DI makes a huge difference in FI engine survival as well as emissions. I won't be doing another FI car without it. At the risk of oversimplification, DI postpones fuel injection until it's almost time to fire the cylinder, and since the fuel is evaporating for a while after being injected it keeps the mixture cooled until firing time. There's far less risk of knock due to early detonation even at stoich AF. ----- Original Message ----- From: Larry Alster To: [email protected] Sent: Sunday, May 03, 2009 10:02 AM Subject: AF on FI non-Miata
Just interested in the opinions of the people here. Over on my HHR forum the guys with the factory turbo cars are getting them dyno'd. Most have never seen a turbo in their life and don't understand much but the results are coming back with them running A/F ratios of 13.1 or leaner under boost. Some are as lean as 13.8. This is with a stock engine car or the factory Stage I kit. They can be making as much as 28 psi boost and 300 FWHP with this setup. No one seems concerned about how lean the AF is and the answer from a few of them is that is fine because the engine is Direct Injected. DI or not it still seems lean to me. Anyone have any knowledge about this kind of AF ration being okay on a DI engine?? Larry White Knight 1991 Crystal White #99 CSP Silver Bullet 1992 Silverstone #17 SM2 FM I+ Turbo Honey B 1992 Sunburst Yellow #99 SM2L JR Supercharger Whooosh 2004 Titanium Mazdaspeed MX-5 LowCountry Miata http://www.lowcountrymiataclub.net Masters Miata RAGS 074 ------------------------------------------------------------------------------ _______________________________________________ Miatapower mailing list [email protected] http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower
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