Chunger

Ok... I'll start with an 'easy' one....

 

morepower2

Its a no-brainer, if you are not, you should be!

Mike

Chunger

That's not always true...

Boost loss could equal or be greater than gains of cooling in certain cases.

Anyone with a S/C using one? How much boost/type of cooling?

morepower2

Only if you are running a poorly designed system with a big delta p across the heat exchanger. With the poor efficiency of a supercharger, it is really needed.

It is easy to calculate the difference in air density accross the heat exchager tro know for sure if you can measure temp and pressure in and out of it.

Mike

ClassicSE-R

What is very interesting about positive displacement superchargers (like a Roots style blower), is that the relationship between supercharger inlet air density and intake manifold density is solely a function of the displacement, speed, and volumetric efficiency of the engine and the supercharger. It is entirely independant of the pressure and temperature drop of the plumbing system.

If you add an intercooler to Roots-style supercharger, you will reduce the intake manifold temperature. This would normally produce an increase in intake manifold density. Since the engine is also a positive displacement pump, this has the result of increasing the mass flow rate through both the supercharger and the engine. However, the supercharger is a constant displacment device. Therefore, it cannot flow more air. Therefore, boost pressure will drop in response to reduced intake manifold temperature. This is not due to pressure loss in the intercooler (although that is what it is commonly attributed to). It is a attibute of a constant-displacement machine.

By the same token, placing a restictor in the intake piping will cause the supercharger to create more boost in order to make intake manifold density remain the same. So, putting in a nasty restriction will make supercharger outlet pressure go up, but it won't change intake manifold pressure much.

This means that adding an intercooler to a Roots blower won't give you increased intake charge density (like you will get with a turbocharger, for example). However, adding an intercooler will cause the supercharger to make less boost. This means that you will get the same intake manifold density for less compressor work. This will reduce parasitic power loss from the supercharger, and will give you some increased power.

Cooler intake temperatures will also let you lean out your mixture and advance your timing, which will make more power. You can also run more boost within the detonation threshold.

So, intercoolers help on a Roots blower, but not as much as they do on a centrifugal compressor.

Rob

 

Chunger

Coolness... Looks like I have an aftercooler project for this summer on my Vortech. Thanks folks.

morepower2

The cool thing is that it is much easier on a vortech than on a roots type blower due to how it is all packaged.

Perhaps you can drive the blower a little faster with the lower intake temps

Mike

Chunger

Already got the 3.25" pulley and FMU recalibration disc sitting in my room...

So many projects so little time... lol

morepower2

Any dyno numbers yet?

Mike

Chunger

It was too busy at Stillen's Open House Day...

Besides... I want to put in my homemade CAI (sitting around too) before so I have a good baseline... One of our other members dyno'd at 249hp FWHP... with virtually the same setup (except he has the V1)

 

morepower2

If you want some cheap dyno time, come to the SERCA dyno day at R&D Dyno on the 18th after you put on the CAI. I think it's 35 bucks or something. Rob and I will be there.

Mike

Skinny G

If I am understanding this correctly, this would mean that given a set air charge density and pressure, once cooled, the density increases and the boost decreases correspondingly.

Could I then merely increase boost (pulley ratio) on the motor to make this up?