Twin Charging a Honda CRX 3

[patprimmer]

I having a moment of madness and considering twin charging a 1988 Aussie model CRX.

Aussie model has the DOHC D16A8 engine and factory A/C and P/S both of which I must retain.

The plan would involve a second hand Toyota SC14 roots type blower.

I already have a turbo being a brand new Garrett GT2859R-707160-9. M24 cast on compressor.
Ball bearing, water cooled bearings.
Compressor is 44.5 inducer, 59.4 exducer, 56 trim, 0.42 A/R
Turbine is 53.8 wheel dia, 62 trim, 0.64 A/R
It has an internal waste gate but I also have a 41mm Chinese external wastegate.

The turbo is correct size for my ambitions turbo only, but probably a bit small for twin charged.





Regards
Pat
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[70btdc]

I just had a crazy idea after reading through your post again-- The orientation of VNT vanes was at which position for max boost in your installation - vanes lying parallel to turbine circuference or perpendicular to it?

 

[Warpspeed]

Maximum boost always corresponds with maximum turbine rpm.
And that corresponds to maximum tangential exhaust velocity coming out of the vanes.
A smaller a/r or vanes closed up will always produce more boost, unfortunately it also dramatically increases turbine back pressure.

Vanes wide open might give 5psi Boost, and 5psi back pressure.
Vanes closed might give 15psi boost and 80psi back pressure.

Closing the vanes just to get a higher boost reading, especially at low rpm, does not make the engine happier.

You simply cannot get something for nothing.
If the exhaust mass flow is minimal, trying to force it all through a pin hole just to rev up the exhaust turbine, only produces unacceptably high back pressure.