Bsfc Vs Fuel Specifics

[randy]

I've always looked at the bsfc numbers on the dyno sheet to see how effective the engine was using the fuel to produce power. I came across an article where the engine builder says they use the fuel specifics to tell them what the engine wants. Is the fuel specifics a better way to tell or is this just another term for the bsfc.

[Cammer]

Randy,

I tune to A/F numbers and check BSFC numbers.

BSFC numbers are influenced by nearly everything on the engine so learn to tune with A/F numbers.

Select a dyno with a good WBO2 setup for best tuning results.

____________________________________

[rookie]

Originally Posted by Cammer

Randy,

I tune to A/F numbers and check BSFC numbers.

BSFC numbers are influenced by nearly everything on the engine so learn to tune with A/F numbers.

Select a dyno with a good WBO2 setup for best tuning results.

____________________________________

Wow this sounds like one of those cellular telly commercials about
text messaging.
Correct me if I’m wrong (like usual). I’m not sure what all the engine lingo means.
Bsfc - base specific fuel consumption, is the amount of fuel the engine is using to make a given amount of horsepower.

A/F – air to fuel ratio would be the mixture as measured by the O2 sensor or sensors.
Is this the same as fuel specifics as mentioned previously?

WBO2 – would be Wide band O2 sensor

[gregory]

Hi Cammer,

"BSFC numbers are influenced by nearly everything on the engine so learn to tune with A/F numbers."

When you tune with A/F numbers,what does that tell you about whats happening in the combustion process?

[Dusty]

Brake Specific Fuel Consumption by definition is pounds of fuel per horsepower hour
BSFC= lbfuel / hp * hr
Its often used as a reference while tuning when better information ie O2 sensors aren't available. BSFC numbers are something you can tune by but they are engine specific. What I mean by this is that imagine you had a crankcase fuel of subzero molasses the BSFC would go way up because of the friction. Every engines mechanical loses are different from one another. So these numbers are only really relevant on dyno tests with the same engine and oil temps.When you compare BSFC numbers with other engines you are comparing their efficiency you cannot "derive" their tune.

[rookie]

Originally Posted by Dusty

Brake Specific Fuel Consumption by definition is pounds of fuel per horsepower hour
BSFC= lbfuel / hp * hr
Its often used as a reference while tuning when better information ie O2 sensors aren't available. BSFC numbers are something you can tune by but they are engine specific. What I mean by this is that imagine you had a crankcase fuel of subzero molasses the BSFC would go way up because of the friction. Every engines mechanical loses are different from one another. So these numbers are only really relevant on dyno tests with the same engine and oil temps.When you compare BSFC numbers with other engines you are comparing their efficiency you cannot "derive" their tune.

So with that being said would thinner oil (sufficient to application) with proper tune give you better fuel economy?

[Dusty]

Yes anything that reduces mechanical loses will free up hp