Twin-turbo future for AMG?
2008-07-21 11:12
AMG V8
AMG might be necessitated to return to forced induction in a bid to reconcile epic performance with emissions regulation.
Five years ago the supercharged 5.4-litre V8 which powered the E55 AMG moved the German four-door performance car parameters off the sanity scale – beyond the mythical 500 imperial horsepower marker.
Despite its huge performance, the supercharged 5.4-litre V8 has all but been replaced in the AMG range by a 6.2-litre V8 and 6-litre bi-turbo. The only ‘other’ AMG you can buy locally is the naturally aspirated 5.4-litre V8 powering the SLK AMG.
Bye-bye big, bad V8...
BMW and Audi loyalists have lambasted the behemoth 6.2-litre V8 as an engineering anarchism - an uncouth cubic capacity ode to American powertrain engineering.
Despite these comments the naturally aspirated V8 lump has provided a very linear performance driving experience with immense torque available at low revs and is comparatively less complicated than a forced induction engine. Logic would dictate it to be more reliable too.
From the 336kW C63 AMG to the 386kW CL63 AMG, the 6.2-litre V8 has proved highly flexible and massively powerful in all AMG applications. Unfortunately ever more stringent emission regulations are curtailing the lifespan of large capacity, naturally aspirated engines.
BMW will surely move to forced induction for the next generation M5 and Audi has all but admitted it’s new S4 and RS4 models will also feature ‘blown’ engines too, in the form of a highly tuned 3-litre V6 TFSI motor.
Now rumours from Europe have it AMG are set to revert back to forced induction too - complete with a smaller V8 engine architecture.
What are the AMG options?
AMG might decide to come full circle and employ the manic McLaren SLR 5.4-litre supercharged V8 - in detuned trim - for future AMG performance vehicles if current available supercharging options are tabled. Pragmatically though, the trick 5.4-litre engine is expensive and could hurt SLR residuals if it were to become a mainstream AMG powerplant.
Any possibility of supercharging the 6.2-litre has been curtailed by limited under bonnet packaging space and safety issues pertaining to pedestrian crash impact ratings. Transferring the bi-turbo 6-litre V12 is also unlikely considering packaging issues in C- and E-Class ranges.
A left field solution could be the introduction of a rumoured 5-litre twin-turbo V8, which would produce around 367kW and 900Nm in standard AMG trim. The 5-litre engine could also be available in a more exclusive version producing 514kW and 1200Nm to replace the current 6-litre V12 bi-turbo as the AMG powerplant leader.
The key issue pertaining to these rumoured outputs – especially the torque figures - would be the necessity for a new line of gearboxes as the new 7G Tronic automatic would not cope with engines as powerful as AMG is rumoured to be planning.
AMG could hardly expect customers to be content with the five-speed SLR or SL65 sourced gearboxes either – despite the latter being able to cope with a 1 000Nm torque number. An electrically controlled direct-drive gearbox will allegedly herald the solution…
Confronting future realities
Ultimately the issue facing AMG is trimming capacity down to ensure Co2 emissions and fuel economy is realigned to be within regulation target range, whilst still producing enough power to satisfy customer demand for extraordinarily high performance. “We’re almost at the top in terms of power now,” says Wolf Zimmerman, head of research and development at Affalterbach.
Within the gambit of this design and engineering conundrum, forced induction - with its ability to garner both high efficiency and power from limited capacity – is the technical solution of the moment.
If the radical Mercedes-Benz F700 concept car, with its direct injection, twin-turbocharged 1.8-litre DiesOtto engine is an indication of what Mercedes engine design is destined for, a 5-litre twin-turbo V8 engine option becomes the most plausible reality for future AMG products.
