Project Polo GTI - 1.8T ECU Remap and Chip Tuning - what next ?

Why the Polo GTI ?

Well its small, reasonably lightweight compared to its larger relatives, and equipped with a K03S powered 1.8T, and of course cheap enough to buy compared to a new Golf 2.0T GTI.

It starts at 150 bhp...

So we all know that 150bhp is not enough and so remapping to increase boost, optimise fueling and ignition timing pushes the power to a much stronger 195+bhp... Polo GTI enthusiasts with just a remap and uprated full exhaust have recorded sub 6 second 0-60 times on the strip.

Next the brakes...and a bigger turbo...

Well it makes sense to increase stopping power if you dramatically increase the BHP. Luckily the Polo GTI can use many parts from other VAG group cars to achieve this. We have fitted the standard brakes from an Audi TT225 Quattro. The uprated fronts at 312mm fit just under the standard 16" Monza wheels. Parts needed for the Polo are caliper carriers, calipers, discs and pads - and they all just bolt on.

With the fronts done it makes even more sense to tackle the back brakes, again TT225 256mm vented rear discs with Skoda VRS carriers and calipers is all that is needed - again they all bolt straight on.

The difference in braking ability is amazing - you can brake with confidence. 

The Standard turbo is the well known, tried and tested K03s - good for spooling fast but lacking somewhat in the top of the rev range. Improvements can be made by fitting the K04-001 which spools just as fast but keeps going long into the rev range. The K04 is also good for a little more peak boost than the K03s so helping make further gains.

We sourced the K04-001 from an up and coming specialist turbo manufacturer in China - Dragon Parts email ... dragonparts@yahoo.cn for more information. Keenly priced at approx £325 delivered with 1 year guarantee it was definately worth a try. The K04-001 is a direct replacement for the K03 or K03s. After we fitted it to the Polo with no other mods improvements over the K03s were obvious. It could spool sooner in the "fifth gear low speed torque pick-up test" - by some 2-300 rpm and then WOOO HOOOO it just kept going to the red line.

The K04-001 is not a massive power maker but is good for 240-260bhp, depending on other mods, which is more than enough for the standard clutch and gearbox to handle. Max we would run the K03s is 1.0bar but we will run the K04-001 at  max of 1.2-1.4bar once all the mods are complete. Currently we have the boost set at 1.0bar and make just slightly more max power than the the K03s at 1.0 bar.

But to make the most of the K04-001 you ideally need a good turbo back exhaust to help breathing, back pressure generated with the K04-001 and standard exhaust can overcome the wastegate of the K04-001.

Above pictures show how restrictive the standard downpipe parts are.

We initially fitted a custom downpipe with decat.

If you want to push big boost and plenty of ignition advance then better cooling of the induction charge is also a good idea. A front mount intercooler is the perfect option - available from Forge Motorsport.

Then we need some custom mapping for these mods to maximise the driveability and BHP.

So this is where we were with our Polo GTI 1.8T beginning of Jan 09 ......

Forge silicon intake and intercooler hoses

K04-001 Turbo 

Custom 2.5" downpipe

4 bar fuel pressure regulator

K&N panel filter with modded airbox

Custom mapping (producing approx 230 bhp at 5800 rpm with max 1.2 bar boost)

312mm Front TT225 brakes

256mm Vented rear TT225 brakes (Octavia VRS Carriers)

The K04-001 flows much better, so much better that it causes "MAF signal to high" errors at high RPM, it just can't measure the airflow.The standard cure for this is to fit a larger MAF housing with the standard MAF sensor.

How does it drive..... with our latest version of the test software we are concentrating on getting the top end right, getting the boost and fueling how we want it and settling the MAF down. The next test version will work on the bottom end where things are deliberately "flat" at the moment. So at the the moment.... put your foot down in any gear and things wind on slowly at first (which is actually good for traction and the clutch) but as revs rise past 3000, 4000 rpm then boost is brought in maxing at 1.2 bar causing superb acceleration with good strong power. It really is starting to feel quick.... its so smooth right up to the MAF error at 5500-6000 rpm... where boost hasnt tailed off.. its still just as strong.

Everwhere you read about K04-001 upgrades over the K03s some say its not worth it as power only goes up 10-20 bhp - but what they dont understand is how that power is delivered. The K04-001 is just ballistic at high rpm - feels much stronger than the K03s

To maximise flow and fueling we have fitted a complete TT225 3" MAF and Bosch 315CC injectors. We are in the process of re-writing the software to take these into account.

Boost is now 1.5 BAR ...... and the car is strong... intake charge cooling now requires attention...

Feb 2009 - the urge to mod continues....

Its time for some bling... so we source some MS Design "QT" 7.5x17 wheels from Audi and have wrapped them in Yokohama Parada. The car was going to look too tall with the bigger wheels so we have fitted H&R lowering springs. Low enough without too much loss of ride comfort.

We have replaced all the brake discs with grooved and vented running EBC "Red Stuff" ceramic pads.

Fueling has been improved with the addition of S3/TT225 386cc injectors, these work much better with the 3" MAF and 4 bar FPR.

To help with airflow we have simply fastened a LARGE cone filter direct to the MAF, this gives a very subtle sucking noise on boost with a delicate dump when you lift off.

Mid Feb 09 it was time to go further with the exhaust so we dropped the car off at Blueflame Headquarters for them to do some extensive exhaust work.... a week later... well we are so pleased with the results....

The exhaust has made a huge difference to the way boost is delivered, it is smoother and stronger.

While we were playing with the exhaust we took a look at the exhaust manifold - wow this thing is thin and looks pretty restrictive. So we have replaced it with the much "fatter" high flow version from ATP.

Software wise we run two versions depending on how we feel. There is a 1.2 bar version that is very quick low down and revs right round to 7,000rpm making the 0-60 dash extremely quick. Then we have the "race" version that peaks at 1.6 bar slowly dropping off to 1.5 bar which it manages to hold past 6,000 rpm. This is really too strong for the standard intercooler so we generally run the 1.2 bar version, well until we fit the intercooler from Forge Motorsport...

So coming soon.....

But we reckon that the K04-001 is not enough, we want silly power now and we are keen to show how well we can map the Big Turbo 1.8T, so we are researching for suitable suppliers of highly reliable, easy bolt on Big Turbo upgrades....

It would seem that the obvious choice is an Eliminator from ATP Turbo in the USA, they do a range of specific bolt on upgrades capable of 250-450 bhp listed for transverse 1.8T in the Golf and Leon, etc.

We are just waiting for them to get back to us with how they can help for the Polo 1.8T.

March 09 Update

The Forge FMIC is fitted...this allows the car to remain strong and torquey for how ever long it is pushed. The intercooler keeps the intake temps much lower.

The driveshafts were knocking against the Anti Roll Bar since the H&R lowering springs were fitted - cure has been to fit slightly shorter droplinks from a 2003 Ford Mondeo.

April 09 Update

We play with a new software version and adjust the wastegate actuator rod to give the desired boost characteristics. So we have good smooth delivery with controllable boost. Peak boost is approx 22psi (1.5bar) with it holding a good 15-17 psi higher up the rev range. The car feels good. Now we still deliberate over the next turbo choice ... so watch this space....

May 09 Update

Sadly Project Polo has come to an end.... next it is Project BMW 330D M Sport.

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