To get the extra power from your engine in a nutshell there are two main ways; add more fuel and air, or make the car more efficient by removing restriction or weight. Only take on board this article if you are a capable and seek advice as not all modifications will benefit your engine i.e. sport spark plugs don’t exist in a diesel engine.  Your car should be fully serviced and in good working order before modifying. Before do anything after stage 1 seek professional advice as some modifications could damage your car if set up incorrectly and if done without proper equipment  Always contact your insurance company before making modifications to see if it will effect your cover.

Instructions

Difficulty: Moderately Easy

Things you’ll need:

• Spanners
• Screwdrivers
• Socket set

Step 1 – Air intake

Performance can be added through more air, less restriction and cooler and denser air. 

Panel filter:

A performance panel filter or carburettor ring filter would be you first step on any engine including diesels, a 5 minute job at best. Its looks the same as the original paper one but it is made with a higher flowing material such as pleated cotton (pleated to give bigger surface area) foam or steel gauze which causes less restriction.

Benefits: 1-5% power increase

Induction kit:

Replaces the original air system and restrictions completely and bolts on to the intake. This is normally a cone shaped filter on the end of the kit.  It can give more power and noise than a panel filter, but if it’s not located in cold area or doesn’t come with a decent cold air intake then the warmer air is less dense, which means it has less oxygen. This can result in a power loss, even though there’s more air being drawn in. For a carburettor a pancake filter is available were all the top intake is removed and is replaced by a nice chromed bolt on filter. Green and K&N supply these.

Benefits: -5%-+15% power increase

Sealed induction:

These kits can give you the most power usually by being an induction kit enclosed in heat reflective shell like carbon fibre.  These kits don’t draw in warm air as the air intake is completely sealed onto the unit.  Some times they are not worth their high retail price as some retail as much as £250.

Benefits: 1%-20% power increase

Tip: With all these above kits don’t buy a universal option.  The later two kits may need to be bolted onto the car sensors (fuel injection cars) and a universal kit will not have the parts required to bolt on properly or have been tested for your car.  Look for rolling road graphs to prove the power increases. Some cars have silencer boxes that can be removed for less restriction benefits; here you would replace the box with a straight pipe.

My air filter on car

Typical induction cone filter

Step 2 – Exhaust system

Work by removing restrictions like noise filters or by putting more efficient filters in. The more reputable full systems work by increasing bore size a little and by using mandrel bends which are the same circumference all around. The cheaper exhausts on the market get compression bent, thus leaving a bump/kink inside the exhaust which causes restriction.

Back box:

This can increase throttle response but doesn’t really give power, it will give you the noise if you like that sort off thing (only a little difference of noise on diesels).

Benefits: Improved throttle response

Cat back:

Catalytic converter back is the best option in my opinion; it removes and changes all centre boxes and piping restriction, this is normally fitted at the very front off the car.

Benefits: 1%-15% possible power gains

De-cat or sports cat:

Are worth a mention; de-cat removes the converter out of the car and the sports one puts a more efficient one on. De-cats will give you an MOT failure due to the emissions making your vehicle illegal and sports cats are not normally worth there very expensive cost. These products are compatible with cat backs and back boxes. Diesels are not judged on emissions the same way as petrol cars, so you could pass the test with a diesel car, but removing the cat itself is a fail. People have been known to remove inners off the cat with good gains but still a very dubious area to be in.

Benefits: 1%-5% possible power gains

my old vs new exhaust

Compressions bend vs. Mandrel bend

Step 3 – Removing weight

Wonder why a lotus Elise is so fast with a relatively small engine? This is because it weighs next to nothing. Some people remove the spare wheel, carpets or the back seats. Race cars put plastic instead of glass in their windows and carbon bonnets.  Some people say that if you reduce your car by 10lbs it is like having an extra 1hp. Rotational weight (things that spin; fly wheels, alloy wheels etc.) equates to 4-10 times that, so 1lb equals 4-10lbs of reduction. This does improve acceleration but also handling too as there less weight to force around a corner.

My uncle evo 6 bonnet

Light weight carbon fibre bonnet

Step 4 – Ignition systems (petrol engine only)

Performance spark plugs

Plugs can be good at this point; they can work by using a longer reach (a bigger gap) to make a bigger spark or by using more conductive precious metals like platinum and iridium. Some have extra electrodes that give more places to spark too if one is blocked. (Multi electrodes still only spark to one electrode not two or more that’s a myth)

HT leads

Newer cars don’t generally have them; these work by being more conductive and saving more energy for the spark.  This is handy if you’ve gaped your spark plugs or are running higher boost thanks to a remap, as the increased air and fuel makes the mixture denser and harder to spark through.

Upgraded coil packs

These are available on newer cars that have more voltage from the start.

Benefits: 1%-3% possible power gains

Tip: I wouldn’t recommend gapping the electrode on turbo cars running higher boost levels.

my uncles ht leads

Performance HT leads

Step 5 – Generic Remap, chipping/custom remap injection systems or jets for carburettors

A generic remap will give you a good return on the above investments but a custom remap will take into account all modifications you have previously made, so it should be your last step. If you go further into stage 2 you will have to get another remap, if you get it done at this point to make the most of stage 2 or even to get your car too work. You don’t have to get it done for stage 1 but it does help a lot. Remaps work by adding more fuel; changing the valve timing and increasing air intake (if you have forced induction i.e. a turbo).  If you’re a carburettor man look at jet kits to add extra fuel to make the most of you extra air and efficiency.

Tip: A cheap but very basic option is to reset you ECU and let the engine learn the above modifications, but this will not give you anywhere near the gains of a remap.

Benefits: Expected gains are anything from 5-15% on petrol engines or 15-40% on a petrol turbo/supercharged engine or diesel engine and a lot more in conjunction with bigger turbo/supercharger, injectors, intercoolers and forged pistons as I’ve seen gains over 500%.

example off a chip from my odds and ends

A chip

Tips & Warnings

• All above modifications work well with each other and can further increase their expected gains, for example you have a more efficient air filter it allows more air to flow into the engine allowing more fuel to be added at your remap.
• Expected gains are a very rough guide and the condition and model off your engine can affect this wildly.
• Fully service your engine. There is no point tuning your engine if it’s losing power through dirty oil and clogged filters and not sparking properly with worn plugs (petrol cars only).  The extra performance from stage 1 will add very little wear and tear but an engine in need of a service could make this an issue.

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