ESE's works engine tuner

[husaberg]

Ok, great. Our motors move the bike and us. Tq is a static measurement, not moving us yet until you enter time into the equation. Hp moves us. Rate is the time then, correct?

I understand you guys threw them out a couple of hundred years ago, but English please?
Torque is work, HP is the rate at which this work is performed.
Remember the horse and the bucket.

[Sketchy_Racer]

Ok, great. Our motors move the bike and us. Tq is a static measurement, not moving us yet until you enter time into the equation. Hp moves us. Rate is the time then, correct?

Yes, Hp (which i hate, as we use Torque in Nm (metric) and power in HP?? I prefer kW but i digress...) Is the "power" we have available to move us. The faster we move the more work is done the more power is required.

But in terms of looking at how the motor is best performing then torque shows where the motor is working the most efficiently irrespective of the power output (which is a product of the torque.rpm) Eg: Peak torque will be where cylinder filling and combustion is the best.

[husaberg]

Yes, Hp (which i hate, as we use Torque in Nm (metric) and power in HP?? I prefer kW but i digress...) Is the "power" we have available to move us. The faster we move the more work is done the more power is required.

But in terms of looking at how the motor is best performing then torque shows where the motor is working the most efficiently irrespective of the power output (which is a product of the torque.rpm) Eg: Peak torque will be where cylinder filling and combustion is the best.

BMEP is I think the best measure of an engines efficiency (but I have been wrong more times than I care to count)
But lap times and race wins are what actually counts.

[paul gane]

This is my first post, I've been following this fantastic thread for over a year now, and have learned so much, many thanks to you all.
I have been building a TZ350 with a 58mm banshee crankshaft. We're now at the stage where I need to weld a plate to top surface of the cylinder. I see Wobbly has already done this on the Frepin TZ350, with great success. I am planning on keeping the standard bore size 64mm, I need advice on what is the best grade of aluminium plate for the welding, and any tips on minimising bore distortion during the process. Many thanks in advance.
PS can't wait for the Ryger technology to be posted.

[TZ350]

BMEP is I think the best measure of an engines efficiency. But lap times and race wins are what actually counts.

Race wins for sure but BMEP has the benefit of allowing you to compare one engine to another of the same type. Whether it is an industrial engine being compared to a lawn mower or something more racy. BMEP is a yardstick for comparing engine performance and can also give you an indication whether the stated claims for an engine are probable or not.

BMEP is just a number and is defined something like the mean average pressure that if applied uniformly to the top of a piston throughout the full stroke would produce the same torque as measured for that engine.

[Frits Overmars]

Hi Frits. So I guess I've misinterpreted this part of my 2T education . This may also kill off my other two deto interventions, namely 1) Putting a Thermal Barrier Coating on the smooth surfaced ex port duct (easily removed, phew) 2) Fabricating a Ti header section. Am I following your logic correctly? Or would I have been better to put the TBC on the textured transfers and keep the ex duct as a heatsink for the gas column?

I'd say you've grasped it Nick. A thermal barrier coating will do a good job any place where the fresh mixture comes into contact with hotter surfaces, excepting surfaces that also come into contact with even hotter spent gases.
These latter surfaces are all surfaces of the combustion chamber, including the top of the piston, and the first part of the exhaust duct.
As a rule of thumb I'd say that the length of this first part of the duct should be such that it can contain a volume equal to one cylinder capacity.
Isolating the remainder of the exhaust system, where fresh mixture does not come, is fine. So you can build your titanium header section, and the whole rest of the pipe, from that distance on.

The faster we move the more work is done the more power is required. But in terms of looking at how the motor is best performing then torque shows where the motor is working the most efficiently irrespective of the power output (which is a product of the torque x rpm) Eg: Peak torque will be where cylinder filling and combustion is the best.

BMEP is I think the best measure of an engines efficiency (but I have been wrong more times than I care to count)

Not this time Husa; you're quite right. A BMEP-curve and a torque curve are identical, just with different values along the Y-axis.
Torque curve values are also dependent on cylinder capacity; BMEP-values are not. So like TZ350 says, BMEP-curves are the best means of comparing engines.

Sure did Frits, and I agree completely that we should be using the blowdown as a basis for all this, as it has a direct relationship to the power capability available. Now that we are seeing the real possibilities surrounding lifting the port floor, this is again making the port window area even more irrelevant so I need to start generating a data point set to indicate the numbers we need to be looking at based on blowdown STA. Add to this the duct length factors I detailed before and then real gains can be made with ease.
Neels has done an update to the EngMod RSW sim using the above numbers that will make your socks roll up and down.

Yes, I had an exciting email-exchange with Neels; I think we should permit ourselves a wee single malt, Wob .

[nick gill]

As a rule of thumb I'd say that the length of this first part of the duct should be such that it can contain a volume equal to one cylinder capacity.

Thank you Frits. Excellent information as usual.

[ief]

Perhaps related.. In engmod you see possible outcome in the STA and then one sees exhaust port say 5 hp and blowdown 6 hp. That seems weird since the blowdown is part of that same exhaust port or... not?

[Vannik]

I thought it would make for interesting results doing a Wobbly exhaust port duct on a very high performance engine - something much better than the best HRC could do. So what better to use an Aprillia RSW125 as developed by Jan Thiel?

It makes for interesting results:

[AndreasL]

I thought it would make for interesting results doing a Wobbly exhaust port duct on a very high performance engine - something much better than the best HRC could do. So what better to use an Aprillia RSW125 as developed by Jan Thiel?

Nice work Neels (and Wobs)!

Is this new theories something that can be "included to the code" in the future? "Wobbly exhaust design radio button"
The homework to understand whats happening is ofcorse every end users responsibility.

[AndreasL]

Moving on with the Mach numbers in EngMod.

I'm still stuck with my crap transfers. Straight (tapered) walls, no inner radius etc etc.
I'm aware of the "non importance" of the "entry to exit area ratio", but any way...

I like to try some sort of inner radius but since theres limited material in the outside wall, that can't be altered much.

As PtrMach only gives the port mach numbers I'm not sure if this tells us anything usefull for what I like to find out.

Any approach to determine if transfer port cross sectional area is sufficient is welcomed.

Or when thinking about it some more...make it as constant as possible, don't change more then one direction at the time...all related to the sufficient transfer STA already present.

Asking questions is good...it makes you think!

[wobbly]

EngMod gives you the Ex Port STA as well as the Blowdown for that same port.
The blowdown number is only related to the configuration above the transfers, and as we are coming to realize what goes on below that point
is becoming increasingly redundant.
Blowdown sets the actual power capability of the port,how good the duct geometry is will help to bump up power for free in effect.

Lifting the port floor and filling in the bottom corner rads is what Jan was doing in stages at Aprilia, and now TeeZee and his ESE gang are off on a new tangent
that will give us all some pointers as to how important the A port short circuiting factor is Vs the port window area.
Neels has already included a radio button to set the duct exit area at 75% that we know is a good start point for a T or 3 port,but the 1.5 * bore for the smallest nozzle area length
and the 2* bore for the start of the header is usually limited by the physical layout of your cylinder/spigot.
So I think its best to leave this as a user input,related to what can actually be done with the project engine you are working on.

The results of a small change to Jans RSW 125 duct layout shows what can be achieved by applying a scientific approach to any engine, no matter how good/bad it may be, and I hope this
silences the few shortsighted critics that have their heads sarcastically buried in HRC quicksand.

[wobbly]

I think you have a good part of the answer already Andreas.
Where you have crap duct geometry the only real way of ensuring some sort of equality of Cd with the Blowdown STA is as you say
to ensure singular directional changes,but more importantly just increase the Transfer STA to compensate.

This was done sort of in reverse with the RSA 125.
The Blowdown Cd was VERY good in this engine due to the big Aux and the big radius on the opening edge of the Ex ports.
Thus the transfer STA had to be made larger in relation to the Ex, even though the transfer duct geometry in Jans opinion was as good as could be
achieved within the stud limitations that were fixed.

Remember the sim is a single dimensional analysis tool, and within the limitations of the scavenging models Neels has applied,the model has no way of predicting
the inlet/outlet Cd ratios that are set by the duct geometries of the ports.

[AndreasL]

Thanks Wobbly (2x),

A great summery of "what we know".
Its good to have it in print though.

Think I will cut/measure my transfer molds to find out what is doable within limits.

Starting to get really exiting.

Edit: Realize that I have a 55mm exhaust duct length. 39mm bore x 1.5 = 58.5. Close enough I say!
Finally ONE positive thing with this engine.

[ief]

Moving on with the Mach numbers in EngMod.

I'm aware of the "non importance" of the "entry to exit area ratio", but any way...

Asking questions is good...it makes you think!

I think it's not totally unimportend since engmod uses it to calculate duct volume to calculate CCR?