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Old 10-25-2019, 02:06 AM   #16 (permalink)
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Originally Posted by Hersbird View Post
I have heard that just plain direct injection is going to probably need DEF and a catalyst in the near future.
You only need DEF for NOx reduction if the engine runs lean. It's hard to imagine most car companies being okay with adding that cost.

What is true is that plain direct injection will probably require a particulate filter in the future, because stratified injection is so useful. Notably, Toyota used to use the side "fan spray" injector that only ran on the intake stroke, but has now switched to piezoelectric injectors that can spray multiple times (can spray at the end of the compression stroke to create a stratified charge).
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