andrewtac
Well-Known Member
- Thread starter
- #1
Paxton kit, ran the 3.6 while getting everything dialed in. Changed to a 3.48 pulley, went for a dyno run. It ended up at about the same power, which kind of through me for a loop was expecting more. Looking at the weather it was probably the most humid and hottest day of the year, in addition density altitude was up; likely that was the issue after looking at the logs.
I went home, decided to put on the 3.375 pulley (tuner gave me the thumbs up) and make a couple logs. They felt strong, but at this point I doubt I can tell any difference, still getting used to the car. Looking at the logs and comparing MAP, the 3.48 pulley was up over the 3.6 3-4psi over the RPM range, and was climbing at a very similar rate as the 3.6 pulley. The 3.375 had less MAP over the range than the the 3.48 pulley and it slowed way down increasing PSIT about 5800-7000 (actually went backwards a little at the end). Also, the rate of climb seemed to die off over the RPM range. This was with the same belt as the 3.48 pulley and the tension pulley in the same location (o o x o). Figured this was slip for sure, then went to one size smaller belt. It would not fit, so I moved the pulley over one (o o o x) and the tension seemed about the same as bigger belt and other pulley location. Ran this belt and very similar results.
I guess first question is MAP a good indicator of boost? If so looking at the data below, am do I possibly have belt slip with the smaller pulley? Or am I chasing a problem that doesn't exist?
I went home, decided to put on the 3.375 pulley (tuner gave me the thumbs up) and make a couple logs. They felt strong, but at this point I doubt I can tell any difference, still getting used to the car. Looking at the logs and comparing MAP, the 3.48 pulley was up over the 3.6 3-4psi over the RPM range, and was climbing at a very similar rate as the 3.6 pulley. The 3.375 had less MAP over the range than the the 3.48 pulley and it slowed way down increasing PSIT about 5800-7000 (actually went backwards a little at the end). Also, the rate of climb seemed to die off over the RPM range. This was with the same belt as the 3.48 pulley and the tension pulley in the same location (o o x o). Figured this was slip for sure, then went to one size smaller belt. It would not fit, so I moved the pulley over one (o o o x) and the tension seemed about the same as bigger belt and other pulley location. Ran this belt and very similar results.
I guess first question is MAP a good indicator of boost? If so looking at the data below, am do I possibly have belt slip with the smaller pulley? Or am I chasing a problem that doesn't exist?
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