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abminternet June 30, 2011 06:04

Manifold Absolute Pressure in Engine Simulations
Hi guys,

So I am trying to simulate a 4-stroke engine (cold flow) with moving valves and piston. From the specifications of the engine I get that the MAP (Manifold Absolute Pressure) is 46 kPa. So I am no expert, and don't really know what this would mean, but I read it is the difference in pressure between the pressure in the manifold (intake I guess) and the atmospheric pressure. So I guess my questions are:

Should I specify a 46kPa static pressure at the inlet, or 46kPa + atmospheric pressure?

or Does is the MAP induced by the piston sucking and pushing the air, so I would just need to specify atmospheric pressure?

or Any other suggestions?

I would greatly appreciate any help :D

Best regards,

Peter_600 July 1, 2011 14:21


I suppose u are modelling a natural aspirated gasoline engine. This should be the pressure after the throttle (part load), which induces a pressure drop.


abminternet July 4, 2011 05:56

hey Peter, good to see you again, thanks for your reply, so if I am simulating a cold flow, should I specify atmospheric pressure at the port inlet or should I specify the Manifold absolute pressure? im a bit confused by this :S

Peter_600 July 4, 2011 08:33

Hi :)
I would impose MAP as b.c. at the inlet.
If you want to simulate a fully opened throttle you could rather use atmospheric pressure (assuming we have no significant pressure drop upstream of the throttle)

Could you make some progress with the accordion class?
Did wou make already combustion simulations with engineFoam?


abminternet July 4, 2011 11:45

Great thanks :D

No I haven't made many advances in the accordion class yet, I haven't had the time to work on int further, but I'm still very interested :D I haven't made combustion simulations, I am concentrating on cold flow at the moment, but if i can help let me know, wont hurt to learn a bit too :P

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