Whether you’re tuning a car or tyre-kicking for a new one, there’s one figure that petrolheads (or dieselheads?) always like to see more of: brake horsepower (BHP). Even though it’s hard to determine a car’s performance from a solitary figure on a piece of paper, along with 0-60, top speed and torque; people have a tendency to use bhp as a benchmark. Continue reading for our top ways to increase your BHP.
If you’re new to performance tuning, then you might feel a bit confused by all the options available – so below we’ve assembled a list of six of the easiest ways to put more ponies under your bonnet.
Before we start, it’s important to say that this isn’t a video game, and there’s no way to say for sure whether a part will give your particular engine 3 bhp or 10 bhp before you fit it. There are a lot of variables at play here, so the only way to know for sure is to put your car on a dyno. None of the mods below are going to turn your 1.6 lump into a 1000 bhp Skyline engine, but all of them should free up a few horses, and most will make it at least sound more aggressive.
Remember that if you don’t know one end of a spanner from the other, we have a fully equipped performance fitting centre here in Wrexham, where our experienced mechanics can fit most parts while you wait (just give us a shout for a booking). We even have free wifi in our customer viewing area!
Before we get into the details it’s also important to remember to check that any modifications you make to your car won’t void any warranties or insurance that you have.
Performance Air Filter
The cheapest way to add some power to your car is generally to fit a performance air filter. These come in a few different flavours, and the one you choose will depend on both your car and your budget. On most cars, your standard air filter will probably be made from paper – meaning that it is cheap to produce – and it will generally get replaced at every service. Whilst paper is cheap, and does the job of keeping dirt out of your engine well, it is also quite restrictive and will stop your engine from sucking air in as easily as it could otherwise (imagine breathing through a paper bag). Performance variants tend to be made of more expensive materials such as oiled foam or cotton, and will generally last for the lifetime of your car with proper maintenance. K&N, for instance, give their filters a million-mile warranty!
The most basic type of performance air filter is a panel filter or replacement element – which literally just replaces your original air filter with one made out of
Induction Kits / Intake Kits
If you want something more than you can get with just a replacement element, then you should look at an induction kit (or intake kit as they are also known). These filters generally replace some or all of the original airbox with hardware designed to get more air into the engine.
Normally the original panel filter is replaced with a racing-style cone filter to give the maximum surface-area (and even less resistance). As a side effect of all this easy-breathing, you’ll also be able to hear your engine roar properly – which will make it sound a lot sportier.
A lot of induction kits come with a cold air feed in the box. This is an extra bit of pipework that channels cold air from outside the engine bay onto the air filter.
More expensive variants of the induction kit also tend to include either heat shields or sealed intakes to stop your engine breathing in too much warm air (cold air is denser and better for performance).
Other features to look out for are the pipework around the air box being replaced with better flowing aluminium or silicone pipework. The plastic flexi-hose a lot of the factory air pipes are made of can slow the air down on its way into your engine which can also put a crimp in things.
Universal kits are available if you drive something really obscure and these come with most of the same hardware but may require you to do a bit of work to mount them under your bonnet. Please contact us if you need advice or details on fitting one of these.
Cat-Backs and Back-Boxes
Ok, so you’ve fitted a performance air filter and cold air feed, and your engine now breathes a little bit less like it’s asthmatic. The trouble is, it’s still constipated! Yes, your engine needs to dump out all that extra gas, and your standard exhaust probably isn’t cutting it. Whilst you can buy performance back boxes, these generally just change your exhaust note and look a bit better – giving you very little (if any) extra power.
The thing you want if you’re looking to improve performance is a cat-back performance exhaust system (so called because they replace every part of your exhaust from the catalytic converter backwards). As a bonus, most performance exhausts are made from stainless steel and come with lifetime warranties – so they’ll probably never cost you anything to replace. Fitted in conjunction with a decent induction system, a performance exhaust should give you a few extra bhp and let your engine rev a bit easier.
If you’re concerned about noise, then bear in mind that most manufacturers (like Milltek, Scorpion, Cobra etc.) offer a you a choice of how much silencer you want on your exhaust. This may be in the form of the same system with and without some of the silencers / boxes. It may also be in the form of resonated or non-resonated versions of the same exhaust. A resonator cuts out certain sound frequencies, like those heard when the engine is at low revs, whilst enhancing others. This means you only hear your car when you’re driving it hard.
Performance exhaust systems range from around £200 upwards – but fitments for most cars will be well below £500. Fitting an exhaust system can be fairly easy, and it can also be fairly difficult – mostly depending on how rusty your old bolts and fittings have become. You’ll definitely want some WD40, put it that way! If in doubt, you can always have us do the hard work for you.
Downpipes, De-cats, and Sports-Cats
That’s quite the mouthful but bear with us. If replacing the rear section of the exhaust system is good, replacing the downpipe is even better.
As the name suggests, the downpipe is the bit of pipework that runs down from the engine bay to the rest of the exhaust system. On a turbo car it sits just behind the turbine side of the turbo which means it has a big impact on performance. Normally you want as little restriction as possible behind the turbo, for peak efficiency.
It also contains the main catalytic converter on most cars. This makes it doubly important for performance reasons, as the catalytic converter is usually the most restrictive single part of an exhaust. A sports-cat will use different materials and a less restrictive cat structure to allow exhaust gas to flow through the cat better.
A de-cat will remove this restrictive section of exhaust entirely, but unless the car is only being driven off-road this is not normally an option.
Why not always replace it? Well, in some parts of the world replacing the original cat is not road legal. Your cars ECU is also expecting to see the original catalytic converter. When you replace or remove it, you need to remap the engine to take advantage of the extra performance on offer.
Engine Management Upgrade
You know that scene in the Matrix, where Neo has all the extra software downloaded into his brain and instantly becomes a Kung Fu grandmaster? Well after you’ve sorted out both ends of your engine’s breathing, the next step is kind of similar – it’s time to upgrade its brain! Modern fuel injected engines are controlled by an on-board computer (the ECU or engine control unit), which takes readings from your engine’s various sensors and then gives out settings that are appropriate to the demands of your engine. This is happening constantly whenever the engine is running.
In the past, it was common to ‘chip’ the ECU – swapping parts out entirely – but nowadays, it is much more common simply to ‘remap’ the ECU – rewriting the code that the engine listens to, but leaving the original parts in place. This is because ECUs have developed a long way since the days of chipping – and now contain a lot of your car’s unique security information (which obviously needs to stay!).
When a car’s ECU is first programmed, manufacturers include certain compromises in its programming in order to safeguard the engine against things like drivers who ignore service intervals or who use substandard fuel. Because performance ECU remaps are aimed at enthusiasts like you, these compromises can be done away with – freeing up the engine’s potential for greater power and torque.
How much power is freed up?
This depends on the type of engine.
Non-turbo engines can gain up to
10%. Other improvements
, like smoother, more immediate
throttle response are to be had as well. This does depend a bit on the type of
engine. High tech performance engines do better.
A performance remap is even more useful when applied to a turbocharged engine – because the ECU also controls the maximum amount of boost provided by the turbo. By adjusting the boost (as well as altering fuelling to suit it), a remap can give a turbocharged car (petrol or diesel) a very useful kick in the rear.
Power gains of up to 20% (with torque gains of up to 25%) are typical for turbo petrol engines, and up to 30% more power and torque for turbo diesel models.
You may also see fuel economy improvements, as with a fatter torque curve you’ll be downshifting less. We never promise improvements though, as it depends heavily on driving style and with more power on offer you’re likely to put your foot down more and enjoy it.
We offer a mix of remapping methods, some of which you can actually do yourself at home. The Superchips Bluefin and Cobb Accessport hook up to your cars diagnostic port and allow you to remap your car in a DIY fashion using a handset.
High Performance Intercooler
Once you’ve got your engine breathing and thinking more efficiently, it’s time to get a bit more serious. If you’ve got a naturally aspirated (non-turbo or supercharged) engine, this is also where things tend to start getting more complicated. There’s a few more mods you can do to make your exhaust system flow freely (e.g., tubular manifold, sports cat), and you can add a power boost valve to aid your fuelling, but before too long you’re going to want to open your engine up and start swapping camshafts, etc.
Cars with forced induction (turbo, supercharged, or even both!) are much easier to tune, and there’s generally still some room for improvement at this point without having to ‘open ‘er up’. As we mentioned before, cold air is what you want your engine to breathe if you want top performance from it – because it’s denser – but
Although most modern cars with forced
induction come from the factory with an intercooler, they tend to be quite small
or fitted in inefficient locations like on top of the engine (we’re looking at you
Subaru Impreza STI!). Fitting a much larger
alloy intercooler – and locating it behind the front grille
(which can often be enlarged to suit) will ensure that the air your engine breathes
is much cooler – giving you
One problem with enlarging the pressurised space between your turbo (or supercharger) and the inlet like this, is that it will lower the pressure of the air going from the turbo into your engine. This can be counteracted by upping the boost provided by the turbo
– meaning that you’ll notice the best performance gains when fitting a performance intercooler in conjunction with an ECU remap. It’s also best to stick to good brands who do the proper research and development on their kit.
Performance intercoolers from firms like Forge Motorsport, Revo or Mishimoto can provide gains of up to 40 bhp on cars like the Audi RS3. Exact gains will vary from car to car, and you should also bear in mind the power you won’t lose as the engine and ambient temperatures heat up. The intercooler kits we sell range in price from around £400 upwards, depending on the fitment required. Fitting isn’t usually too difficult, and shouldn’t pose a problem for the competent enthusiast with a decent set of tools – although relocation kits will generally be trickier to fit than direct replacement parts, and your front bumper will need removing in many cases.
Taking things further…
We’ve tried to keep it simple with the improvements we’ve listed here, but there are many more you can do if you want to take things further.
A few of the more intermediate technical mods we would suggest are listed below:
Water Meth Injection
No, not what Walter White was making on Breaking Bad, but rather a mixture of water and methanol. The science behind water meth injection is actually pretty simple. By squirting atomised water and methanol into the air going into the engine, you cool everything down. As with an intercooler, this means you can boost harder.
Individual Throttle Bodies
A lot of what we’ve talked about here is for engines with a turbo or a
Most engines can benefit from upgraded cams. The cams control how long the valves that let air into the engine and exhaust gases out of the engine stay open. A set of different cams can keep these open longer, making the engine breathe better.
Once you’ve done everything we’ve talked about here on a turbo car, a common next step is to look at the turbo itself. There’s a lot of physics happening behind the scenes, but basically the size and shape of the two wheels in a turbo have a big impact on how much air it pumps into your engine, how quickly it spools up, and where in the rev range your car makes its power. A small turbo is responsive but can quickly become a limiting factor in how much power can be made. Fitting a bigger or upgraded turbo can up these limits considerably.
Can you think of anything we’ve missed? Let us know below!
Want advice on anything we’ve mentioned? Get in touch!
Enjoyed this? Read more of our latest news:
Where To Next?
Looking for the latest performance & tuning parts? Check out our wide range from top brands.
Want to know more about our story? Learn about who we are and why we’ve been driven by passion for over 50 years.
Interested in everything we do? Catch up on all the latest Demon Tweeks news.