Hi all -
I'm getting a noise (not a squeal) that sounds similar to a blowoff valve on a turbo car. It's kind of similar to the howl of spinning performance tires.
It happens only at 4300 rpm or higher, AND only at full boost (11-12psi)
10% OD blower pulley
10% OD JS pulley - all done with proper belt lengths.
Ported m90 on a 1989 engine installed in a 98 Mustang.
New belts and tensioner springs last year, best quality I could find.
When it happens, all gages remain steady (no drop in boost). I don't have the Wideband on it, so I'm not sure what happens with the AFR. But, the car continues to run smooth and pull good power. No hiccups or performance issues, just the noise.
Weird thing is, I've been running with this combination for 4yrs with no issues until recently.
I can hold 12psi no problem until 4300rpm, then the noise.
Any ideas?
I was thinking either belt slip or something with the bypass valve. I was going to try Comet powder on the belt to see if that makes any difference (good or bad). At least I would know what to go after.
Any help is appreciated.
Thanks!
Scott
I'm getting a noise (not a squeal) that sounds similar to a blowoff valve on a turbo car. It's kind of similar to the howl of spinning performance tires.
It happens only at 4300 rpm or higher, AND only at full boost (11-12psi)
10% OD blower pulley
10% OD JS pulley - all done with proper belt lengths.
Ported m90 on a 1989 engine installed in a 98 Mustang.
New belts and tensioner springs last year, best quality I could find.
When it happens, all gages remain steady (no drop in boost). I don't have the Wideband on it, so I'm not sure what happens with the AFR. But, the car continues to run smooth and pull good power. No hiccups or performance issues, just the noise.
Weird thing is, I've been running with this combination for 4yrs with no issues until recently.
I can hold 12psi no problem until 4300rpm, then the noise.
Any ideas?
I was thinking either belt slip or something with the bypass valve. I was going to try Comet powder on the belt to see if that makes any difference (good or bad). At least I would know what to go after.
Any help is appreciated.
Thanks!
Scott