Tuesday, 28 April 2015

The powertrain future is bright

Olof Persson had something interesting to say about the future of engines Volvo before he was unceremoniously dismissed from the top spot.

Unfortunately for observers of the scene, Persson raised more questions than he gave answers. More to the point, did he know the powertrain future at Volvo before he spoke a few weeks back at the North American Trucking Show in Louisville, Kentucky?

Did he then know his future at the company was bleak? Possibly not. Because, if he did know that he was on skid row heading for the front door, would he be allowed to make the utterances he did? 

Or did he make his comments simply because he knew of his impeding departure and wanted to be provocative on front of his American audience?

Or did he make his pronouncement simply because he did know the future. That the powertrain future at Volvo is bright. As the boss of the Swedish truck and bus builder he ought to know what is on the drawing board.

And, if the powertrain future is bright, then surely he will be remembered for laying the stepping stones in the same way that Daniel Ustian will be remembered for laying the stepping stones of Navistar International’s downfall through his intransigence not to back SCR – selective catalytic reduction – for heavy diesels.

So what is going on in the powertrain offices of Volvo? In a few words, we don’t know. Because the powers that be at Volvo say very little about the direction in which the company is heading. We can only go by what the great man said.

And to that we can put in place the notion that Martin Lundstedt, the Swede from rival Scania who takes Persson’s place in July, will not over-rule Persson’s plan, but accede to it.

So what did Persson say that has provoked this blog?

Persson, speaking to the Press in Louisville, Kentucky, said tantalisingly that ‘engines can get smaller and more powerful’.

To be provocative, he dismissed the adage that ‘there is no replacement for displacement’.  Instead said, ‘there is a replacement for displacement; it’s called innovation’.

Persson suggested it was ‘plausible’ for a future derivative of Volvo’s 10.8-litre diesel, which develops between 355 to 405bhp deliver up to 505bhp.

Teasingly, Persson reminded his audience, that 505bhp is slap, bang ‘in the middle of the power range of the (15-litre) Cummins ISX15 engine’. 

So how will Volvo ‘innovate’ and achieve 505bhp from a 10.8-litre engine in what really amounts to a new trend in downsizing of commercial vehicle engines? In one sense, Volvo has already exceeded this output level with its high-performance, six-cylinder marine engine, as mentioned below.

But in the world of road vehicles, downsizing has long been a reality in the passenger car world with the arrival of three-cylinder engines. And now there is talk of two-cylinder engines. But in general these engines have aluminium cylinder blocks and heads.

There can surely be only one answer to the question of 505bhp – compacted graphite iron (CGI).

Volvo has said very little in public about CGI. Seemingly its last pronouncement was on 31 July 2008 when Volvo Penta launched its new 11-litre marine diesel engine at the Sydney International Boat Show, specifically referring to the use of a robust CGI cylinder block.This engine can develop 725bhp at 2,500 rev/min.

But it is well known that Daf uses CGI for the cylinder blocks and heads of its Euro 6 MX-11 and MX-13 engines. The CGI components for both engines (the MX-11 being the latest to arrive) are supplied by Fritz Winter in Germany and Tupy SA in Brazil. Quite how the volumes are split between the two is known possibly only to Daf but Tupy claims to be the world’s biggest supplier of CGI engine components.

MAN in Germany also uses CGI for its similarly-sized truck engines while Scania too has moved in that direction for its large, premium truck engines.

Buyers of new truck in Europe now accept smaller and lighter diesel engines of a given output can bring benefits of additional payload without compromising engine life or operational downtime. And there is the added bonus of improved fuel consumption from reduced friction losses within a smaller engine.  

Engine manufacturers’ assertions that higher-strength CGI cylinder heads and blocks can address issues of reliability and durability have been proved correct. By the same token, the bogey man of the difficulty of machining CGI has been overcome, thanks to the help of machine tool and cutting tool suppliers. This improvement in machining and assembly has led indirectly to an increase in peak firing pressures.

So, higher, strength, lower noise, greater and more consistent machining accuracy, and finally improvements in fuel injection systems have all contributed to higher torques, without having to resort to increased engine speeds and thus increased wear of pistons and bore surfaces.

Where does that leave us? Persson is out, but departs with a shot across the bows that 505bhp is possible from a 10.8-litre engine. Engine production and development man Martin Lundstedt is due to arrive from Scania to replace him and will step into the hot seat in July.

Lundstedt knows about CGI, how to cast it, how machine it and the benefits the material can bring. Scania uses CGI for its large 16-litre V8 engines. The company also uses CGI for its 13-litre engines. Scania's engineers have allocated different power levels and emission compliance levels (on-road as against off-road) with the result that some engines use CGI while others use grey iron. But many of the 13-litre engines already use CGI, implying the Swedish company has substantial experience with this advanced engine material. .  

The future is bright. The future has to be CGI at Volvo?

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