ESE's works engine tuner

[jonny quest]

TZ350, as an expirement I'd try disabling PV to full open. Then try a try it.

The NSR as well as later generation CR125 offer little to no blowdown when PV is closed.

This could play a huge part as to why it's so difficult to tune. I would definitely limit the PV travel.

[Muhr]

By the way had this in the computer regarding previous discussions about transfer radius.

[jasonu]

A snip at 3000 Euro

Some have spent more on their Buckets.

[F5 Dave]

Not many. Fraction of a percent.

[SwePatrick]

By the way had this in the computer regarding previous discussions about transfer radius.

What does the colours stand for?
Speed, density, pressure?

First thing that comes to mind is that the runners are having some problems at the beginning, and as i said before, one should be careful with to much tapering in a runner.
Secondary what comes to mind, is the simulation based on constant flow or a pressurized volume with a sudden release when piston is opening the port?

[pete376403]

I have managed for o-rings to change their shape, but only because they had been misused (heavily overpressed, overheated etc) The cheapest way is to get o-ring wire and o-ring glue from a rubber shop and just glue the ends together after you've generated the desired shape. You can also use the glue to fixate the o-ring inside the groove in e.g. tight bends or so. If the groove is as it should be (height and width), no special shape should be necessary.

Do you have a special application in mind?

Loctite make (made) a kit for that. As assortment of cross sections and different materials, and adhesive to suit

[F5 Dave]

Many times. But its a skill not to create a hard spot, but also roll the ring on a bend to expose an open side.

[TZ350]

TZ350, as an expirement I'd try disabling PV to full open. Then try it.

PV fully open is not a bad idea, I saw a PV curve recently that had the PV fully open when the engine was idling. I am not sure if that is the norm or not. But I will re visit the PV, thanks for suggesting it.

My first 2T EFI attempts were with an air cooled Suzuki GP125 engine and they don't have power valves. Made 31 RWHP @ 12250 RPM but still had the throttling problem below 25%.



The first air cooled cylinder had direct through the B port and under piston injection. The second air cooled cylinder had under piston injection and injection across the A and B port entrance at the crankcase. I liked that arrangement, it gave promising results.

Flettner has talked about something similar, two primary injectors firing against the air flow in the B ports and secondary's in the A ports but with them all firing when the trapping efficiency is peaking and the motor is making real power. This arrangement would keep fuel away from the exhaust port when the trapping efficiency was not that great and air was spilling out the exhaust.

The water cooled cylinder has B port injection but squirting against the air flow. All the cylinders have three physical injectors but only two logical injectors as the B port injectors are fired together. The fourth picture shows the underside with the piston at TDC.

I have tried a lot of different combinations, primary injector in the inlet, in the crankcase, in the B ports with the secondary in the alternative injection ports. And all sorts of other combinations like firing from one side of the crankcase across the top of the flywheels and directly into the incoming inlet air.

The least successful was direct inlet injection from the outside (the 5th picture), my favorite was under the piston and horizontal across the transfer ports but that is difficult to arrange with the water cooled cylinder. But under piston for the slow injector and injecting in the B ports against the air flow makes good power and looks to be more economic than a carburetor too. With EFI there is much less of a fuel puddle on the dyno deck beneath the inlet. With a carb there is a much bigger puddle.

Along the way I have learnt a lot and figured out most of the puzzle but I am just missing that last piece of the jigsaw, how to account for randomly changing air flow through the motor below 25% TP. It seems that the more highly strung the motor the more unstably changeable the air flow is below 25% throttle position.

Its like trying to sail an unstable "P" class learner yacht in gusty changeable wind conditions, its much easier when the wind is steady and consistently from one direction.



I am hoping that a MAP sensor in the crankcase and an Arduino Nano interpreting what it sees might be able to make sense of the air flow below that troublesome 25% throttle position.

[Muhr]

What does the colours stand for?
Speed, density, pressure?

First thing that comes to mind is that the runners are having some problems at the beginning, and as i said before, one should be careful with to much tapering in a runner.
Secondary what comes to mind, is the simulation based on constant flow or a pressurized volume with a sudden release when piston is opening the port?

Yes, things happen different before and after this simulation.
What I tried with here was to study flow separation on the top of the inner radius. The color is velocity.
Based on what I've seen, Fritz is right that a larger constant radius is better for flow separation

[RomeuPT]

I suggest you look at the IAME piston,that has a 5* angled edge for around 7mm that then becomes a flat top.
This setup in a TM with a new insert ( with the plug alot closer to the piston and a very flat bathtub ) makes better power than the 4* TM setup ( same cc ).

Any reason this shape or a 4º degree taper might not work so good on a T port Honda cylinder?

[jbiplane]

I have tried a lot of different combinations, primary injector in the inlet, in the crankcase, in the B ports with the secondary in the alternative injection ports.

We made in 2015 injection in intake noise silencer for experimental 50cc 4-cylinder axial engine rotating 24000 rpm (12.5cc per cylinder). Intake silencer volume was about 1400cc and flow inside was practically luminaire.
The only one nozzle were firing inside silencer according air volume flow with few time less frequency than rpm. May be similar approach will work in other cases?

[jonny quest]

Fabricate a quick straight pipe 4 stroke style. That will tell you if it's the pipe causing havoc under 25%.

[F5 Dave]

TZ, that curve with PV open at idle may, if you look again, be so it is open for kickstarting then closes for idle which might be at say 1300rpm.

[TZ350]

TZ, that curve with PV open at idle may, if you look again, be so it is open for kickstarting then closes for idle which might be at say 1300rpm.

Good point, we are playing with Av's GP/NSR110 on the dyno now. Things aren't going well, suspect some other issue is clouding the results.

[wobbly]

Romeu, the IAME piston I use in the TM engine,is in my opinion only, the best shape for a 2T piston.
It combines all the elements that have been used over the years with success, all for different reasons.
Yamaha have used a very narrow, angled edge that than becomes a flat top for many years in many designs.
The angled edge helps flow ( bulk, and cooling attachment ) at small port opening angles, and of course the flat top allows the use of a toroid to get the plug down very low
within the combustion space.
The IAME has an angled edge 7mm wide that matches a normal squish width in a 125 bore,but in the case of the KZ engines we cant go that wide.
But the next test,using a 1mm radius on the timing edge, combined with its 0.5mm higher deck height, makes what I consider a really good setup for the kart engine
where I cant use a toroid.
I have already proven the angle/flat top makes more power than the straight 4* conic that TM use,so if the radius added is better again, then that will be a real winner.
In a T port engine, the same logic would apply, but in your class of racing you can use the toroid as well - and get better power again than I can.