ESE's works engine tuner

[Frits Overmars]

Could someone tell me what this ports are used for? I see no reason for them, or how they work. Thank you. Jeff

These aren't Boyesen ports because they do not form a direct connection between inlet and transfer ducts.These are just extra inlet ports, adding a bit more port width to the central inlet port. This layout can be used in reed valve inlet systems as in your cylinder, as well as in piston-controlled inlets.

[SwePatrick]

Is not 53.21nm at 10567RPM 80.07 HP

Hehe,, if it was so easy, the software reports torque at crank and hp at wheel, with hp at crank in paranteses.

[Muhr]

Hehe,, if it was so easy, the software reports torque at crank and hp at wheel, with hp at crank in paranteses.

Bummer!
What does the blue line represent? Is that the second pull?

[SwePatrick]

As it reports in this strange way it is actually the torque.

[TZ350]

[jfn2]

Thank you Frits for your reply. I understand about the 'NON' Boyesen ports. The cylinder I'm showing you is one that I'm thinking about purchasing for a spare and to do some mod work to.
I do not know about the extra inlet ports as to, if they were cast in place or cut after casting. I have not seen other cylinders with these extra ports, so I believe they were added after casting.
Looks like a pretty good job. Also I noticed that the exhaust port was altered (circled in the pics) and was wondering why only this small amount instead of the whole port? This cylinder is from a Kawasaki Kx 65cc engine. I have heard that this engine is blowdown deficient and looking at the pics I think that's correct. I also understand I can widen the wings on the exhaust ports to gain more blowdown. The manual states the exhaust opens at 87.6 degs b/atdc and the A and B transfers at 116.5 degs b/atdc and C boost port at 119.9 degs b/atdc. I can not confirm this or check the deck height because I don't have my engine apart yet, the boy's still riding it. I guess what I'm looking for are some thoughts and opinions about the extra inlet ports and the altered exhaust ports. I have dealt with extra inlet ports before but only on piston port engines where they worked very well. And I can not ask about the height difference in the exhaust port. Bore is 44.5mm Stroke is 41.6mm Con rod is 85mm center to center.

[Frits Overmars]

I do not know about the extra inlet ports as to, if they were cast in place or cut after casting.... I noticed that the exhaust port was altered (circled in the pics) and was wondering why only this small amount instead of the whole port? This cylinder is from a Kawasaki Kx 65cc engine. I have heard that this engine is blowdown deficient and looking at the pics I think that's correct. I also understand I can widen the wings on the exhaust ports to gain more blowdown. The manual states the exhaust opens at 87.6 degs b/atdc and the A and B transfers at 116.5 degs b/atdc and C boost port at 119.9 degs b/atdc. .

Those inlet ports look like cast to me. The modifications on the exhaust port are too narrow to contribute much to the blowdown angle.area. Modifications of this kind usually have the purpose of weakening the initial exhaust pulse for the sake of noise reduction, and sometimes for the sake of taming the rate of torque and power rise at the beginning of the power band, to make a bike more kiddy-friendly, which may well have been the reason in the case of this 65cc bike..

[Vannik]

Naming of porting events.

Since starting to look at opposed piston engines where the phasing of the crankshafts are possible I have run into a nomenclature problem. On a conventional two-stroke the blowdown duration is the same as the plugging duration. On a phased OP engine you have four options:

• Smaller blowdown than plugging duration,
• Same blowdown and plugging duration,
• Zero plugging duration, and
• Negative plugging duration where the exhaust port closes before the transfer ports.

So what do we call this "negative plugging duration"?

[yatasaki]

I would call it "no short circuit duration"

[Frits Overmars]

Naming of porting events.

• Negative plugging duration where the exhaust port closes before the transfer ports.

So what do we call this "negative plugging duration"?

Supercharging is already taken (and has a different meaning). Aftercharging, or afterloading, maybe? ('nachladen' exists in German, and 'naladen' in Dutch).

EDIT: not good enough. The word we are looking for must make it clear that the transfers are still open (and hopefully active) and the exhausts are not.
Aftertransfer, maybe?

[ken seeber]

PECTD
Post Exhaust Close Transfer Duration

[Vannik]

The way the OP2T works is making for interesting findings. Mostly obvious but because I never had the opportunity to vary plugging duration independent from blowdown duration I never thought about it:

1. As we shorten the plugging duration the effect of the plugging pulse becomes less and less. So while on a conventional 2T the blowdown STA is critical, on an OP engine the plugging STA is also critical, depending on whether a tuned pipe or a blower is used.

2. When the plugging duration becomes negative (The duration that still needs a name) the better pipe becomes a megaphone, we only want to extract gas and not plug anything back as the transfers keep flowing and filling the cylinder after exhaust port closure.

[flyincat]

How about BONUS TRANSFER or CLEAN TRANSFER?

[lohring]

I'm probably the start of this issue since I've been playing with the opposed piston version of EngMod. I was surprised to find that the power increased as I lowered the exhaust lead from 12 degrees to 4 degrees. I'm going to revisit this with some of the mild modifications I have been making along the way. It's a piston port engine with a tuned pipe designed for peak power at around 18 to 19,000 rpm. I'm in the process of measuring the volumes more exactly in my model. I can then look at the predicted pressures, flows, and Mach numbers with the different leads. We'll see if it looks like real life. So far I'm getting 29 hp at 19,000 rpm from a 60 cc engine.

Lohring Miller

[OopsClunkThud]

is "TDC" in the diagram related to just one crank or is it the smallest volume based on the phasing of the cranks? seems like as displayed it's off the transfer crank in one and the exhaust crank in the other.