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Some of this week's Letters to AutoSpeed!

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The Language Harrier...

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I noticed your article on the Toyota Harrier (New Car Test - Toyota Harrier/Lexus RX300) and enjoyed reading it - especially the part about the central LCD screen... "although its Japanese language certainly takes some exploration!"

I have just purchased such a vehicle - a 1999 model - and have received a full handbook for the multi-function display. Unfortunately, it is in Japanese and we do not even have a Japanese Embassy here. Can you help with a short instruction as to the clock and air-con functions? Thanks from Africa.

Peter Breitenstein

Sorry, we can’t help you out – it’s been four years since we drove the Harrier and we don’t remember how to operate the clock and air-con (even if we once knew at all!). But congratulations on your purchase – great vehicle.

O2 Sensor Fitment

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I was wondering if the Smart Mixture Display (Smart Mixture Meter, Part 1) would work with an older car if I fit an O2 sensor. I have a Datsun 260Z with twin SUs and would like to see the mixtures and make adjustments to the needles, if necessary.

John Gilbert

Yes, this approach can work – we’ve fitted an oxy sensor to a carby car before. We used a single wire oxygen sensor (which takes longer to reach operating temperature but is relatively easy to hook up). Fitment will usually require drilling a hole through the front section of exhaust and welding on a lug (or nut) with the same thread as the sensor. Alternatively, some Daihatsu and Toyota oxy sensors use a 2-bolt flange.

Note that you’ll need to run the engine on lead-free fuel to avoid poisoning the sensor element.  

Which Gauge?

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In your article Eliminating Negative Boost - Part 2 you give much detail and importance to the Dwyer Magnehelic Gauge. I contacted Dwyer and requested a catalogue which I received. I'm confused as to what model in the 2000 series would best serve my purpose. I'm interested in finding restrictions to airflow and finding the best location for cold air intake ducts as you did. Some read in "kPa" units and some read in "inches of water" and there are various ranges. Which is best?

Daniel Gigante

The highest flow restriction we’ve seen in a factory air intake is just over 50 inches of water - as measured in a ’94 Subaru WRX. That means, for intake restriction measurement, you should use a gauge that reaches around 50 inches of water.

On the other hand, to site a cold air intake, you need a gauge that is sensitive enough to identify aerodynamic pressures at moderate road speed. For this, you want a gauge that measures up to around 5 inches of water at full scale deflection.

Unfortunately, no single Magnehelic gauge can be used to accurately measure aero pressure (at a sane road speed) as well as total intake system restriction.

For aero testing we use a gauge with either a 1 or 3 inches of water range. For intake testing, we use a gauge that reads up to 40 inches of water – and even that wasn’t enough in the case of the WRX!

It doesn’t matter if you go for a gauge that reads in kPa or inches of water – to convert a measurement from inches of water to kPa, simply multiply by 0.248.

Under-Bonnet Pressure Ideas

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Great article on under-bonnet pressures - Undertrays, Spoilers & Bonnet Vents, Part 1.

A suggestion for a future article... increasing airflow through top-mounted hood scoops and intercoolers. One can tell from the dirt deposited on the TMIC on Subies that most of the airflow is (of course) at the back of the IC. How can we improve that?

Subies are very good in not overheating (ie they maintain a stable coolant temperature). I wonder if I could block off part of my Subaru’s radiator intake to decrease the under-bonnet pressure and maybe get more air flowing through my hood scoop?

Mako Koiwai

Interesting idea. In theory, your idea of reducing radiator flow makes sense – just be careful how much you block off if you try it! If you go ahead with it let us know your results. Note that a bigger bonnet scoop is said to make a difference to WRX intercooler performance – but we haven’t tried it.

Turbo at its Limit?

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Can a T25G turbo (from a Nissan S13 Silvia) support 220kW? If not, can you suggest a no-lag turbo that I can throw into my non turbo S13? Even if a T25G can support 220kW, would a different turbo deliver better power?


From what we’ve seen, a standard Silvia SR turbocharger can manage 220kW – so long as there’s good intercooling and everything else is running as it should. This is, however, running near its limit - the ceramic turbine can fail if used for extended periods at this sort of power output. In a street application you shouldn’t have any major issues.

Yes, a bigger turbo will let you make more power – even at the same boost level. The downside is worse lag, bottom-end torque and cost.

Handy Access

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Got an interesting item for your Using Multimeters series - a plastic clamp that fits over a wire and allows you to probe it through a hole in the clamp. No slips into your finger, shorts or broken wires! (The clamp pictured here is available from Elecspress Pty Ltd – phone +61 3 9294 1000.)

Rob Elliott

Celsior Qs

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I have a 1992 Celsior, engine code 1UZ-FE 3968cc. Is this engine supercharged? What would the horsepower be? What does the two-way switch market ‘ECT’ (next to the auto gear stick) stand for?


No, the 1UZ-FE is a naturally aspirated DOHC, 32 valve V8. We have seen aftermarket supercharger kits, but a blower was never factory fitted. Early (non variable cam timing) 1UZ-FEs are listed at around 190kW. ECT = electronically controlled transmission. There are two modes – one for economy and one for power.

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