FEATURE ASTON MARTIN AMR-ONE
A single turbocharger configuration was chosen, but early tests with an inboard location caused problems with heat management and power potential, so an outboard location was run at Le Mans. The tream are currently working on a new iteration of the system
Te choice of an in-line six harks back to the famous Bentley- designed Lagonda six fitted to the Le Mans class-winning Aston Martin DB2. However, in the modern era, such an engine layout is rare, especially turbocharged. Tis choice has put Aston Martin’s engineers in the firing line for a lot of criticism, so we gave AMR’s engine boss the chance to set the record straight. ‘What people need to understand with this engine is that when
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we talk about development problems, we need to make clear that the engine does not suffer from any sort of epidemic. We are doing a completely new engine, from a clean sheet of paper. We started running it in January and, when you look at our competitors, they have a clear process of six months from when the engine is run to when it goes in a car. We had to have ours in the car in February! Believe me when I say that the guys running round with four rings on their car would have the same problems, but they do it behind closed doors… we are doing ours on track’
Six of the best Tese are the words of Jason Hill, head of engine development for Aston Martin Racing. When AMR announced that its new LMP1 contender would be powered by a small capacity, straight six engine, there were more than a few raised eyebrows. It has been several decades since such an engine configuration appeared in racing, and was a major departure from the large capacity, naturally aspirated V12 of the DBR9, and later the Lola Aston Martin. However, the selection of such an unusual configuration is not as strange as it might first appear, as Hill explains: ‘Tere are several key reasons for opting to go with the straight six. Predominantly, you cannot look at the engine in isolation, you need to look at the complete package. In terms of establishing the
hen Aston Martin Racing (AMR) was given the green light for the AMR-ONE programme one of the major issues it faced was what kind of powertrain to install.
The doubters were qquick to crticise AMR’s chice of a turbochaarged in-line six, but the company are convinced of its worth, stating that individual cylinder loads are lower than with a four cylinder, and its installed height is lower, too
architecture, you have to look at the peak cylinder loads and peak bearing loads. If you need larger bearings then this will affect the installation height of the engine and the overall packaging. So you have to ask what the advantages of a four over a six really are. Okay, it is shorter, but the car is 5m long so you are going to end up with a space behind the engine. Tough the six is longer, the installation height is reduced and the individual cylinder loads
“sometimes in life you have to make commitments about things”
are decreased. Te only area [where the four has an advantage] is friction but, if you do the work, there is not much in it between the two configurations.’ With the engine layout decided, the team were up against
a perilously tight deadline to design and build the new engine. Although initial plans were laid out for factors such as crankshaft geometry and general architecture in 2009, no real design work could be completed until the project was confirmed in 2010. Te first engine then ran on the dyno in January 2011, so it was no mean feat to get the unit operational in time for Le Mans at the start of June.
Direct injection The intention was always to run with a direct injection system, and AMR opted to utilise Bosch Motorsport’s customer system, which the company is able to tailor to individual applications. Te direct injection system developed for the V12 engine also provided the designers with many valuable lessons in terms of port design and combustion chamber shape, but the addition of a turbocharger was new territory. Due to the high boost pressures
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www.racecarengineering.com • August 2011 13
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