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Some of this week's Letters to AutoSpeed!

15 June 2003

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Pocket Performer!

I have a 1984 G11 Daihatsu Charade turbo and was curious to know what I need to do to my engine to allow it to run 10 psi boost on a regular and reliable basis. I don't like thrashing my cars, but at the same time I like to get the power the engine can handle without pushing it. Would you suggest a metal head gasket and change the rings? Just wondering if you guys could help me out with any info or if you can supply some of the parts my car will require. Thanks.

David Turner

You're in luck David!

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AutoSpeed staffer Michael Knowling happened to own a G11 Charade turbo, which went on to run a 15.6 second ET - respectable for a 1.0-litre carby turbo!

To run 10 psi boost we'd advise your running an intercooler. You needn't spend too much - any air-to-air core off an engine rated at more than 100kW would be ample (the bigger the better). In addition to running a 'cooler, we'd make sure we run the engine on either leaded or PULP; our car used a Japanese-spec replacement motor, which was happy to run PULP with no problems.

In case you're interested, our 15.6-second ET was achieved with the single cam carby motor running a Toyota MR2 air-to-air intercooler (in front of the radiator), a K&N pod air filter on the compressor inlet, a slightly larger secondary jet in the carby, a 2 1/4-inch exhaust (with a single straight-through muffler) and, yes, plenty of boost. Between 14 and 17 psi from memory.

The little IHI RHB32 turbos tended not to last too long at those boost pressures, however - though we only ever bothered replacing them with second-hand Japanese import jobs. Note that ex-Japan Charade turbo parts are now quite scarce; we'd now be inclined to keep boost to a max of about 12 psi to help preserve the turbo, engine and driveline.

Real Gains?

Thanks for the continued effort on this publication. I refer to your article titled "WRX Power!"...

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I have just gone through a tuning process on my car and I note an interesting difference in how you report on "performance improvements" gained as a result of ChipTorque's mods and tuning. In your article the standard car is tested at 11 psi and generates X amount and then the car is tuned and the next reading you give is based on 18 psi. This does not give an idea to the REAL gain of the modifications; given the car's mechanical mods plus the alteration of fuelling and ignition, the tuner should be able to get extra performance out of the engine WITHOUT increasing the boost pressure. Sure the engine can now run safely at 18 psi because it has been properly tuned at this level but what was the REAL gain without upping the boost?

Stuart Coleman

We can see where you're coming from - what would have been the gains with just the exhaust, intake, IC replacement pipe and adjusted fuelling and timing? The truth is, though, just about everyone that gets their ECU modified - whether they use an interceptor or a chip rewrite - wants an increase in boost pressure as well. If the opportunity is there to increase boost - as it is with ChipTorque's upgrade - most people take it. In any case, what we quoted was in fact the "real gain".

XR6T Rampage!

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A suggestion - do a story/road test on APS's kit for the XR6T. It's still in development, but they're getting 315.6kW at the wheels from an XR6T!

Andrew McKellar

We have a couple of XR6T upgrade stories scheduled for the very near future. We've driven a couple (not the APS vehicle as yet) and we can only say it's amazing how much grunt is being extracted with fairly limited mods. Stay tuned!

Put an End to the Mischief

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About the 'Mischief' DVD... I've long admired the responsible and straightforward reporting offered by AutoSpeed. However, I'm very disappointed that AutoSpeed not only reviewed but also offers for sale merchandise of this nature. These activities on the streets are the exact reason why genuine enthusiasts are being sought out and penalised by legislators and policing authorities as they try to stamp out irresponsible clowns like those on these videos.

Please consider removing this product from the AutoSpeed shop as it will only inhibit and further endanger the future of our hobbies and passion.

Matt King

Airflow Fan

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I stumbled across your article on the Turbo Zet and, while your power draw claim is accurate, it doesn't make electric supercharging completely unpractical. Your conclusion is that it would take over a thousand amps to power a 'real' supercharger electrically. However, a high-powered 12V computer ball-bearing cooling fan will run 131.5 cfm while drawing only .66 amps - only 7.92W in total. At that rate, you could run several computer fans in parallel and not even impact the alternator. These fans are designed for continuous use, as PCs usually stay switched on for years straight. Your thoughts?


Computer fans are designed to run in a virtually 'free-air' environment - in other words, they operate with barely any airflow restriction on their inlet and outlet sides.

The output air volume of a computer fan - or any electric fan with such a small current draw for that matter - falls off dramatically when it's being 'loaded' due to a flow restriction.

Subaru Exhaust Breathing

In regard to your "WRX Blows" article... I own a Subaru RS Liberty and have recently been doing similar mods. I noted (as mentioned in "MY01 WRX Power Up - Part 1") the APS '01 WRX kit goes 2 ½-inch under the rear axle, so I've decided to go 2 ½-inch from the first standard flange joint back. The system uses a 800mm long resonator in the centre and a straight-through 2 ½ 'cream can' out the back; it's very nearly as quiet as standard and a local place made the whole lot up for $450.

The funny thing is it made only a small difference to the mid/top-end, but bigger gains in the low/mid, leading me to believe the turbo dump pipe is the restriction over 4000 rpm. Exiting the turbo is the sticky point, though - a 3-inch cat and dump pipe is too expensive for what I'd like. Anyway your article has confirmed much of this and will be helpful in giving me some ideas about were to look for solutions on this next stage.

Matt King

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From memory, the Liberty RS Turbo's factory exhaust is even more restrictive than the early WRX's - certainly the pipework leading into the rear muffler is smaller. Your existing system should yield some improvements, but we'd strongly advise going for a 3-inch cat and some kind of high-flow dump pipe. As mentioned in Rex Blows, good second-hand ones come up for sale cheap all the time!

Oh, and be careful when comparing to the AutoSpeed '94 Rex - it uses a larger (than RS Liberty) TD05 turbo and a higher compression Japanese-spec engine.

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