ESE's works engine tuner

[TZ350]

[ken seeber]

Was looking up info on air brake dynos and remembered this article in my scrapbook. It is readable, but you might have to persevere a tad.

So interesting is the fact that it is 40 years old and old mate, Barry Hart, is on about things that are still being discussed today.

http://yorkshireferret.blogspot.com/...-and-more.html

[husaberg]

Was looking up info on air brake dynos and remembered this article in my scrapbook. It is readable, but you might have to persevere a tad.

So interesting is the fact that it is 40 years old and old mate, Barry Hart, is on about things that are still being discussed today.

http://yorkshireferret.blogspot.com/...-and-more.html

Herbert Munro
https://www.kiwibiker.co.nz/forums/s...post1130432948

[RomeuPT]

I have to ask , why are you using 1mm - I have tested this twice now on completely different engines.
0.8 makes better power.
1mm in SS would be a nightmare to hammer , as you have found.
But if the cuts are shallow enough , and with well purged welds you dont need to hammer them - in this case , no power lost.

Edit - added a un hamered pipe pic

Thanks for all answers

I am using 1mm because it's for decent lasting exhaust's. 0,8 cant stand long on engines with shittie ton of vibration that some ignore has normal, then even with 1mm I have occasional header welds cracked which is bad for feedback. Also welds easier.

It's not hard to hammer, its just that I have done alot over the years and its getting heavy.

In some cases 20€ is enought to lose a sell to others, so It wont pay a decent spring adapter either.

The pipes are not for racing but for weekend road use, fun... poeple like to see the header welds and it helps selling.

Looking for tools to keep doing my job not to change the product, but thanks anyway

[Mike Fisher]

Was looking up info on air brake dynos and remembered this article in my scrapbook. It is readable, but you might have to persevere a tad.

So interesting is the fact that it is 40 years old and old mate, Barry Hart, is on about things that are still being discussed today.

http://yorkshireferret.blogspot.com/...-and-more.html

Barry Hart has published a book 'Pursuit of Dreams' and an e-book technical supplement that starts with 'How to Win Races' then includes Producing gear change selector drums, Producing crankshafts, Aligning crankshaft gears, Tuning Engines & dyno Testing, Basic Tuning theory , The importance of Torque, Variable true compression pressure Engines (VCE), Specific Time Areas, Twin Firing Order, Power Valves, Exhaust Power Valves, Inlet power valves, etc. available from https://www.pursuitofdreams.co.uk

[Pursang]

Ok!...Burt was able to load nearly 100 bhp with 2 plywood paddles of 8" x 14" rotating at 2000rpm.

If one had access to a machinery salvage site and could obtain something like this it might allow a safer setup.



Rated at 100bhp for mine ventilation, grain drying, lots of uses.

Redirect the outlet for engine cooling.

Cheers, Daryl.

[Larry Wiechman]

Dobeck air dyno.http://www.axisdyno.com/

[OopsClunkThud]

CFD of the exhaust has turned into quite the rabbit hole.

The results on simscale were showing the adding side wall angle was almost always helpful, but kind of all over the map in trying to find "the best" angle. Started looking at 2D simulation of the port roof and piston crown first and have the first insight that I think is useful.

The flow is sonic for most or all of the blowdown. There is clearly separation at the port roof but to keep the same timing any radius there will have to impose on the flow (same at the side wall). That is likely worth it, still need to check that out. But to speed up the flow before it gets to the port needs something inside the cylinder, like a radius on the edge of the piston maybe... At sonic speeds it does not take much of a chamfer to create an expansion fan. This test has a chamfer that is 2mm in from the edge of the piston and angled down only 10° from the tangent line of the piston crown. This lowers the timing edge of the piston by .4mm, far less than a full radius. I was expecting to see two things:

1. The point where the flow goes sonic moves inward from the timing edge of the piston to the edge of the chamfer (result: Yup)
2. The mass flow rate across the port face increases (result: ~5% increase)



The image on the left has a normal domed top piston and the flow goes sonic at the timing edge. Image on the right has a shallow chamfer on the edge of the piston and the flow goes sonic sooner, at the start of the chamfer, while it’s still inside the cylinder.

One other observation is that depending on the shaping of the port walls you can end up with shock diamonds (wasting a lot of the exhaust energy) or a single shock when it drops back to subsonic.

[wobbly]

The CFD results sure are interesting. And looking at EngMod results for the RSA at 13,000 , yes the port face is sonic almost till TPO.
What I have wondered about is the results I have got from two tests.
First was a piston comparison. Normal 4* conical Vs a flat top with a 1mm radius .The flat top was 0.5mm taller so the effective EPO/TPO was the same.
The result , with identical compression and squish , was a good gain to the radius piston up the front side to peak , but an even bigger loss in overev power.
It would be interesting to see what effect the radius has on boost port flow , as it has been reported here that deleting the radius over the boost , and adjusting the timing back to original
gave an increase in power everywhere.
This I have not had time to do as of yet.
My take on it is that the radius over the boost pulls the boost port flow that has stayed attached to the piston , down toward the Exhaust port , instead of up the rear wall.
Be interesting to see what CFD shows in this area.

[andreas]

CFD of the exhaust has turned into quite the rabbit hole.

The results on simscale were showing the adding side wall angle was almost always helpful, but kind of all over the map in trying to find "the best" angle. Started looking at 2D simulation of the port roof and piston crown first and have the first insight that I think is useful.

The flow is sonic for most or all of the blowdown. There is clearly separation at the port roof but to keep the same timing any radius there will have to impose on the flow (same at the side wall). That is likely worth it, still need to check that out. But to speed up the flow before it gets to the port needs something inside the cylinder, like a radius on the edge of the piston maybe... At sonic speeds it does not take much of a chamfer to create an expansion fan. This test has a chamfer that is 2mm in from the edge of the piston and angled down only 10° from the tangent line of the piston crown. This lowers the timing edge of the piston by .4mm, far less than a full radius. I was expecting to see two things:

1. The point where the flow goes sonic moves inward from the timing edge of the piston to the edge of the chamfer (result: Yup)
2. The mass flow rate across the port face increases (result: ~5% increase)



The image on the left has a normal domed top piston and the flow goes sonic at the timing edge. Image on the right has a shallow chamfer on the edge of the piston and the flow goes sonic sooner, at the start of the chamfer, while it’s still inside the cylinder.

One other observation is that depending on the shaping of the port walls you can end up with shock diamonds (wasting a lot of the exhaust energy) or a single shock when it drops back to subsonic.

Excuse the ignorance, but what is, and what is the cause of shock diamonds? Nevermind I just remembered where they explain stuff. But for sure is interesting.

[OopsClunkThud]

...what is, and what is the cause of shock diamonds?

It's a pattern that forms in a supersonic flow that has expanded and dropped to a pressure of its surroundings. Mostly seen in rockets and afterburners, the gas passes through a shock wave that brings it subsonic, then passes through an expansion fan and goes super sonic, creating the pattern. It's not like we want the exhaust to be a rocket (I don't think we do) but we do want to conserve the energy as a pressure wave and not just heat. So if it's not too hard to prevent them I think it may be worth doing.

Wind tunnels have lots of tricks to prevent them, and a taper in the exhaust stub looks a lot like some of those tricks.

https://en.wikipedia.org/wiki/Shock_diamond

Much of this is beyond my pay grade, but rabbit holes... oh and sonic flow is weird

[Muhr]

An explanation for us mortals.

http://franciscoalario.aero/shock-diamonds/

The question is whether this happens to any great extent what is the pressure difference vs velosity?

"They are triggered by the gas pressure at the exit of the engine bell being higher than the surrounding air pressure"

"The mass flow rate for a compressible fluid will increase with increased upstream pressure, which will increase the density of the fluid through the constriction (though the velocity will remain constant). This is the principle of operation of a Laval nozzle. Increasing source temperature will also increase the local sonic velocity, thus allowing for increased mass flow rate but only if the nozzle area is also increased to compensate for the resulting decrease in density."

https://digital.library.adelaide.edu.../2/02whole.pdf

[ceci]

Upon discovering this patent.

https://patents.google.com/patent/US...?oq=US3289656A

The title or name of it made me think about this:

And adding to the effect of having very high exhaust duration you can cut the skirts short such that the port is open a few mm when the piston is at TDC.
Wreaks havoc with the jetting , but in the project i tried that we were using big pumper carbs.
Very easy to adjust the fuel curve as was needed - but I doubt a normal carb could be made to work.
This setup on a " stock " 950 SeaDoo gave an added 8 Hp in about 80 , so 10% - enough for the title at Havasu.
On a 1180 twin race motor the bump was 15 Hp in 120 so a little less.

that is precisely because of this word "crossfeed"

There are structural differences between this and Wobbly's and it may be that in these differences this is the key to success, wobbly if it has shown the increase in power.

Does anyone know if in motoGP 500 and motoGP 250 if they investigated with something similar.
With the multitude of projects that people do multi-cylinder, nobody works on anything like that

[OopsClunkThud]

The CFD results sure are interesting. And looking at EngMod results for the RSA at 13,000 , yes the port face is sonic almost till TPO.
What I have wondered about is the results I have got from two tests.
First was a piston comparison. Normal 4* conical Vs a flat top with a 1mm radius .The flat top was 0.5mm taller so the effective EPO/TPO was the same.
The result , with identical compression and squish , was a good gain to the radius piston up the front side to peak , but an even bigger loss in overev power.
It would be interesting to see what effect the radius has on boost port flow , as it has been reported here that deleting the radius over the boost , and adjusting the timing back to original
gave an increase in power everywhere.
This I have not had time to do as of yet.
My take on it is that the radius over the boost pulls the boost port flow that has stayed attached to the piston , down toward the Exhaust port , instead of up the rear wall.
Be interesting to see what CFD shows in this area.

for the "Normal 4* conical" did that have a flat in the center? if so did the flat extend to the edge of the squish?

[wobbly]

In the radius tests I did the normal 4* conical did not have a flat top.
That design came later as one of the planned updates for the R1 engine.

I tested first the flat top extending right out to the squish edge of the chamber , but in the KZ engines the SAR is only about 34% due to the straight line ignition curve.
Next I made the flat top 50% of the piston area , this combined with lowering the plug/roof as much as possible within the cc constraints , made easily the best power.

For some reason beyond my grasp of Italian tech talk , the factory combined my proven flat top design , with a new piston skirt having a big cutout above the pin to reduce weight.
This almost halves the power gain , given by simply taking the older model light weight design with a 0.8 ring and machining 1.2mm off the conical dome.
That trick proved the dome was too thick to start with , and ends up being much lighter than the new Vertex effort.