ESE's works engine tuner

[wobbly]

Yep , tape up around the reeds and use plasticine around the piston edges.
Re the reed block , make the spitter as thin as you can under the petal tips with a right angle step as you had on the 1/2 moon sides previously.

[Grumph]

Had a visit today from a pensioner who lives around the corner. Quite liked the latest project. Plenty of ideas and memories discussed.

[wobbly]

That pensioner has forgotten more than most of us have learned yet.

[mprestwi]

Wobbly sir, with this recent discussion around stepped reed cages you had mentioned in the past that you had other examples where non-aerodynamic applications went against expected results and made more hp. Any chance you could elaborate on this?

[wobbly]

Only ones that come to mind are the 2mm smaller venturi inside the reed block , that is smaller then the already too small carb , and , not having a slow taper exiting from a stinger insert.
This should have a 45* step , and reduces the effect of the waves bouncing up and down the stinger , from the atmospheric end ( the muffler entry in the case of a KZ ).
These can interfere with the main positive reflection off the reverse cone , as the + wave bouncing off the open ended pipe reverses sign and travels back to the stinger entry.

Edit - the other I just thought of was the geometry of what Neels refers to as the " contact discontinuity " at the interface of the spigot transition from round ( at the header start ) to oval ( with ears in a 3 port ).
Where this very tapered transition meets the cylinder duct , the best geometry is to have the taper on the floor of the spigot colinear with the duct floor.
This in effect means the spigot centerline is moved up , such that most of the transition taper is in the roof.

Again counter intuitive , in that you would think " helping " the return wave front along the roof would give the best return pulse amplitude , when its needed , as the piston is nearing closure.
Not so , I built 3 spigots in CAD and had them CNC cut , one with the male spigot centered on the duct exit , one with it lowered 3mm , and one with it lifted 3mm.
Guess which one was 3Hp up at 14500 over the worst.

[wobbly]

Sir - that assumes I am a gentleman , this proves otherwise.

[jfn2]

Wobbly
A few pages back you were talking about reeds and UFO's and other air directional devices. Back in the late nineties, early 2000's a couple of us guy's were on the MacDizzy forum talking about how to get better air flow through the carburetor and we were working with placing a divider (UFO) in the venturi and that instead of using a straight center bar that using an up-side down air foil worked much better. We also found that the placement of the horiz bar didn't necessarily have to be in the middle of the bore. In fact if it was placed about 10mm above the top of the needle jet spout it worked better. Of course it would (I think) depend on the size of the carb. I was using it with a Mikuni 38mm AS carb. We placed this UFO right up to the carb throttle valve. We also tried using 2 bars, one in the middle of the bore and one down a little bit. We also used a honeycombed alumn waffer in the front of the carb air horn. In fact we milled a slot for it to set into, at the very front of the air horn. Both of these together worked very well. But we didn't have a dyno or flowbench back then to test with. I was building bikes to run in the GNCC on the east coast of the US. Made for very good throttle response. And we could run a size bigger carb. Why couldn't a airfoil be used in the reed cages? Or a bent airfoil? Also, I used to work for an asphalt co. that made asphalt for road use and in their plants they use a very big fan and a 48" duct work to clean and dry the stone. There is a big cost associated with running a big electric motor to turn the fan. To make it more efficient the accepted practice is to put dividers in the air duct in the, usually, 90 deg turn into the fan. These dividers are bent at 2- 45 degs and if only using one divider placed in the middle of the flow, or if using 2, are placed at the 1/3 and 2/3 part of the flow. It works. Why couldn't this be done in the intake manifold to the reed cage?
Also wanted to ask you about the rear cone of the expansion chamber pipe. What %'s do you suggest to use for a 2 and 3 part cone? Thanks Jeff

[wobbly]

The thingy called a UFO ( Ultimate Flow Optimizer ) from Thunder Products goes into the bottom of a Mikuni round slide.
What you are talking about is an even bigger marketing masturbation called a Quad Flow Torque Wing.
Both work , the first to increase the idle and transition signal at low throttle openings , and to reduce turbulence from the slide cavity at WOT.
The second , effectively divides the carb in 1/2 at part throttle , again , increasing response in a carb with shit part throttle response.
This is all fine if you want ( or have to ) use Mikuni round slides - not needed at all in a flat slide of recent manufacture.

The next idea of a wing cross section in the middle of a reed block entry has been used forever by VeeForce , only because that is the only way to build one.
I have tried all manner of splitters/wings etc in the KZ application where a small carb feeds a big reed block.

After 3D printing more blocks than my lifetimes hot meals total , I have given up.
A simple horizontal divider made from carbon reed material or thin sheet metal works the best with the stepped end under the reed tips.
As usual being a 2T designed to disappoint at every opportunity , I got real clever and made a wing section with the forward end tipped down to help bias the flow upwards as it exits into the case chamber.
We already do this with much differing petal and backup stiffness on the top and bottom reed sets.
Did it work - of course not - picture of failure number 9576 enclosed.

Lastly the rear cone geometry.
Forget a 2 cone - its not even in the same area code as a 3 cone.
What the 3 cone concept allows is you can ameliorate the annoying trend , that as you increase the rear cone included angle , you increase the upper front side and peak power , at the direct expense of overev
bandwidth.

Each engine application is usually highly specific re overev requirement - look at a drag race CVT vs a Roadrace bike.
One needs NO overev , the other as much as can be generated without sacrificing too much front side and peak.
There are no guidelines to get you in the ballpark with this.

Suffice to say the length and angle of the last cone sets the peak and overev potential , and the middle cone sets the front side bandwidth.
The only way is to run a shit ton of EM2T sims , with maybe a little guidance from the R1 pipe design I have published - but that is super end use specific design , of no use whatever in other applications.

[mprestwi]

Thanks for the reply Wobbly. No disrespect intended.

[wobbly]

None taken , just been dying to show the sign I put up in the kitchen when the mother in law arrives.

[jfn2]

Thanks Wobbly for the reply.
As they say.... No rest for the weary.
I do appreciate the time taken. And the info.
Jeff

[Pagi]

Wobbly, sorry to ask again a question about reeds ( my english is poor....and google translate too!!!!), but what do you mine by " the divider with a stepped end under the reeds tips" ?....do you have a drawing or picture....

[Condyn]

Edit - the other I just thought of was the geometry of what Neels refers to as the " contact discontinuity " at the interface of the spigot transition from round ( at the header start ) to oval ( with ears in a 3 port ).
Where this very tapered transition meets the cylinder duct , the best geometry is to have the taper on the floor of the spigot colinear with the duct floor.
This in effect means the spigot centerline is moved up , such that most of the transition taper is in the roof.

Again counter intuitive , in that you would think " helping " the return wave front along the roof would give the best return pulse amplitude , when its needed , as the piston is nearing closure.
Not so , I built 3 spigots in CAD and had them CNC cut , one with the male spigot centered on the duct exit , one with it lowered 3mm , and one with it lifted 3mm.
Guess which one was 3Hp up at 14500 over the worst.

The complexity of that transition makes my brain hurt, the counter-intuitive aspect as well. Does anyone have any theories on why the roof taper works better?

[Pagi]

Thanks Wobbly for the reply.
As they say.... No rest for the weary.
I do appreciate the time taken. And the info.
Jeff

Wobbly, sorry to ask again a question about reeds ( my english is poor....and google translate too!!!!), but what do you mine by " the divider with a stepped end under the reeds tips" ?....do you have a drawing or picture....

sorry ( my poor english again... i just see my error in my question.....i need to return at school:rolleyes ), but what do you mean with a step at the end of the divider under the reeds tips.

[wobbly]

Super secret squirrel shit this.
Seems to work well with the asymmetric reed tensions biasing flow upward under the piston.