Rajay turbos

[Carl Summers]

Hi Clay,
    I realized my .cal wouldn't work with your ecu too late...I would be
glad to forward if it will help but requires a different processor in the
Autronic box....have you datalogged the pressure in comparison of boost vs
back pressure vs turbo???? I truly don't know alot about turbos but after
Turbonetics bored the inlet and changed the impeller in a project I was
involved in, I had no idea that it could mean so much...same boost different
backpressure was worth over 200hp on a 1200hp engine...on the dyno.....maybe
not real world but was impressive...I understand after correcting AFR the
EGT's were lower because of less restriction....what I don't and haven't
understood is why with a low vs high compression engine and no blower/turbo,
EGT's are high when the effective overlap is lowered....is it that it
becomes more efficient and heat is energy????
-Carl Summers



-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
Behalf Of clayb
Sent: Wednesday, October 04, 2000 9:38 PM
To: diy_efi at diy-efi.org
Subject: OT: Rajay turbos


OK, I put the disclaimer in the title. And I know alot of folks install
EFI to keep the turbos happy, and some sharp people read this list.

If any of you are familiar with turbos, help me out, please.

It may be time to overhaul the old Rajays. On of them has a slightly
loose shaft, and I don't want to be sidelined with a turbocharger
rebuild in the middle of the season, next year.

I've heard tales that the compressor side of the old Rajays is pretty
inefficient. Anyone know if the exhaust side is any good? Can I put a
nice compressor wheel on during a rebuild, and get some extra kick out
of these things? The current compressor wheels have shorter vanes
(axially) in between the larger vanes on the compressor. I'm not sure
how unusual that is.

I haven't run them very long, before burning the flange gaskets, but
they're capable of at least 17 psi on my 454 chevy, and definitely need
wastes operational to control the boost. They can generate 8 psi boost
as low as 2500 RPM. The model is 301 E 10. I think the "10" is for a 1.0
exhaust housing, and the "E" is the compressor trim?

What are the implications of a more efficient compressor? I already can
get alot of boost, and the turbos seem capable of flowing 454-sized
volume. I haven't done alot of driving at 6000 RPM yet, tho. How do I
know if I could benefit more from a higher pressure ratio for more
boost, or higher ultimate flow, or is it possible to achieve both?

Will I see less exhaust back pressure, for a given intake manifold
pressure, or, a higher ultimate manifold pressure with the same exhaust
back pressure?

Any recommendations on parts suppliers or shops for old Rajays?
- Clay
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