The BSFC chart thread (post 'em if you got 'em)

[Daox]

Yes.

[TEiN]

Thanks.

[cfg83]

pasadena_commut -

Originally Posted by pasadena_commut

NM = Newton meters. Torque units are force X distance.

Thank you for the correction. It didn't look right, but I didn't know what else it might be.

CarloSW2

[cfg83]

Hello -

Here is the max(?) torque rating for my engine :



What are the units of this? Are they also Newton-meters (Nm)?

EDIT: Answering my own question :

HowStuffWorks "How do you convert engine torque to horsepower?"

Have you ever looked at the specs of an engine in a magazine and seen something like "this engine makes 300 pound-feet of torque at 4,000 RPM," and wondered how much power that was? How much horsepower are we talking about here? You can calculate how many foot-pounds of horsepower this engine produces using a common equation: ...

From this, I can go here to convert to Nm :

Torque Conversion
122 lb-ft => 165.41004 Nm

This makes me happy because this agrees with my BSFC chart.

Thanks,

CarloSW2

[cfg83]

Hello -

Based on this assumption :

Originally Posted by cfg83

...

HowStuffWorks "How do you convert engine torque to horsepower?"


From this, I can go here to convert to Nm :

Torque Conversion
122 lb-ft => 165.41004 Nm

This makes me happy because this agrees with my BSFC chart.

...

I made this table to correlate Torque and the OBDII "LOD" (engine load) parameter :



Question: Does the above look correct?

If the answer is yes, then I have the ability to predict fuel consumption based on OBDII LOD and RPM parameters.

CarloSW2

[Daox]

Looks right to me.

[MetroMPG]

Are you sure the LOD value corresponds to absolute peak theoretical torque output? Or does it mean maximum torque output for a given engine speed? EG: if you floor the gas and hold it there in top gear at 1000 RPM, does it not read LOD=100, and continue to read LOD=100 while the RPM climbs?

EDIT: from the SGII user manual

LOD = This is a percentage of the maximum power available currently being generated. In some vehicles it is the maximum available at the present RPM.

Seems to be an "it depends" situation.

[cfg83]

MetroMPG -

Originally Posted by MetroMPG

Are you sure the LOD value corresponds to absolute peak theoretical torque output? Or does it mean maximum torque output for a given engine speed? EG: if you floor the gas and hold it there in top gear at 1000 RPM, does it not read LOD=100, and continue to read LOD=100 while the RPM climbs?

EDIT: from the SGII user manual

Seems to be an "it depends" situation.

I can work with that because I have the "torque curve" at the top of the chart.

The "it depends" sounds like a saturnfans question.

CarloSW2

[roflwaffle]

If you slap down the throttle at low rpm and LOD goes to ~100, it's based on peak torque. If it increases w/ rpm at WOT, it's based on peak power. If it's based on torque, as long as you have LOD, RPM, and vehicle speed, you can predict fuel consumption.

[thorpie]

I am curious about how bsfc maps are produced. Could anyone point me to literature on the subject?
Also, is it correct that with fuel injection the mixture (except for warming up/choke) is always stoichiometric (in correct amounts for full combustion)? If so, then is it solely the amount of fuel/air mixture that is in the cylinder that determines the power output, and this amount is lineally dependent upon pressure in the inlet manifold, and this pressure is lineally related to the throttle position?
Thanks in advance.