Pretty much. On mine, the tensioner gets it to a little over 2 on the factory tool so I just nudge it a bit tighter. Once I nudge it tighter, it stays that way till clamped down. I'm sure somewhere in the archives at Porsche, they have data to support the notion that 2.4 is tight enough but 2.3 isn't, but it's pretty clear that plenty of people seem to be getting by without necessarily being exactly within Porsche's specs.

 

And that's why I bought the tensioning tool... Now I don't have to guess.

 

So what is the correct tension for both the TB and the BS belt, if using the Arnnworx tool? Is there a different value on their tension between the OP's car and a 89 951?

 

Actually there is another possible explanation- apart from the balance shaft belt being to tight, there is a metal idler pulley for the balance shaft belt located directly above lower balance shaft. This pulley has an eccentricity to it, so there is often a debate where it should be extended. The pulley should be extended towards the 10pm position. However, if left to sag towards the 6pm position it can make contact with the metal edge of lower balance shaft pulley cover, and makes a very distinctive metallic supercharger whine. So check this out as well.

 

sounds like mine.....just got the Maxi Kit from Bruce...so hoping to get the balance belt properly tuned up...bit whinny at the moment........