2 stroke thread (with occasional F1 relevance!)

[J.A.W.]

Kevin Cameron article suggests KTM could sell its new TPI 2T's in road-legal format, stateside:

http://www.cycleworld.com/ktm-transfer- ... for-street

IMO, a logical next step for KTM, ought to be - that 2T TPI engine - in a dedicated roadbike chassis.

[manolis]

Hello J.A.W.

Here is my comment just added to Kevin Cameron article:


Hello.

Quote from the dirt-bike-rider:

“Also KTM had problems with euro 4 and some KTM dealers can’t anymore sell 2017 models in their country’s. But new 2018model will come with euro 4 and it will easy pass euro 4 with elections fuel injection and lower emissions. But there is new problem for KTM, in 2020 we will have new big problem called euro5. But we all hope KTM will find solution for this and make EXC and XC models legal for street.”


According the euro5 regulations (in force from 2020) it is required a 60% further reduction of the Hydrocarbons (0.10gr/Km instead of the 0.17gr/Km allowed by euro4).

Reasonably the KTM EXC 250/300 TPI cannot comply with the euro5 emission regulations without a significant reduction of their power output.

With the exhaust port remaining open for several crankshaft degrees after the end of the transfer (isn’t this what the KTM is doing?), what stops the fuel (already entered into the cylinder) from escaping to the exhaust?

For greener (euro5) and powerful at the same time 2-strokes, the exhaust must close before the transfer. Substantially.

How?

Take a look at the patented PatATi design and prototype at http://www.pattakon.com/pattakonPatAT.htm , and then at the PatATE 2-stroke design at http://www.pattakon.com/pattakonPatATE.htm

Thanks
Manolis Pattakos

[J.A.W.]

As an example of the inherent attributes of the 2T as a road race machine (where not banned, of course):

http://www.iomtt.com/News/2017/08/26/An ... -Race.aspx

Ironic for Honda that it was one of their 2T's - after their embarrassing F1 & Moto GP 4T DNF's - last W/end..

I note that Bruce Anstey has qualified at No1, for the Classic Superbike race - on a 500cc 2T, as well.

[J.A.W.]

Hello J.A.W.

Here is my comment just added to Kevin Cameron article:


Hello.

Quote from the dirt-bike-rider:

“Also KTM had problems with euro 4 and some KTM dealers can’t anymore sell 2017 models in their country’s. But new 2018model will come with euro 4 and it will easy pass euro 4 with elections fuel injection and lower emissions. But there is new problem for KTM, in 2020 we will have new big problem called euro5. But we all hope KTM will find solution for this and make EXC and XC models legal for street.”


According the euro5 regulations (in force from 2020) it is required a 60% further reduction of the Hydrocarbons (0.10gr/Km instead of the 0.17gr/Km allowed by euro4).

Reasonably the KTM EXC 250/300 TPI cannot comply with the euro5 emission regulations without a significant reduction of their power output.

With the exhaust port remaining open for several crankshaft degrees after the end of the transfer (isn’t this what the KTM is doing?), what stops the fuel (already entered into the cylinder) from escaping to the exhaust?

For greener (euro5) and powerful at the same time 2-strokes, the exhaust must close before the transfer. Substantially.

How?

Take a look at the patented PatATi design and prototype at http://www.pattakon.com/pattakonPatAT.htm , and then at the PatATE 2-stroke design at http://www.pattakon.com/pattakonPatATE.htm

Thanks
Manolis Pattakos

Indeed Manolis..
- if they do want to be Euro 5 compliant in 2020, then doubtless KTM will have to be already test-running
both 4T & 2T machines.. albeit their US market share is quite large, & USA has its own emissions reg's..

I note that other 2T enduro off/on-road motorcycle manufacturers have simply evaded the issue..
..by selling a 'nominally compliant' - but heavily restricted machine, along with a 'free upgrade kit'..
..which restores proper performance - at the operators liability - for operating a non-compliant bike..

[Pinger]

With the exhaust port remaining open for several crankshaft degrees after the end of the transfer (isn’t this what the KTM is doing?), what stops the fuel (already entered into the cylinder) from escaping to the exhaust?

This:

''The injection of fuel is timed such that none of it can reach the cylinder's exhaust port before it closes.''

according to the article.

It is though, another engine prepared to sacrifice fresh (fuel-less) air to the exhaust port thus creating oxygen content in the exhaust system incompatible with Lambda sensor control for fuelling.

[manolis]

Hello Pinger.


A correction:

The 10gr/Km Hydrocarbons of euro5 relative to the 17gr/Km Hydrocarbons of euro4:



(the table is from http://www.motorcyclenews.com/news/2016 ... lly-means/ )

is “only” a 41% reduction (and not a 60%, as I wrote).




With or without a lambda sensor (for feedback control), if an engine complies with the emission regulations, it is OK.




“The injection of fuel is timed such that none of it can reach the cylinder's exhaust port before it closes.”

However the timing of the “indirect” injection of the KTM EXC 250/300 TPI of 2018 is limited between the opening and the closing of the transfer ports.

With the closing of the transfer port, all the fuel / mixture is in the cylinder with the exhaust port still substantially opened (and remaining open for another 25, or so, crankshaft degrees).

Depending on the operational conditions (revs, load etc) this is a big time interval for the fuel to find the exhaust and escape unburnt.


With the TPI the KTM EXC250/300 of 2018 complies with the euro4 emission regulations.

With the exhaust closing earlier (just after, or before, or substantially before the transfer, as with the PatATi and the PatATE designs), the euro5 limits seem achievable even tomorrow.

Thanks
Manolis Pattakos

[Pinger]

With or without a lambda sensor (for feedback control), if an engine complies with the emission regulations, it is OK.

True, but Lambda control obviates the need for a mass airflow sensor or rigid pre-programmed control map.

“The injection of fuel is timed such that none of it can reach the cylinder's exhaust port before it closes.”

However the timing of the “indirect” injection of the KTM EXC 250/300 TPI of 2018 is limited between the opening and the closing of the transfer ports.

With the closing of the transfer port, all the fuel / mixture is in the cylinder with the exhaust port still substantially opened (and remaining open for another 25, or so, crankshaft degrees).

Depending on the operational conditions (revs, load etc) this is a big time interval for the fuel to find the exhaust and escape unburnt.

Yes, but it would appear that KTM are manipulating the transfer streams such that only raw (fuel-less) air is present adjacent to the exhaust port. Viable, if the streams are maintained as streams with a lean (fuel-less) head and rich (enough) tail. Another form of (mild) stratification which accepts lost air as the price paid for fuel retention.

With the exhaust closing earlier (just after, or before, or substantially before the transfer, as with the PatATi and the PatATE designs), the euro5 limits seem achievable even tomorrow.

I see it pretty much as you do ie, physical exhaust port closure is the ultimate (possibly only) solution over the entire speed/load range. How best to achieve that is the question. (The external valves just don't do it for me. Bulky, inelegant, and hardly the most effective shape to seal).

[J.A.W.]

Kiwi Bruce Anstey finished 2nd in the IoM Classic Superbike race riding a well-prepared 2T Yamaha YZR 500..
..a not-too-shabby finish, with time lost due to a long pit-stop & after suffering vision problems from dirt 'n' debris..

Anstey did snare the class lap record - on his final lap @ average speed of 127.496 - so, good effort, on a 'classic' bike..

[uniflow]

Manolis, the KTM system (my YZ unit copied by KTM) will archive between 14 and 21% fuel savings over a standard carburetor. We have tested our TPI YZ against a standard YZ to get these results. I built and tested this while KTM were still working with Orbital on their direct injection.
Knocking out the pulse tuned exhaust will render your engine to lawn mower use, that's what will happen if you shut the exhaust port off so early. No doubt someone else here has pointed that out I'm just reminding you. That reverse pulse from the pipe is very desirable, after transfer is closed.

[manolis]

Hello Uniflow.


You write:
“Manolis, the KTM system (my YZ unit copied by KTM) will archive between 14 and 21% fuel savings over a standard carburetor. We have tested our TPI YZ against a standard YZ to get these results. I built and tested this while KTM were still working with Orbital on their direct injection.”


According the DirtBikeTest ( https://dirtbiketest.com/fresh-dirt/201 ... sxs0tXc.97 ) : “fuel consumption is claimed to be 20-30% improved” in the KTM TPI / 2018




You also write:
“ Knocking out the pulse tuned exhaust will render your engine to lawn mower use, that's what will happen if you shut the exhaust port off so early. No doubt someone else here has pointed that out I'm just reminding you. That reverse pulse from the pipe is very desirable, after transfer is closed.”


Even so, it would be a cleaner lawn mower engine (aren’t the emissions the worst weakness of the 2-stroke engines? This is the problem the PatATi, the PatATeco and the PatATE designs try to solve).

It would be, also a lawn mower engine needing substantially less lubricant (unless the, by far, lower peak temperatures on the cylinder around the exhaust port area, and on the piston side that slides over the exhaust port, of the PatATE are not strong advantages over yours / KTM’s / Rotax’s TPI and conventional 2-stroke designs.

It would be, also, a lawn mower engine providing substantially more time from the moment the exhaust closes to the moment the combustion happens, which means there is time for better mixing / preparation, capability for higher revving, more efficient combustion.



On the other hand, think that the 4-strokes are stronger than the 2-strokes (as regards the quantity of air trapped into the cylinder per induction cycle) without needing a tuned exhaust.

Take the Ducati Panigale 1199 that makes 110mN/lit specific torque.
This requires a quantity of, say, 110 units of air to be trapped in the cylinder per lit of engine capacity, after each induction cycle.
Now take the KTM EXC300 / 2018 that traps, per induction cycle, less than 80units of air into the cylinder per lit of engine capacity.
This is less than 3/4.

Imagine a 2-stroke with the breathing capacity “per induction cycle” of the Panigale.
At the same revs it would make more than 35% more power than the current 2-strokes.


Thanks
Manolis Pattakos

[J.A.W.]

Hi Manolis..

In fact, Uniflow is quite correct to point out that a pulse-tuned 2Texhaust is well worthwhile using..
& for sure, the Ducati Panigale uses the 4T equivalent - for its exhaust too..

What isn't directly comparable, is the off-road/dirt-bike tune KTM, with a Panigale 'superbike'..
However, the specific output of the KTM - AFAIR, still betters the Ducati on an hp/Ltr basis

The last 2T twin-cylinder sports roadbike was the Aprilia RS 250, which claimed 70hp,( thus 280hp/Ltr).
A current 2T twin, which is also a closer equivalent to the Ducati, is the BRP/Rotax Ski-Doo E-TEC 850,@160+hp..

[uniflow]

last twostroke 125 GP bike at 55hp

[manolis]

Hello J.A.W.

You write:
“In fact, Uniflow is quite correct to point out that a pulse-tuned 2Texhaust is well worthwhile using..
& for sure, the Ducati Panigale uses the 4T equivalent - for its exhaust too..”


It seems you forget that the PatATE is a highly unconventional 2-stroke:



that relates more with 4-strokes having large overlap :



than with the conventional 2-strokes.


The exhaust of the 4-strokes has a limited effect on the volumetric efficiency (just think for how many degrees, at the beginning of the induction stroke, and with the piston still at, or near, the TDC, the exhaust communicates with the cylinder).

Nothing to do with the tuned exhaust of the conventional 2-strokes.

The best 4-strokes, like the Ducati Panigale and the sport motorcycle engines, work more with their induction system, than with their exhaust. A good thing when working with the induction system is that anything pushed outside the cylinder will be recycled in the next cycles.



I get no answer yet to my question / comment for Kevin Cameron article:

“With the exhaustport remaining open for several crankshaft degrees after the end of the transfer (isn’t this what the KTM is doing?), what stops the fuel (already entered into the cylinder) from escaping to the exhaust?

The TPI solution seems “fragile”.
To have stratified charge at specific conditions of revs and loads seems attainable.
But how can you do it at all revs and loads with a big exhaust port waiting open?


The The PatATE gives a quite unconventional option: close the exhaust earlier.

Thanks
Manolis Pattakos

[Pinger]

I get no answer yet to my question / comment for Kevin Cameron article:

“With the exhaustport remaining open for several crankshaft degrees after the end of the transfer (isn’t this what the KTM is doing?), what stops the fuel (already entered into the cylinder) from escaping to the exhaust?

Answered in the fifth post on this page.

[manolis]

Hello Pinger.

The article may claim that:

"The injection of fuel is timed such that none of it can reach the cylinder's exhaust port before it closes."

however this is not a convincing answer.


The injection of the fuel in the KTM 250/300EXC/TPI / 2018 cannot help starting substantially (say, 40-50 crank degrees) before the closing of the transfer port, and cannot help ending before the closing of the transfer port.

Add to the above 40-50 crank degrees the crank degrees the exhaust port remains open after the closing of the transfer port (say 25?), and you have, for some 65-75 crank degrees, air, air-fuel mixture and fuel droplets entering violently into the cylinder, with the exhaust port open.

Well?

“What stops the fuel (already entered into the cylinder) from escaping to the exhaust?"

Thanks
Manolis Pattakos