ESE's works engine tuner

[Frits Overmars]

Looks like there's some kind of separate exhaust timing thing going on, clever!

You noticed, didn't you? But you didn't hear it from me .

[TZ350]

They do it the other way around TeeZee: late-starting direct injection at low load to avoid fuel losses, and indirect injection at high load, stirring the mixture in the crankcase in order to create a homogeneous mixture.

Thanks for that, maybe they got their better results by pointing the injector down, I must try that.

[ken seeber]

Looks like there's some kind of separate exhaust timing thing going on, clever!

Alex, thinking about your supercharged engine thoughts and your concern re crankcase contamination with fuel.
Years ago I was with Orbital, developing both our 2 stroke engines for auto use and the 2 fluid DI injection system for various applications.
Of the auto engines, we commenced with the mainstay 3 cyl crank scavenged X engine but also a 3 cyl (1 litre) and 6 cyl (2 litre) externally scavenged engines. These were wet sumped with pressure fed crank.
All scavenging was done by an engine driven Roots style blower. Interestingly this allowed us to have a common manifold on either side of the engine. From these we had vertical passages. In between each pair of adjacent cylinders, these were bifurcated at the top, such that one side feeding the two adjacent A ports, the other side feeding the two B ports. Probably not ideal in terms of flow due to the bifurcations, but certainly allowed us to maintain tight bore centres. Obviously these only transferred air, as these were DI.
Bit of a long story to get to the pistons. To prevent (uncontrolled/copious) oil entry up the bore and into the combustion area, the piston had an oil scraper ring at the base of the piston skirt, this being situated low enough to not uncover the exhaust or transfer ports. Obviously the piston was full skirted and longer (by a bit) than the engine stroke. Lubrication of the piston skirts and compression rings was achieved by oil being carried up the bore via the honing. A bit uncontrollable maybe, but I don’t remember any concerns with excess oil consumption and certainly no smoke or smell. Maybe not so suited to your max power only requirement, as these will necessarily be heavy. I think I might have one kicking around work, so will post a pic if I can find something.
These engines featured an exh power valve which allowed the exh timing to be very considerably lowered, providing the opportunity to pressurise the trapped volume to a degree.
So, I reckon that whatever cylinder you use, get one with a power valve that can go quite low.
As you might be aware, I am personally keen on having the exhaust drawing in air (or mixture) directly from the atmosphere, bypassing all the reed/crankcase/transfer passage losses, ideally on a wet sump bottom end.
There is another site: https://www.facebook.com/groups/1055...?ref=bookmarks where various things are discussed, one being the concept of a small electric motor providing enough flow to get the engine started There is also a range of other engine scavenging thoughts.

[JanBros]

Alex, why would you still put reads in the intakes, when there is only flow in one direction

[F5 Dave]

For what its worth, we laser cut 1.5mm steel plates to replace the 2mm plates in the NSR dry clutches and get an extra steel and fiber plate. I thought that they may warp badly but mines been in there for two seasons now and still works a charm.

Choice, sounds like a plan. Must get that lamba sensor back to you. Cheers.

[breezy]

not sure my pm thing is working.. so tz350 can you tell me what size hole is required in the crank wheels/ webs to fit a 22mm crank pin. i had a suzuki gp 125 crank machined a few years ago which renderd it useless in its present form. thanks .

thanks TZ, not sure if im doing something wrong but my pm messages are disappearing into space still... https://youtu.be/PU5xxh5UX4U

[41juergen]

what kind of chassis do you have ? my passage was far to short. to get it any where near 1.5x it would of needed to be 135mm. this was not possible because the front tire would of smashed the header during suspension travel

As said, I will replace the constant diameter part with the cnc machined one, so no further space needed. The bike is a TZR250R type 3XV. I bit similar like the TZ250 4DP ones...

[TZ350]

thanks TZ, not sure if im doing something wrong but my pm messages are disappearing into space still.

Sketchy_Racer is your man for crank mods.

[adegnes]

You noticed, didn't you? But you didn't hear it from me .

Can you tell me how far it is in development?
Getting second thoughts about my port blocker pipe...

Alex, thinking about your supercharged engine thoughts and your concern re crankcase contamination with fuel.
Years ago I was with Orbital, developing both our 2 stroke engines for auto use and the 2 fluid DI injection system for various applications.
Of the auto engines, we commenced with the mainstay 3 cyl crank scavenged X engine but also a 3 cyl (1 litre) and 6 cyl (2 litre) externally scavenged engines. These were wet sumped with pressure fed crank.
All scavenging was done by an engine driven Roots style blower. Interestingly this allowed us to have a common manifold on either side of the engine. From these we had vertical passages. In between each pair of adjacent cylinders, these were bifurcated at the top, such that one side feeding the two adjacent A ports, the other side feeding the two B ports. Probably not ideal in terms of flow due to the bifurcations, but certainly allowed us to maintain tight bore centres. Obviously these only transferred air, as these were DI.
Bit of a long story to get to the pistons. To prevent (uncontrolled/copious) oil entry up the bore and into the combustion area, the piston had an oil scraper ring at the base of the piston skirt, this being situated low enough to not uncover the exhaust or transfer ports. Obviously the piston was full skirted and longer (by a bit) than the engine stroke. Lubrication of the piston skirts and compression rings was achieved by oil being carried up the bore via the honing. A bit uncontrollable maybe, but I don’t remember any concerns with excess oil consumption and certainly no smoke or smell. Maybe not so suited to your max power only requirement, as these will necessarily be heavy. I think I might have one kicking around work, so will post a pic if I can find something.
These engines featured an exh power valve which allowed the exh timing to be very considerably lowered, providing the opportunity to pressurise the trapped volume to a degree.
So, I reckon that whatever cylinder you use, get one with a power valve that can go quite low.
As you might be aware, I am personally keen on having the exhaust drawing in air (or mixture) directly from the atmosphere, bypassing all the reed/crankcase/transfer passage losses, ideally on a wet sump bottom end.
There is another site: https://www.facebook.com/groups/1055...?ref=bookmarks where various things are discussed, one being the concept of a small electric motor providing enough flow to get the engine started There is also a range of other engine scavenging thoughts.

That sounds like an ideal setup if one could keep the piston weight down. Yep some kind of exhaust valve is probably necessary, this Neg engine looks like it uses a secondary piston, maybe spinning at 2x crank speed. Too complicated for my "prototype", maybe a drum valve could work?
Your exhaust as intake idea is interesting!
Thanks for the link, I'll check it out!

Alex, why would you still put reads in the intakes, when there is only flow in one direction

Good point... :facepalm

[Frits Overmars]

Can you tell me how far it is in development?

. . .

[adegnes]

You noticed, didn't you? But you didn't hear it from me .

I thought he'd just left the spark plug out in the picture, but word on the street says it's a diesel. Phew, can rest my shoulders again...

[tjbw]

They do it the other way around TeeZee: late-starting direct injection at low load to avoid fuel losses, and indirect injection at high load, stirring the mixture in the crankcase in order to create a homogeneous mixture.


Yes, it says Turbo but in this case it is merely a promotional term because turbos are hot these days.
Technically speaking it's not a turbo: the centrifugal compressor is not driven by an exhaust gas turbine but it is geared to the crankshaft.
The gear ratio is 8 to 1 and for now that is all I am allowed to say about it by the man behind the engine, my mate Roland Holzner.
Attachment 328899 Attachment 328900

Is it a supercharged diesel two stroke uniflow engine, with a single side valve for exhaust?

The exhaust is not controlled by a poppet valve, but by a little piston, with asymmetric timing?

[Michael Moore]

the piston had an oil scraper ring at the base of the piston skirt,

Laverda 125/150 singles had a piston like that. I found it interesting that every one I took apart had the bottom of the piston broken off at the ring groove.

cheers,
Michael

[breezy]

I thought he'd just left the spark plug out in the picture, but word on the street says it's a diesel. Phew, can rest my shoulders again...

dont let the big boys hold you back.. theyll be scratchin their arses most of the time..

[adegnes]

dont let the big boys hold you back.. theyll be scratchin their arses most of the time..

Too bad that's what I do most of the time too...