Author Topic: A Simple Fuel/Air ratio Question  (Read 1005 times)

July 24, 2017, 11:46:28 pm


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A Simple Fuel/Air ratio Question
« on: July 24, 2017, 11:46:28 pm »
I am relatively new to diesels.  I understand how they work and why they work the way that they do.  I would like to ask some questions to better understand what changes to the fuel/air will do.

1. I understand that if you turn up the fuel and keep the amount of air the same you will increase power to a point but you will also create lots of smoke from unburned fuel and increase you EGT's.  Is this correct?

2. My main question is what happens if you put on a huge turbo but keep the fuel the same as stock?  I don't know what intake pressure the ALH normally runs at but if it was 20psi and you raised it to 30psi what would happen?

Thanks, Matt.

Reply #1July 30, 2017, 08:30:33 pm


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Re: A Simple Fuel/Air ratio Question
« Reply #1 on: July 30, 2017, 08:30:33 pm »
1. Increasing fuel without adding air will increase power but will also increase temperatures. Once the AFR starts getting below 18:1 you'll start seeing smoke most likely. 16:1 is about the limit without melting things.

2. Increasing boost without adding fuel won't show much if any change in power output. It may reduce engine output due to increased exhaust restriction. Assuming there's enough air present to fully combustion the fuel being injected adding more air doesn't create any more power since there's nothing more to burn.

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