Fuel consumption: how much is normal?
Discussion
Hi guys,
I suspect my V8 is running rich, just by the strong smell of unburnt fuel in the exhaust.
Over a long steady motorway trip, I measured and calculted fuel consumption: the car does 15.4 mpg at a steady 105 mph.
Given that the engine is a fairly conservative 350 Chevy with Edelbrock heads, EFI and about 400BHP on the bench, redlined at 5500 rpm, would you consider this normal or slightly excessive consumption? I would have hoped for about 18 mpg given the tiny frontal area.
How would I test for over-richness? Would I need to have an 02 reading done at an MOT center, or is there a crude technique like holding a sheet of paper over the exhaust and seeing if it gets sooty??
Thanks,
Alex
Note: The Stack shows an Air Temp readout of -99°C. Would this be outside air, or air measured in the intake manifold for ECU purposes? If the latter, maybe the Air Temp sensor needs changing and because the ECU thinks the air is freezing cold is incorrectly enriching the mixture... How can I tell??
I suspect my V8 is running rich, just by the strong smell of unburnt fuel in the exhaust.
Over a long steady motorway trip, I measured and calculted fuel consumption: the car does 15.4 mpg at a steady 105 mph.
Given that the engine is a fairly conservative 350 Chevy with Edelbrock heads, EFI and about 400BHP on the bench, redlined at 5500 rpm, would you consider this normal or slightly excessive consumption? I would have hoped for about 18 mpg given the tiny frontal area.
How would I test for over-richness? Would I need to have an 02 reading done at an MOT center, or is there a crude technique like holding a sheet of paper over the exhaust and seeing if it gets sooty??
Thanks,
Alex
Note: The Stack shows an Air Temp readout of -99°C. Would this be outside air, or air measured in the intake manifold for ECU purposes? If the latter, maybe the Air Temp sensor needs changing and because the ECU thinks the air is freezing cold is incorrectly enriching the mixture... How can I tell??
Alex , get yourself an AF guage (air fuel). It varies, but the Chevy in my car runs 12.8
You dont want to tinker with it as you can run it lean & ruin your engine. You will find people thinki its overfuleing, but has it a choke fitted, or is it a 4 barrel carb etc. As a rule I can get around 20 mpg out of mine pottering around. At 105 mph, I wouldnt know.
You dont want to tinker with it as you can run it lean & ruin your engine. You will find people thinki its overfuleing, but has it a choke fitted, or is it a 4 barrel carb etc. As a rule I can get around 20 mpg out of mine pottering around. At 105 mph, I wouldnt know.
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