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Peak ve

EFI Tuning Fundamentals

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Discussion and questions related to the course EFI Tuning Fundamentals

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How do i know or can see when the engine has reached peak ve?

It should follow your torque curve, most engines will have a peak region, and then start to taper off on the other side of this area.

As BlackRex has said, the VE curve will have the same shape as the torque curve since torque is airflow. You can tell what is happening by monitoring your air fuel ratio - If the air fuel ratio is leaner than your target, you need to increase your VE number in this area. Conversely if the AFR is richer than your target you would reduce the VE number. Once your measured air fuel ratio is tracking your target AFR throughout a full ramp run, your VE curve will be accurate.

Can you exceed 100 % ve with forced induction?

Yes, but it is not linear to the boost pressure. This is because boost pressure is a measurement of the restriction of air flow through the engine. On boosted engines, the best that I have seen is around 120% efficiency, this is on an engine that had been ported with big cams and valves.

So if you were tuning a race engine. And you did all the calculations for ve. If it exceed 100% ve the engine would be lean correct? Just trying to make sure I am properly understand ve

No, it just means that you are able to fill the cylinders with a greater volume of air than the cylinders volume. As long as you have all of your calibrations correct, and the fuel system can maintain the requested fuel flow, then the engine should not go lean with values over 100%.

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