The LSA and LS9 both went with a 4 lobe supercharger. Any ideas on why?

I go into it little here:

http://www.cadillacforums.com/forums/cadillac-cts-v-series-forum-2004/128379-supercharger-options-2.html

Norm

Decreased noise, decreased temperature. Basically, increased efficiency.

Decreased temperature? That is a huge advantage. Especially with non forged pistons.

There are quite a few advantages of this new Eaton blower. The 3 lobe design was decent, but when HP demands reach higher than the blower is capable it makes it difficult for the previous gen blower to keep up. The new 6th gen blower (4 lobe) uses 160 degree high twist vs. the previous generation using a 3 lobe 60 degree setup. The old blower also used two pre-charge slits to help lower NVH. The new blower doesnt need it. Also the new blower has a much better adiabatic efficiency when pushed vs. the 5th gen 3 lobe that starts to fall off like a rock when pushed past its limits.

There is a slight difference in the LSA & LS9 blowers. The LSA uses a 1900 and the LS9 uses a 2300. That 2300 is capable of supporting up to 950HP where as the LSA blower supports up to 750.

There are obviously other advantages to list, but this should help for now.

Thanks,

Dr. Design
D3 Cadillac

can you retrofit the 4 lobe to the 3 lobe charger? Meaning, just plop a new 4 lober onto the manifold of an STSv?


F

:D We could only wish it would be that easy! There is a M122H that is used in the Ford GT motor. This is essentially the same as the M122 used in the STSV/XLRV engine. With slight modifications you could use the M122H rotor pack, but the gains might not be enough to justify doing the conversion.

We (D3) are developing a new SC replacement that uses the 1900 blower.... This would work for your STS-V/XLR-V applications.
Thanks,

Dr. Design
D3 Cadillac

can you retrofit the 4 lobe to the 3 lobe charger? Meaning, just plop a new 4 lober onto the manifold of an STSv?


F

This is what I picked up on one site:

The single biggest difference leading to lower output for the Cadillac is the supercharger displacement. While the LS9 has a 2.3L blower, the unit in the CTS-V only displaces 1.9L. Aside from the size, the blower is based on the same four lobe rotor design with 160 degrees of twist to the lobes. The design provides greater efficiency and thirty-five percent less power draw than the previous three lobe design in addition to much quieter operation. The maximum boost pressure is reduced from 10.5 psi to 9.0 psi.

Makes sense.