Quote:
Originally Posted by detltu
So what is the big holdup with DI and why is it not a given in pretty much every new engine GM comes out with.
Is it a cost issue? Controls? What is different about putting DI in a 4 cyl versus an 8. Why has it taken so long anyways.
Anybody got any ideas?
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To convert an existing motor from port injection to direct injection you need to:
- Redesign the head(s) to add another hole for the injector and raise compression.
- Redesign the pistons to deal with having fuel sprayed on them.
- Replace the injectors with more expensive ones that can handle the pressure and temperature.
- Add a (really) high pressure fuel pump, these have been failing on the LNF & BMWs 335
- Replace the O2 sensors with more expensive wideband units.
- Rewrite the software to run the injection and probably upgrade the ECM.
- Since you are redesigning the pistons you may as well revise them and the oiling system to add squirters to cool the pistons and allow you to raise the compression some more.
So I’d say that GM is converting as fast as it can, but that is a lot of work. It would be a lot easier to adjust the bore and/or stroke to create new engine that without much more than a new crank, rods, pistons and maybe a little tweak to the software.
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