The GMR 600 aftermarket supercharger conversion breathes new life into the Aston Martin V8 Vantage. Very tempting

What is it?

The GMR 600 is an Aston Martin V8 Aston Martin Vantage given special powers by Taunton-based engineering outfit GMR Design

Company owner and former aero engineer Graham Heane has been working on an engine conversion for Aston’s early 4.3-litre V8 Vantage since 2010. Identifying the strong supply of affordable used Vantages that currently exists, sharing the same appreciation of the baby Aston’s charms that so many feel, but aware of the limitations of early cars too, Heane has developed a low-impact, low-pressure supercharger installation with a twist: a proprietary water-injection system.

Running with just 6.5psi of boost pressure, a special ECU and a leaner fuel-to-air mixture than standard, the 4.3-litre GMR 600 Vantage trumps even the new Aston V12 Vantage S for power – developing a peak 573bhp along with 445lb ft of torque from 3500rpm. The conversion on newer 4.7-litre engines puts peak power above the 600bhp threshold.

Aston’s 0-60mph claim for the last V12 Vantage was 4.1sec. For the current one, it’s 3.7sec. This V8 will do it in 3.6sec; less on an absolutely perfect run. And the conversion costs £20,000 including VAT - on cars widely available used from just £30,000.

What's it like?

The water injection system works by cooling the mixture entering the cylinders and ensuring more efficient, stable combustion. It’s similar in principal to the ones used on WWII aircraft engines, and quite commonly still in drag racing, albeit without the alcohol those cars use.

It injects water at high pressure into the V8’s intake plenum, which acts to cool the compressed air supplied by the supercharger to almost atmospheric levels. It also eliminates the need to throw extra fuel into the engine to ward off irregular combustion as many high-performance production engines currently do. 

The injection system is governed by GMR’s own ECU, but the V8 engine operates under the standard, but remapped ECU – the latter allowing for the special fuelling. The system ensures the engine runs cool even under high loads without the need for extra heat exchangers. It prevents the build-up of carbon deposits inside the engine by effectively steam cleaning with every combustion cycle. When it’s out of water the ECU simply disables the supercharger, and a red warning light on the steering column tells you to top up the tank – ideally with 90 per cent water, 10 per cent methythelated spirit/denatured alcohol.

Heane has done 50,000 miles in his engineering prototype, which just happens to be his daily driver. “We wanted a reliable, drivable solution suitable for everyday use,” Heane says. “After every second fill of fuel, you just lift the bonnet and refill the injection system’s 5.5-litre water tank. And because the water acts as an anti-detonant, we can run much leaner fuelling than Aston itself does, so economy actually improves.” Automotive voodoo at work.

The GMR 600 has one of those accelerators you squeeze down gently at first. There’s a hint of softness in the pedal response below 3000rpm, but above 3500rpm the V8 is developing peak torque and behaves itself very well indeed, in smart proportion to your inputs. Outright performance is comfortably in the first-order super sports car league; hugely torquey in the mid-range, but still building nicely as the revs rise.

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GMR doesn’t change the V8’s standard exhaust downstream of the catalytic converters, but it sounds like a different system all right: louder, harder edged but still cultured and tuneful. Especially over the last 1500rpm before the 7300rpm redline, where the engine retains the same pleasing elasticity of the standard tune.

The net result is a very fast car indeed, but a well-mannered one too – and which could be as discrete as you wanted it to be. Heane recommends you upgrade the factory brakes on your Vantage after you’ve had the engine overhaul. He offers a range of stoppers, but doesn’t offer a carbon-rich bodykit to accompany his work, nor an aftermarket suspension overhaul. Aston’s own optional sports suspension is firm enough he says, as fitted to his own car. We wouldn't disagree: body control’s excellent, ride quality is a little noisy but entirely acceptable. The car’s meaty, informative steering and chassis balance, meanwhile, are equally great. 

And the GMR badging is optional, by the way. “One of our customers doesn’t want his wife to know he’s having the work done,” says Graham. “Assuming she doesn’t drive his car, he might even get away with it!”

Should I buy one?

For now, there’s still a bit of groundwork to be done. Heane will finalise the dealer network for the GMR 600 very soon, and will begin satisfying orders later this spring. 

But once he does start the ball rolling, he should expect plenty of interest from canny British sports car fans looking to make their own £50,000 used alternative to a Vantage V12 S. From one-time TVR owners as well, you’d expect, seeking out the kind of bang-for-buck experience their Tuscans, Griffiths and Cerberas used to give them.

Whatever quarter it comes from, the interest will be richly deserved. Engine conversions on ageing British coupés aren’t for everyone. Still, few people have, in our experience, managed to make an aftermarket tune-up job such a fiendishly attractive, grown-up prospect as this.

GMR 600 Aston Martin V8 Vantage

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Price £20,000 (engine conversion only); 0-62mph 3.6sec (est); Top speed tbc; Economy 26mpg (est); CO2 na; Kerb weight 1600kg (est); Engine V8, 4282cc, petrol, supercharged with water injection; Installation Front, longitudinal; Power 583bhp at 7300rpm; Torque 445lb ft at 3500rpm; Gearbox 6-spd manual

Matt Saunders

Matt Saunders Autocar
Title: Road test editor

As Autocar’s chief car tester and reviewer, it’s Matt’s job to ensure the quality, objectivity, relevance and rigour of the entirety of Autocar’s reviews output, as well contributing a great many detailed road tests, group tests and drive reviews himself.

Matt has been an Autocar staffer since the autumn of 2003, and has been lucky enough to work alongside some of the magazine’s best-known writers and contributors over that time. He served as staff writer, features editor, assistant editor and digital editor, before joining the road test desk in 2011.

Since then he’s driven, measured, lap-timed, figured, and reported on cars as varied as the Bugatti Veyron, Rolls-Royce PhantomTesla RoadsterAriel Hipercar, Tata Nano, McLaren SennaRenault Twizy and Toyota Mirai. Among his wider personal highlights of the job have been covering Sebastien Loeb’s record-breaking run at Pikes Peak in 2013; doing 190mph on derestricted German autobahn in a Brabus Rocket; and driving McLaren’s legendary ‘XP5’ F1 prototype. His own car is a trusty Mazda CX-5.

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Add a comment…
Citytiger 28 February 2014

Stating the obvious

in picture 10 of 11, the caption states "Theres a fair bit of road noise transmitted through the tyres". However the failed to mention the are "WINTER" tyres as can clearly be seen written on them, and winter tyres do generally tend to be a bit noisier in my experience..
Citytiger 28 February 2014

But why when you can get a

But why when you can get a fairly new XKR 5.0 for just over £30k and a nearly new one for just over £40k fully loaded.
Peter Cavellini 28 February 2014


Still only if you've got money to burn,still expensive to service,and whose going to care about economy with the performance of this car,and your not exactly going to fettle it yourself, are you?,you've got a man to do that for you!
kendwilcox47 28 February 2014

Sounds so good.

If after a road test the car was as good as it sounds one would be on my drive.
If only I had the money.!!!!!
Symanski 1 March 2014

Still interesting.

Peter Cavellini wrote:

and whose going to care about economy with the performance of this car,and your not exactly going to fettle it yourself, are you?

Shouldn't that be Who Is? Anyway, my interest in the economy was more general than just for this Aston (although extra mpg means going further before the hassle of refills - not a bad idea for a GT). If this can improve MPG just by adding water couldn't that be added to all cars which have turbos or other forms of forced induction? (Although in my experience the bio-fuel that is now added to petrol is worse that water - adding fuel which gives you less mpg!).