Here is a much better scan of this important chart.
This is from Mazda authored SAE paper number 841017.
"Recent Tech. Develop. of High Powered Rotary Engine
at Mazda."

Paul Lamar

bcgardner wrote:

Paul, let me ask a dumb question. I understand the reasons for controlling
intake manifold length and exhaust pipe length for naturally aspirated
Mazdas. However, if one has a turbo, aren't these both moot? After all, the
intake side no longer depends on sucking in the mixture but relies on the
positive turbo pressure instead. And on the exhaust side, the turbo gets in
the way of improved scavenging of the exhaust, making the exhaust pipe
length immaterial.

You plan to run a turbo on your KIS Cruiser. Is this what you're thinking or
am I missing something?

Barry Gardner
Wheaton, IL

Good question Barry. I suspect you are right when the turbo is generating
some boost. In the car however the turbo generates little or no boost most
of the time and the tuned intake probably pays off in lower fuel consumption
and better initial torque before the turbo spins up. I am guessing about this
as I have no data to support it. I also suspect that with a given boost level
the overall volumetric efficiency is greater with the tuned intake system
hence more torque and HP and perhaps better BSFC. Mazda felt it was important 
to have a tuned intake system with their turbo cars so I guess it works.

A little more evidence in favor of a tuned turbo intake system is Abel Ibara is
getting well over 700 HP with the Extrude Honed stock tuned intake system with
a much larger throttle body.

I am going to use the tuned intake system with a turbo just because I can 
and I have plenty of room for it.

Paul Lamar
 
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