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Toyota unveils new diesels with advanced thermal insulation combustion; 15% more fuel efficient, 25% more torque; 44% thermal efficiency

2.8-liter 1GD-FTV direct-injection turbo diesel engine. Click to enlarge.

Toyota has introduced a new line of turbodiesel engines with more torque, greater efficiency and lower emissions. The new GD engines feature Toyota’s next-generation advanced thermal insulation diesel combustion to reduce cooling loss significantly.

The use of Thermo Swing Wall Insulation Technology (TSWIN) helps make the 2.8-liter 1GD-FTV engine one of the most thermally efficient, with a maximum thermal efficiency of 44% (measured in-house). Despite smaller engine displacement in comparison to the current KD engine, maximum torque is improved by 25% and low speed torque improved by 11%, while fuel efficiency has received a 15% boost.

Toyota will gradually phase out the current globally deployed KD diesel engines and replace them with GD engines. By 2016, production will reach approximately 700,000 units a year with introduction in approximately 90 markets, set to expand to at least 150 markets by 2020.

The newly developed 1GD-FTV is currently available in the new Hilux small pickup truck launched in Thailand in May 2015, and in the partially redesigned Land Cruiser Prado launched in Japan on 17 June. The same engine lineup includes the 2GD-FTV 2.4-liter direct-injection turbo diesel engine.

GD engines main specifications
Displacement 2,754 cc 2,393 cc
Bore/stroke ratio 92×103.6 mm 92×90 mm
Compression ratio 15.6 15.6
Maximum output 130 kw (177 PS)
@ 3,400 rpm
110 kw (150 PS)
@ 3,400 rpm
Maximum torque 450 N・m (332 lb-ft)
@ 1,600-2,400 rpm
400 N・m (295 lb-ft)
@ 1,600-2,000 rpm
Low speed torque 370 N・m (273 lb-ft)
@ 1,200 rpm
330 N・m (243 lb-ft)
@ 1,200 rpm

Advanced thermal insulation diesel combustion. Toyota’s new advanced diesel combustion system features a number of elements. A port shape more conducive to air intake significantly increases the amount of air flow into the cylinders—some 11% greater with the new GD port than with the port used on the previous generation KD diesels.


Precise pilot injection matching the state of the ambient air occurs before the main injection to shorten ignition delay, achieving stable combustion even in the world’s harshest environments, while ensuring quiet operation and high thermal efficiency.

A newly developed piston combustion chamber shape and a common-rail fuel injection system that achieves higher pressure and more advanced control of fuel injection pressure are used to optimize the injection of fuel into the combustion chamber. This maximizes air consumption, enabling higher thermal efficiency and lower emissions.

Due to the world-first use of Thermo Swing Wall Insulation Technology and the use of silica-reinforced porous anodized aluminum (SiRPA) on the pistons, cooling loss during combustion is reduced by approximately 30%. SiRPA is a high insulation and dissipation material that is easy to heat and easy to cool.


In a 2013 paper describing the Thermal Swing concept, Toyota engineers noted that the surface temperature of the commonly-used metals for combustion chambers—i.e., iron or aluminum—have almost constant surface temperatures udring the whole engine cycle. As a result, the difference of temperature between the working gas and the wall surface during the combustion period is large. This is the main cause of heat loss in the combustion chamber.

Traditional adiabatic engines, including the engines with ceramic thermal barrier coatings, cause almost invariably high temperature on the wall surface during the whole cycle including the intake stroke…and result in decrease in the volumetric efficiency, increase in working gas temperature, and facilitate the occurrence of engine knock.

On the other hand, using a “Temperature Swing” coat, which is a low-heat-conductivity and low-heat-capacity material, on the combustion chamber walls, leads to a large change in surface temperature. … the surface temperature with the insulation coat follows the transient gase temperature, which decreases het loss without heating intake air.

—Kosaka et al.

In that 2013 paper, the Toyota engineers also noted that the effect of the “Temperature Swing” coast is larger in a turbocharged diesel engine than in a naturally-aspirated diesel engine. They attributed this to two factors:

  • The larger temperature fluctuation of the wall due to large heat transfer coefficient based on both higher cylinder pressure and higher gas flow speed in diesel engines.

  • The larger reduction rate of the temperature difference between the working gas and the combustion wall surface resulting form the lower peak of gas temperature.

  • Another factor is that the exhaust energy increased by heat insulation is recovered with a turbocharger.

Turbocharger. The new compact high-efficiency variable geometry turbocharger (produced in-house by Toyota) used by the GD engines is 30% smaller than its current equivalent, and features a newly developed turbine that improves efficiency, and a newly developed impeller that provides instantaneous acceleration response and produces maximum torque over a wide range of RPM.


By reducing size and increasing efficiency, the newly developed turbocharger with the GD engine delivers approximately a 50% faster response in the rate of boost pressure increase.

Toyota-first urea selective catalyst reduction (SCR) system. Use of Toyota’s proprietary, compact, high-dispersion urea selective catalyst reduction (SCR) system eliminates up to 99% of emissions of NOx. This will help vehicles conform to Euro 6 and the 2010 emissions standards set by Japan’s Ministry of Land, Infrastructure and Transport.



  • Kosaka, H., Wakisaka, Y., Nomura, Y., Hotta, Y. et al. (2013) “Concept of “Temperature Swing Heat Insulation” in Combustion Chamber Walls, and Appropriate Thermo-Physical Properties for Heat Insulation Coat,” SAE Int. J. Engines 6(1):142-149 doi: 10.4271/2013-01-0274



It is amazing how replacing one Texas oil whore and 'the old GM' with a black man and EVs suddenly leads to 'impossible' new 44% engine efficiency, over 100 mpge, and an 'oil glut' with US gas prices often over a dollar lower.


The nice thing about GCC is that there are not nearly as many wildly stupid, politically oriented conspiracy theory posts compared to the majority of the "new mobility" echo chamber. Generally much more technically-driven articles and discussions.

And then, sadly, posts like Kelly's ooze in the site.

Kelly, your provincial, politically narrow, biased and frankly cretinous thinking is the only thing that could make you think engine developments in a Japanese auto company lab -- for products that will likely not be sold in America for years -- are driven by the bizarre local conspiratorial theories you hold dear. Please post your excrement elsewhere.


Good move by GM to reduce weight and wasted energy?


The CAFE car fleet average was at 20 MPG FOR DECADES and surges with Obama by over 25%.

Bush CRUSHED the 1000's of EV1 era EVs, CARB laws and progress. No doubt, your driving one of his, now 13th year, Hydrogen Initiative fuel cell cars - but no one else is.

"ZSW: more than 400,000 plug-in cars on road worldwide at beginning of 2014; 2x 2013"

"6 DOE-funded applied battery research projects targeting Li-ion cells with >200 Wh/kg for PHEVs and EVs"

Facts, and technically-driven articles and discussions, are on this site and the Obama energy funding and advances are VASTLY beyond the "addicted to oil wars" Texan and Obama energy policy deserves a great deal of the credit.


Good move by GM to reduce weight and wasted energy?


The CAFE car fleet average was at 20 MPG FOR DECADES and surges with Obama by over 25%.

Bush CRUSHED the 1000's of EV1 era EVs, CARB laws and progress. No doubt, your driving one of his, now 13th year, Hydrogen Initiative fuel cell cars - but no one else is.

"ZSW: more than 400,000 plug-in cars on road worldwide at beginning of 2014; 2x 2013"

"6 DOE-funded applied battery research projects targeting Li-ion cells with >200 Wh/kg for PHEVs and EVs"

Facts, and technically-driven articles and discussions, are on this site and the Obama energy funding and advances are VASTLY beyond the "addicted to oil wars" Texan and Obama energy policy deserves a great deal of the credit.


@ Harvey

GM? Where in this article does it mention General Motors?


Sorry I hit the wrong key


It is very impressive but we need smaller ones for cars: approximately 1.4, 1.6 and 2.0L capacity.
Maybe you could build a 1.8 with a 3 cylinder 2.4 and a 2.1 with a 3 cylinder 2.8
I wonder what a 2 cylinder 1.4 (1/2 a 2.8) would sound like - a bit rough perhaps.


"Bush CRUSHED the 1000's of EV1 era EVs, CARB laws and progress."

Wow... I missed seeing President Bush operating the crusher for GM. I also am having trouble finding the legal records of how he declared California Air Resources Board regs invalid. But of course I'll keep looking for all that along with the demise of Tesla free energy and the 100mpg carburetor. In the meantime let's be certain to congratulate President Obama on forcing Toyota to develop much more efficient diesels for a product line that is sold completely outside of the US.

It's shocking how American presidential politics is the sole influence on global automotive technology. You're probably shocked too... oops, I forgot: you're a moron.


Since you can't/haven't found ANY REFERENCES supporting your statements..

"..The plaintiffs maintained that ZEV rules amounted to a regulation of fuel economy .. On October 9, 2002, the Bush Administration, in an unusual move, joined the lawsuit, filing an amicus (friend of the court) brief, claiming that the state, by regulating emissions, was trying to set a gasoline mileage standard, which" only the federal government can do." -- -- again, foreign auto makers, like Toyota, usually meet the US/Obama oil saving/pollution reduction EPA standards before past/future US bankrupts.

If your capable, at least try watching [hint: its a movie about who killed EVs]


Which 90 countries are they to be introduced into first? I only see mention of Thailand and Japan. What about timing for the U.S., Europe?


Why would 44% be impossible? I have seen data on 2-liter passenger car diesel engines (e.g. VW) with specific fuel consumption of ~195 g/kWh. With energy content of 42.64 MJ/kg, this equals 43.3% efficiency. Suppose that Toyota has 43.6% efficiency and round it to 44%. Then, there is not much difference. If we take cylinder size into account (if anyone is interested in finding out how to calculate that, I can explain this separately later), the smaller engine I mentioned is actually more efficient.

Low swirl and combination of a helical and a tangential port is nothing new. I cannot see anything radically new in the VG turbocharger. Urea SCR might be new to Toyota but it has been used by competitors for many years now.

The only “invention” I can see is the thermal insulation. This is very interesting! However, the thermal barrier is only on top of the piston crown, not inside the combustion chamber. Thus, the insulated area is only used on a small fraction of the piston, particularly with such a wide combustion chamber as in this case. Presumably the complex shape of the combustion chamber prevents the use of a thermal barrier (for some reason…). Finally, we have to note that steel pistons also significantly reduce thermal loss. In addition, steel pistons have many other advantages as well.


If you want to read about the GM EV1 saga, you could read "The Great Race" by Levi Tillermann.


So road-going diesel engines are now at 44% efficiency. Toyota recently announced the gasoline engine in the next Prius manages 40% efficiency. Not far off the much touted 50% efficiency of PEM fuel cells. Anyone still fancy a Mirai?


FCVs have no combustion leading to less smog, less heart disease and less imported oil. Reform bio methanol on the FCV for renewable transport.


Fantastic. Toyota has just achieved 44% thermal efficiency. The exact same thermal efficiency my 1930's designed Lister CS diesel achieves at it's peak. Of course, the Lister CS uses a cast iron piston, chrome plated bore and cast iron cylinder head. This results in less combustion heat rejection than similar aluminum parts.


44% efficiency for a Lister CS? You should realize that this cannot be true. No way! Perhaps the efficiency has been calculated from BSFC data by mixing g/bhp with g/kWh?


Even if your Lister CS diesel reaches 44% thermal (brake) efficiency, what are the exhaust emissions?... Probably not good..


Air pollution is responsible for over 2,000,000 premature human deaths/year. China and India account for 1,600,000/year.

The 44,000/year in the middle East make the daily news but not the 2,000,000/year. Why not?

CPPs, Gas and OIL industries and ICEVs are the main culprits. Aviation with 3% of GHGs accounts for almost 12% (and rising) of total air pollution. Older high pollution planes can last for 40+ years.


The Toyota engine has DPF which will give lower concentration of PM in the exhaust than in ambient air (in a polluted city). It will clean the air. An EV version of the same car could never accomplish this.

Roger Pham

The Lister CS is listed as having peak efficiency of 21% from fuel to electricity when using vegetable oil. As a genset, it puts out 3 kW of power max, and the genset weighs 450 lbs! Try to put this in a car or truck!! :-(


Peter X...many ICEV manufacturers, clean coal and clean tobacco advocates have made that false claim before?

Inhaling the exhaust of ICEVs and CPPs is deadly and often more so than cigarette & cigar smoke.

Forest fires (other open fires + BBQ etc) are important air pollution sources that we should better manage.


But what about all the independent measurements that show low emissions from DPF diesel cars? Are these also false claims? What evidence do you need? I have measured on my own car. It has a PM2.5 concentration of 2 ug/m3. The ambient air limit for PM2.5 is 25 ug/m3. I am cleaning the air under such conditions. I know I can never convince some people with facts but I hope you are not one of them.

In contrast, you cannot find any independent studies that show low levels from tobacco smoke. And, in a direct comparison, tobacco smoke is more harmful than dirty city air.


Peter XX, how and under what conditions did you measure the PM2.5 emissions of your car? Is there a relatively cheap way to do so, as I am also interested in doing it.

Also, noted the diesel energy density of 42.64 MJ/kg that you used to calculate the TDI efficiency is a bit optimistic. I find typical numbers around 45.0 - 45.8 MJ/kg, which leads to peak efficiency of ~41% for the TDI engine.

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