[ARCHIVED THREAD] - Engineering Question: Brake Mean Effective Pressure

Posted: 9/24/2007 10:18:47 AM EDT

Why is BMEP higher for a gasoline engine than a Diesel engine assuming the two engines are of the same size (displacement)?

Is it because a gasoline engine adds fuel at a constant volume, increasing pressure process? Thus cylinder pressures are higher when the fuel is ignited?

Posted: 9/24/2007 2:02:12 PM EDT

[#1]

Anyone?

Posted: 9/24/2007 2:03:43 PM EDT

[#2]

tell me what " Brake Mean Effective Pressure " and il have an answer for you..

edit:
and your offline..

Posted: 9/24/2007 2:31:16 PM EDT

[#3]

gasoline has a slightly higher specific energy than diesel. that could be the answer assuming all other variables are equal.

Posted: 9/24/2007 2:40:26 PM EDT

[#4]

It is the theoretical average pressure in the cylinders to produce a corresponding output torque measured with a brake device.

Posted: 9/24/2007 4:50:15 PM EDT

[#5]

Quoted:
gasoline has a slightly higher specific energy than diesel. that could be the answer assuming all other variables are equal.

I think it might be as the "explosion" in the cylinder would be more violent.

However, this would mean the gas engine would have more torque and I always thought diesel had more torque.

Posted: 9/24/2007 4:52:59 PM EDT

[#6]

Could it be that diesel ignites under significant pressue in the absence of a spark plug, so it is compressed more to ignite; whereas a regular gasoline engine users a spark plug so does not need the high amounts of compression pressure?

Posted: 9/24/2007 4:57:50 PM EDT

[#7]

wouldn't you get better answers for the engine theory questions you've been asking on a SEMA forum?

Posted: 9/25/2007 5:31:29 AM EDT

[#8]

Quoted:

Quoted:
Why is BMEP higher for a gasoline engine than a Diesel engine assuming the two engines are of the same size (displacement)?

BMEP is higher for a gasoline engine is because most of the combustion has already taken place by the time the piston starts to move after TDC. Diesel engines start the fuel add at TDC and burn takes place as the piston decends. Thus the gas engine adds heat at constant volume and the diesel engine adds heat at constant pressure.

That sounds correct.

[ARCHIVED THREAD] - Engineering Question: Brake Mean Effective Pressure

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[ARCHIVED THREAD] - Engineering Question: Brake Mean Effective Pressure

[ARCHIVED THREAD] - Engineering Question: Brake Mean Effective Pressure