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Old 02-05-2012, 03:17 PM   #70 (permalink)
Mechanical engineer
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Join Date: Jan 2009
Location: Kitee (Finland)
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Siitin - '98 Seat Cordoba Vario
90 day: 58.56 mpg (US)

VW Lupo 3L --> 2L - '00 VolksWagen Lupo 3L
90 day: 104.94 mpg (US)

A8 luxury fuel sipper - '97 Audi A8 1.2 TDI 6 speed manual
90 day: 64.64 mpg (US)

Audi A4B6 Avant Niistäjä - '02 Audi A4b6 1.9tdi 96kW 3L
90 day: 54.57 mpg (US)

Tourekki - '04 VW Touareg 2.5TDI R5 6 speed manual
90 day: 32.98 mpg (US)

A2 1.4TDI - '03 Audi A2 1.4 TDI
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If you are so much scared about your emissions how can you withstand the fact that everytime you make the first start you will pollute a lot before the catalysator is fully warm up? You can only fasten that process by putting the catalysator closer the exhaust manifold and by using exhaust wrap around the pipe. You can also install smaller diameter catalysator but that is illegal because its not designed for your car at least in europe. So it does not matter how good your intentions are...

Only real choice would be EV.

Good points has also being made about the fact that fuel does not come up clean from soil. First you need to pump it process it and also haul to the fuel station. Usually those machines arent the most eco friendly at all.

In Finland test is made so that they first rev the catalysator hot about 30 seconds and measure the values from the pipe first at high revs about 3000RPM and after that with idle revs. If values arent good tehy rev it little bit more to make the the cat hotter. If you have hypermiled the car and never revved it properly you need to drive up to 7 miles with second gear revs on the redline to clear the catalysator. Go back to measuring place and see if the catalysator is clear.

If you get proper values your catalysator still works like it should. If you cannot reach the target values you need to change the CAT.

So you do need sometimes to rev the engine like you stole the car to work properly. Usually I do that in motorway incoming ramps flat out rev each gear to redline.

I would say in each case its better to burn less fuel than produce few HC, NOX, particles of pollution less.

Vesa Tiainen innovation engineer and automotive enthusiast
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