Peanut Projects - Part One

Do you have a Do-It-Yourself streak? Like that feeling of satisfaction when you achieve a massive power gain for only a third of what it would cost in a go-fast workshop? Well, here’s a compilation of cars that are dead-easy and cheap to work on...

Time to clear out all that junk in the shed and get workin’!

Holden 5.0i V8

When the faithful Holden 5.0 litre V8 was reborn in 1988, it opened up a whole new era of modification.

The injected 5.0 V8 – as found in VN to VT Series 1 Commodores and contemporary Statesman/Caprice models – is a great base for anyone wanting to enhance some late-model V8 muscle. The relatively simple mechanics, the abundance of parts (OE and aftermarket) and the wealth of tuning knowledge make this hard to go past.

In base form, the injected 5.0 generates 165kW and 385Nm of torque. It achieves this with a relatively restrictive intake manifold that’s focussed on low rpm torque (see photo). If you want to extract real power without resorting to forced induction, the Holden Group A intake manifold is a direct bolt-on and – even by today’s standards – it’s a ripper manifold. It employs tuned length ram tubes for each cylinder, a large volume plenum chamber and dual staged throttle bodies. The only accompanying mod that might be necessary is a bonnet hump or cut-out to clear the top of the new manifold.

Oh, and when you upgrade the intake manifold, it’s also the perfect time to revise the pre-throttle induction system – again, the Group A intake is a very good set-up. All you really need to do is enlarge the entry to the airbox.

With a free-flowing air intake, you can make the most of a camshaft upgrade. Of course, there’s only one camshaft in the ol’ Holden V8. There are many different profiles on the market – all you need to do is chose your desired rev range and power output. See New Stick for our article on installing a Crane H286 camshaft in a VS Commodore V8.

The 2-valve cylinder heads are generally good, but the casting dags can be easily cleaned up at home with a grinder. For applications over about 300kW, you’re strongly advised to replace the factory cast pistons. The standard compression ratio is a lowly 8.4:1 to begin with, so a set of high compression forged pistons is probably on your shopping list anyway.

There are a number of approaches to optimise the 5.0 V8’s engine management. Take your choice from a custom chip, a Kalmaker reprogram, plug-in Haltech ECU, interceptor or stand-alone aftermarket management. Note that the injected 5.0 runs a MAP sensor up until the VT.

For all-out applications the Holden engine can rebuilt with a stroker kit up to about 6.2 litres. The Harrop 5.7 litre upgrade is a popular choice and came factory fitted to the HSV GTS-R.

If you don’t like the idea of an in-depth backyard engine tear-down you can always purchase an off-the-shelf supercharger kit. Brand new, a basic blower kit costs anywhere between AUD$4000 – $8000 but keep an eye in the classifieds – you can generally pick one up for about half the new price. Ready-to-go intercooler kits can also be purchased, but if you’re a true Do-It-Yourselfer you’ll tackle this with a custom set-up.

And, yes, there is more to a Commodore than just its engine. They are easily upgraded in terms of suspension, brakes and interior.

The potential is almost unlimited.

Daihatsu Mira TR-XX/Leeza TR-ZZ

At the opposite end of the spectrum is this – the Japanese market Daihatsu Mira TR-XX/Leeza TR-ZZ. Both are 15 year old Japanese imports that can be readily picked up for just AUD$4k (plus ADR-ing).

If you like small performers – and you don’t realistically expect to run with ‘the big boys’ – you’ll love these!

The Japanese-market Mira TR-XX is based on the little L70 Daihatsu chassis (known in Australia as the Handivan). The only difference is a big serving of attitude. The little Kei-classer is made more appealing thanks to a full body kit comprising a rear spoiler (which surrounds the entire tailgate glass), side skirts, a front lip, bonnet scoop, central roof-mounted aerial and 12 inch alloy wheels. The ride height is also a bit lower than everyday Miras. Oh, and some examples also feature a dual outlet exhaust – a hint to the awesome grunt on tap.

Well, not quite...

Under the bonnet, the TR-XX boasts a turbocharged and intercooled 550cc three-pot! The EB20-series turbo engine is available in two main specifications – carby and EFI.

The base version (released in 1986 and continued until 1990) uses a blow-through down-draught carburettor and a static compression ratio of 8.3:1. This engine is rated at 38kW and 70Nm (at 6500 and 4000 rpm respectively).

More desirable is the multi-point EFI version, which was released alongside the carby turbo engine in 1987. Interestingly, the EFI engine employs a 0.3:1 lower static compression ratio but power is up to 43kW (at 6500 rpm) and torque steps up to 73Nm (at 4400 rpm). Later (circa 1989) EFI models are listed with the Japanese regulation 47kW output.

Interestingly, the TR-XX was built in both manual and automatic guises – the former being the most common. The TR-XX manual version can accelerate to 100 km/h in around 10 - 11 seconds. Obviously, it’s no speed machine – but you don’t need much more power to get the 570kg kerb mass hooking along! We’ll come to that shortly.

The overall appeal of the TR-XX is enhanced with its standard sports trim and instrumentation comprising a tacho and LED boost meter. Air conditioning is fitted to most examples and the top-line TR-XX Limited boasts power windows. Of course, the cabin is very tight in terms of width but leg and headroom are not issues for most drivers.

If the commercial-based Daihatsu Mira isn’t exclusive enough for you, it is worthwhile checking out the Leeza TR-ZZ stable mate. The L100 Leeza reputedly shares a Mira chassis but flaunts a sportier body with gentler curves. The biggest downside is almost none of the panels are interchangeable L70. Oh, and note that a soft-top ‘spider’ version was also released – great for demonstrating chassis flex... Under the bonnet everything remains identical to the Mira TR-XX.

Okay, so what can you do with these pint-size little tigers?

Well, you can do everything you’d normally do to a larger turbo car - except everything can be downscaled and is much cheaper.

The exhaust needn’t be anything more than a press bent 2¼ inch system with an OE cat and muffler off, say, a Falcon or Commodore. For about AUD$200 you can have an exhaust that poses zero backpressure!

Similarly, the air intake can be enhanced very cheaply. The easiest approach is to buy a pod filter and mount it directly on the compressor inlet, but you might be able to squeeze in the airbox from a larger car. A Holden VL/VN airbox and filter can be bought very cheaply.

The standard top-mount intercooler is one of the smallest we’ve ever seen. Everything is relative, of course, so an intercooler that’s considered rubbish on a R32 Skyline is intercooling overkill on a 550cc engine. Good intercooler performance should be achievable on a budget of around AUD$100!

Boost – and a whole lot of it – will be required to get the Mira or Leeza really hauling. Unfortunately, the standard IHI RHB31 turbochargers are relatively delicate and don’t last long at high boost pressure. An effective upgrade – which we believe should be a bolt-on – is the RHB32 turbocharger found on the locally delivered Daihatsu Charade turbo. Those that have survived the crusher...

With these mods, you’ll have plenty of wheelspin and straight-line performance to scare the pants off many Saturday night traffic light demons. What could be more fun?

Stay tuned for the second – and last – instalment of this series. We’ll take a look at some hot sixes...