I just purchased a 2004 Marauder with what I am pretty sure is the Vortech S/C kit for the 2003-2004 Mach 1 Mustang. The part #s seem to line up. This is my first S/C car since my '03 Cobra and first car ever with aftermarket mods to this extent. I road tripped it from CA to GA with no issues other than a weak alternator. On the advice of tons of threads on this forum I ordered a DB Electrical 160A alternator, 6G to match the belt in place.
Since I was going to be removing the alternator I decided to go ahead and do the serpentine belt and pulleys while I was at it. This is where things started getting a little odd. I was using the install guide for the S/C kit as a reference to order parts. Got all the parts, took the S/C bracket assembly and alternator off and noticed that some installed parts didn't match the Vortech parts list.
The belt Vortech calls for is a Gates 061115, 111 7/8" long. The belt on the car was a NAPA 25061099, 110.5" long. The composite Vortech-supplied flanged pulley was missing, and in it's place was a flat metal idler pulley of the same size (see diagram). The grooved "stock" idler pulley wasn't stock - it was 1" smaller in diameter (see diagram).
I replaced the tensioner pulley, all stock idler pulleys and the composite pulley that was included with the S/C kit with their direct replacements per the S/C kit parts guide...Gates all around except the composite Vortech pulley.
I replaced everything, reassembled with much cursing and started the car. Immediately the belt started squealing. Turned AC off, squealing stopped. AC on, squeal. Took it for a drive. Under light throttle no squeal, under heavy throttle with the S/C making boost, squeal. I also noticed pulling in the garage that the voltage meter was all over the place. While driving and stopped it seemed to hold a perfect 13.8 volts, but pulling up my driveway and into the garage it was bouncing up and down.
Any ideas? I am taking the car to a local speed shop who is familiar with Marauders next Friday, but I'd like to get this sorted before I take it in. I still have the old, smaller pulley, and can get a replacement smaller belt...I just find it odd that those parts weren't the same as called for in the Vortech kit.
New alternator:
https://www.dbelectrical.com/product...2003-2004.html
Diagram of pulleys:
Marauder pulleys.jpg