02-02-2015, 11:06 PM
First thing to do is to really get to grips with what you're looking at and understanding compressor maps, figure the maths behind how much airflow you want/need... Once you've got that under your belt then the sizing of the turbochargers will fall into place...
Get out of the idea of "one to spool fast", "one for high rpms" - they have to be matched better than just lobbing two turbos together, you need to not only know their spool characteristics, but their characteristics at high pressure/low flow and low pressure/high flow - two seemingly identical turbochargers can have two totally different characteristics in terms of how they perform with regards to pressure/flow.
Compounding is win, but exactly as Tom said above, you can likely get similar performance to what your injection pump will provide, or exceed what a realistic VE pump without extreme (and detrimental to driveability) modification with a good, modern variable nozzle turbocharger... End of the day, you can now buy small diesel suitable 350hp capable Garrett VNT turbochargers off the shelf!
Get out of the idea of "one to spool fast", "one for high rpms" - they have to be matched better than just lobbing two turbos together, you need to not only know their spool characteristics, but their characteristics at high pressure/low flow and low pressure/high flow - two seemingly identical turbochargers can have two totally different characteristics in terms of how they perform with regards to pressure/flow.
Compounding is win, but exactly as Tom said above, you can likely get similar performance to what your injection pump will provide, or exceed what a realistic VE pump without extreme (and detrimental to driveability) modification with a good, modern variable nozzle turbocharger... End of the day, you can now buy small diesel suitable 350hp capable Garrett VNT turbochargers off the shelf!
