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Why do domestics knock so bad?
Posted: Mon Sep 30, 2013 6:00 pm
by Mike_Levy
Trying to figure it out. It only seems to be the domestics that knock. I was running 22psi of turbo boost on a 10:1 compression with the BMW and it never knocked or had KR. And now I'm running 11psi supercharger boost on 10.5:1, and not a peep. Obviously direct injection makes a difference, but it can't be the only thing. What are the domestic marques doing wrong? The Hemis, Mopar 3.5's, Vortecs, and some Coyotes knock with no boost at all. The LS based boosted motors knock, especially when boost is increased, and I'm sure the Coyote and Hemis are right on the edge of death when boosted. Something ain't right. Germany knows something that the US don't.
Re: Why do domestics knock so bad?
Posted: Tue Oct 01, 2013 10:43 am
by mikel
DCX knock calibrations are way too sensitive.
GM knock calibrations are actually pretty perfect. Adding boost will always increase the possibility of knock, but the GMs handle it very well.
Ford, well, they use a different knock strategy, they are often adding timing to quench knock, if that even makes sense, so there is much more to it on a Ford.
Re: Why do domestics knock so bad?
Posted: Tue Oct 01, 2013 11:20 am
by Mike_Levy
Adding timing to quench knock??? No, that doesn't make sense. I don't even think I want to know why they would think thats a good idea. But, then again, Ford does a lot of stupid stuff, so I expect it from them.