Modding upgrading and tuning the Suzuki K series K15 engine!

All you need to know about "K series K15 Modifications"

K series K15 Modifications Guide

How to modify and upgrade the Suzuki K series K15

"Comprehensive guide to performance tuning the Suzuki K series K15 engine!"

Forums like the one at TorqueCars often are getting emails requesting information on how to improve the K series K15 from people inquiring about getting more power from the K series K15 and wanting to know what are the best K series K15 power upgrades. So let us look into Suzuki K series K15 upgrades and outline the best modifications on this great engine and point out some common pitfalls along the way.

The Suzuki K series K15 are popular engines and with a few sensible mods like ECU maps, turbo kits and camshafts you will dramatically improve your driving pleasure.

Our aim here is to review and look at K series K15 tuning and summarise the greatest modifications for your car.

The optimum K series K15 tuning parts on an engine are usually the ones that give the best power gain for your hard earned cash.

We won't be swayed by popular K series K15 tuning parts, they need to be cost effective.

K series K15 induction kits

Improving air intake on the K series K15

You need air matched to fuel for an engine to work. If there is a lack of fuel then it will run lean, if there is insufficient air it runs rich sapping power which risks damage to the K series K15. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the fundamental goal to any engine performance tuning task to force fuel and air into each cylinder but this has a knock on effect with the air flow sensor.

It is not unusual that there is a restriction in the air flow sensor AFM/MAF on the K series K15 when a lot more air is being fed into the engine.

When tuning you may well find you need to get an air sensor or flow meter capable of upto 4 bars to cope with quite large power gains, whereas the OEM air sensor sapped bhp at a much lower level.

Engine intake manifolds flow the on the suck phase from the filter and allow it to be drawn into the engine and mixed with fuel.

Design and flow rate of the Intake headers can make a large effect on to fuel atomisation on the K series K15.

We often see intake are improved through aftermarket tuning parts, although a few OEM provide decently flowing intake.

Larger K series K15 valves, getting port matching and head flowing will also boost performance, & importantly will afford you a greater performance increase on other tuning mods.

K series K15 performance cam tips.

Some K series K15 engines respond better to mild camshaft durations than others.

The ECU mapping and fuel pump and injectors also will make differences on the torque gains you'll make.

Longer valve durations can alter the torque band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

The camshaft profile plays a big part in the engines power output so camshaft upgrades make quite a large difference. The intake and exhaust durations will alter depending on the chosen camshaft profile, so large engines power gains are on offer for camshaft upgrades.

NB: Fast road cams usually bump the performance across the rev range, you may sacrifice a little bottom end bhp but top end will improve.

Motorsport cams, bump the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

In a car used daily you must carefully try to optimize your bhp range to your usage of the car.

You'll never have found a K series K15 Race camshaft is a pleasure to live with when in heavy traffic.

Stage 1, 2 and 3 mods for the K series K15

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

  1. Suspension Upgrades - always improve your cars handling
  2. Brake Upgrades - Even before adding power improve those brakes
  3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
  5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
  6. Fuelling - when you've increased power you'll need to match this with more fuel
  7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 K series K15 parts:

Panel air filters, Intake headers, Remaps/piggy back ECU, Drilled & smoothed airbox, Fast road camshaft, Sports exhaust manifold.

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Stage 2 K series K15 parts:

Ported and polished head, Sports catalyst & performance exhaust, fuel pump upgrades, Fast road cam, induction kit, high flow fuel injectors.

Stage 3 K series K15 parts:

Competition cam, Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting, Twin charging conversions.

The K series K15 engines make great tuning projects and we're finding that there is a growing number of upgrades and performance parts about.

Remapping will help release the full potential of all the upgrades you've done to your K series K15.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the outcome may differs on the upgrades you've applied and the condition of your engine.

Turbo modifications on the K series K15

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the K series K15.

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes excellent power gains.

If a car is fitted with a turbocharger tuning mods are going to net you a larger power gain and you'll see that turbo charged engines are built with more solid components.

However engines will have power limits

We recommend you find these restrictions and upgrade to forged components to survive the power.

There are many drivers spending a loads on turbo charger upgrades on the K series K15 only to suffer the indignity of watching the K series K15 go up in smoke soon after it's used on the roads.

Bigger capacity turbos tend to experience no power at low rpm, and small turbos spool up more quickly but won't have the high rpm torque gains.

Thanks to progress the choice of turbochargers is always developing and we are seeing variable vane turbochargers, where the vane profile is altered according to speed to lower lag and increase top end performance.

Twin scroll turbochargers divert the exhaust gases into two channels and direct these at differently angled vanes in the turbo. They also help the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large bhp and torque gains, although more complex to install. We have this in depth look at twinchargers if you want to read more.

Tips about fuel supply on the K series K15

You will need to ensure that the engine is not starved of fuel so will need to ramp up the fuelling when you start going beyond 20% of a power hike. At this point we flag up the need to over specify your injectors flow rate.

As a rule of thumb add another 20% when buying an injector, helps cope with injector deterioration and provides some spare capacity should the engine need more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended K series K15 performance exhaust upgrades

We'd only recommend you look to increase your exhaust system with an upgraded one is if your current exhaust is creating a restriction in flow.

On most factory exhausts you'll see your flow rate is good even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Don't go with the largest exhaust you can source this will reduce the exhaust flow rate - the best for power gains are usually between one and a half to two and half inches. Your exhaust design, the bend angles and construction are what have more effect on flow rates than your pipe width to a certain extent. So the exhaust design is a big factor.

Usual exhaust restrictions are in the emissions filters installed, so adding a freer flowing race alternative will help avoid this restriction.

Catalyst removal (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the K series K15

Like most engines an K series K15, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the K series K15, failure to do this will exacerbate engine wear, on a tuned K series K15 this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your K series K15 why not pop over to the forums at TorqueCars where you can chat about K series K15 tuning options and read about others projects who may be planning to do similar modifications on their K series K15.

We need your help to complete and improve this page, so do give us your feedback in the comments box below.

We want to know your experiences with parts on your K series K15, it helps us improve our tips and keeps us current so please use the comments box to drop a tip.

If you liked this page please share it with your friends, drop a link to it in your favourite forum or use the bookmarking options to save it to your social media profile.

Check out TorqueCars new YouTube channel, and see their awesome new content...


Please use our forums if you wish to ask a tuning question, and please note we do not sell parts or services, we are just an online magazine.

Help us improve, leave a suggestion or tip

Your Constructive comments on this article