ESE's works engine tuner

[jonny quest]

"You may not have enough space between exhaust port and A port"

Is this maybe what you meant, Frits?

[jonny quest]

Jan Thiel once suggested that you cannot have too much blowdown time.area. But you can have too much exhaust timing,

you can have too much vicinity between the exhaust port and the A-transfers,

you can have shortcircuiting between the auxiliary exhaust ports and the transfers via the gudgeon pin bores in the piston, and finally you can have port shapes that are too harsh on the piston ring.

You wrote this Frits. In my above post I was wondering if what I wrote, is what you meant to say.

[SwePatrick]

About durations on aux exhaustports vs main exhaustport.

The powerloss due to too high duration on auxports, wouldn´t it also depend on the shape of the auxports runners?

If they are taking a big curve before entering the exhaustduct it would be more important to let them have less duration then the main?
Thereby it would be less important if they are having a almost 'straight shot' from face of the port down against the exhaustduct?

I´m thinking of what Wobbly wrote about the aux is 'bleeding' the 'rest' of the exhaustpressure.

Rgds
Patrick

[peewee]

I don't recall anybody asking about this. since most cylinders have a exh passage far to short I guess its still recommended to put the exit at 75% ? some cylinders cant get even close to a proper passage length because of packaging limitations. mine was only 50mm on a 500cc but there was really not much I could do since the front tire would of smashed it every time the suspension compressed

[Nath88]

Does anyone have experience with spark plug ion sensing with 2 stroke engines (or other types)?



Essentially pinches a little bit of the spark current to charge the capacitor, which then applies the charge to the spark gap after the spark current has finished.
The amount of current that flows is proportional to the concentration of ionised gas at the plug gap which indicates pressure. No combustion = no current flow so misfire is easily detected. Post processing can detect knock (rapid pressure rise) and optimise spark timing (peak pressure timing).

All I'm looking for is accurate misfire detection... How hard could it be.

[Frits Overmars]

Pretty hard - in a two-stroke. Saab did quite some spark plug ionisation monitoring research with good results, but that was in a four-stroke.
In a two-stroke the squish action is much more violent and the concentration of ionized gas at the plug gap depends more on squish velocity than on pressure.
Here is some reading on the subject.

[2T Institute]

Does anyone have experience with spark plug ion sensing with 2 stroke engines (or other types)?



Essentially pinches a little bit of the spark current to charge the capacitor, which then applies the charge to the spark gap after the spark current has finished.
The amount of current that flows is proportional to the concentration of ionised gas at the plug gap which indicates pressure. No combustion = no current flow so misfire is easily detected. Post processing can detect knock (rapid pressure rise) and optimise spark timing (peak pressure timing).

All I'm looking for is accurate misfire detection... How hard could it be.

Is that from that famous bit of plastic snake oil the Icat/Direct Hits or whatever they call it now?

[seattle smitty]

FWIW (repeat, repeat), an electronics engineer, inventor, and sometime amateur drag-racer, Christopher Jacobs, PhD, developed an aftermarket ignition for the automotive world, mostly, about 25 years ago, that purported to do what you describe. The ignition was well-liked by some, the company (Jacobs Electronics) seemed to have some problems, and I gather that Jacobs became tired of business hassles and sold the company so he could get back to inventing, in the medical field. He wrote a book on the basics of ignition systems: The Doctor's Step By Step Guide to Optimizing Your Ignition.

[teriks]

Does anyone have experience with spark plug ion sensing with 2 stroke engines (or other types)?



Essentially pinches a little bit of the spark current to charge the capacitor, which then applies the charge to the spark gap after the spark current has finished.
The amount of current that flows is proportional to the concentration of ionised gas at the plug gap which indicates pressure. No combustion = no current flow so misfire is easily detected. Post processing can detect knock (rapid pressure rise) and optimise spark timing (peak pressure timing).

All I'm looking for is accurate misfire detection... How hard could it be.

Only as a user, SAAB used ion sensing in their car engines since 1994.
Never had to mess with it though, haven't had a problem.. so far.

Saab Trionic’s ignition system ...
The spark plugs are used as sensors to detect combustion and preignition/pinging.
This renders camshaft position detector and knock sensor redundant.

[crbbt]

Harley also ion sensing for knock detection. apparently the motor is too mechanically noisy to use a regular knock sensor.

I believe one of the issues with ion sensing and data logging accurately was the lack of time greater than 6000rpm. I was interested in peak cylinder pressure which can be worked out using ion sensing

[Jannem]

Harley also ion sensing for knock detection. apparently the motor is too mechanically noisy to use a regular knock sensor.

I believe one of the issues with ion sensing and data logging accurately was the lack of time greater than 6000rpm. I was interested in peak cylinder pressure which can be worked out using ion sensing

The owner of TFX is also into 2 strokes and their stuff could be used in addition of cylinder pressure to measure real life pipe and case resonances. http://www.tfxengine.com/

[Norman]

I saw some info about the Mozzi piston. It had a titan center insert in the top of the piston. If to believe the dyno chart it gave some extra power. BUt, what if you put a well chosen ceramic layer at the top of the piston, leaving the squish area without ceramic, would this give the same effect? Titan has a themal conductivity of about 20 W/(m*K) and some ceramics I have seen has 0,5-2 W/(m*K). If the titan insert has a thickness of 5 mm and we substitute this with a 0,5 mm ceramic? What do you think about this Wobbly? The higher curve is for a Mozzi piston, the lower is original.

[wobbly]

The latest 3D printers can do two materials concurrently https://www.desktopmetal.com/ so that may be an option if they can do the correct high silicon alloy.
But I use HPC ceramic coating of the combustion chamber bowl only, and the non squish area of the piston in many engines.
The best example was a SeaDoo World Champ Ski, this was a " stock " 950 " and made just over 8 Hp more doing that treatment.
It very quickly ended up with burnt on oil so looked completely normal.

[chrisc]

On a 50 (39.5mm bore), is there any advantage to running a 10mm plug such as a NGK R0373A-10 over the 14mm R7376-10?
Potentially less surface area on the small combustion chamber to extract heat? Maybe less room in the chamber to create the right shape?

Would a 19mm reach plug would be better than a 12.7mm reach plug on the basis that there's more plug in the head insert and more vertical surface area to pull heat out of the plug, into the insert then into the coolant?

Is the 10 heat range plug a reasonable heat range to start with for this 50 I'm building?

[Norman]

The latest 3D printers can do two materials concurrently https://www.desktopmetal.com/ so that may be an option if they can do the correct high silicon alloy.
But I use HPC ceramic coating of the combustion chamber bowl only, and the non squish area of the piston in many engines.
The best example was a SeaDoo World Champ Ski, this was a " stock " 950 " and made just over 8 Hp more doing that treatment.
It very quickly ended up with burnt on oil so looked completely normal.

Thank you for your reply Wobbly. With the risk of knocking on open doors here, I am thinking that the squish is getting even better cooled, as well as the plug, using the method you describe. Very interesting.