## IP and MEP - whats the difference

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The Dieselduck
Posts: 3059
Joined: Sun Jul 22, 2007 1:41 pm

### IP and MEP - whats the difference

I got an email on IP and MEP, can anyone help, got my hands full in shipyard...

Martin

I got general doubt regarding MIP(Mean Indicated Pressure) and MEP(Mean Effective Pressure).
Is there any specific difference between these two terms?

From the indicator diagram of 2-stroke engine, we calculate the area; and divide it by length of indicator diagram and multiply by spring constant. This gives Pressure which is MIP or MEP?

Over the net, I could not find the difference. Either they mention it as Indicated Mean Effective pressure or simply mean effective pressure.

Thank you, sir. It would be great help for me.
Martin Leduc
Certified Marine Engineer and Webmaster
Martin's Marine Engineering Page
http://www.dieselduck.net

Big Pete
Engineering Mentor
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Currently located: Solihull, England

### Re: IP and MEP - whats the difference

MIP, Mean Indicated Pressure, is the mean of the pressures recorded on the indicator diagram, calculated using a planimeter or electronically. Inputting this Pressure value into the PLAN formuala will enable you to calculat the Indicated Power.

MEP, Mean Effective Pressure is calculated backwards from the measured Brake power using the PLAN formuala. Where P is the pressure, L is length of stroke, A is area and N is Number of power strokes.

The Indicated Power and Pressure will always be greater than the MEP and Brake Power because of friction in the engine.

Hope this helps.

BP
It is always better to ask a stupid question than to do a stupid thing.

The Dieselduck
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Joined: Sun Jul 22, 2007 1:41 pm

### Re: IP and MEP - whats the difference

I will pass it on, thanks.
Martin Leduc
Certified Marine Engineer and Webmaster
Martin's Marine Engineering Page
http://www.dieselduck.net

JollyJack
Fleet Engineer
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### Re: IP and MEP - whats the difference

As BP says, indicated power is the theoretical power, gained by working out the PLANn formula, effective power is, as it says, actual power at the sharp end. The difference is losses within the engine.
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jimmys
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Currently located: Glasgow Scotland

### Re: IP and MEP - whats the difference

The Indicated Mean Effective Pressure(IMEP) is derived by measuring the area of an indicator card and dividing it by its length. This is also known as the Mean Indicated Pressure (MIP). It is P in the PLAN formula.
MEP, I dont know what it means maybe Member of European Parliament. This is an old trick question. If its indicator cards always append by "indicated". Everybody gets mixed up with it.