ESE's works engine tuner

[41juergen]

Wob, you mentioned longer time ago that the Aux Exports shall be lower as the main port to ensure a better / stronger flow pulse starting from the main port. How much should the Aux port be lower, about 1mm or even more (which would of course reduce a bit more the blow down)?

[Frits Overmars]

Wob, you mentioned longer time ago that the Aux Exports shall be lower as the main port to ensure a better / stronger flow pulse starting from the main port. How much should the Aux port be lower, about 1mm or even more (which would of course reduce a bit more the blow down)?

Jürgen, an answer in millimeters would be useless unless you also specify the engine's stroke; 1 mm would be not nearly enough for a 250 cc engine and far too much for a 6,5 cc model engine. You may have mentioned your engine's stroke here before, but not all of us will recall it.
I'd say that the aux ports are usually about 3° lower than the main exhaust port. And even this could lead to misunderstandings: if the main exhaust timing were 194°, then the aux ports would have a timing of about 188°. Geddit?
Now let's hear Wobbly's preference.

[wobbly]

C'mon Frits we all know the Aprilia had 2mm of stagger so that surely must be the magic number.
But in reality ( and Neels sim is firmly in that realm ) the amount of stagger is end use and setup specific.
As you lift the Aux, you of course increase the Blowdown STA, and the natural effects of this are to pump up the area around peak power and into overev,
and to loose mid power.
This approach though then starts to reach the diminishing returns quandry - more Blowdown helps power, less stagger starts to reduce peak power, catch 22 again.
Sadly you loose more mid than you gain top ( I ruined a KZ10 doing exactly that ) but if the cylinder has a PV that closes off the Aux then this system
greatly ameliorates that problem.

A CVT needs a ton of front side and peak power, so the Aux can be higher,as mid is unimportant ,especially with a good PV servo system.
Then we have the variable of how wide the Aux are,and the shape.
A really wide Aux around to bore center,can be much lower and still maintain the STA, a pure triangle shape can also be higher as this reduces the port linking
( helped by small end plugs as well ) but high square Aux have very good STA numbers that sadly also increase the A port short circuiting, so cant be as wide or you loose
power everywhere.
In short, the only way to get this nailed down is to take all this info into account and optimize the STA needed for your end use in EngMod.
Remembering at the same time, a single dimensional sim cant detect the bad effects of A port short circuiting, so your own intuition is just as important as the computer result,before hitting the dyno.
As always - no free lunch, and no simple answer.

[ief]

Hence why Jan made changes 0.25mm at a time, didn't get it right first time neither.

[adegnes]

The latest software has a new pipe heat release model incorporated, and for a racebike like the NSR you should use rpm driven pipe temp.
325*C at the start of the powerband and 425*C at peak power, say 8000 and 12,000.
If using a solenoid powerjet then this is modeled best by going to 450* in the overev.

Are these numbers for avgas, unleaded, or it doesn't matter?

[wobbly]

The numbers I gave I have used for nearly every engine on AvGas, as we are not allowed 110 etc here,and very few race engines use unleaded.
But as a general rule unleaded makes better power when slightly richer than AvGas, so the egt is a little lower, thus so will the pipe wall heat release model.
Against dyno testing charts on AvGas the model is all but perfect, we need some confirming dyno info from a really good sim to predict unleaded accurately.

[JdG]

Came across this video and had to share this with you guys. I think it's just enough Bucket related... http://www.flabber.nl/artikel/gast-o...maha-xj6-47490

Here's the link to the guys webpage: http://niculin93.jimdo.com/motori/zirri-m1l-2014/

Greetz,

Jacob

[41juergen]

@Frits: of course you are right, I'm too much focused with working on my engine... So it's a 56mm bore and 50,7mm stroke (TZR250 3XV) 125cc cylinder. To get better blow down I went up to 200° CA main ex port and will go round to the center line of the bore with the aux ports (with plugged piston pins).
@Wob: got it, will change the parameters in EngMod and will see were to go. The cylinder has the Yamaha drum PV with servo motor, so I can play with that a bit.

I'm still struggling with the changes in the turbulent model to get the sim back close to what I saw with the 2015 version. It looks like that the TUbMax numbers jump much more between the iterations than before, not sure how to improve that...

[FastFred]

http://www.flabber.nl/artikel/gast-o...maha-xj6-47490 Here's the link to the guys webpage: http://niculin93.jimdo.com/motori/zirri-m1l-2014/ Jacob

super fun ....................

[wobbly]

You will get much different results with the correct Turbulent numbers entered in the combustion inputs.
The initial Burnrate prescribed averages, are just that, very average, and as soon as you start to get high turbulence in the chamber from
an MSV number that is working correctly the TuB will rise due to the increase in flame speed ( and thats just one parameter ).

[adegnes]

I just run turbulent all the time. Youtube keeps me busy while waiting for sims to finish(and usually my sims are within a small rpm range, say 12-16k). It's not that slow anymore, noticed a huge difference moving to a faster computer. When doing full rpm range runs on my old 1ghz beater I used to leave it overnight...

[wobbly]

Running Turbulent is still way slower than entering the correct Burnrate numbers.
I have a 4.2GHz overclocked twin core rocket computer, and no way could I sit there watching the traces slowly walk across the screen.
when in Burnrate you cant keep up with the trace speed.
Its so easy to write a file and enter it, that seems a real waste of time not to do it.

[41juergen]

I run the turbulent model when defining the chamber with squish and comp and than put the data into the pre described table. Neels told me he modified the combustion part which changed the TUbMax and of course power. But as I have dyno curves of some of my projects which correlated very good I'm now getting definitively to low with the power estimate. Don't know how to fix that, went down with comp and combustion efficiency, but as said now being to low in the power estimate. Does anybody have a good idea for me what parameter to change?

[adegnes]

Running Turbulent is still way slower than entering the correct Burnrate numbers.
I have a 4.2GHz overclocked twin core rocket computer, and no way could I sit there watching the traces slowly walk across the screen.
when in Burnrate you cant keep up with the trace speed.
Its so easy to write a file and enter it, that seems a real waste of time not to do it.

You are absolutely right...but there's alot of interesting stuff on youtube!

[adegnes]

I run the turbulent model when defining the chamber with squish and comp and than put the data into the pre described table. Neels told me he modified the combustion part which changed the TUbMax and of course power. But as I have dyno curves of some of my projects which correlated very good I'm now getting definitively to low with the power estimate. Don't know how to fix that, went down with comp and combustion efficiency, but as said now being to low in the power estimate. Does anybody have a good idea for me what parameter to change?

Are your sims showing too low numbers?