Subaru Impreza S204 - This Limited Edition Scooby Runs RON95

Some of you regulars and those who know me personally are aware that I happen to drive a global specced (one that the official Subaru dealer brings in instead of those grey market imports) Subaru Impreza 1.6ts and the good thing about this car is that it has 80% of the performance of the Impreza WRX and the fuel consumption of a regular 1.6liter car (mine anyway).

Now the other fun thing about running a global spec Subaru is that it runs happily on RON92, 95, 97, 98 or even 100. This is unlike the JDM (Japanese Domestic Market) cars that are actually very very happy with 100RON. You put our 97 and it basically runs happy albeit with slightly less power due to the ECU retarding ignition timing a fair bit. Then you try RON95 because RON97 costs a whole lot more these days. Now non-turbo cars wouldn't have much problems as things aren't tuned so aggressively but when you have a turboed Impreza or even a Lancer Evolution, the car's ECU would already be working overtime trying to keep the engine from running lean and then prematurely detonating thereby requiring an expensive overhaul.

And when you start modding the darn thing it gets trickier. Add an exhaust system, intake and up the boost things go wonky and the stock ECU that is already compensating for lower octane will give up and head for home if you try running RON95. If you still cannot get it, it basically means that the engine bites the dust, kicks the bucket, heads for the happy hunting grounds, swims with the fishes or gets killed to death if there ever was such a term. So how do you go about doing up a Subaru Impreza WRX or a Mitsubishi Evolution properly? You go for a proper tune-up job.

Let's just talk Subaru Impreza WRX STI for now. There are many tuners out there that say they can safely tune the WRX STI but I somehow feel that there is only one person that can actually tune a WRX STI properly so that it can run RON95. That chap is Mr Andy Lee, proprietor of LMY Automobile & Services Sdn Bhd located in Subang Jaya, Selangor.

The reason is this. Unlike most of the Subaru specialists in and around town he is the only one I know who actually OWNS a darn Scooby. He owns a Subaru Impreza S204, one of those limited run Impreza WRX STI based on the Spec C with all the goodies and some luxury too (instead of being bare like a Spec C). This is the same S204 that was featured in an earlier article about the Zerotohundred.com Time Attack event in Sepang sometime last year. If you noticed, tuners in the UK, like Litchfield, Powerstation, Roger Clark Motorsports or those from Japan like HKS Kansai, Flatt Racing, Cusco etc all have their own demonstrator Subarus to show off their talents. Andy Lee of LMY is like one of the tuners mentioned, albeit he is Malaysian and he loves his 'yamcha' sessions like any of us.

He tunes the Impreza on a proper dyno machine based on the Opensource ECU system and somehow it works. Some use a piggyback, but what I am personally aware of is that the WRX ECU is very, very conservative and does not like its signals intercepted. It will revert to safe-mode in an instant. It is actually better to re-flash the ECU via OpenEcu software or the likes of ECUTEK (which is basically a branded version of the same mumbo-jumbo – so you pay more). Buy a piggyback and it would be a waste of your money.

The reason it works is that on RON97 the car makes over 391whp and 51kg/m torque. That's wheel horsepower folks. The Impreza will usually lose 20% of its power through transmission loss and if you add this then the actual horsepower that the S204 you see in the pictures is about 480bhp at the engine. A stock S204 makes 320bhp at the engine. This S204 has some hotter cams, a larger turbine, a full decat exhaust system and a cold air intake. It however runs stock S204 internals, this means that it is still a 2.0liter flat-four.

Now when RON97 went up in price to RM2.80 per liter, even people who can afford a limited edition Subaru would feel the pinch. So off to the rollers the S204 went (this car has done over 400 dyno runs to date, check out the picture above showing run number 359 - this is why a demonstrator is so important, so that customer cars don't go Kaboom!) so that it can safely run RON95. It does, and still makes about 367bhp and the same number of torque. And to tell you the truth, the car still feels the same. I still feel the same very nauseating first run where my brain gets squashed to the rear of my skull and I go all light-headed after the re-tune.

It is all torque for acceleration. The extra 20 or so horses will make itself felt at the higher reaches of the rev-range. On road, you will only, actually feel that 20hp when you've crossed 200km/h. You see, any Impreza turbo can hit 240km/h but how fast it reaches that speed depends on horsepower. So on a B-road or in town, that 20hp would not make a big difference. You may see it missing on the Sepang circuit though, or on the North-South highway very early in the morning.

Now the main point of this article is that this S204 safely runs RON95 which is cheaper by almost a Ringgit. Fill up 10liters of RON95 compared to RON97 and you save RM9.00. Its as simple as that. Of course the ECU tuning isn't going to cost you peanuts. It will cost you more than a thousand Ringgit for sure. It is pretty obvious that if you pay peanuts, you get a monkey tuning your car. Tuning via the butt will not hack it. Tuning the Impreza needs some actual know-how and somehow after years of doing it, Andy does it properly. No engines destroyed.

So to those with the patience to read my ramblings and view some pictures of an Impreza S204 with loads of horsepower running on cheap petrol, with big brakes that fill out those gorgeous 18 inch alloy wheels and one that actually did quite well in a time attack event quite recently I present to you a video below showing you how an Impreza S204 sings on the dyno rollers. No Subaru Boxer burble mind you, blame the equal length exhaust manifold and the twin scroll turbocharger.

Note: By the time this article is published the S204 would have been replaced by another monster of a car. It could be said that he has mastered all that he can with the Impreza WRX/WRX STI and the sort and has decided that it is time to try something else. This time is is a Nissan, still AWD, still can sit four people but it does not have rear doors, has a V6 engine and is also recommended to run on 100RON petrol. He can tune this car to run safely on RON95 too. Watch this blog for more on this at a later date!