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New Volvo Inline-Six: More Power, Lower Fuel Consumption

The new compact inline-six

Volvo has introduced a new high-efficiency, compact six-cylinder engine to accompany its all new Volvo S80.

The new six-cylinder engine, designed by Volvo, is of an all-new, compact design. Its main structure is made entirely of aluminium and has a larger displacement than its predecessor, 3.2 liters as against the previous 2.9. Power increases to 175 kW (235 hp) as is torque, at 320 Nm.

This corresponds to increases of 31 kW (+21.5%) and 40 Nm (+14.2%) respectively. Fuel consumption decreases 0.7 l/100km to 9.9 l/100km (24 mpg), a 7% decrease.

An advanced valvetrain and a variable intake system (VIS) mean that the engine can be exploited efficiently throughout the rev range, thus promoting quick response and solid performance. At the same time, the engine is very fuel-efficient.

The valvetrain features VCT (Variable Cam Timing) and CPS (Cam Profile Switching) on the inlet side. CPS (Cam Profile Switching) means that the camshaft is designed such that the inlet valves are lifted to two different heights depending on engine speed and load.

In normal driving, with normal throttle opening and low engine revs, fuel consumption is modest at the same time as torque is sufficient to provide good driveability.

In more aggressive driving involving full throttle opening and high engine revs, the engine responds instantly to the accelerator and provides a thrust of power, both at low and at high speeds.

In principle, Cam Profile Switching creates two engines in one. We can unite widely differing demands on one and the same engine and easily meet the requirements of customers with entirely different wishes. For instance, we can equally easily satisfy customers who prioritize performance as well as those who are more interested in driving comfort and fuel economy.

—Derek Crabb, Vice President Powertrain, Volvo Cars

The VIS is equipped with two throttle flap valves which adjust the intake manifold volume to suit the current driving situation. This results in a uniformly high and broad torque curve.

Through precise interplay with the flap valves we actually get three different torque curves that are integrated with one another. Consequently, we can exploit the engine’s capacity to the maximum and extract the highest possible power throughout the rev range.

—Derek Crabb

Transverse mounting of the 3.2-liter engine.

The complete engine package is only 3 millimeters longer than Volvo’s five-cylinder engine, allowing for it to be mounted transversely. The engine itself cannot be made all that much smaller since the cylinder spacing and block structure are roughly the same as in a five-cylinder engine. Instead, the focus was on building the entire installation, encompassing the engine, automatic transmission and ancillaries, in as compact a package as possible. One additional condition that had to be taken into account was that the transmission would be a six-speed automatic.

The ancillary systems, such as the Power Assisted Steering Pump and Air Conditioning Compressor are placed behind the engine in the space above the gearbox. Consequently, there is no front-end drive of the ancillaries; rather they are driven via gears by the rear end of the crankshaft.

This design approach is known as READ—Rear End Ancillary Drive. The alternator is direct-driven and installed on the engine block. This solution means that the entire engine and transmission package takes up minimum space, particularly in the car’s longitudinal direction.

By designing the drive system in the form of a small gearbox with an intermediate shaft inside the driveshaft—known as a Shaft In Shaft design—it was possible to ensure a very short package. The two shafts are driven by different gears that give them different speeds (one speed for camshaft drive and one for the ancillaries).

The engine will start series production in week 13, 2006.


The Icelander

Small engine, small transmission, small components and a new technology for connecting ancillary systems.

That won't be expensive or difficult to fix at all.


I do like the aluminum construction, though.


Looks to me like it's set up so a future version could replace the alternator with a starter/generator to run accessories and restart the engine to support start/stop functionality. Or maybe I'm just dreaming...


Ford must be getting more involved with Volvo development now.....touting this CPS (Cam Profile Switching) technology, when Honda has been using the same thing (VTEC) in mass produced cars since the mid-90s. Typical.

Tim Russell

For major component replacement they probably have to lower the engine and drive train out of the car. The Boxster has been like that for some time.

Angelo, Yes Honda had VTEC out years before anyone else had variable valve timing but still many engines do not have that feature to this day. So all you were saying was "Honda had it first". Hell did you know that Harly Davidson had a 4 valve per cyl racing engine in the 19teens.

The Variable cam timing and variable intake are also used on the Mustangs V8 for that matter. Sounds like the variable intake is more advanced on this engine however. I think it's great that they added power and reduced fuel usage at the same time. I'd look for more things like doing away with belt driven accessorys etc.

Mike GR

I'm still waiting for the day when automakers decide to *gasp* not increase power. Wouldn't it be nice if a press release said: "Oh, so we thought it already had enough power, so this new version has the same output as the previous one, but the fuel economy is much improved!"


Mike GR, why? Fuel economy and power are not mutually exclusive. I don't know why you seem to think they are. Most of the technologies that make an engine more powerfull also make it more efficient. These two things go hand in hand. In most circumstances a more powerfull engine running at a low RPM will be more fuel efficent than a smaller engine at higher RPM in the same vehicle. Peak HP is irrelevant for fuel consumption in normal driving.

Robert Schwartz

Ford shareholders cannot be happy. Ford has a very nice 3 V6 that is used in a lot of Ford and Jaguar models. Why go to the expense of developing this motor?


Response to Justin: I'm pretty sure that most engines have an optimum range of load or power output. If you don't load it enough or you load it too much, the efficiency falls off. Simply running at a lower rpm doesn't necessarily make anything better. It really depends on the engine though.

Shirley E

In my experience, the straight six configuration produces a darn good engine. Some of BMW's most highly regarded engines are straight sixes, for example. My grandfather always swore by his old GM 292. I imagine this one will be a solid choice for anyone buying a Volvo, at least until the 3CC electric is available!


My grandpappy swore by Rufus the 21 year old grey plow horse. And in my experience, a straight one cylinder Briggs and Stratton produces a darn good engine. Some of my lawn mower's most highly regarded engines are straight ones. Shirley, my drivel written here is as useful as your post. At least this one shows a logical point: sarcasm.



The point that Mike GR tried to make was that, if Volvo had chosen to reduce the displacement instead of increasing it, they could have produced an engine with the same power and achieve even more fuel savings. If you look at it at that way, yes indeed, power and fuel efficiency ARE mutually exclusive.

[quote]In most circumstances a more powerfull engine running at a low RPM will be more fuel efficent than a smaller engine at higher RPM in the same vehicle.[/quote]

This is a purely theoretical situation. In normal, every day use, a car with a smaller engine is more fuel efficient. Modern cars with small engines already have loads of spare power and are generally run far below their optimum efficiency, so increasing power can do only one thing: make things worse.


Volvo will still offer the 2.5 litre turbo in the new S80. There is no practical reason to make a 6 cyl engine of less than 3.0 litre. Either way the new 3.2 is more effient than the old 2.9.
The engine range for the new S80 as it stands right now:
2.5t 5cyl base engine
3.2 6cyl
4.4 V8
There will also be a 2.4 diesel like the old one which won't make it to the US... again.


The old 6cyl was only offered with a GM produced 4 speed auto. The new engine's smaller size allows Volvo to use a 6 speed auto for the first time with a 6cyl. Thats a big part of the fuel economy increase.


re: ICE efficiency/displacement

In general, a smaller engine running closer to it's maximum power will be more efficient than a larger engine running at partial load--and automobile engines spend their lives running at partial load. Gasoline engines lose efficiency at partial load due to pumping losses, friction, etc. (I believe one of the tricks Honda does with VTEC is to reduce pumping losses by keeping exhaust valves open longer at partial load). Added weight of a larger engine also reduces mileage--you've got more inertia to overcome on acceleration. It looks like this engine is optimized to mitigate these disadvantages by reducing weight, VVT, intake tuning, etc. However, those same techniques applied to a smaller, even lighter engine with less power could undoubtedly have resulted in higher mileage. Ford/Volvo thinks they need to sell power as well as efficiency, so they didn't do that.


If you want a smaller engine just buy the 2.5 litre 5 cyl and don't complain.


I'm not complaining, and I didn't say I wanted a smaller engine; I'm just stating the facts.

The 2.5 L engine has older technology. Does the it get as good mileage as it might with all the new technology incorporated into the new 6cyl? It will be interesting to compare the mileage of the two engines when comparable figures become available. Volvo's website lists the 2005 2wd, 2.5L figures as 21/30.

Shirley E


I'm sorry that my post didn't meet your intellectual standard. But one wonders why you would feel so strongly as to post a sarcastic response rather than just pass over it. In any case, I anxiously await your future scholarly ruminations.

I still say a straight six makes a darn good engine, by the way. >:b


Update: I found the comarable figures. A 2wd S80 with the 2.5L, turbo engine (210 hp) is listed at 10l/km using automatic transmission, which is *lower mpg* than the 9.9l/km of the new (235 hp) six. The new engine is more efficient, as well as more powerful, than even the old turbo 5/2.5. Perhaps Ford/Volvo will upgrade their smaller-displacement engines with some of the same tech.


Volvos old whiteblock family of engines first introduced in 1990 i the Volvo 960 was a modular design where 4, 5, and 6 cyl engines could be produced on the same assembly using the same pistons, rods, valves and so on. The 2.5 5 cyl is the last engine of that family. The new SI6 is the first of the next generation of modular engines. So there will eventually be a new 5 and 4 cyl engine incorporating all the technologies of this new 6 cyl. Very smart thinking on Volvo's part. Ford will eventually replace their ancient 3.0 V6 with this engine in other Jaguar, Land Rover and Lincoln models. Volvo is the technology power house in the Ford empire. Its also one of the few devisions turning a profit.


"Ford will eventually replace their ancient 3.0 V6 with this engine in other Jaguar, Land Rover and Lincoln models."

Maybe, but what about Ford's new, more efficient V6 (see

which also has VVT, etc?


Inline 6 engine is inherently smoother than a V6 engine. The inline 6 designed to be installed both lengthwise and sideways in the car so it can be used in RWD aplications. Also the Volvo engine has a switcable dual cam profile system like honda's VTEC on top of VVT. V6 doesn't. Inline 6 will be built in the UK to also supply Jaguar and Land Rover. V6 is build in the US.


Just a tidbit for folks to note. The first mass market car to use variable valve timing was Alfa Romeo back in the early '80s.

"Performance gradually increased from its all-time low of 1981. Alfa kept refining and tuning the engine as much as possible to get power, economy, and emissions control. To this end, in 1980 Alfa incorporated variable valve timing (or VVT). The system is essentially an electromechanical piston on the intake camshaft. Developed in the 1970s by Ing Giampaolo Garcea for Alfa, it was termed "variatore de fase" by the Italian engineers. This was promptly renamed "the phaser" by the Americans involved with the team, and the name stuck.

At first only used as an emissions control device, later versions allowed improved cam timing, giving better performance at high RPM but allowing controlled emissions at idle. I believe it was the only production car available in the US (perhaps anywhere) with such an advanced system until well into the ‘90s. FIAT has rediscovered this device and now fits it to several of its own engine designs. (special thanks to BD for information on the VVT system)"

As for inline 6 engines, they are very well suited to luxury cars because of a low of vibration. However it seems that Volvo didn't make an especially powerful engine, given the number of other car makers out there with V6 and inline 6 engines that produce substantially more power - if not the fuel economy. Has anyone seen the actual economy numbers yet? The Alfa 3.2 makes 250hp. VW makes a 250hp 3.2 VR6. Audi makes a 3.2 (technically a 3.1) with 255hp. And note that all these engines produce good torque at reasonable rpms.


Has anyone ever tried to get a shop manual for the newer Volvos. You cannot unless you rent time on their internet site and it is very expensive what a rip off. Last Volvo I will ever buy 2006 S60 owner


i had no trouble purchasing my shop manual for the original b6304 engine (i am building it up now, actually), go to, they should have any manual that you need.

as for the inline 6, i'm a fan. naturally balanced and easier to work on - thumbs-up.

by lightening the rotating assembly, going to longer rods and shorter pistons (piston max speed to rpm is decreased in this way, and the piston follows a different curve to that top speed, with more symmetry on the up and down strokes), increasing the compression, doing some mild porting in the head and intake manifold, using better fuel/spark maps with a wide band oxygen sensor, and running tuned exhaust headers i think that one could break the 30 mpg mark on a sub-3000 lb volvo 240 (if you had the initiative to swap the i6 in). if one did it right you could probably break the 100 horsepower/liter mark as well.

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