Quote:
Originally Posted by Tygen1
In my opinion, the Turbine side of the 6.0 turbos is much to large to get a reasonable amount of spool, not to mention they weigh almost 40 lb's. There is also a GT3576VA that was on the VT365 International motors. The Turbine side on the GT3576VA is a bit smaller than the 6.0 version, but my feeling is that it is just too big. Remember it's not just airflow that drives a turbine, it's the expansion happening from the combustion. Expansion from the heat generated during combustion. When you're lean, you combustion temperatures will be lower and you will have more difficulty driving the turbine. When I was dreaming of turbos, I thought a VW TDI VNT turbo might be ideal. I don't imagine it would be hard to create a control for the VNT and they are quite small and have many aftermarket options. There is also the Dodge/Mercedes Sprinters that are a GT2056 VNT turbo if you want somthing a bit bigger...
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One of the things I have found while on the road to lean-burn is that you can produce the same amount of power running 107kPa intake pressure at 22:1 A/F as you would be running 79kPa intake pressure at 14.7 A/F. You will also have a 6.4% decrease in fuel consumption and a 28% decrease in combustion temperature. Plus a 4% increase at P3 compression while maintaining the same P4 pressure. It took me a while to understand this because the exhaust pressure is the same but the internal combustion temperature has drop significantly and so has the EGT's. Then after doing my turbo compound system I have realized that the turbo is a basically a
time delayed dam that stacks up not only pressure but also heat.
My mid-mount low pressure turbo gets very hot pre-turbine, to the point I now have to add some heat shield in that area 6' back from the high pressure turbo.
F1 with their new power units are really breaking some new ground when it comes to lean burn and making more energy from the MGUH or "turbo generator/motor unit". They have found that they can run much leaner then stoich, increase the boost to get back to their target 100kg/hr fuel limit and double the amount of exhaust energy to feed the battery without much of a ICE power decrease.
