charged 3800 pulley
09-21-2009, 10:59 PM
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charged 3800 pulley my cousin is wanting to put a pulley on his 01 gtp. i dont know alot about forced induction, he wants me to tune it with hp tuners. ive done some basic tuning thats it.
i know im supposed to look for knock retard when i scan it. youre supposed to change the high octane timing table to get rid of the knock retard, correct? if so how do i use the scan data to know how much to change the timing?
i know im supposed to look for knock retard when i scan it. youre supposed to change the high octane timing table to get rid of the knock retard, correct? if so how do i use the scan data to know how much to change the timing?
09-22-2009, 12:56 AM
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is this pretty much all i need to do?
4. ELIMINATING KNOCK RETARD -
A. In the VCM Scanner>Histogram display>Retard, look for ANY knock retard. For example, cell (4.0, .20) shows 4 degrees of knock retard. This should be 0, so SUBTRACT 4 from the VCM Editor>Edit>Engine>Spark Advance>Main Spark vs. Airflow vs. RPM Open Throttle/Moving>High Octane (4000, .20) cell. Values cannot be less than zero in this table.
B. In the VCM Editor>Edit>Engine>Spark Advance>Main Spark vs. Airflow vs. RPM Open Throttle/Moving>High Octane, go to the (4000, .20) cell AND/OR whatever other cells that have knock retard and SUBTRACT the amount of knock retard that is present in the Histogram display from the value that is in the corresponding cell in the VCM Editor>Edit>Engine>Spark Advance>Main Spark vs. Airflow vs. RPM Open Throttle/Moving>High Octane table. Subtract by simply clicking on the Plus selection and in the box type -4 or whatever number you have to subtract by and click commit.
C. Scan again and verify NO knock retard is present. If still present, repeat from step A.
A. In the VCM Scanner>Histogram display>Retard, look for ANY knock retard. For example, cell (4.0, .20) shows 4 degrees of knock retard. This should be 0, so SUBTRACT 4 from the VCM Editor>Edit>Engine>Spark Advance>Main Spark vs. Airflow vs. RPM Open Throttle/Moving>High Octane (4000, .20) cell. Values cannot be less than zero in this table.
B. In the VCM Editor>Edit>Engine>Spark Advance>Main Spark vs. Airflow vs. RPM Open Throttle/Moving>High Octane, go to the (4000, .20) cell AND/OR whatever other cells that have knock retard and SUBTRACT the amount of knock retard that is present in the Histogram display from the value that is in the corresponding cell in the VCM Editor>Edit>Engine>Spark Advance>Main Spark vs. Airflow vs. RPM Open Throttle/Moving>High Octane table. Subtract by simply clicking on the Plus selection and in the box type -4 or whatever number you have to subtract by and click commit.
C. Scan again and verify NO knock retard is present. If still present, repeat from step A.
09-22-2009, 08:26 AM
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The GTPs have problems with knock retard stock. Upping the boost makes it an even bigger problem. If he doesn't already have it, he should look into some ported manifolds and a downpipe before going with a smaller pulley. Those couple of mods make a huge difference when dealing with the inherent knock that those cars have.
09-22-2009, 09:40 AM
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The GTPs have problems with knock retard stock. Upping the boost makes it an even bigger problem. If he doesn't already have it, he should look into some ported manifolds and a downpipe before going with a smaller pulley. Those couple of mods make a huge difference when dealing with the inherent knock that those cars have.
09-23-2009, 10:24 AM
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The mild bolt-on setups are usually more picky, since there's no aftermarket valvetrain work helping flow the extra air. Setups like that on 3800's require a low-low 11's commanded A/F, usually to compensate. The spark should typically be a solid 16* in the range it'll see under boost for most basic street setups.
I honestly have less trouble eliminating KR the 11sec h/c turbo 3800 Regal I built for a guy this year, than most of the cars brought by just wanting a pulley and headers. (honestly can't wait to be able to avoid 3800's all-together, and strictly deal with local LSx builds next year... Studderin got the right idea 2-3yrs before I did)
- Dave
I honestly have less trouble eliminating KR the 11sec h/c turbo 3800 Regal I built for a guy this year, than most of the cars brought by just wanting a pulley and headers. (honestly can't wait to be able to avoid 3800's all-together, and strictly deal with local LSx builds next year... Studderin got the right idea 2-3yrs before I did)
- Dave
