A light car is a fast car. But how can you make your car lighter and faster? Here’s how…
While a lot of quotes car-folk like to mention at any given opportunity are pretty awful, there’s two quotes that are 100 percent correct and sum this feature up perfectly. And they’re both by the same man too – Colin Chapman.
These quotes are: “To add speed, add lightness”. And: “Adding power makes you faster on the straights, subtracting weight makes you faster everywhere”.
Who is Colin Chapman? Well, he’s the founder of Lotus, and under his control they won the Formula One world championship seven times. So it’s fair to say he knows
a thing or two about making cars fast…
SO WHAT WILL LOSING WEIGHT REALLY DO FOR MY CAR’S PERFORMANCE?
In basic terms, less weight improves every single performance aspect of your car. But let’s break it down so you get a true idea of what happens…
With less weight to haul along your car accelerates faster. BHP per tonne is key here. It’s why a lightweight 200bhp hot hatch can be seriously quick, but a huge lorry, even with 500bhp, isn’t going to win any races.
With less weight to control, your car’s brakes have an easier job to slow the car down, and your tyres are less likely to lock up and skid, too. A lightweight car can often out-brake heavier cars despite the big car having correspondingly large brakes.
With less weight for the suspension and tyres to control, overall handling and cornering speed is improved. Adjusting the weight distribution by removing weight from the front or rear of the car can affect how much it over or under steers, and removing weight from higher up in the car lowers the centre of gravity – another great thing for handling.
Response and feel
This is something often forgotten about until you experience it. But lighter cars, if all else is equal, are more responsive to your actions, give more feedback and feel to you as a driver, allowing you to drive them to the limit easier, and most of all, tend to be a lot more fun to drive hard as well.
Yes, it’s true. If your car weighs less it puts less stress on literally everything. Your engine, brakes, suspension and tyres all have an easier life than if they were fitted to a big heavy tank. Even when driven gently, light cars are far easier on things like brakes, tyres and suspension bushes. And on cars driven hard on road and track, this situation is hugely magnified.
SO HOW DO I MAKE MY CAR LIGHTER?
While it doesn’t take a genius to simply start ripping bits off your car, with a bit of thought you can save considerable amounts without spending a fortune, or indeed totally wrecking the usability of your car. While many parts won’t save you as much as you might think, in some cases they’ll save a whole lot more…
Let’s start with the one thing a lot of people do – removing the rear seats. To be honest, it’s a bit pointless unless done as one of a great number of things. It’s rare for a car’s rear seats to weigh more than around 5kg – not much at all. So unless you’re stripping a car’s interior bare, we wouldn’t bother. The front seats on the other hand are heavy as hell on almost all cars, up to 50kg per seat on posh electric adjustable items. And with lightweight buckets weighing as little as 5kg each, that’s a huge weight saving. To top it off, bucket seats allow the driver and passenger to be sat far lower than standard, significantly lowering the centre of gravity.
While there’s a huge amount of trim covering the interior of a car, unfortunately it’s almost all thin plastic and weighs next to nothing. Making it fairly pointless to remove from a performance point of view unless taking the weight savings to the extreme. Removing things like the carpet, doorcards, roof lining and dashboard all save very little weight, but tend to make the car not only look a mess but make it pretty horrendous to drive on the road too. Unless this is a fully lightened race car, don’t do it!
Not hugely heavy, but even the standard stereo equipment can add up to over 10kg on some cars. As long as you don’t want to listen to music, there’s literally no downside to removing it, so the choice is yours. If it’s a car fitted with a serious ICE system though, especially big amplifiers and sub boxes, these simply have to go. They weigh a hell of a lot and will kill performance.
This is the most forgotten about but surprisingly heavy thing in most cars. While the thick fluffy spongy stuff under the carpet is a pretty obvious thing to chuck in the skip. It’s the thinner harder stuff that’s literally stuck to your car’s floorpan that most people fail to remove and weighs quite a lot – as much as 25kg on some cars. It can be a long, messy job to remove with a hammer and chisel. But even on a small hot hatch you can easily remove 10kg of the stuff – and on bigger cars you often end up with a bin bag full of this surprisingly heavy muck. A good trick on road driven cars is to remove all the sound deadening then refit the carpet afterwards, as the carpets rarely weigh more than a couple of kg and also makes the interior a much nicer place to be.
Standard alloy wheels, even on high performance cars, are often made with looks in mind rather than performance, and can weigh a hell of a lot – lightweight wheels are a significant improvement. A typical set of standard 18in alloys can weigh up to 12kg each, while lightweight aftermarket ones can be as light as 7kg, giving a saving of 20kg in total. But, and this is a big but, wheels are not only unsprung weight (which we’ll cover later), but are also rotating, which massively magnifies the effect of the weight – some say as much as 10 times over normal weight loss, which in this instance would mean the equivalent of saving 200kg from the body of the car. One thing is for sure, the real world effect of simply fitting lightweight wheels is very noticeable in all performance aspects.
Lower suspension means the centre of gravity is lower, but uprated suspension, especially coilovers, tends to be much lighter than standard. Up to 10kg with just the shocks and springs alone. Adjustable suspension arms tend to save even more weight, albeit relatively minor amounts, so we’d only do it if you wanted to for improved handling, rather than simply weight loss.
Not something you’ll want to do to a road car, as you’ll be stuck using sliders rather than opening windows, and with pillar-less windows it’s practically impossible to stop the things flapping around at speed. But on a track weapon you can save up to 25kg by replacing the side and rear windows with lightweight plastic items. Lightweight windows tend to be quite cheap to buy too, one of the cheaper lightweight replacement parts on the market.
Lightweight body panels are rarely cheap, but if you pick the right ones you can save serious amounts of weight. The first thing worth mentioning is cheaper carbon panels are often reinforced with heavy layers of fibreglass to prevent them from being so weak, so make sure you know the weight before you buy them. We’ve seen carbon bonnets that weigh more than the standard metal ones. Fibreglass panels, while not as sexy looking as carbon, tend to be much lighter than cheap carbon, relatively cheap, and only very slightly heavier than the most expensive carbon panels, so are often a good choice. If your budget doesn’t stretch to aftermarket panels, some skilful work with a disc cutter and hole saw and you can take significant amounts of weight from body panels without them looking any different. Well, from the outside at least…
While smaller normally means lighter, with brakes the opposite is often true. Standard brake discs and callipers are almost always solid cast iron, and therefore are far from light to say the least. Aftermarket brakes on the other hand often use alloy callipers and two piece brake discs with alloy centre bells, and because of this they are often significantly lighter, sometimes upwards of 5kg a corner; even if the discs and callipers are much bigger and better.
While almost everyone upgrades their exhaust to improve engine power, performance exhausts commonly save as much as 10kg in weight over the standard items. This is because of smaller or indeed less silencers, less complex pipework routing, and also often lighter weight materials too. More power and less weight, a win-win situation.
MAKING CARS LIGHTER FAQS
WHAT IS UNSPRUNG WEIGHT?
I’m sure most of us have heard of unsprung weight, but knowing what it is is another thing entirely. Unsprung weight is anything not supported by the shocks and springs, so basically the wheels, tyres, brakes, hubs and suspension arms. The significance of unsprung weight is that it affects the handling far more than sprung weight – as much as six times more. So anything you can do to reduce it can have a huge effect on a track car especially.
WHAT ABOUT WEIGHT DISTRIBUTION?
Manufacturers use things like “50/50 weight distribution” as a big selling point, and while it’s a bonus, we’d honestly say don’t worry about it too much. We’ve seen some people refusing to lighten their car as they think it will spoil their weight distribution, despite the fact the lighter weight will have a much better performance effect. Weight distribution is great bonus if all else is already optimal. But suspension setup and front and rear tyre size are normally the bigger issues that dictate how a car handles, even when they’ve got 50-50 weight distribution, so we’d pay more attention to simply making your car lighter.
That said, if you’ve got an option where you can choose where to place items in your car, as low as possible and as central as possible are the ideal situations. And balancing out front heavy cars by moving parts rearward, or indeed the opposite on mid/rear engine cars, are well worth doing if you have the option to.
HOW IMPORTANT IS POWER TO WEIGHT RATIO?
While gearing, traction and aerodynamics are also big factors, when it comes to rolling start acceleration of a car, power to weight ratio is by far the king. It’s that important to acceleration that a car having a higher power to weight ratio than another is a very good estimation to what car would out-accelerate the other in a rolling start race. Especially things like 30-130mph, where aerodynamics are less of an issue.
A good example of this is the Ariel Atom 500, which despite having half the power of a Bugatti Veyron, and far less traction too, is faster both 0-60mph and 0-100mph, as it weighs next to nothing. The Caterham R500 is another example, only 263bhp, less than many standard hot hatches. But as it’s so light it’s 520bhp per tonne, and from a rolling start can sit alongside a Veyron in full acceleration – to around 130mph anyhow.
Things get far more interesting when it comes to tuned and lightened cars, as fully lightening a car can increase the bhp per tonne figure by over 100bhp. And on many cars, especially if the engine has already been tuned, that’s far easier than simply increasing engine power. This is what turns tuned hot hatches in to things that easily pull away from big money sports cars. And what turns relatively affordable sports cars in to true supercar destroyers.
As an example of how easy it can be, a Clio 172, a hot hatch that can be had for barely over £1,000 these days, may only be 153bhp per tonne as standard. But as they can be stripped to 850kg without spending big money, and 230bhp is easily achieved with a basic turbo conversion, that makes the car 270bhp per tonne, more than an Audi R8 V8 – which also has the disadvantage of much longer gearing and bigger transmission power losses due to the 4WD system. If the car was left at standard weight, the bhp per tonne would only be on par with an E46 BMW M3 – fast, but nowhere near as stupid. A supercar beater for shopping car money? Yes, it’s possible!
HOW MUCH WEIGHT CAN I REMOVE FROM MY CAR?
While it’d take a lot to cover this for all popular makes and models, typical road cars can be lightened by 20-30 percent. Though with extreme (ie expensive!) measures done to full race cars, or on cars with particularly luxurious interiors, even bigger percentages have been achieved.
IS IT WORTH REMOVING LITTLE THINGS?
If you’re truly intent on making your car as light as possible, it’s not just the big things that need taking care of. The countless smaller things can often add up to weigh more than most of the more obvious parts. Excess wiring and brackets from the interior, lighter engine components, and many more small parts all add up when you do a large number of them. We’ve even seen drilled door handles to save every last gram!
MY CAR IS MY DAILY, HOW MUCH SHOULD I STRIP IT?
While lighter weight is great for performance, unless every last millisecond of performance is your sole goal, don’t strip a road car too much as you will make it a horrible, noisy, uncomfortable place to be – ruining your enjoyment of the car. Feel free to fit bucket seats, a roll cage, remove the stereo, the sound deadening. But removing parts like the dashboard, trim and carpet, not only removes minimal weight, but it makes the car a pretty horrible place to be in as a road car.
DOES MAKING YOUR CAR LIGHTER REALLY MAKE THAT MUCH DIFFERENCE?
It’s all well and good talking about lightening cars, but over the years I’ve done a number of tests, and let me tell you, it’s more effective in reality than I imagined.
Over the years I’ve gone 3.5 seconds faster from 20-80mph, just by slightly lightening a car from 115bhp per tonne to 165bhp per tonne. On a different test I took 3.3secs off the 30-90mph time by improving the bhp per tonne, by just 20bhp from 105bhp to 125bhp per tonne.
Saving just 5kg per wheel knocked 3secs off the lap time, 0.5secs off the 60-100mph time, 0.8secs off the 80-120mph time, and even stopped the car 15ft sooner from 100mph.
The numbers only ever told half the story too. Throttle response felt sharper, the cars were hugely more fun to drive on corners, and after fitting the lighter wheels, brake fade, something was a huge problem after repeated high-speed stops on the original wheels, totally disappeared.
Away from testing, I tend to lighten all my own tuned cars for both road and track use, especially lighter seats and wheels, and some to much bigger extremes. Combined with more power, uprated suspension and adjusted diff ratios, that can make cars handle and accelerate in a way most would never believe if they simply read the spec and didn’t experience the things for themselves. So what are you waiting for? Go for it!
Words Stav Photos various