Here's an idea. An Aston Martin Vantage with a manual gearbox and a 573hp supercharged V8 engine, for as little as a third of the £140,000 a new V12 would cost you all-in. The appeal is obvious. For all its considerable charisma the V12 puts around 80kg extra over the nose of the Vantage, the V8 having an all-round better balance as a result. And while the V12 sounds fabulous, as you'll see from the short video clip below, the V8 isn't wanting for aural drama. It's not like it looks outdated either; the blue supercharged car here is 10 years older than the V12 it's parked alongside. If pose value matters it's a private plate and a detailing session away from being all-but indistinguishable to everyone.
This supercharger package from Taunton based GMR puts the 4.3-litre V8 Vantage on more or less equal terms power and torque-wise with the V12 for a cost of £18,300 fitted. A fair chunk of money. But with potential donor cars now starting at less than £30K (and a full PH Buying Guide here to help you choose one), the man maths equation is a little easier to make. Certainly if you're looking for something British, raucous and V8 powered while you wait for TVR to finally pull the covers off its new car, this could be just the thing...
The opportunity to compare the supercharged V8 alongside the manual V12 Vantage S was irresistible enough for GMR boss Graham Heane to drive up from Taunton to Buckinghamshire on 24 hours notice. A former aircraft engineer, he's been perfecting his supercharger installation over a number of years, the kit based around a Magnuson unit built to an Eaton design. To date he's racked up nearly 80,000 post-conversion miles in the 4.3-litre Vantage you see here, hopefully demonstrating the car can take the increase in power. So far he's fitted over a dozen kits; following a new tie-up with TVR specialists Topcats Racing he's hoping to reach a much bigger audience.
Back to back with the V12, the comparison is fascinating. The 6.0-litre engine is a classic, big capacity, normally-aspirated motor with power and charisma to spare. In a car as small as the Vantage it's amusingly unhinged, the uncorrupted throttle response and huge punch throughout the rev range its stand-out features compared with the mainly turbocharged rivals.
With or without a supercharger the 4.3-litre V8 can't match that instantaneous response to the throttle and there is a slight softness to the initial pedal movement compared with the V12. It doesn't last long.
Normally-aspirated Aston Martin engines usually require a few revs on the dial before giving their best, the standard 4.3 not delivering its peak torque of 295lb ft until showing 5,000rpm. According to GMR's figures the supercharged engine's peak 445lb ft is there from 3,500rpm and remains in play all the way to the redline, at which point it's delivering 573hp. This from the stock 385hp. Stick it on a later 4.7 and you'll be looking at more like 600hp and 500lb ft.
And on the road the supercharged car just feels like it has a much bigger engine, not one fed by forced induction. There is some interesting technology at play here too, Graham's self-designed 'Geyser' water injection system used in place of a conventional intercooler he says would be a more intrusive and less efficient installation. This works in a similar way to the system in the BMW M4 GTS we drove recently, water injected at 100psi into the intake manifold increasing the charge density and lowering the mixture temperature. This, of course, means more power and improved knock resistance without having to lower the compression ratio from the stock 11.3:1. There's a thorough - and convincing - explanation of the science on GMR's homepage if you're interested in the motivation behind it. And, like the BMW, the water reservoir should only need topping up every few tankfuls of petrol, depending on use, with a failsafe that bypasses the supercharger if it runs dry. Tap water is fine too, a 1:10 mix with conventional methylated spirits enough to prevent icing. Enough theory for now though; this is a chance to prove the concept.
Extracting more power isn't that hard; successfully calibrating an aftermarket forced induction kit to feel predictable, balanced and natural throughout the rev range is where the work really goes. And it shows.
One of the more impressive demonstrations is when Graham forces me to leave the car in sixth and pick up from about 40mph. It doesn't bog down, the V8 picking up almost immediately and going from a low-rev grumble, picking up at about 3,000rpm into the real meat of that huge mid-range and then offering the sense something extremely exciting (and naughty) lies beyond. Certainly from the lower gears it's evident the engine has lost none of its appetite for revs and will happily play both sides of the coin, be that relaxed, torquey hauler or howling, redline-chasing hooligan.
Suffice it to say, this is a fast, fast car. Rain stopped play before we could do any meaningful comparisons with the V12, Graham's car also on its winter wheels given he justifiably didn't fancy driving up from Somerset in pouring rain on track rubber. But in any gear and at any revs the GMR car - much like the V12 - pulls with the kind of vigour that'll have you giggling out loud. Assuming you'd hear yourself over a noise raucous enough to make the factory V12 sound a little meek. It is both explosively, thrillingly fast and yet tractable and refined too. As a package it feels keener and more naturally balanced on a twisty road too, working with the twists and turns rather than simply beating them into submission - where the V12's USP is its formidable point-and-squirt firepower the V8 feels more about flow. Albeit at a significantly faster rate than before.
It's worth pointing out that 10 years of development are evident in the newer car's better interior, faster 15:1 steering rack (introduced on the V8 S) and improved three-mode damping. Given the increase in performance anyone thinking of adding a GMR kit to an old Vantage is advised to also consider upgrading/refreshing springs, dampers, bushings and other chassis components accordingly. At heart the Vantage seems well able to cope with the increase in power though, the vast majority of the bits on Graham's Sports Pack car remaining as standard. This is, after all, a fundamentally simple, balanced car with a proven manual transmission, mechanical limited-slip differential and favourable weight distribution.
ASTON MARTIN V8 VANTAGE 4.3 GMR SUPERCHARGED
Engine: 4,280cc supercharged V8
Transmission: 6-speed manual, rear-wheel drive
Power (hp): 573 (385@7,000/405hp with Sports Pack upgrade)
Torque (lb ft): 445@3,500rpm (295@5,000/310lb ft with Sports Pack upgrade)
0-62mph: 3.6sec* (original car 5.0sec)
Top speed: 197mph* (original car 174mph)
Weight: c. 1,630kg
MPG: 16.4mpg (Pre-conversion official figure, NEDC combined)
CO2: 406g/km (Pre-conversion official figure)
Price: c. £30,000 upwards, before conversion; GMR supercharger kit £18,300 inc. VAT and fitting
Figures in brackets for factory standard V8 Vantage 4.3
*GMR claimed figures
Want to see the GMR Vantage for yourself? Topcats Racing is holding an open day on June 25 at its base, located between Aylesbury and Bicester. The car featured here will be there and available for test drives while Nitron will also be present and showing off its dedicated Vantage suspension kits. Windscreen passes are required to access the Westcott Venture Park site - contact Topcats for more information.
Watch the video here