirt windows
on the inflow of a cylinder reed - as do the shape and area of so called Boyesen ports.

[nick gill]

Frits + Wobbly Love your work !!

Thanks for short cutting what would take me a very long time to discover in isolation.

[peewee]

wob i got these pistons back finally . i think what ill do is cut the sleeves out and put the aux exh ports in then reinstall some new sleeves. pretty sure the casting will pull miles away from the sleeve otherwise

[nick gill]

Is that a Blaster Piston Peewee?
I just bought a Banshee piston in 66mm because the compression height suits me better than a blaster. I bought a Namura piston because of all I learned from Jan and Frits - it is cast not forged, skirt coated, and anodised dome to harden it without effecting it thermally. Problem is Namura thought they'd do us all a favour and lighten it by shortening the skirt 10mm to 60mm. Well my stroke is 62mm, so Dang! It will sit on the shelf for years....

[peewee]

the pistons jan and frits used werent made by namura. namura i believe is taiwan or china, i dont have much faith in either place

[Frits Overmars]

Namura thought they'd do us all a favour and lighten it by shortening the skirt 10mm to 60mm. Well my stroke is 62mm...

Well, maybe Namura (first time I've heard of it) did do you a favour. The skirt length is not determined by the stroke but by the distance from TDC to exhaust port bottom. If you raise that bottom (TZ350 posted lots of how-to pictures) you can use your pistons and you may also be in for a pleasant surprise, power-wise.