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Volvo D13 turbo compound engine delivers up to 6.5% improvement in fuel efficiency

Volvo Trucks North America’s new VNL series delivers up to 7.5% improved fuel efficiency when spec’d with Volvo’s available D13 Turbo Compound engine (D13TC). (Earlier post.) Designed for customers with long-haul, steady-speed operations, the 13-liter Volvo D13TC utilizes turbo compounding technology that recovers energy typically wasted through the exhaust, converting it into useable mechanical energy that is transferred back to the engine.

By employing a secondary exhaust turbine downstream of the main turbocharger, the normally lost energy is routed to the flywheel, recovering as much as 50 hp and helping to improve fuel economy by up to 6.5% when compared with previous GHG14 D13 engine models.

Combined with an additional 1 percent fuel efficiency benefit from the improved aerodynamics of the new VNL series, customers spec’ing the D13TC will see up to a 7.5 percent improvement overall.

—Göran Nyberg, president of Volvo Trucks North America

Volvo D13 With Turbo Compound. Click to enlarge.

Customers are able to pair the D13TC with Volvo’s XE—eXceptional Efficiency—powertrain packages. XE packages rely on Volvo’s fully integrated I-Shift automated manual transmission to downspeed the engine, enabling a cruise rpm up to 300 rpm less than the average truck sold today, saving fuel.

The VNL series comes standard with the Volvo D13 engine, with the D13TC available as an option. Customers choosing Daycab and VNL 400 models also have the option of spec’ing the 11-liter Volvo D11 as an alternative. The 15-liter Cummins X15 is also available in the VNL series.

All three Volvo engines feature the patented wave piston, which employs a uniquely designed piston crown. The new wave piston increases compression ratio from 16:1 to 17:1, increasing efficiency. Improved flame propagation increases cylinder efficiency while at the same time reducing soot.

A proven common rail fuel injection system improves fuel efficiency by enabling finer control and more accurate fuel injection.

The engines also feature a revised EGR flow sensor with a new double-wall casing to reduce condensation and soot buildup in cold weather, preventing downtime.  An available two-speed coolant pump also contributes to improved fuel efficiency as a result of reduced parasitic losses. The new intake throttle enables a faster warmup when the engine is started.



AS i said before, i perfectly knew that they were wasting energy throu the exhaust pressure and heat. They decided just to harness exhaust pressure and still waste exhaust heat.

I clearly said to build and commercialize gasoline serial hybrid with exhaust pressure and HEAT capture for doing over 120 mpg in cars.


Im sure they can increase efficiency furthermore by adopting serie hybrid instead


Mechanically interesting but also relatively complicated. If I was given the job to design something like this, I think that I would try to build an electrically separated turbo charger with the turbine driving an alternator and a motor driven compressor, a relatively small battery pack and a motor connected to the drive train. That way the compressor could driven for better power response and the turbine could absorb more power under normal driving conditions with excess power being diverted to the power train. This would also support using the power train motor/alternator in a hybrid mode during braking or going downhill.


Well, sd, I understand why you are not employed by the industry. Your idea would be less efficient than the one used by Volvo. Try to figure out why and post your thoughts on this site. Try to find the errors in your own arguments. If you wish, I can help you.



The electric alternators/motors probably have something around a 90% efficiency (might be a bit better) and there is also a loss associated with the required electronic drives so there is loss that occurs with each pass thru an alternator and motor. However there is also about a 2% loss thru each gear mesh assuming high quality gears and lubrication (a good assumption in this case). I counted 6 gear meshes so that is about 88% efficient from the turbine to the flywheel. Now we need to worry about turbine efficiency. In Volvo's design, the turbine is geared directly to the flywheel so the turbine speed is dictated by the engine speed. In my proposed design the turbine is allowed to run where it develops the most power. My design also allows direct engine braking with the energy being returned to a battery for later use.

Now you can enlighten me as to why I am wrong. Also, I did work on an experimental opposed piston diesel about 15 years ago that was designed to have an electrically split turbo charger but I was not the thermal dynamics expert.

Liviu Giurca

There are internal combustion engines with internal heat recovery which largely surpass the diesel compound engine efficieny. See

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