Calan
DSM Wiseman
- 7,251
- 363
- Jan 16, 2007
-
OKC,
Oklahoma
Are you guys retuning, or doing a straight comparison when changing the ACG's? I see major changes in fuel trims and AFR's due to increased/decreased EGR (I expected some change but not this much), and performance also changes due to increased/decreased ignition timing of course. I'm wondering if you guys are recalibrating airflow and retuning after every change so that you get a good baseline.
Also, I'm starting to wonder if everyone's settings are in reference to properly degreed cams, given the widely varying results. Is it possible that retarding or advancing cams for some people is really just bringing them closer to 0, rather than going away from it?
So far I've had decent results with the exhaust retarded 2-3* and intake at 0*, with no other changes. Power increased, and seemed to move just a bit higher in the RPM range.
Retarding the exhaust 2* and advancing the intake 2* seemed to improve power somewhat, and unexpectedly smoothed out my idle a little (which was pretty smooth already). AFR's were really lean initially due to the increased overlap and EGR, and required quite a bit of compensation to keep from pegging the fuel trims. I need some more experimentation with this setting.
Retarding both the exhaust and intake by 2* was surprisingly just craptastic. Power was down by around 70 HP, but a lot of this was probably due to a drop in ignition timing that I didn't compensate for. Even with more timing, I don't have a good feeling about this setting. Power may be increasing higher up in the RPM range, but I don't want to rev my stroker/stock head that high to find out.
I'm currently testing 2* advance on the exhaust, and 2* retarded on the intake...along with 4* of ignition timing advance across the board. To be honest I can't tell a whole lot of difference between this and the optimal degreed settings I was at originally. If anything, the butt dyno says it is down on power and just feels 'off". (I adjusted the ACGs to this last night and have driven around a bit, but haven't been able to get a log to study yet). I need to run it some more, do a little tuning, and see if there is any power hiding in it.
My conclusion so far is that slightly retarding just the exhaust, (and possibly adding some advance to the intake along with some retuning) will probably give the best results on my car... but to be honest I just haven't seen any "HOLY SHIT!" type of results that couldn't be achieved with some different tuning on the original degreed values.
My gut says I'll probably end up running about 3-4* retard on the exhaust and 0-1* advance on the intake...but I still have some more testing to do.
Also, I'm starting to wonder if everyone's settings are in reference to properly degreed cams, given the widely varying results. Is it possible that retarding or advancing cams for some people is really just bringing them closer to 0, rather than going away from it?
So far I've had decent results with the exhaust retarded 2-3* and intake at 0*, with no other changes. Power increased, and seemed to move just a bit higher in the RPM range.
Retarding the exhaust 2* and advancing the intake 2* seemed to improve power somewhat, and unexpectedly smoothed out my idle a little (which was pretty smooth already). AFR's were really lean initially due to the increased overlap and EGR, and required quite a bit of compensation to keep from pegging the fuel trims. I need some more experimentation with this setting.
Retarding both the exhaust and intake by 2* was surprisingly just craptastic. Power was down by around 70 HP, but a lot of this was probably due to a drop in ignition timing that I didn't compensate for. Even with more timing, I don't have a good feeling about this setting. Power may be increasing higher up in the RPM range, but I don't want to rev my stroker/stock head that high to find out.
I'm currently testing 2* advance on the exhaust, and 2* retarded on the intake...along with 4* of ignition timing advance across the board. To be honest I can't tell a whole lot of difference between this and the optimal degreed settings I was at originally. If anything, the butt dyno says it is down on power and just feels 'off". (I adjusted the ACGs to this last night and have driven around a bit, but haven't been able to get a log to study yet). I need to run it some more, do a little tuning, and see if there is any power hiding in it.
My conclusion so far is that slightly retarding just the exhaust, (and possibly adding some advance to the intake along with some retuning) will probably give the best results on my car... but to be honest I just haven't seen any "HOLY SHIT!" type of results that couldn't be achieved with some different tuning on the original degreed values.
My gut says I'll probably end up running about 3-4* retard on the exhaust and 0-1* advance on the intake...but I still have some more testing to do.
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