The 2 stroke direct injection engines

Direct injection on a 2 stroke engine.

Text: Marc ALIAS, technical journalist. CP No. 94236. Photos: Marc ALIAS and DR

Keywords: direct injection 2 time SYNERJECT, SIDA, motor, power pollution standards

While 4 time propaganda initiated and orchestrated the largest Global manufacturer of 2 wheels comes from Formula 1 (!) And the moto gp, MX and karting, traditional media and dealers, also seem abused that end 1995, with the resounding true false trial Diesel! Today, everyone recognizes the TDI, CDI and other HDI their immense virtues including ecological, due to their economical diesel cycle in nature. Yet it is still very tempting and very easy to find a scapegoat for all the serious problems we face, particularly pollution. Now, under this pretext to fashion, it is for his skillful promoter as a simple but important economic strategy to promote their eternal creed and 4 time ... especially to sell licenses and old engine manufacturing plants 4 time in China, Asia and even in Europe! Demonstration of this global deception with the undisputed and indisputable specialists pneumatic direct injection, I named: Synerject!

Aprilia SR50 Direct Injection

Why follow the herd?

Remember, at the end of 2001, under this slightly provocative title, I had already mentioned this innovative company in the first article which initiated the “2-stroke” section in issue 43 of Moto technology. It was a tribute to Aprilia for the courageous marketing of the first European “Ditech” direct injection system on the 50 cm3 SR 50 scooter: A very relevant strategy against the Japanese. So consider: the SR 50 goes to 560 km of autonomy still with its 8 liters of gasoline, 4500 km of autonomy on the engine oil side, and still 8.5 hp at 8500 rpm without supercharging! Who says better ? No one ! Suddenly, this system which revolutionized 2-stroke, has spread, to the chagrin of 4-stroke professionals! Indeed, we currently have more than 30 2-stroke models including 7 on two wheels, direct injection therefore depolluted and suitable for Euro 2 and Euro 3 2006 standards! Note in passing, during the very last Mondial du 2 Roues in Paris, that Peugeot Mtc even announced to go from 50 cm3 to 125 cm3 TSDI (Two Strokes Direct Injection) with its superb Ludix which took the opportunity to glean the 2nd design prize. Scooter category, awarded by the famous Motorcycle Design Association. Let us recall that he has already obtained the Janus de l'Industrie in 2003, the Senate prize of the Lépine Competition in 2004 and quite recently, a star of the Observateur du design 2005.. In addition, Peugeot ad Mtc rightly that this new model will outperform its competitors in performance 4 time upon its release in France delayed 2005 common for marketing reasons to launch the 125 4 time compressor. By the way, I bet you that the Ludix 125 2 time TSDI be as effective if not more unbridled and still more fuel efficient: rather annoying for a simultaneous launch is not it? Moreover, the record release Peugeot 2004 not dried up praise for this perfect symbiosis between pneumatic and direct injection Synerject 2 time rather judge by this extract:

 Ludix: The return of 2 time in 125 cm3. In comparison to a “4-stroke” engine with the same displacement (and at the same speeds, ndla), a “2-stroke” engine is:

- 30% lighter

- 30% cheaper

- 30 to 40% less bulky

- up to 50% more efficient " 

It is clear that the future of the 2-stroke engine passes through direct electronic fuel injection in the cylinder head, because once equipped with such a system, like that of the Synerject Orbital used on our 50 cm3 TSDI, this engine forgets most traditional 2-stroke disadvantages:

- It complies with Euro 2 anti-pollution regulations and will comply with Euro 3 levels at the same cost as a 4-stroke, or even less ...

- He becomes fittest than a 4-stroke engine to accept more stringent pollution control levels (4-stroke is penalized by its CO and NOx emissions).

- It hardly emits visible smoke anymore (and remember that the worst pollution escapes you… ndla)

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- Its fuel consumption is 10 to 20% weaker than that of a 4-stroke carburettor of the same displacement and equivalent to the most recent 4-stroke 4-valve indirect injection of the Honda Zoomer 50.

In addition, its small size allows it to be installed in compact vehicles which thus become extremely dynamic. "... and not lymphatic or modestly" utilitarian "like all 4 times.

So this is not only my personal opinion that I share with you for over 3 years through the columns of the press bike, but the one of a large French manufacturer technically on top, which already applies to four different models in its range! I welcome here this authentic more "diplomatic" ... technical feat, given the product managers and ignorant "old" leaders guarantor of outdated traditions, a priori, more skeptical than you! After much wandering and even made "walking on the head" their engineers, our policymakers are now attracted by the concrete results in line with forecasts consultants. While other manufacturers are on the same track, 2 time and direct injection, as with his Piaggio NRG Scooter cm50 3 and 50 Purejet Gilera Runner. We should also mention, Aprilia has revealed Motorcycle Show in Milan 2003, a project maxi-scooter Leonardo 2 Time mono cylinder to breaking performance in 500 atmospheric cm3 with 2,9 liter SP 95 to 110 km / h, 12,5 s at 400 m DA and 170 km / h in a point, and as a sign of dynamism, Kymco itself, with its KDI Synerject system (see box 1) .Espérons that the financial difficulties of Aprilia are not going to collapse ... in this daring project summary, a strong European 2 time forehead stands against the pandemic 4 time of the empire of the rising sun, led by Honda monotype strategy. How did he 2 time could return against the will of the most powerful world leader in 2 wheels? It's not a miracle, but simply a good technical solution to a technical problem ..., exactly!

internal official demonstration September 2002 at Piaggio engine division. These measures are confidential proprietary finally declassified. Again, the small displacement can not hide the flaws of 4 time in power as a couple. A emission standards (Euro2) and equal displacement, the time is always 2 winner with 61% torque and 72% more power than 4-time and at comparable regimes. These superb performances are obtained for 2 liters / 100 km on the ECE cycle 47.

Welcome to Synerject

Is the title of the presentation prepared me Loze Dominique, director of the Toulouse location deSynerject SAS. This joint venture equally between SiemensVDO Automotiveet Orbital Engine Corporation (Australia) is present on four continents including our thanks to Siemens VDO site. There, since 1997, 25 its engineers and technicians design and are internally realize the direct injection pneumatic injection module (OCP DI). The following year, in 1998, the responsibility of the motor control of the two wheels will be entrusted to them then spread from this year, marine applications, Snow motorcycle, quads etc ... In short, everything that is not automobile. In parallel with Synerject North America, Europe Synerject ensures the integration and development of OCP for its customers and the essential quality monitoring with a resident on site, as needed, as Peugeot, Aprilia and Rotax. This company like no other, develops and markets two injection systems based on the Orbital Combustion Process Australian: SEPI or Synerject électronic Port Injection, an indirect injection system 4 called EFI time at Peugeot and Sida or air assist Direct Injection for the revival of two time our subject. Let's see together in detail how this miraculous power system ...

Here is one of the secrets of the stratified combustion in direct injection: note the concentration of pre-carbureted to plug spray. The degrees indicate the crank angle before top dead center (TDC).

Sida on!

Sida developed by Orbital Australia takes on different trade names and special arrangements depending on the application but remain identical on the operating principle that we illustrate with the example of Peugeot TSDI (Two Stroke Direct Injection)

The basic principle of operation of the direct injection system for 2 stroke engines is to measure engine speed and load through the measurement of the throttle opening, type TPS, to determine the optimum amount of fuel to be injected. This system requires no user adjustment side and allows 35 fuel economy over 50 2% compared to a carburetor time and with less 80% in emission HC!

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In 2 classic stroke engine, at admission by valves or not, it enters the engine a fuel mixture by ... the carburetor or air and fuel vapor. This mixture is first stored in the pump sump and then pre-compressed under the piston and therefore driven towards the combustion chamber via the transfer. Here, it is abordutilisé for discharging the burnt gases. This is the famous scan that can be found in some regimes 4 time during valve overlap. That said, for the scan is complete and efficient, it is necessary to extend the thatthe fresh mixture (air + fuel) starts to come out of the exhaust. Pity! This phenomenon, called short circuit, which characterizes the mixture exits the exhaust especially outside the agreed plans of expansion chamber. Of course, this lack fuel mixture to the engine power and pollutes unnecessarily!

Exploded DAO air / fuel rail Sida: Right, the inlet ports (purple) and back (green) fuel surplus overcome that of air arrived from 5 bars (yellow). Above, the fuel injector SiemensVDO (blue) with its retaining flange. Finally on the top left, the pressure regulator and gas fastening cover (in light blue).

Synerject with Sida, the scan is performed with the air lubricated by an electric pump electronically controlled from the pump crankcase but do not include fuel. This will later be injected with a little air through two injectors mounted in series and directly into the cylinder during the compression when the piston will reverse. Note here, oil 60% saving engine and more reliable !. To transport the fuel mixture in the combustion chamber, the system uses air pressurized by a small mechanical compressor driven by an eccentric added to standard crankshaft. A bit like a diesel engine, 1 / 14 at full power, the richness of the fuel mixture varies from 1 / 50 idling at 1 / 30 in low loads typically in town for the benefit of energy efficiency and pollution.


Let's take a concrete example, presented at the World 2001 motorcycle by Peugeot Motorcycles (PMTC), the Looxor 50 cm3 TSDI mentioned above. As with all Sida, it is an integral injection system assisted by air controlled by an electronic computer managing the metering of fuel, the fuel pump, the oil minipump, the phases of injections, and ignition.

See his general representation:

1 scheme: perpetual notes (Synerject / Peugeot) 1- fuel tank, 2- electric fuel pump, regulator 3- pressure differential between air and fuel ignition circuit: 4- Coil High Energy and Noise, 5- Candle Resistive . injection circuit SP 95: 6- injector fuel, 7- injector air. Lubrication System: Oil tank 8- two time 9- electric oil pump. compressed air system: Compressor 10- clean air. transponder circuit: 11- housing imobilisateur theft. Fuel system: Antenna 12-

Now please refer to the following diagram:

1- injector fuel, fuel 2- Back to A 2,5 bars, 3- Air to B 5,5 bars, 4- fuel input to the pressure regulator (8 - 5,5) C- Special combustor stratified charge

pressurized fuel (A) to 8 bars, is injected via a conventional Siemens VDO injector in the mixing chamber (B) of the second specific Sida carburetted mixture injector. An alternative pump (10) of 3 cm3 provided Air under pressure 5,5 bars. The latter (D) arriving in the mixing chamber (B) of the air injector, is intimately mixed with the sprayed liquid fuel 2,5 bars more maintained through the controller (D). When this fuel mixture representing 1% of the final volume, is released by the second injector, it arrives directly into a combustion chamber (C) special leading them to the spark plug. At this level, a high energy ignition coil causes a powerful spark in the rich area is confined or the fuel mixture. This first combustion allows, for torch effect, igniting everything else including areas normally too poor: it is quite common principle of stratified combustion. Overall, especially in low charges in the city include the mixture is poor performance in earnings and consumption, just like ... Diesel, too, accused of every evil there is little! In truth, these new engines gives the upset and disturb the forces in place, the ecology of profit without resign themselves to performance much lower, on the contrary. One more thing: the oil being electronically metered and mixed with the intake air without fuel, there is no dilution and lubrication improved. Peugeot was able to obtain a gain of almost 60% of the oil consumption of 40 50% to essenceet therefore much more independence! Coté pollution is less 80% in HC compliance with Euro 1 and 2 without recourse to expensive catalyst: better than 4 time, please! Of course, it will be necessary to spend Euro 2006 3. In addition to these dramatic gains, the performance claims Looxor rising, lack of exhaust fumes, starting and superior driveability and greater engine brake. All this from the same 2 stroke engine carburetor because the 4 time remains far behind!

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2 4 above!

This quick demonstration proves it once again. I could multiply examples and studies favorable to 2 time aviation, marine, military and transportation among others. In engine terms, less time is required for a complete cycle, the larger the engine Engine ... exactly! That's not what we ask? The other phases are parasites and consume the power created by the engine alone time. So therefore forget this amalgam of "always more ..." if aberrant mechanical and let you ponder the 40000 2 Sida wheels that roll in France on 250000 in total, mainly in Italy. Note also that Suzuki has released a scooter Katana 50 cm3 direct injection (with the Piaggio block) and which works wonders in these small cars will work miracles in 500 more ... Note also that the world of light aviation, awaits the resurrection of this great technology for half a century since the last time 2 engines already in diesel direct injection as the US Napier Nomad E 145 and V12 Rolls Royce Crecy cm26.100 3, 2 other time direct gasoline injection 5000 horses, a record that still stands far ahead of the equivalent 4 time! In the same spirit " revolutionary " and finally on a glance, remember that Jaguar, premiere, just released its X-Type diesel TDCI ...!

For more information:


Synerject Europe:

The Peugeot site:

Appendix: Extract local press: Taipei, October. 7, 2003 (CENS) -

Manufacturers of motorized two-wheelers are adopting various strategies to counter the hyperstrict emission regulations expected in Taiwan for 2.

“Taiwanese powered two wheeler (PTW) manufacturers are adopting different strategies to enable their products to successfully pass the government-imposed fourth-degree emission regulation series of pollution tests.

According to the manufacturers of PTW, this brutally very severe emission regulation, the strictest known in the world (California included! Note), will be implemented in January 2004. This hyper selective regulation is planned to derail the two-stroke 50cc (with carburettors, note) currently sold in the domestic market and the manufacturers foresee a crisis because the industrial adaptation is far too fast, with even momentary suspensions of production!

Although a few manufacturers, including Kwang Co., Ltd. (With KYMCO brand) and Sanyang Industry Co., Ltd. (SYM) have launched a 50cc four-stroke model of scooter to test the market, yet their efforts have been dissuaded by customer complaints because of the relatively low power of such engines (which the displacement can't hide here, ndla).

Faced with this new challenge, Kwang Yang recently announced that he would adopt the most advanced technique available, namely direct injection (KDI), the technology jointly developed with an internationally famous partner, Orbital Corporation of Australia, on a few new 50cc and 100cc scooters have been planned to be launched next year. Kwang Yang said KDI's new technology, developed after seven years of cooperation with Orbital, can pass Taiwan's two fourth-degree emission regulations in 2004 and Europe's Euro 3 scheduled for 2006.

According to Kwang Yang, KDI's technology adopts an eight-bit engine control system (EMS) to calculate the best fuel injection point to optimize fuel combustion to the extreme. Such technology can provide a much higher efficiency of the PTW engine and further reduce the volume of pollutant gas emissions.

Kwang Yang admitted, however, that the new technology will result in an additional production cost of 178 266 to Euros on every new model of PTW and cleared. The PTW manufacturer in Taiwan will first apply the new technology on a 100cc and then a 50cc. "Source:

This article reveals the globalizing policy at all times conducted 4 and imposed on Japanese manufacturers for the most powerful of them, then exported as a mono-culture ... technology!

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