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Ten Tech Tips

Ten automotive pearls of wisdom

By Michael Knowling

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If you own a car with an automatic transmission, you’re probably aware that it requires routine trans fluid changes. Most people will drain the fluid from the oil pan, refill ‘er and give themselves a pat on the back for a preventative maintenance job well done. Well, unfortunately, this only a half-measure – it doesn’t flush the fluid lurking in the torque converter, cooler and cooler lines. A proper transmission flush should involve removing the filter (where fitted) and ensuring all fluid is replaced. One approach is to disconnect the oil cooler pipe returning to the transmission, run the engine for up to a minute or until no more fluid is discharged from the pipe, switch off, drain the pan and refill. No fancy pump required.

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If you’ve got a V-configuration engine and you’re looking for a bit more grunt, it’s worthwhile considering the asymmetric turbocharging principle as used by Saab in the late ‘90s. This system, where only one bank of cylinders is used to drive the turbocharger, simplifies manifold construction and can potentially save a lot of money. However, you’ll need to consider the relationship between compressor and turbine size – you need a compressor big enough to provide your desired max power but a turbine small enough that it’ll spool up when required. You might also encounter tuning issues relating to variation in backpressure and heat. There are some hurdles but it’s a very interesting concept that deserves exploration.

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Another interesting approach to forced induction is twin-charging – using a supercharger to provide ample low-down grunt and a turbocharger to provide a more efficient top-end. We’ve recently been asked the best way to set-up such a system – and the answer is to copy Nissan! The late ‘80s Nissan March Super Turbo is one of those rare production vehicles with a twin-charger setup. At low revs, the Nissan turbocharger blows through the working supercharger while when engine rpm and load increases, the blower’s electro-magnetic clutch is disengaged and the turbocharger provides boost to the engine via a supercharger bypass passage. Airflow through the bypass is controlled by a differential pressure valve which starts to open as the turbo nears operating rpm. In standard guise, the supercharger is used to deliver 7 psi boost and the turbo forces 13 psi. Food for thought!

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Oh, and when embarking on a custom turbocharger fitment, you might also be interested to learn that ball-bearing turbos can survive on a much reduced oil pressure/flow than conventional sleeve bearing turbos. In fact, given generous water cooling, it’s quite possible a ball-bearing turbo will survive on only around 10 psi oil pressure (depending how hard you’re working it). This means you can configure a stand-alone turbo lubrication system that uses a relatively low power electric pump and, where space permits, a sump. This avoids dumping excess turbo heat into the engine’s lubrication system and can make installation easier.

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Although widely seen as a relic of ‘80s turbocharging, the humble over-boost pressure relief valve (aka pop-off valve) deserves attention. We’ve recently heard of several engine failures related to turbo over-boosting caused by sticking external wastegates and inadequate turbo hose systems. In each of these cases, a relief valve would have vented excess boost pressure and saved the expense of an engine rebuild. Not a bad investment, given an over-boost relief valve might cost only a few dollars... One approach is to modify the relief valve fitted to early Nissan turbo engines (such as RB30ET and E15ET) or you can fit a different spring to an aftermarket blow-off valve – as detailed in Venting Boost, Part 1

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Weight reduction is one of the easiest ways to improve the performance of your car - but how do you reduce weight if you don’t want to sacrifice all the mod-cons that come standard in today’s cars? Well, you can typically shed a few kilograms by switching to a smaller dry-cell Odyssey battery and removing the spare wheel to carry an electric air compressor and puncture repair kit (as found in some European vehicles). You’ll also be surprised how much weight you’ll save by replacing the factory exhaust system – a standard S13 Nissan exhaust weights more than 25 kilograms! Oh, and relatively small diameter alloy wheels also weight considerably less than some of the tasty looking aftermarket jobs on the market.

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With most new cars of the last five years employing a variable intake manifold, there’s a great opportunity to pick one up cheap from a wrecker and adapt it to fit an older engine. If you’ve got a straight six, the variable length manifold from a post-EF Ford Falcon is probably one of the best bang-for-buck propositions. If you’re after something smaller, pretty well all of today’s four-cylinder engines have ‘em – Mitsubishis, Hondas and Toyotas. In the V6 segment you should look at the high performance version of the new Holden V6 (however, the Holden system merely alters plenum volume rather than runner length). Also check out the dual throttle intake manifolds fitted to Japanese import VG30DE engines. Sure, you may need to make some elaborate manifold adaptors, play around with the dual-stage switch-over point and throttle linkages but there’s certainly an opportunity to achieve substantial gains.

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AutoSpeed has always promoted taking measurements to find out whether its worthwhile upgrading your car’s exhaust, air intake or throttle body. Unfortunately, due to the wide range of test pressures, it’s been necessary to collect a range of different gauges. Well, now there’s a single hand-held digital meter than can measure positive and negative pressure (vacuum) up to 30 psi – it’s ideal for automotive testing. You can also select your preferred unit of measurement and use the handy max/min hold function. See our full test at Handheld Digital Manometer

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For anyone reacting to the recent increase in fuel prices, it really does pay to do some sums before buying a used ‘economical’ car. In many instances, you’ll find that diesel or small, fuel-efficient vehicles cost substantially more than large petrol-engine’d vehicles that might’ve cost twice as much at the time of release... It’s quite conceivable that you’ll sell your up-market family sedan only to step into a bare-bones hatch with hubcaps and wind-up windows! In addition, there are times when the figures simply don’t add up in your favour – take into account the reduced fuel consumption bill and compare it to the amount extra you’re paying for purchase and it’s sometimes not worth it. Don’t get caught up in the hysteria!

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If you’ve read the press release on the Mitsubishi 380 you may have noticed the hoo-ha surrounding the use of pulse width modulated thermo fans. Compared to a basic on/off wiring arrangement, pulse width modulated control improves electrical efficiency and there’s no annoying fan cycling. Well, for a few bucks, you can introduce pulse width modulated thermo fan control to your car! Using the Silicon Chip Nitrous Fuel Controller you can control fan speed up to a maximum rating of 10A. For more, see The Nitrous Fuel Controller - That's Also a Lot More!

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