I am in the process of coming up with a cold air intake solution that doesn't use a K&N filter. I have found some possibilities but I need to know how many CFM a 617 turbo engine requires. I'm a little "math challenged" so I was hoping some of the engineers here would be able to figure this one out. Thanks, RT

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Natural aspiration,

4500 rev / min x 3.0 liter / 2 = 1.5 liter / rev = 6,750 liter / min

6,750 liter / 28.3 cu. ft. = 239 cfm

Assume 2x volume for 1.0 bar (atmosphere) boost = 478 cfm

500cfm is in the ballpark.

Best Regards,
Jim

Jim

I was just in the process of coming up with similar numbers, but I divided by 4 not 2, since only "about" 1/4 of the engines volume is on the intake cycle each revolution. It would be easier with a 4 cylinder 4 stroke engine, where only 1 cylinder is on intake each stroke, but I figure it's close enough with a 5 cylinder.

As a result my numbers were all about half of what yours are.

Kevin

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Kevin, as I understand, engine 'displacement' is taken as the total volume of all of its cylinders.

One complete revolution is used for intake and compression, and one complete revolution is for power stroke/exhaust. So, I divide by 2 to calculate volume of air introduced by the intake cycle of the cylinders.

Best Regards,
Jim

If we were discussing Normally aspirated engines then velocity and CFM would be more critical to be matched to the engine so intake pulses would reinforce each other helping in getting the most air into the cylider........

With a turbo the key is to have the filter with the largest surface area possible to offer the least restriction within the given space you have.

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Jim

Ah yes I see. I had confused strokes with revolutions. There are indeed two strokes per revolution, one down and one up.

Thanks

Kevin

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