Mira, Mira Off the Wall

One of the most intriguing cars to arrive in Australia during the 1980s turbo era was the Daihatsu Charade Turbo (G11R). With a 1.0 litre 3 cylinder turbo engine under the lid, this little off-beat hatch was about as quirky as you could get.

But the undisputed Daihatsu king of quirk lived in Japan – the miniscule L70 series Mira TR-XX 550cc turbo!

Now available as a 15+ year old Japanese import, the 1986 – 1990 Mira TX-XX is the Japanese market performance version of the Daihatsu Kei-class hatch. As you may be aware, the L70 body was sold in Australia as the Handivan and was intended primarily for light delivery duties.

But pop the bonnet and you’ll see there’s not much in common.

The TR-XX engine wears a tiny IHI RBH31 turbocharger blowing through an equally diminutive top-mount air-to-air intercooler. The intercooler core is fed cooling air by a forward-facing bonnet scoop and incorporates a pneumatic actuator that appears to bypass the intercooler core at light engine loads (perhaps to improve throttle response). Boosting to a maximum of 10 psi, the little turbo system dramatically increases the power and torque output of the EB-series 550cc 3 cylinder engine. Note that early versions of the TR-XX were available with a blow-through carby set-up, while an EFI version was added to the line-up in later years. Our test car was a carby version complete with a manual choke – an unusual sight these days!

The carby turbo 550cc engine puts out 38kW and 70Nm (at 6500 and 4000 rpm respectively). EFI versions debuted with 43kW, increasing to 47kW. The latter models are the ones to get if you have a choice.

TR-XX Miras come standard with a 5 speed gearbox with remarkably short gearing – cruising at 100 km/h in top gear equates to an engine speed of around 4400 rpm! This helps keep some revs onboard while cruising and the little turbocharger starts boosting very early – it’s very difficult to identify this as a turbocharged engine.

Weighing 570kg, the L70 Mira TR-XX is no rocket in standard form but it’s brisk enough to provide some fun. We weren’t able to perform 0 – 100 km/h tests because our test vehicle had a slipping clutch and a worn turbo, but you can expect the sprint to take 10 or 11 seconds.

One of the big advantages of the TR-XX over the Australian-delivered G11R Charade Turbo is the sophistication of its suspension. The Mira runs a cute little independent rear-end together with garden-variety MacPherson struts at the front. Ride height is slightly lower than a local L70 Handivan.

There’s no need for power assistance for the rack and pinion steering – the Mira has good steering weight and a wonderfully direct feel. Oh, and its turning circle is pretty handy too!

The braking arrangement comprises discs at the front and drums at the rear. We had no problems with their performance.

The stock TR-XX attracts plenty of second glances driving through in traffic. The ‘little lightening’ scores a centrally roof-mounted aerial, dual exhaust outlets, side skirts, a front lip, bonnet scoop and rear spoiler that frames the entire rear window. Cute 12 inch alloys wearing 145/70s and some attention-getting stickers also give necessary a boost in cred.

But nothing causes as much confusion as when you zip past other drivers with the turbocharger on full whistle! Weeeee...

Inside, the cabin is also a quantum leap ahead of the cabin of an Australian-delivered Handivan. The TR-XX is decked out with sports door trims and seats, a ‘Turbo’ flat-bottom steering wheel, air conditioning and sports instrumentation. The TR-XX binnacle offers a centrally mounted tacho (with a 7250 redline), a 130 km/h speedo, fuel and temp gauges and a LED boost meter marked from 0 – 500mmHG (0 – 10 psi). All controls are simple to operate and it’s a very easy car to drive.

The Mira cabin offers ample front head and leg room but shoulder space is minimal with two persons abreast. The TR-XX also comes with a small 2 person rear seat – it’s best suited for occasional use only.

The L70 Daihatsu Mira TR-XX is a great car for anyone wanting to have some fun on the cheap. Our 1987 test vehicle – which needed a clutch replacement, new turbo and some body detailing – was being offered for AUD$3900 (plus compliance) through Adelaide’s YahooMotorsport. Note that compliance should be cheap and easy due to the availability of local L70 Handivans – you can buy specific parts from a wrecker or pick up an entire vehicle for only a few hundred dollars.

Okay, it’s time to be honest - the 550cc TR-XX will never be a WRX beater. However, the amount of fun you can have and the tuning potential is huge. This is a machine really get stuck into.

The exhaust should be one of the first stock parts to hit the bin. We suggest a 2 ¼ inch press bent system using a cheap and readily available Commodore or Falcon cat converter. Oh, and try to keep the trick-looking dual outlet arrangement with the new big-bore system – you wouldn’t want to lose that! The total cost for the upgrade exhaust shouldn’t be more than about AUD$200 - some people spend more than that on just a muffler...

Next would be the air intake. A VL/VN Commodore airbox would offer ample airflow, but the biggest challenge is finding enough space to mount it under the bonnet. An easier – but less creative - alternative is to mount an aftermarket pod filter directly onto the turbo compressor inlet.

The standard intercooler is tiny and unable to shed the heat generated under long periods of boost. We also discovered it gets quite hot to touch after idling around in traffic. A cost-effective solution is to employ a medium size OE intercooler (Mazda RX-7, Toyota 1G and Nissan R32 cores spring to mind as some the most attractive options). Be sure to mount the intercooler in the nosecone to avoid heat soak issues.

These three basic mods will get the TR-XX breathing and running much more efficiently but you really need a big whack of boost to really get it hauling. A simple bleed valve can be used to deliver up to, say, 15 psi of manifold pressure. However, note that the air-cooled little turbo has a relatively short life – you might want to look at fitting the slightly larger RHB32 huffer from the local G11R Charade Turbo. Both of these turbos are from the same family and share a 3 bolt mounting flange.

EFI versions of the TR-XX can be upgraded with bigger injectors fitted by modifying the MAP sensor load input to the ECU. Carby versions can have larger jets fitted to provide any necessary extra fuel flow. The ignition timing on both engines can be altered by simply turning the distributor.

One of the only downsides of the L70 Mira TR-XX is its 550cc EB-series engine was never released in Australia. If you’re unlucky enough to melt the engine you’ll probably have to build up another based on the naturally aspirated 3 cylinder found in the local Handivans – this might not be such a bad thing since the local Handivans come with a ‘big’ 850cc three-pot...

A big block Mira TR-XX?! It’s sure to make the guys with small block Chev V8s tremble with fear!

Contact: Yahoo Motorsport www.yahoomotorsport.com.au +61 8 8345 0939/ 0416 080462

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