Engine Charge Cooling Gain and Fuel Properties

[glausb23]

Hello,
I am in the process of double checking all initial engine setup parameters and have noticed some discrepancies between what are shown for available setup options on my GPRP package and what's used in the GP package that's used in the MoTeC webinar pertinent to this topic.

In the video, the host has the fuel parameters available to change, as seen in the attached picture titled "MoTeC snippet of Webinar Fuel options."

MoTeC snippet of Webinar Fuel options.JPG (45.25 KiB) Viewed 3375 times

Our interface looks a little different, as seen in the attached picture titled "Our MoTeC fuel options"

Our MoTeC fuel options.JPG (128.55 KiB) Viewed 3375 times

I am wondering if pre-selecting a fuel from the drop-down options in "fuel properties calibration" that we have essentially fills in background parameters for fuel density, molar mass, stoich ratio, and most importantly charge cooling gain?

This engine will run on 93 octane pump gas. The closest option in the fuels drop-down is "Gasoline 98 Octane 1.0" which in the context help says will also work for 91 and 95 octane gasoline. I am assuming it will also suffice for 93?

When this fuel is selected from the drop down, does it automatically enter assumed values for fuel density, molar mass, and charge cooling gain, or must these values still be setup manually?

Any clarification on this would be greatly appreciated.

Thank you,

Benjamin

[NathanB]

Hi Benjamin,

When you select a defined fuel property, it populates the Molar mass, density stoich ratio and thermal expansion properties, with the values as defined in the help.

Gasoline 98 octane is referring to the RON value, which is a MON of 90 and the US value of 94 (R+M)/2

If you select a defined fuel type, and then select manual, with will find all these properties are pre filled with the last defined fuel type.


It does not however do anything with the cooling charge gain values. The reason for this is that although the fuel properties play a large part in the cooling charge gain, the injector location, and many other factors influence the cooling charge gain.
A direct injected application will have a different amount of cooling charge gain to a port injected application for example. even in a port injected application, an injector that is close to the inlet valve will behave differently to on that is mounted pre throttle body. For this reason, the cooling charge gain needs to be done manually.

[glausb23]

Thank you for the clarification on that. It does make sense after looking through the context help for those parameters more.

Benjamin