Low boost 4700-6700 rpm, fine again at 7000.
 

Hi
I'm running a M45 supercharger on my 90' 1,6. Had been on the car for 3 years, but dynoed first time 2 weeks ago.
They told me that it was strange that my boost level droped between 4700-6700 rpm (down to 5,8psi). Up to 4700 and +7000 its at 7,3 psi again. I think it has always acted like that.

I can't find any leaks and belt is new and doesn't slip (at least more tention dont help).
Is it normal or do I have a problem, and can look forward to more torque? :firedevil

PS: Sorry, found the superharging site, but can't move this thread.

Could it be due to good flow in the head and manifold (4-2-1), so the M45 can't follow up? (until the flow drops again)

Either you have an RPM dependent boost leak, or your belt is slipping.

My money is on the belt.