Stroked Suzuki Swift - K12M to K14B Conversion

August 28, 2013

What's the big deal about a 1.4 liter Swift?
To put it simply - You cannot buy a 1400CC Suzuki Swift in India as on date so why not build one! To the best of my knowledge my Swift 1.4 is the first and maybe the only K14B Swift in India outside of Maruti Suzuki. The previous generation Suzuki Swift was launched in India in 2005 with the 1.3 liter G13BB engine, it continued to sell till 2010 with the same G13BB petrol engine but later that year Maruti Suzuki decided to put their new generation but lower capacity 1.2 liter K12M engine in it. They kept on selling this model till around mid 2011, and later in 2011 Maruti Suzuki phased this out and brought in the new generation Swift, launched internationally in 2010, with an updated K12M engine with Variable Valve Timing (VVT) for the intake camshaft.

I referred to the 1.2L engine as the K12M not the K12B which is sold in markets outside of India. To the best of my knowledge the K12M is an India only engine with an engine capacity of 1197CC, its a de-stroked version of the 1242CC K12B engine. Maruti Suzuki did this to keep the engine capacity under 1200cc for excise duty benefits.

K12M Specifications:
Cubic capacity: 1197CC
Bore x Stroke: 73mm x 71.5mm
Compression ratio: 10.0:1
Cylinders: 4
Valves: 16
Power: 87 PS@6000 RPM
Torque: 114 NM@4000RPM

K12B Specifications:
Cubic capacity: 1242CC
Bore x Stroke: 73mm x 74.2mm
Compression ratio: 11.0:1
Cylinders: 4
Valves: 16
Power: 94 PS@6000 RPM
Torque: 118 NM@4800 RPM

Suzuki Swift with the K14B engine is on sale in other markets though. Below is the engine specifications of Suzuki Swift 1.4 from Australian website. The Suzuki Ertiga we get here as the same engine specification.

K14B Specifications:
Cubic capacity: 1372CC
Bore x Stroke: 73mm x 82mm
Compression ratio: 10.0:1
Cylinders: 4
Valves: 16
Power: 95 PS@6000 RPM
Torque: 130 NM@4800 RPM

Swift 1.2 to 1.4 VVT Conversion

It was a stock Maruti Suzuki Swift with a K12M 1.2 VVT engine running a Unichip Q+ piggy back ECU which gave a small boost in torque and power which was slightly better than a bone stock 1.2 Swift. Later during its evolution I installed exhaust headers from N1 Engineering, Mumbai and revised the air intake setup with BMC OTA air box. The latest addition was Magnaflow universal muffler which helped making the car respond faster to the throttle pedal.

Power is never enough, what next?

I was thinking of forced induction as the next step but one fine day i was comparing the specification of the K12B and the K14B engine and the idea of a 1.4 litre Swift sparked in my mind. I contacted JB of Spitfire Performance, Coimbatore regarding this, he supported the idea and this gave me some confidence and decided to research a bit into the feasibility of this. Into the research across parts books and shop manuals and the Internet and once we had enough details on this, we decided to do it! And so it started - collecting the parts required for the stroker engine transformation. After collecting almost all the major components it was time to visit Coimbatore.

Meanwhile I even considered getting this conversion done at Trivandrum or Cochin its closer to where I live so I can watch it being built and take the car to Spitfire for the dyno tuning session. But in the end I decided to go to Spitfire because of their technical expertise and experience in racing, rallying,engine rebuilding and tuning. They have their own rolling road too. In hindsight I should have got the conversion done locally and went there for tuning.

There was no point in delaying the rebuild further once the parts were in, so in the first of August 2013 I alongwith my friend set off to Coimbatore to hand over the car to JB. We left the car in the safe custody of JB and came back home and started the wait. I've been following up with Jb almost every other day and soon on the last week of August 2013 the car was ready to go on the rolling road! The work done included: 1) Stroker conversion, 2) Head porting--more like a clean up work, 3) Increased compression slightly 4) Improved my DIY air filter installation for aesthetics and robustness.

One thing to take note of was that bumping up the compression on this engine was not a simple head milling job since this engine runs an enclosed timing chain instead of an external belt. So the timing chain cover tolerances had to be matched with perfection since that holds the VVT mechanism among other things.

The dyno day came and again my friend and I landed at Coimbatore early that morning, we didn't have much clue as to what to expect from the engine. Just had a hunch that it will probably be good.

The car was put on the Dastek Dyno and JB went to work doing the tuning. After the first session it was decided that injector overdriver was to be put in to get desired AFR at a particular band. The first map gave a very very nice figure of 115BHP (at the crank), but it was decided to detune it to 109BHP to be on the safer side with this new engine. I would've liked it to be kept at 115BHP but Jb was very particular about reliability (in all of his projects, Petrols and Diesels) and didn't want to bump it up now. There is not enough documentation or case studies about tuning the Suzuki K series motor, so the engine being new and me staying 500Km away, it was decided to let go of a few horses. Not complaining because the torque figures we got is 145Nm in the detuned mode, 145Nm is no mean feat for a puny 1.4 liter NA petrol! Tuning took 4 to 5 hours and JB was on it till he was satisfied with the outcome. We got two maps stored in the Unichip, selectable using a two way toggle switch; daily drive map is good enough for 109BHP and 145Nm of torque and the high octane map is good enough for 112BHP and 149Nm of torque. This is good for now!

Driving characteristics have totally changed, there is enough torque in all the gears including 5th gear! Acceleration is really fast when comparing with stock, keeping up or overtaking faster vehicles has never been this fun in this car before! On the highway it feels like it could use a slightly taller final drive ratio which should increase the top speed, and return a bit more fuel economy while cruising.

A few things that I am proud about with regard to this conversion.

This is my baby. I figured out this swap myself and I did the homework myself. There were no international forums to refer to all did my work except the assembling.
No one will know what you are running inside, not even authorized service center can make it out unless they open up the engine. (I like this!)
The engine isn't stressed and it doesn't feel stressed either.
The engine didn't feel like it was ever opened, it was as smooth as it was before and drives like a factory-tuned high output refined engine!
Goodies

K14B crankshaft and connecting rods. These are cracked rods.

K14B Dished piston. K12M motor has flat pistons.


Short and Coated Skirt




K14B Rings are different. Possibly due to increased piston speeds.

Pistons, Gaskets and O-rings


Porting before

Porting after

"The ports were cleaned up to remove imperfections. There were also some mismatches in port profiles between the manifold-to-head connecting duct and the manifold itself - these were made equal. There were also some steps in the inlet ports which would have clearly caused flow disturbances. These were removed".

Intake port and exhaust port

Milled head

Car on Dastek Dyno with power and torque figures

Old K12M Crankshaft

Crank position toothed wheel

Pistons and rods. These are flat top pistons.




List of Parts Required for K12M to K14B Conversion


Note: Prices are in INR, Year 2014.
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Update: Back home in Trivandrum and after a couple of weeks the car started misfiring and shuddering and I found that it was caused due to the injector over driver unit JB installed. I removed that and the car was back to normal, but probably running a bit lean.
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Update: Installed an AEM AFR meter and found than even without overdriver the ratio was in the safe range so decided to remove it and not bother with correcting it again.
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Unichipped Suzuki Swift K12M

December 31, 2012

What is Unichip?
"The Unichip is a sophisticated supplemental computer integrated into your vehicle's engine management system putting the power of electronic engine control into the tuner's hands. It's not just data squirted into your car, it's a fully functional computer working seamlessly with your car's engine management system".

Unichip in Swift 1.2 VVT
In short its a piggyback ECU that sits parallel to the stock ECU of the engine and can alter ignition and fueling parameters. Its more than a basic fuel computer as it does more than that.

I decided to get one for my car as a performance mod and as the first addition to make my car ready for the performance goodies that are to follow. Many people will say that for a naturally aspirated engine one should get exhaust headers and air intake revision before they go for any piggybacks and i kind of agree with it because a piggyback will give the most results in an engine with its breathing sorted. But i decided to go for a piggy back first for two reasons 1) To see how much power my car really makes bone stock and 2) to see what kind of improvements i can expect from just a piggyback.

Unichip is good when it comes to piggybacks and certain applications and we had a fully equipped dealer with a Dastek Dynamometer in Tamil Nadu.

So on December 31st 2012 i scheduled a visit to Spitfire Performance at Coimbatore for the Unichip installation. At Spitfire I met J. Balamurugan (JB) who is the bossman there. Jb is a very down to earth person, he explains what the chip is and what it can do and how it works and he himself does the mapping on the dyno. The people there are very commited towards this and on the day i was here they even skipped their lunch so that they are able to finish my car well in time.

Now about the chip, it looks almost as big as the Car's ECU and is quite heavy too. I got the Q+ version although i needed only the Q, Q+ is for forced induction applications and Q is for normally aspirated applications. The Q+ variant can drive additional injectors directly and do couple of other things. I bought the Q+ since i have plans to go boosted with my car in future. With this installation Unichip has been setup to control the AFR and ignition timing in my car. If need be Unichip can also alter the drive by wire setting and the variable valve timing settings in my car, but it was chosen not to go there this time.

After the tune up the car gained about 5BHP and about 5NM of torque, it may not look like much on the graph but there is a noticeable difference in performance which i noticed on the drive back to Kerala. Overtaking in 2nd and 3rd gear is quicker than before. The car responds well to throttle inputs even in 5th gear while cruising, earlier 5th gear response was sluggish. Overall i'm very pleased with Unichip. A fringe benefit is that i'm getting a better fuel economy!

With better breathing provided by headers and an air intake revision Unichip can get the engine to a better state of tune, I intend to get the car re-tuned once again after i get those installed. But since i now have the stock numbers for reference i can know how much of a difference each mod gives on the dyno. On the day of the dyno the car was stock except for Denso Iridium Power spark plugs and slightly wider Michelin 185/70/14 tyres.

Notes:
Unichip not a tuning box like Petes Box, Race Chip, Spider Tuning Box etc., Unichip is far more powerful and fully programmable piggy back engine computer. It will work with both Diesels and Petrols, can work on any vehicle with an ECU. Has to be programmed/tuned for that particular vehicle. So if i upgrade to another vehicle in the future i will just put it in my new ride and get it tuned for it.

Unichip Q+ installed

Setting up the car on the dyno for the tune up

A video of the tuning session on the dyno. This is not a power run.

Power and Torque figures

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Engine Bay Heat Management

Excess heat is the enemy of performance and controlling heat inside the engine bay will net some minor to noticeable improvement in performance. The amount of improvement will depend on how bad the the heat soak was in the engine bay to begin with and by minimising it to lower the Intake Air Temperature and Fuel Rail temperatures.

This is about my experimentation with wrapping the airbox and fuel rail with heat reflecting materials to minimise heat soak, i'll continue with this article in two sections - 1) Air box heat insulation and 2) Fuel rail heat insulation. Speaking about fuel rail this is a non-return type fuel rail and the fuel that comes upto the engine bay stays there till its injected. For wrapping I used DEI ReflectAGold after reading about a lot of available options and checking availability.

Air Box heat Insulation

Fuel Rail Heat Insulation

Header Wrap

Wrapping the exhaust is the most effective way to control heat in the engine bay and also it keeps the exhaust gases hot and the gas velocity high, but that is for another day.

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Gapping Iridium Spark Plugs

Suzuki shop manual recommended spark plug gap for the Suzuki Swift with K-Series engine (K12B, K14B) is 0.95 to 1.05mm (.37" to .41"), but both Denso IXU and NGK Iridium IX spark plugs come pre-gapped from the factory at .76mm (.30"). While this is not a cause for worry and these Iridium plugs do work very well straight out of the box in the Suzuki engine and with proper gap these plugs should work even better. As the gap increases more spark energy is required to bridge the gap and this is not good for the ignition coil. Iridium plugs with their thinner electrodes needs lower spark energy to jump off and bridge the gap, because of this lower energy requirement i believe it should be able to fire reliably even with a wider than factory recommended gap without straining the coils.

I changed to Denso Iridium Power IXU22 spark plugs from the stock NGK KR6A-10 as soon as i bought my Swift, but then i put the plugs in as it is at their preset gap of .30". Eventhough Iridium plugs are long life no maintenance plugs i decided to try some NGK Iridiums as i got a set of 4 for really good price, the car has done 19400KMs, barely any distance to wear out the older Denso Iridiums. So when i make the switch to NGK I decided to gap the plugs to .45".

Here is a good read (PDF) on Understanding Spark Plugs by NGK

Denso has to say this: "Ignition by electrical spark occurs because the fuel particles between the electrodes are activated by the spark to discharge, a chemical reaction (oxidation) is triggered, the heat of reaction is generated, and the flame core is formed. This heat activates the surrounding air-fuel mixture, eventually a flame core is formed that spreads the combustion to the surroundings itself.However, if the quenching effect between the electrodes (the work of the electrodes absorbing the heat and extinguishing the flame) is greater than the flame core heat generation action, the flame core is extinguished and the combustion stops. If the plug gap is wide, the flame core is larger and the quenching effect is smaller, so reliable ignition can be expected, but if the gap is too wide, a large discharge voltage becomes necessary, the limits of the coil performance are exceeded, and discharge becomes impossible."

Gapping Iridium Spark Plugs

Common knowledge when it comes to gapping Iridium splark plugs is "Don't do it". Its is very rarely recommended to gap Iridium spark plugs, the reason is the thin laser welded Iridium center electrode is fragile, and with a wrong move its easy to snap it off or crack its weld. NEVER EVER use a SCREWDRIVER tip to gap a thin electrode Iridium spark plug! It is recommended to use a proper gapping tool or a thin nose pliers to set the gap. And when doing it take your time and take care not to touch the center electrode.

NGK Iridium IX DCPR7EIX Gap .30" Done 13000KMs from my previous Suzuki Astar (K10B Engine), gap as good as new.

Denso Iridium Power IXU22 Gap .30" Done 19000KMs in my Swift, barely any wear.

Brand new NGK Iridium IX DCPR7EIX with gap set to .45"

Spark plug gap measuring and gapping tool. This tool is made by Powerbuilt, and i don't like the gapping bit because the metal piece is not sturdy. Measuring bits are good enough.

Nose pliers can also be used to carefully pull the ground electrode strap, but be careful and thinner pliers would be even better.

NGK Iridium IX DCPR7EIX. New gapped to .45" on the left and old with factory gap of .30" on the right.

Set of 4 and Set of 3 (old) NGK Iridium IX DCPR7EIX and Set of 4 Denso Iridium IXU22

References:

http://www.ngksparkplugs.com/docs/tech/racing_spark_plugs_performance_applications.pdf
http://www.globaldenso.com/en/products/aftermarket/plug/basic_knowledge/spark/index.html

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Update - March 12, 2014:
After two days of city drives with the gapped Iridium plugs i have noticed a very slight improvement in torque from 2000 RPM. No negatives noticed with wider gap so far, starts and idles the same. I will update on the high RPM performance shortly.

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Update - March 13, 2014:
No high RPM misfires or loss of power noticed. Torque has definitely increased and is noticeable. Highly recommend doing this if you decide to put in Iridiums.

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Getting The Most Out Of A Stock Airbox

I have heard this being asked often "Why didn't the manufacturer put in a cold air intake or a K&N filter in there if it gave more power and more FE?" The obvious answer to this question is "Stock filter is cheap and K&N is expensive". While i think that is partly true i believe the reasons why the manufacturer doesn't install a higher flowing K&N type filter is "ease of servicing"!
Anyone who has used a K&N type filter will know that to properly clean, dry and oil the filter it will take a minimum of 2 hours (or more if done thoroughly) if its an oil-less type dry element filter like AEM it will take atleast 1 hour to clean and properly air dry (not blow dry) the filter. Time is money and authorised service centers can't afford to waste for 1 to 2 hours for cleaning and re-installing air filters in customer cars when they have to deliver 10 to 20 cars at a minimum on an average day! Not to mention if the oiling wasn't perfect the customer is either going to come back or ruin his engine!! Too risky for the manufacturer and the dealers!

So the hunt for a freer flowing air intake begins to replace the stock paper filter and the stock airbox, and this hunt lead me to buy one of the best air filter systems out there the BMC OTA. While i do like my BMC OTA carbon fiber airbox with the cold air feed for the performance it delivers at the top end of the RPM range i wish it was a bit easier to clean. It requires the complete removal of the airbox from the vehicle and further unscrewing of 4 small little screws to take out the filter element. Its not that it needs cleaning every month or even every 6 months and the filter is good to go without cleaning for atleast 5000KMs in light to moderate dusty conditions, but the thought of taking the filter assembly out to clean the air filter element is tiring. Yes, looks like I'm beginning to appreciate convenience these days. With the factory airbox you undo two clips take out the filter and you clean or replace it and shut the airbox. That's it! Done! How easy?!

So this got me thinking, i needed the convenience of the stock airbox but with more power and better airflow than what a stock factory airbox would allow. Is it possible, can the stock airbox be improved?

If you open the stock airbox and look inside you will find lot of plastic moulded ribs inside, both in the pre-filtered and post-filtered area. You will be wondering how these would influence airflow inside the box, I don't think it enhances the airflow, these should hurt the smoother airflow. In 4 Stroke Performance Tuning by Graham Bell it is mentioned that the job of these ribs are for sound suppression! Yes! That could be it! I remember when this model was launched Suzuki has claimed lower Noise Vibration and Harshness (NVH) for the new generation Swift and yes the engine sound refined compared to the previous model K-Series Swift (my cousin has one) with the 1.2 engine which had an airbox with smoother insides. I don't mind slightly higher NVH if it could get the engine breathing better all around. So, time to do some cutting and grinding with my Dremel Fortiflex.

What Mr. Bell said

The photos below with before and after comparisons so that you can see what exactly has been done to the stock Suzuki airbox.

Pre air filter side of the airbox

Post air filter side of the airbox

While doing this i decided to seal off the resonator hole in the intake pipe too. I used a bit of 3M aluminium tape for this and it sticks really well to plastic. This helps.

Impressions
Honestly I did not expect much improvement in drive-ability before i embarked on this airbox smoothing job. I was expecting an improvement in breathing at the higher RPM band. When i took it for a drive after the smoothed out and resonator sealed airbox was installed there was a very noticeable improvement in the throttle response and torque from just past 1500RPM to a much noticeable improvement from 2000 RPM upwards, much like a mild rush! At higher RPM near the redline it is considerably better than stock with the engine feeling eager to revv out. When the car is running on headers in place of the stock cat-con exhaust the stock airbox wasn't able to keep up with the airflow demands and it used to hit a brickwall near 5000 RPM, so the BMC OTA was the only option when i had the exhaust headers installed. With this smoothed out setup the engine goes clean till the redline. What this means is that the smoothed out box is flowing well enough to support the headers! All this with the stock paper filter! I'll try out the K&N stock replacement filter in this airbox and let you know how it goes.

NVH
Yes, as expected the engine noise is slightly on higher side, but not too intrusive. There is a light booming sound at about 4500RPM, i think its cool :) Anyway the stereo should help drown that out!

Improving it further
Another interesting bit about air intakes in Bell's book, 4 Stroke Performance Tuning, the author states that most of the factory airboxes have a smaller air inlet opening to minimise the intake suction noise. The author further suggests that the airbox's air inlet opening should be of the same size as that of exit on the throttle body side. The Swift's stock airbox has a rubber funnel at the tip of the airbox inlet pipe, this funnel instead of flaring out like a bellmouth, reduces in diameter before opening up slightly.

I bought a length of 60mm ID air inlet duct from ebay and installed it at the end of air box after taking off the (now sealed) resonator section. A larger bellmouth, which i got with BMC OTA, is installed on the other end of this duct and the duct is then routed to the opening just behind the front grill section. The airbox now gets air from outside of the engine compartment at all times, the BMC bellmouth helps direct the air into the duct efficiently.

Here is how it looks. The duct you see in the photos is a 70mm ID an outer duct over the 60mm ID duct inside. The outer duct offers a bit of heat insulation and abrasion resistance. The gold reflective tape was applied as the part of heat management within engine bay. I will make a post about it soon.

Apart from having a larger air inlet opening, less restrictive breathing, a possible ram effect at higher speeds an additional advantage with this setup is that now engine gets its airfeed from outside of the engine bay directly, that means cooler air. IAT reading confirms that.

Check out this article Honda Insight air intake revision on Autospeed.com they have done a very similar experiment with a bellmouth and an air feed on a Honda Insight with good results and data to back it up.

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