Volvo RWD 900 Forum

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fuel consumption 900

i've installed a 2,5" simons exhaust from the original header and back, no cat. Engine is B230FB (na 940 gl man m47)
Performance increase can be felt, but also mpg seems to be worse. With stock exhaust i used to get around 22-23 mpg. but now i get around
20-21 mpg. My driving style is the same freeway and some town but I suspect driving around i 2nd gear sometimes for 15-25 min every day trying to find a parking space might have a bad impact on fuel economy? I found a crack in the join where the two secondary pipes of the original header connects but i got that welded now. Theres is a small leak about 80 cm behind the lamda sond. Can this fool the lamda? I find it hard to believe that air can get sucked in there upstream of the exhaust flow? I have changed to studded winter tyres about the same time as i changed the exhaust. Also temperature here is down to 14 deg F (-10 C) in the night and morning. About 32- 41 in the day. Can this be the reason for the higher fuel consumption? I quess it really isn't that bad for a volvo? I recently bought the car from my father and he usually got around 24 mpg combined and 30 mpg highway. My average speed is proabably 15-20 kmh faster than him. I will get a unitek 4-2-1 header soon and also have all the joints in the exhaust welded up. It also appears that when i upshift at around 2K engine seem to "hang around" at that rpm for a split second, but i not sure if this came wiht the new exhaust. There are on error codes.(LH-2.4)
Is there something wrong or is there nothing to worry about?








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fuel consumption 900

hmmm..

couple of things....

1. fuel econnomy can be largely determined by the behaviour of your right foot...those who seek 2.5" exhausts and headers normally have heavier right foots that their fathers....

2. the main benefit of fitting headers/larger exhaust (sic...always assuming that the system is properly designed, balanced and air tight) is to increase airflow through the engine (or to tune the powerband)...engines like 14.7:1 air to fuel by WEIGHT, if your pumping more air...your using more fuel.....

3. personnaly if i got 20 anything miles to the galon with a normally asperated brick I would sell it and buy a turbo, same fuel consumption lots more fun...unless your being VERY heavy footed in the NA..in which case just buy a turbo anyway you will enjoy it a LOT more...

4. all trhe above assumes your not running a NOX kit, high lift cams and a seriously played with engine and stripping it at the weekend...in which case 2.5" is WAY to small anyway.....








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fuel consumption 900

The standard error of measurement would seem to me to be greater than 1-2 mpg.
--
John Shatzer, '97 V90 @ 105K







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