John Simister: Is an undetectable turnkey classic possible?

That's one of the reasons why many of us love classic cars, their character and occasional capriciousness, the smells of hydrocarbons and hot metal that waft from that under-bonnet lair. One of the key contributors to all of this, the smells and the occasional shortcoming in what development engineers call 'driveability' (no stalling, no hiccups, no special treatment needed to make the thing go from a cold start), is the carburettor, a precision device of often imprecise behaviour.

The way people use classic cars is changing. Often, they sit for weeks at a time without being started, which is never healthy for a car designed on the basis that it will be used, and then they suddenly decide they won't go. Often, they sit in heavy traffic, getting hot and upsetting those delicate carbs as petrol vaporises where it shouldn't. Those fortunate enough to buy expensive, exotic classics may get especially annoyed when their symbol of connoisseurship fails to proceed and a passenger, perhaps less tuned into the classic-car vibe, is unimpressed. And there's also the matter of fuel thirst: a rapid GT from the 1960s, with a trio of slurping Webers, can be dipsomaniac and with today's fuel prices the cost of frequent fill-ups on the grand tour can hurt even the most resilient bank account. 

Modern cars don't make you suffer like this. Can a classic car be taught similar manners? Indeed, it can. Systems have been available to fit in place of Webers and their arch-rivals, Dell'Ortos, for years. They replace the carbs with throttle bodies containing fuel injectors, controlled by an ECU along with the ignition. Bingo – modern engine management, civilised manners, proper reliability even when left for weeks. The turnkey classic, literally. 

But those throttle bodies look a bit modern, and the under-bonnet visual ambience is lost. You appear to have sold out; you're not a proper classic person. What you want is an authentic classic look in a car which works.

So, fuel-systems experts have been experimenting with fuel injectors secreted in a dummy carburettor body, with some success. One of the problems has been finding a suitable place to put the injector, so it squirts from the right place and in the right direction. This has proved almost impossible to do properly if an existing carburettor is the starting point, so two new, bespoke systems are now available.

The first comes from Jenvey, a long-established maker of those throttle-body kits which are used in many competition cars. Its Heritage Throttle Body looks like a Weber DCOE, the staple twin-choke side draught carb that feeds many a rapid classic, usually in multiples of two or three so each engine cylinder has its own throttle and air passage from atmosphere to cylinder. Or almost like; the bulge on the top is missing, angled bulges on the sides have appeared (they house the injectors), the mixture-adjusting screws have gone. But at a quick glance, it's pretty Weber-ish, the illusion helped by keeping the original air filter and original-looking fuel pipes, and hiding the wires to the injectors underneath.

Of course, to run these injectors requires an ECU, to be hidden out of the way – perhaps behind the dashboard. And if there's to be an ECU it might as well control the ignition, so you can dispense with the distributor's mechanical innards and use it just, well, to distribute the sparks. I've driven an Aston Martin DB5 fitted with this whole system, by GTC Engineering near Silverstone which co-developed it with Jenvey, and once GTC's tech whizzes had got all the calibrations right on a rolling road it was brilliant. It was as gutsy, torquey, smooth and clean as a modern high-performance engine, and entirely free of bad temperament. 

It's not cheap: you'll be into £3-4000 for a car formerly fitted with triple Webers by the time all the electronics are fitted and the installation set up optimally, but that's a fair price to suit your 1960s exotic to 2018 road conditions and usage patterns. And if your chosen classic has not Webers but SUs, then you too will be able to go electronically clean by the end of the year. At least you will if you have a car powered by a Jaguar XK engine, for which Burlen Fuel Systems (nowadays the keeper of the SU legacy) has nearly finished developing what look like triple SU carburettors but are actually, again, throttle bodies with injectors – one per pair of cylinders.

The 'SUi' kit, previewed at the recent Members' Meeting, will include the ECU and everything else required, and other sizes of virtual-SUs and the equipment to fit them will follow. There's no word on prices yet. 

Objectively, these injection systems make perfect sense especially if your existing carbs and ignition are due for overhaul or replacement anyway. The only minus point is the loss of originality and the fact that a light sprinkling of masochism, and the overcoming of adversity, can be part of what some find appealing in classic cars. 

That said, I have no hesitation in using modern electronic ignition in my old cars, so why should I not see more efficient fuelling in the same way? Is it because I would no longer have any little brass adjusters to fiddle with? For many, not having to worry about any of that stuff would be very liberating, I suspect.