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Response

Some of this week's Letters to AutoSpeed!

4 May 2003

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Thirsty VL-T?

I want to congratulate you first of all on a well-built and interesting publication; I believe the four dollars a month are well spent as I learn a lot from your articles.

I have a question, if you don't mind asking - a problem has been continuously bugging me and I've found no answer even talking to different mechanics and taking the car to different workshops.

I have a 1987 VL turbo automatic that takes 20-litres per 100 kilometres in city driving.

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Now I know you will say take it to a mechanic - I have done so, plus I am an engineer myself, and we couldn't find the fault. All fuel lines have been inspected, fuel pressure is per specifications, airflow meter and oxygen sensor are new and the CO levels have been tuned as per repair manual levels. The injectors have been cleaned (although I don't believe this would have made any difference anyway), the carbon canister valve is working properly and the return line to the fuel tank intact and flowing okay. New spark plugs and wires have been fitted to the car, along with a new air filter, engine and diff oil.

The car runs really well otherwise - it starts really quick when cold and it pulls very hard. I am puzzled at this stage - what can cause the excessive fuel consumption? Any piece of advice would be greatly appreciated.

Marius Hainal
Australia

Your 20-litre per 100km fuel consumption is not good but perhaps not chronic compared to what an auto VL-T should be. From our experiences, such a car should be drinking up to about 14-litres per 100km in city/urban driving; in very heavy peak-hour CBD traffic, you might creep up to somewhere approaching 20-litres per 100. Note that - if you're doing lots of short trips - idling the car up and down will add a large percentage to your fuel consumption over a given distance.

If the conditions are not that bad, however, we'd suggest there is some kind of problem. We'd advise putting the car on a dyno and reading its mixtures under a variety of conditions with a wide-band air-fuel ratio. We'd also check the condition of the cat converter and mufflers. And you've probably heard it a thousand times - maybe take a look at your driving habits.

Hope this helps.

Flat or V Twelve?

I found your Porsche 917 article very interesting but contained one fatal flaw - it had a flat-12 not V12 engine.... Cheers.

Rob Haylock
New Zealand

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I liked your article on the Porsche 917s, especially the 917K10 and K30s that Donahue ran for Penske. But one little thing - I believe they were flat-12s not V12s.

Greg Wood
USA

Great article on the Porsche 917 car, but one there is one thing that stands out - surely a 180-degree V12 is a flat/boxer 12? All other web pages I've seen talking about this car state it is a flat-12.

Sam Marafie
UK

According to our authoritative source of information, Porsche's race engineers had recognised an internal cooling problem with their flat six and eight cylinder engines. The 917's engine was therefore configured differently with two conrods per pin, effectively creating a 180-degree V12. With opposite pistons moving in the same direction air pressure and turbulence inside the crankcase was reduced compared to a more conventional flat-12. Another advantage of this layout was fewer individual bearings.

Having said this, though, we have to agree that most sources of information suggest a flat-12 engine was used to power 917s. Perhaps this is a label the engine was lumbered with since that's what it appears to be from the outside. Can any of our readers provide a definitive answer?

After a Few Drinkies...

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I reckon I have a real comp-laint. You guys ask for an e-mail address etc. to log on to read the articles. My complaint is that after i have had a few drinkies, I cannot type my adress fast enuf to satisfy myself, let alone log in to thi site. Don't grt me wrong, what you do is great, but when I have to type in my emailk adreess, and ive had a few , the problem gets breally severe (pause here to go to refresh galss) now i no u have no idea wot i am talking about, so i will go to bed now and read wit i have missssed tomorreowtty (the next day) Keep upm the good werk, u guys are cool

Mark Naish
Australia

XR6T Man or Auto?

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I loved the reviews of both the atmo and turbo XR6. One thing I think you left out was what the new auto is like. You mention the manual "whines and growls", and another site said to buy the auto and skip the manual. What do you guys think of the new auto?

The XR6T sounds so good I am considering buying one, even though I have always been a Commodore man!

Andrew McKellar
Australia

The atmo XR6 we tested had absolutely no problems in its automatic transmission. The turbo version we tested with a 5-speed manual, however, was the 'problem' gearbox.

We can't be sure if the XR6T we tested had been absolutely flogged, but - regardless - it only had a few thousand kilometres on it. The fact that a stronger gearbox is used on the XR8 (with only 20kW more) certainly points to a weakness in the XR6T's BTR T5 manual. We haven't tested an auto XR6T so we can't say how capably it handles the torque of the turbo - we can only hope it doesn't "whine and growl" like the T5...

Either way, we think you'll be happy with a XR6T - auto or manual!

Go the Water-to-Air!

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Perhaps an idea for your WRX project car - upgrade the air/air intercooler to an RS Legacy water IC! An interesting story from the UK can be found at www.netcomuk.co.uk/~gavinp/airwater.htm

Colin Grant
New Zealand

A good site that will no doubt interest a lot of WRX owners. Note that we've also flow tested the same Liberty/Legacy water-to-air heat exchanger (see "Top-Mount Trial - Part One") and, when combined with the pipe that adjoins the compressor outlet, it has less restriction than all subsequent WRX air-to-air intercooler assemblies.

Also, Adelaide Japanese Dismantlers (www.adelaidejap.com.au) sells complete RS water-to-air systems complete with heat exchanger, front radiator and pump for around $650.

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