One of the reasons we were especially keen to try
the SLK55 AMG
was to have a go with its engine. Now, this is into the realms of speculation but the normally aspirated 5.5-litre V8 in this car is - as touched upon in our earlier story - something of an oddity in the current AMG range. Known as the M152, it's based on the M157 twin-turbo 5.5 which is
now being phased out
in favour of a forthcoming downsized V8 intended to answer restrictions on
bigger engines
in important markets like China.
Well, it's much better looking than the SLK
On the face of it chopping the turbos off and shoving it under the bonnet of the SLK to avoid treading on the toes of the SL63 seems like a pretty cheap way of making an AMG version. But that's not really the way AMG does things and the investment that's gone into an engine that stands a very real possibility of being a one-hit-wonder is considerable.
Compared with the M157 the M152 gets new heads and cam drive, an all-aluminium crankcase, cylinder cut-off, a chunky 12.6:1 compression ratio and 7,000rpm+ redline. In the SLK it achieves 421hp, 398lb ft, 195g/km and a claimed 33.6mpg. Pretty impressive numbers for a normally aspirated V8. And if the SLK55 is a flawed gem where else might this engine find a home?
You can probably see where we're going with this. Yep, given the much discussed AMG-Aston Martin engine supply deal and fresh with the delights of enjoying it in the SLK we got to wondering what a V8 Vantage with this motor might be like. It'd answer any queasiness about Aston going turbocharged for sure and though it matches the existing Aston 4.7 for power it punches harder on torque at 398lb ft against 321lb ft. It also sounds brilliant, a prerequisite for any Aston, while seamlessly switching between four- and eight-cylinder modes for fuel-saving cruising.
A 5.5-litre V8 Vantage? What's not to like?
Aston's V8 doesn't want for charisma but in the modern world its 321g/km and low 20s mpg are increasingly problematic in a world where a Carrera S manages 205g/km and over 30mpg. Much as we like to imagine buyers in this sector don't care about such trifles it's the kind of bottom line figure that might preclude someone even stepping foot in an Aston dealership. Aston hasn't the money to develop an engine like this itself. But there it is in the SLK, ready to go.
So. A 5.5-litre V8 Vantage with sub-200g/km emissions, fuel saving cylinder cut-off, 400hp plus and a wickedly exciting engine note? And some ROI for AMG on an engine that might otherwise have disappeared into obscurity? We can see how this relationship might work well for all concerned, not least those of us who like a noisy normally aspirated V8!
Oh, and we talked to Aston Martin. And got a polite chuckle in response. C'mon guys, even if it's just a stop-gap...