One of the most significant sportscars of the '90s era is the Mazda MX-5. With its abundance of character and finely tuned double wishbone suspension, it's no wonder the little MX became a common sight at racetracks around the country. One thing that the MX-5 lacked, however, was power. Any power. Being propelled by a rear-wheel drive version of the B-series 1.6 or 1.8 litre engine (just like that used in the Ford Laser), the Mazda sportscar lacked any sportscar acceleration. Indeed, MX-5 drivers experienced ecstasy around each corner, but they often found themselves nodding off during those long straights...
Verne of Sydney discovered this flaw in the MX-5's character before the sun went down on his first day of ownership. After picking up his brand new 1999 10th Anniversary MX-5 (one of only 150) he soon fell in love with the Mazda's amazing agility and its 6-speed manual gearbox - but, God, it needed more power. And this was supposed to be the Gun 106kW 1.8 litre version... (See "New Car Test - Mazda MX5 10th Anniversary Model" for AutoSpeed's road test of the stunning-but-slow 10th Anniversary MX5.)
More power was needed, but as Verne says, "Just an exhaust wasn't going to be enough". In search of something substantial, he took the car along to Paul at BD4s. There was no point in showing Verne things like extractors, high compression pistons and such atmospherically inducted goodies - Verne wanted a turbo
Torque was the keyword.
Being Australia's leading HKS distributor, BD4s brought in a HKS MX-5 turbo kit comprising a cast exhaust manifold, Garrett-based HKS T25G turbocharger, dump pipe, crossover pipe into the throttle body and a piggyback Mini F-CON computer. Paul says the whole kit was a 100% straight bolt-on - if only all kits came as well engineered as this!
In addition to the components supplied in the turbo kit, BD4s installed an HKS air filter and a BD4s/Hypertune oil catch can. Supplementing these is an air-to-air intercooler. This had to be a highly efficient unit because the engine was being boosted on top of its relatively high n.a. compression ratio - a combination that often leads to detonation problems. Utilising the cooling 'mouth' at the front of the car, a PlazmaMan 'cooler takes the edge out of charge temperatures and before they arrive back at the throttle body through Hypertune mandrel plumbing. It's all polished to a brilliant shine, of course. Note that a HKS blow-off valve has also been connected into the IC plumbing - that small diameter pipe you can see running out from the post-cooler pipe takes vented air back into the intake track. Verne's not a big fan of those psshht antics.
The most recent mechanical change has been to the exhaust system. Sure, the HKS turbo kit had supplied the dump pipe - but Verne's car still ran with the stockie pipe work from there back. Recognising the restriction that it posed, Liverpool Exhausts were entrusted with fabricating a 2?-inch system with a high flow cat converter and a polished HKS Super Drager muffler on display at the rear. This made a huge difference to response.
So how hyped is this once slow-as-sap MX-5?
Well, in standard form the car rolled out 82kW at the back wheels on a Dyno Dynamic dyno; once turbocharged it made a sizeable 123kW (on 0.45 Bar boost)! That's a nice round figure increase of 50 per cent.... Fitting the air-to-air intercooler wasn't to enable increased power - rather it let the engine reach the same output at a lower boost level - 0.4 Bar. Indeed, it's a much safer way of making the same power. The stretched-to-the-limit fuelling system, however, does need to be improved - this is why nobody's chasing even more power at this stage. Larger injectors and a rewritten chip are on the cards for the near future.
While the turbo kit was still settling in during its run-in phase, Verne had removed the polished factory rims and treated the car to a new set of shoes. The only problem was finding a 40mm offset wheel to suit. Luckily though, Verne is mates with someone that works in Simmons wheels factory - who was able to generate some slip-on FR17s. These 7-inch wide slippers fit perfectly. Grip is also improved by a set of 215/40 Dunlop SP901s.
Once the rolling stock had been seen to, the distance between the bottom edge of the guards and the top of the rims just didn't look right. So - not wanting to undo Mazda's top effort in chassis tuning - Verne went for a set of mildly lowered HKS coil springs. These work together with the factory-fitted Bilstein dampers. As Verne tells us, the car handles great on the street and the racetrack (namely, Wakefield and Calder). The long straights are now equally as exciting as the corners - of course, that much improvement in power will usually do that!
Being a pretty trick kinda car inside straight outa the box, there was no need to touch the standard blue-inset seats, trim or the Nardi wheel and gear knob. A high power Nakamichi in-dash CD changer is the only alteration. This is wired to a pair of Clarion 3-ways in the front doors (well, they're not in the rear doors are they?!). Simple.
Indeed, a car like this is something to be very protective of. Verne tells us it's his "toy car", not an everyday-er. He likes to use it to get away in during the weekend - and, judging the fact that the car racks up around 11,000 kilometres per year, we guess that he likes to get in and drive. And drive.
And that - after all - is what a beautiful handling and power-boosted MX-5 is born to do.
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