[dfiore]

Can anyone tell me what the CFM rating at full throttle is on the insight?

 

[HafNHaf]

assuming 100% volumetric efficiency, i get a whopping 105.4 CFM!

i used:

CFM = (DISP / 1728) x (RPM / 2)

DISP IS IN CUBIC INCHES

CUBIC INCHES = LITERS X 61.024

the engine displaces .995 liters, which yields 60.71 cubic inches

YMMV. also your answer.

 

[Willie Williford]

cfm

At 5,800 rpm of course......... :lol:

Willie

 

[Insightful Trekker]

Not, sure what you want CFM's for Dan.

Given temperature, humidity, and altitude differences a cubic foot of air can vary in mass by a HUGE percentage. Its _mass_ that will determine the O2 content which will then require the correctly proportioned fuel. And result in a corresponding amount of power.

Simply pushing more CFM's at an engine if heat is added in theory could result in _less_ power at the wheels. Changing the intake flow to allow _more_ CFM's without "pushing" will also effect the torque and HP curves of an engine. Commonly reducing the low and increasing the high RPM HP & torque. Not always desirable for street use.

CFM's for internal combustion engine calculations of most anything are almost useless.

HTH!

 

[dfiore]

CFMs

Simply pushing more CFM's at an engine if heat is added in theory could result in _less_ power at the wheels.

Isn't that the whole basis on how a turbo or supercharger works? Shove more air in and the engine compensates by shoving more gas in resulting in more power ::ugh ugh ugh:: - Tim Taylor

 

[Insightful Trekker]

Yup :!: But don't forget the Rut Roh :!: - Scooby Doo.

My example was one to try and expend your thinking. Both turbos & superchargers add heat to the intake air. Thats where inner coolers come into play, a cooling radiator for intake air. A basic law of physics is increased pressure = increased temperature (in a closed system). Given the method and volume of turbos & superchargers the temperature factor is overcome and an increased mass of intake charge is delivered to the engine resulting in more available power at the wheels. Another example along the supercharger lines is that nobody uses vane type superchargers anymore. Its both a reliability _and_ performance issue. The Roots (screw) type is more reliable and heats the air less.

I think I may know where your going with this - an electric blower fan "super" charger. There are a few kits out there. IIRC its been tried without good success on the Insight. The biggest differences with the three is where their sources of energy come from.

A turbo's primarily comes from the energy remaining in the exhaust fumes. Its still very hot and wants to expand further. More CFM's come out the tailpipe that go in the intake :? until you take in to account the temperature expansion. That's where SCFM units come into play. Standard Cubic Foot per Minute, compensated for temperature and pressure. Of course there's the direct pumping energy of the exhaust flow too. But the other percentage is "free".

A supercharger's comes off the crankshaft. Its second in efficiency to the turbo and has the potential for much more overall power at the wheels. It uses quite a bit and there are frictional losses without boost. But it does make more by forced feeding than it uses.

The electric intake blower is the lowest efficiency. A large amount of energy is required to "pre" compress the intake charge. Its energy, like all the others is ultimately derived from gasoline (the alternator or the IMA system in an Insight). There is a much _greater_ loss of efficiency in the conversions, chemical (gasoline) - mechanical (turn the crankshaft for the alternator etc.) - electrical (voltage for an electric intake fan) - mechanical (final conversion to compressed intake air). And _because_ of the amount of electricity needed and size limits for a blower motor its usually the lowest powered of the three. Its performance at the wheels starts out on the lowest rung of this ladder. Usually anemic in comparison to the others.

Or was there something else on your mind :?:

HTH!