after 500 miles and 4-5 retightens they usually settle in. I have 1500-2000 miles on the belt in the pics above and it holds 17 psi over and over. its been said before but I will say it again get the longest belt you can so the tensioner gets used to its full potential. this will increase belt wrap also going to a larger 3.8'' idler pulley helps with that and using a merc- audi idler pulley on the slack side to get the belt to wrap around the blower pulley. this does 2 things it increases the belts contact area and also stop the osculation that occurs on the slack side as this will travel up the belt causing that surface area to shrink. just some observations I have seen over the years

 

thanks - i'll let you know what the shop say tonight. I'm liking what you've done with the additional tensioner though, that definitely makes sense.

 

here is an idler pulley you can add to the driver side of the belt
https://www.amazon.com/Mercedes-Idle...3HD1YZ6Z5CMSFW

 

1220 3.0 upper stock lower seeing 18-19 at 9200 zero slip. I have notches in my pulley makes a huge difference

 

A larger crank pulley also works wonders

 

True

 

Thanks for the pulley info. I'm going to get the blower pulley notched up and try again. The crank pulley is already a 6.5" asp pulley. I think the belt is stretching between runs as well. I noticed the gatorback belts do get very soft with the heat.. I'll keep you all posted.

 

I've seen 22psi with my N1200 with good tension and belt break-in (at least a few hundred miles). I use a 3.0" RR pulley, 5.45" crankshaft pulley, and a Gates green stripe belt.

 

Is that a similar belt size to my 6.5/3.6 combo? And 22psi?! Wow.. I have a fmic but didn't think I'd be getting that much loss!! I couldn't find a greenstripe in my size. My belt was new when it went on the dyno, could have something to do with it..

 

I have no idea which belt you're using, but mine is a K060390HD belt