Sos2k4o8

Answers
1) The current design call for an oil feed to the step up gearing.
2) The only moving parts is the rotors and the associated step up gearing and bearing interfaces. Very simple and effective. Some of RP

 

The best setup would be a combination of both superchargers on one engine. The Axial flow feeding into the roots.

 

[QUOTE=deppenma,Feb 16 2006, 11:05 AM]
With the comment the BRP kit will blow away this unit that has jet to be seen. I have seen some dyno runs (compressors limited to 7psi) done back in the 80

 

The mass flow rate of an axial running at the same pressure as a roots most of the time puts out more CFM depends on the application and thus the stator and rotor blade design..

My money will go to the system that can get a larger mass flow rate(more power) with a lower pressure.

The early cast designs were just too expensive to mass produce on a large scale. Thus you don

 

deppenma -

thanks for the comments. I was unaware that the system could be had for so little $$$.

Regarding the comparison to the BRP kit: The "area under the curve" will most definitely be won by the BRP unit. Even with both kits producing the same maximum boost numbers and the BRP kit sapping 20 hp more than the axial design. The constant boost across the entire rev range (more or less) of the roots type blower will provide more "area" than the linear axial profile.

This kit is shaping up to be a good one though

Sideways -
I'm not sure the roots would react well to this scenario. I think the best FI setup would be a lysholm type positive displacement unit operating at low to mid RPM switching over to a massive turbocharger at higher RPM. Good luck designing the intake system for that Valves everywhere...

 

It can actually be made much cleaner than you'd think. BRP worked with one of their Miata customers to help build this setup: http://miata.cardomain.com/ride/329157/5

As you can see, it's really just a matter of controlling the bypass device to phase out the positive displacement pump once the turbocharger builds a decent amount of boost.

 

the lysholm / axial flow supercharger is not a positive displacement pump

and the design i am trying to get RP to design for the S2k would have pressures as follows (numbers pre intercooler)

4psi at 1K engine RPM
5psi at 2kengine RPM
6psi at 3K engine RPM
7psi at 4k
8psi at 5k
9psi at 6
10psi at 7
11psi at 8


However once you reach you desired manifold pressure the upstream pressure would be regulated by a dump valve located before the after cooler. (Why dump cooled air dump it before the after cooler; to increase the effectiveness of the cooler)

Which would give you higher boost numbers than the BRP roots when below aprox 3500RPM and would start to exceed the BRP boost numbers above that RPM.

Thus giving you the low end torque greater than the BRP and at the same time giving you the high RPM power that is associated with a turbo.

You would get the best of both worlds.

 

You must've intended to say "Latham/axial flow...," as the Lysholm is most certainly a positive-displacement pump (twin-screw).

 

yep my bad just want to make sure that no one thought the Axial was a +displacement pump

I miss read your post

 

We all get a little confused sometimes

If the axial compressor was geared to give 8 psi at max RPM, and the Roots blower was geared to give 8 psi across the rev range, obviously, the Roots would be the "stronger" engine. Even though the axial system would be stronger up top due to less losses in the design.

I'm liking the idea of running the axial compressor with a higher ratio to get the slope of the boost curve (line I should say) to be a little more aggressive. A bypass system could regulate the maximum boost.

While it may seem that the compressor is just wasting the additional boost past the cutoff point, and therefore taking up additional horsepower, I don't think this will be the case due to the high efficiency. Also, the delta P across the compressor is not increasing...just the mass flowrate. The power required to drive the system would, of course, go up but not at the same rate it was going up in the rev range before the max boost was reached.