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Some of this week's Letters to AutoSpeed!

1 June 2003

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Controlled Breeze

Here's an idea for your electronics gurus to develop a kit for - a sophisticated electronic fan controller.

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Many cars (some BMWs, for example) have expensive electric cooling fans that are prone to early burn out from the full current inrush of start/stop cycles. Most cars have only basic on/off control; the fan runs at full speed whenever activated but, in some circumstances, could actually be run slower for less battery drain.

The PSM1 Variflow fan controller - produced by US company than may now be out of business - was one such device, which received many glowing remarks from people who installed it. The PSM1 unit had the following features that I have not seen anywhere else:

  • User selectable temperature cut in/cut out thresholds
  • Soft start for fan motors at cut in temperature (to extend fan life)
  • Variable speed for fan motors according to temperature level
  • Capability for selectable (or temperature controlled) cool down/ramp down period for motor, after car is shut off
  • No external relays required; capability of direct solid state control of two fans, each up to 25 amps

Even if you don't think this idea is worth pursuing, I think you have a great on-line magazine. Keep up the good work. I have a turbocharged BMW 633 as well as a couple of big V8 cars (Pantera and Jensen Interceptor), so your articles are very informative to me. Thanks for your time.

Steve Brenneman

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Check out "Motor Speed Control Module - Part 1". This controller is a cheap DIY project that can alter the speed of an electric fan (or pump) by the turn of a knob. In Part 2 of the special, we also show how the speed of a fan (or pump) can be varied in accordance with engine load; no doubt, a keen electronic tinkerer could instead devise an interface to read off your engine's coolant temperature sensor.

More On Monaro 1

Just a quick comment on the article about the "Incredible success of the Monaro" written by John Guard. He states the following...

"Look at the torque: 465Nm. Not 100 or 200 or even 300Nm, but torque to make the car accelerate when you boot it. Forget the four cylinders, even with a turbo bolted on they're still not in the hunt."

Now I don't mind the Monaro at all - it does look quite good but, considering that I bought a Nissan 200SX for about $20K less and added a 3-inch exhaust and can tell you the CV8 Monaro is not in the hunt after 2nd gear. The funny thing being that I have not even really started with the modifications!

Patrick Tye

More On Monaro 2

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Julian, it is quite obvious from the articles that you have written about the Monaro that you have a strong personal dislike towards the car. Personally, I wouldn't rush out and buy one - I would prefer waiting for the Mazda RX8 to be released then add myself to the waiting list. However, why condemn the Monaro? It is a vehicle enjoyed by many patriotic Australians and others, and although it is not "our cup of tea" I'm sure that it is a good motorcar with fantastic performance and handling. Is it possible that you could be a little more objective when it comes to your articles about the Monaro? The way you have written about them does little for your journalistic credibility in my eyes and I have mostly enjoyed reading your articles from way back.

Peter Parianos

Note, Peter, that JE has written very positively about the HSV GTO - it's set-up is quite different to the Monaro's.

Strip Me

I was looking into serious weight reduction and have come up short on info. I was wondering if you could give me any info on companies that might undertake such vehicle weight reduction and whether or not it would be street legal. I don't want items simply removed - I was thinking about changes to materials used in body structure. Any info would be appreciated.

Adrian Lulic

We imagine most companies would shy away from serious weight reduction on a streetcar due to legal/safety issues.

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Needless to say, start off by removing non-essential comfort items (sound deadening and carpet, hood lining, radio/speakers, boot trim etcetera) and, from there, your budget will come into play. Carbon fibre panels, lightweight rims and suspension components are highly desirable but not cheap. Depending what type of vehicle you're getting stuck into there might be off-the-shelf aftermarket carbon panels available to suit. If not, we suggest attending a circuit meet and speaking to competitors to locate an automotive carbon fibre specialist in your area.

Another approach to weight reduction is drilling 'Swiss cheese' holes through panel support frames - but be aware of the reduced strength.

B4 Chatter

Not a question but a comment - your Liberty B4 feature car article ("A Better B4") got quite a response on our B4 website! I think the conclusion we reached was the guy who bought the car did so under the impression it was simply a larger WRX and, if the dyno readings were correct, we think his car might have had a problem... The first issue we are hearing a bit - people buy the B4 wanting a bigger WRX. It isn't meant to be. It's a sophisticated car with a power delivery that kicks butt if you know how to drive it; in top-end I'd put the B4 against a WRX any day. As one of our members said, "the first turbo makes people think, but when the second kicks in they are left scratching their heads"!

Jennifer McGregor

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The B4 is certainly an intriguing vehicle - especially in its detuned (190kW) Australian guise. No question, that first turbo "makes you think" (it does rocket to 15 psi at very low rpm!), but it's what happens afterward that leaves us cold; the monumental boost drop-off during the transition to the second turbo and the top-end that's slashed in order to cope with local fuel brews. No doubt the JDM Legacy TT - with the full 206kW - would have more going for it!

Confused Monsters?

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I noticed a very bad mistake in your Stealth Strike article regarding the Mogwai and it's reaction to water. Water causes Mogwais to reproduce not turn into a monster. They turn into monsters (Gremlins) only if you feed them after midnight.

Sean Rainey

VS V6 Tricks

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I have purchased and read "DIY Modification of Car Electronic Systems Part 1 and 2", and have also read "Electronic Engine Management Part 1, 2 and 3".

I want to advance the ignition timing and richen the mixture, only at WOT, in my Holden V6 VS Commodore (I will use a switch under the throttle to introduce the circuit changes).

My plan is to add a variable resistor to the air intake temperature sensor so the engine thinks the intake air is colder (this will advance ignition timing) and also decrease the voltage out of the airflow meter (so the ECU will richen the mixture).

I tested my airflow meter today and, at idle, its output is 4.2V. This drops down to about 3.4V as I rev the engine in neutral (maybe it goes lower than 3.4V but I didn't want to redline the engine). Also - something unusual - the airflow meter runs off 12V.

So if I decrease that voltage - lets say by about 0.3V - I assume that mixtures will be richer because the ECU thinks that the is more air flowing there than there really is.

Obviously, I will get detonation if I advance the timing too much, but how will I know where that point is? Will the knock sensors retard the timing before I hear knocking?

And also, because I now know that lower airflow meter voltage equals more fuel injection, could I use a circuit like this one to decrease voltage?

Leon Vincenzi says in your V6 article that he sets WOT advance to about 28-degrees BTDC and air/fuel to about 13:1 - "they love it" he says. Do you think I could achieve these figures?

I know this email is a bit scattered - so is my mind at the moment! - but I hope you can understand what I am trying to do. I would greatly appreciate your input!

Kris Thompson

Changing the output of the airflow meter usually results in altered mixtures and ignition timing. In any case, though, we believe the VS V6 uses a frequency output airflow meter - not a continuos voltage like most common airflow meters.

You have obviously read our interview with Leon Vincenzi and he really is the man to speak to on mods such as this; he knows the exact mixtures and timing they like on various types of fuels. He will also know, from experience, the effect of changes to sensors and the management system itself. Leon's number is +61 8 8277 3927.

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