CFM Continued...

[Greg Hermann]

>Er, this looks like it's assuming 100% VE, True?.
>If so wouldn't 130-140% be a tad closer?
>is there any intercooling?
>Sneezy

It wuz--just using round numbers to try to give him the idea.

Bear
>
>> Then, the engine will be trying to breathe in 434 x 5400 x 0.5 x 1/1728 ,
>> or 678 cfm at the highest speed you will be turning it. The runners to
>each
>> cylinder will be wanting to flow 1/8 of this much, or about 85 cfm each.
>
>> The trick is to size everything in the flow path so that you do not have
>> excessive pressure drop at any one point in the path at the amount of flow
>> the engine wants to draw in. What the guy talking to you is missing is
>that
>> with a pressurized intake--the pressure drop in the runners is
>proportional
>> to the density of the air flowing through them!
>> Of course--you will also have proportionally more pressure you can afford
>> to lose with the turbo motor, So whatever will work well with the same
>size
>> and speed range  NA motor is pretty close for a turbo motor. Going maybe a
>> fuzz BIGGER than what you would use for a similar size/speed NA motor will
>> tend to lower backpressure from the turbo on the motor, and lower EGT's
>> some.
>> Going any smaller than what you would run on an NA 434 would hurt
>> performance some, and durability more.
>> Flow on the inlet side of the turbos will be the amount of air the engine
>> breathes times the manifold density ratio--a LOT more cfm. Everything on
>> the inlet side of the turbos should be sized accordingly, and also to have
>> VERY low pressure losses at this design flow The amount of back pressure
>> which the turbo(s) will put on the engine to make a given amount of boost
>> is EXTREMELY sensitive to losses in the inlet tract to the turbos!.
>> Regards, Greg
>
>>