under drive pulleys
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From: the chi/ addison Il
under drive pulleys I bought my car a few months back. It is a 99 z28 m6 all stock other than pacesetter longtubes, slp airlid and a set of underdrive pulleys. Soon after buying it i purchased a 90mm fast tb and a weiand intake. Bolted everything on and the car was running super lean so i got it tuned. Runs way better but on the dyno sheet their is a fifty horse dip from 4500rpm-5000rpm and continues to climb after that. This on the first pull and the final pull. was wondering what it could be from. I have heard some underdrive pulleys do this namely harmonic balancers.
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From: the chi/ addison Il
just the harmonic balancer causes this or all the pulleys as a system? maybe it could be justbad tuning but it was on the baseline. maybe the weiand intake, anyone running the aluminum one
A stock cammed car will usually stop making power about 5800 or so. KR will pull timing so you won't make the best peak #'ers but will still climb to 5800 or so.
Lack of fuel pressure is my first thought.
Your tuner should be able to figure this out pretty easily though looking through his log and running some simple diagnostics.
Lack of fuel pressure is my first thought.
Your tuner should be able to figure this out pretty easily though looking through his log and running some simple diagnostics.
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From: the chi/ addison Il
the afr looks fine and the shop mostly does ford stuff but did great work on my buddys corvette. ford or gm they should still be able to fix it or figure what it is. after i get my heads and cam installed I might just go to speed inc and see what they say. fuel pressure might be it though. i will have to throw the old gauge on and check it.
