Guest:

Educated guess.  

I think the 992 GT3 engines will have ITBs regardless of potential displacement changes.

I anticipate that the 992.1 GT3 will receive what amounts to a Speedster / 991.2 GT3 RS engine - 4.0L w/ ITBs.  This engine already exists and has been used in two applications already.  The GT3 is pretty well baked I’d imagine; it should debut in 8 months at Geneva.

The 4.2 liter engine (presumably w/ ITBs; will certainly have particulate filter) will be an excellent way of differentiating the GT3 RS from the regular GT3.  The RS will probably trail the GT3 launch by a year.  That will give them more time to test a street application of a 4.2L engine (and lots and lots of race miles too).

Then for the facelift the GT3 will get the outgoing RS engine and the RS will need something additional (hybrid?) to justify its position; if that progression is accurate, I think many people will buy each car successively, as they did in the 991 generation.

I think we shouldn't forget about the euro emission standards.

Porsche is expecting the Euro 7 by 1.1.2023 (the EU wants it by 1.1.2021!) and I doubt that they will meet the standards with a pure N/A engine. 

I assume that the 992.1 GT3 will be presented in March 2020 and the RS a year later, in 2021. 

The GT3 cycle is usually only 2 years, so either the 992.2 GT3 will be produced for only 1 year or it will be hybrid in order to comply with the Euro 7 rules.


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2018 White 911 GT3