ESE's works engine tuner

[wobbly]

That isnt possible.
The problem is that we have a fixed set of lengths in the pipe that can only develop a depression over a certain period in time, but the rpm is varying
as we accelerate thru the powerband.
Thus as I said above the point of max depression moves in relation to BDC as the rpm varies.
We can bias the efficiency of the diffuser to act at the front side of the curve, by having the max ( widest area below atmospheric ) depression occur later
within the pipe length, or we can design it to create then max power around peak, or we can design the pipe to operate better in the overev.
The max depression part of the equation is confined quite rigidly within the boundary's set by a 32% header and a 68% mid section, but the superposition
resonance effect is governed by the port timing and the pipe tuned length, so is much more able to be "tuned" to a specific end effect.
Here is the same engine trace showing the before peak curve - notice no superposition at EPO, and early peak depression.
Then peak Hp - we have superposition and max depression around BDC.
Then in the overev - we have big superposition and late max depression.
This scenario generates the greatest peak power, and gives a long smooth roll off , of the power into the overev.
It possible to reverse the superposition position, but we will always be fighting the impossibility of stopping the natural movement of the peak depression event
due to the fixed pipe length.
We can change the depression curve shape with clever diffuser design, but it will always move from early to late in the cycle as the rpm changes upward.

[senso]

Excuse my dumbness wobbly, are those traces available in engMod after you run the simulations, or only when viewing the simulation while its running and pausing it?

[RomeuPT]

That isnt possible.
The problem is that we have a fixed set of lengths in the pipe that can only develop a depression over a certain period in time, but the rpm is varying
as we accelerate thru the powerband.
Thus as I said above the point of max depression moves in relation to BDC as the rpm varies.
We can bias the efficiency of the diffuser to act at the front side of the curve, by having the max ( widest area below atmospheric ) depression occur later
within the pipe length, or we can design it to create then max power around peak, or we can design the pipe to operate better in the overev.
The max depression part of the equation is confined quite rigidly within the boundary's set by a 32% header and a 68% mid section, but the superposition
resonance effect is governed by the port timing and the pipe tuned length, so is much more able to be "tuned" to a specific end effect.
Here is the same engine trace showing the before peak curve - notice no superposition at EPO, and early peak depression.
Then peak Hp - we have superposition and max depression around BDC.
Then in the overev - we have big superposition and late max depression.
This scenario generates the greatest peak power, and gives a long smooth roll off , of the power into the overev.
It possible to reverse the superposition position, but we will always be fighting the impossibility of stopping the natural movement of the peak depression event
due to the fixed pipe length.
We can change the depression curve shape with clever diffuser design, but it will always move from early to late in the cycle as the rpm changes upward.

What isnt possible? I think I might not being understood :/, my english is not the best
I understanded what you say before, I had read this all topic once, and read all the important coment's and data several times.

I also tested a lot the diffusor position and angles on pipes for several engines. Lately I been varying the baflle inicial percentage to see the effect's.

[wobbly]

What isnt possible is to move the rpm point at which the max depression is seen at,and not have the max depression happen earlyer at lower rpm - then later at higher rpm.
The biggest and widest depression around BDC is seen at the tuned point of the rpm and the pipe length.
The max ( lowest pressure ratio ) point will always move with rpm due to the fixed position of the diffuser.

In answer to seeing the Ex port pressure ratio ( I have the software pressure take off point set a 0 = at the cylinder wall ) yes ,you can see any trace after the run is finished
at any of the rpm points.
Go to Thermo Traces, tick Pressure Traces, load the file, pick the rpm then pick Pex.
This gives you the pressure trace centred on BDC, even easyer to see the differences.

[TZ350]

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http://www.pit-lane.biz/t117-gp125-a...-part-1-locked



There is more interesting stuff here, more stuff than you can shake a stick at .....

[TZ350]

Then peak Hp - we have superposition and max depression around BDC.
Then in the overev - we have big superposition and late max depression.

This scenario generates the greatest peak power, and gives a long smooth roll off , of the power into the overev.

Thanks Wob, this is great .......

Its taking me a bit to get my head around it all, so far I have not been able to design a pipe that EngMod thinks is better than the std RS pipes we use, but its early days.

[wobbly]

Romeau - interesting that you say that you think a " narrow " pipe would work best with a scooter that allows the engine to be
"in the power " all the time - yes this is true, and is why I believe a design that creates max power and then max overev would be the best.
I say that because if correctly designed the much stronger wave action within the pipe at high rpm, can be used to produce alot more total power under the curve.
But then you say the engine has 190* Ex, this will make it impossible to create anything like maximum power.
No engine can ever be anywhere near max output with that duration, but yes it can have superposition over a wider range than a higher Ex port
can create - and this gives a very wide flat torque output , but it will never be a proper match to run with a "narrow " pipe design for max power output.

[RomeuPT]

Romeau - interesting that you say that you think a " narrow " pipe would work best with a scooter that allows the engine to be
"in the power " all the time - yes this is true, and is why I believe a design that creates max power and then max overev would be the best.
I say that because if correctly designed the much stronger wave action within the pipe at high rpm, can be used to produce alot more total power under the curve.
But then you say the engine has 190* Ex, this will make it impossible to create anything like maximum power.
No engine can ever be anywhere near max output with that duration, but yes it can have superposition over a wider range than a higher Ex port
can create - and this gives a very wide flat torque output , but it will never be a proper match to run with a "narrow " pipe design for max power output.

I see, thanks. I just have to make pipes for what people have and the market offers to them, unfortunely most of the engines I have to make the pipes are oversquare, low timing sometimes, weak transfer port areas or entrance angles, trash designed exhaust ports, bullshit cdi's with fixed timing or change just a little, very confused owners sometimes too. It's what I got :/

By the way, the rotax 122/123 engine that is used on the aprilia rs 125 have supposedly about 182/183º exhaust timing. (some other engines have stock timing like this ex. Banshe 350) In a case like this, will this engines take profit from any superposition with a timing relatively lower than 190º? Would the residual pressure wave that arrives too soon to synchronize with the new exit pulse at exhaust open, but still make any positive/noticible effect?

Thanks

[wobbly]

The low Ex timing makes superposition able to be used over a much wider band of rpm.
In this case there is much more opportunity to design the pipe to adjust the powerband shape you want, as the tuned length resonates with the port
over such a wide range.

[WilDun]

There is more interesting stuff here, more stuff than you can shake a stick at .....

TZ - That looks like me having a go at some Hoons ( from "hoon cam") - they abused me when I was out on my mobility scooter a couple of years ago!!

[wobbly]

Quote " unfortunately most of the engines I have to make the pipes are over square, low timing sometimes, weak transfer port areas or entrance angles, trash designed exhaust ports, bullshit cdi's with fixed timing or change just a little, very confused owners sometimes too. It's what I got "

Sounds like some of the people and the engines here - they are called "bucket racers ", thats why ESE got in a Works Engine Tuner from overseas.

[TZ350]

"unfortunately most of the engines I have to make the pipes are over square, low timing sometimes, weak transfer port areas or entrance angles, trash designed exhaust ports, bullshit cdi's with fixed timing or change just a little, very confused owners sometimes too. It's what I got "

Sounds like some of the people and the engines here - they are called "bucket racers ", thats why ESE got in a Works Engine Tuner from overseas.

"very confused owners sometimes" yes, very true, and more than sometimes too ...........



Where it all started, but Thomas did pretty well though, got us to 31rwhp.

Not even Stan Stephan's has done that with an old Suzuki GP125 commuter bike from the 1980's.



And with Wobs help we are aiming for the next level, high 30's, maybe 40 .........

[husaberg]

"very confused owners sometimes" yes, very true ...........



But Thomas did pretty well though.

Thomas is the tuner? I always thought he was shipped over to be Avalons Mail order bride?

[RomeuPT]

The low Ex timing makes superposition able to be used over a much wider band of rpm.
In this case there is much more opportunity to design the pipe to adjust the powerband shape you want, as the tuned length resonates with the port
over such a wide range.

More about pipes, the stock aprilia RS pipe, for example appears to have two stage baffle, combined angles seem to give more than 14º angle.
What happens when you exceed 14º baffle angle? Does the pressure ratio start to drop more then they raise with that angle?
Is it a thin pipe that needed to begin the baffle at more then 77% to get near 14º a good choice or this narrow's to much the power band even with properly design Diffusor? I know this can be quite dependent on the engine, but in general what can you say about this?

Is quite easy to give 14º baffle to a 125cc with a pipe near 800mm and a belly 120+, but to a 80cc with much thinner belly and a little less lenght needs to start the baffle late at +77% to be near 14º.
I don't know exacly what is late or soon to start the baffle, most of the drawings I have seen and pipes measured seem to be in around 76%.

I did in my nsr tested a pipe with 14,4º instead of 14º, same lenght and belly diameter, felt no diference. Without dyno or bench I am very uncapable to draw conclusions.
Thanks

[TZ350]

Here is an oval to round spigot for Robs GP100 with RGV cylinder.
36mm pipe ID, oval shape at the duct exit is 36 wide by 27 high = effective area of a 31mm round..
This nozzle effect doesnt work on single port engines - I have tried.



Re stinger nozzles - if running a 18mm nozzle on a 100cc then you could connect a 20mm stinger tube to it in basically any length and this would not affect the power at all - in fact using the nozzle with a tapered section out to the bigger tube makes more power.
Aprilia/Derby twins do this as the top pipe has a stinger 60mm long, the bottom one is closer to 220, but the effect works on any 2T.

Wobs Oval to round Nozzel .....



Frits Overmars stinger nozzle dwg.