tequilaiam
Member
- 157
- 0
- 16
- Location
- Brazil, IN
Does it matter where you tap the hole for a mechanical boost gauge? Do you need to pick the location carefully to avoid berneulli affect from giving low readings?
So reason I ask is that the first place I tried was the port on top of the intake upper used for the EGR from the factory. That actually read vacuum when I rev'd the motor. Inside of that upper had a tube protruding down into the intake so I assume GM used that as a way generating a vacuum to activate the EGR on the civy trucks.
So anyway, I plugged that hole and tapped a new one on the driver's side of the upper. Now I read up to 5lbs of boost but only on WOT while the engine is wound out. So either there's something else messed up or the speed of the air as it pinches through the upper intake at 90 deg. to the brass nipple is lowering the reading.
The air pressure line for the gauge is fine and the pressurized part of the intake system looks good. I also tried some very stiff springs for the wastegate control and it made no difference. Turbo-aft exhaust is all 3" so that shouldn't be too restrictive.
Turbo is a "GM-1" which from everything I've read should spool and boost quick but choke the motor at higher RPMs.....this is seemingly the opposite.
So I'm just wondering if anyone else has run into this. The pics of other installs available seem to have the senders placed just about anywhere there's a flat spot cast so I wouldn't think it matters BUT this is my first turbo install.
So reason I ask is that the first place I tried was the port on top of the intake upper used for the EGR from the factory. That actually read vacuum when I rev'd the motor. Inside of that upper had a tube protruding down into the intake so I assume GM used that as a way generating a vacuum to activate the EGR on the civy trucks.
So anyway, I plugged that hole and tapped a new one on the driver's side of the upper. Now I read up to 5lbs of boost but only on WOT while the engine is wound out. So either there's something else messed up or the speed of the air as it pinches through the upper intake at 90 deg. to the brass nipple is lowering the reading.
The air pressure line for the gauge is fine and the pressurized part of the intake system looks good. I also tried some very stiff springs for the wastegate control and it made no difference. Turbo-aft exhaust is all 3" so that shouldn't be too restrictive.
Turbo is a "GM-1" which from everything I've read should spool and boost quick but choke the motor at higher RPMs.....this is seemingly the opposite.
So I'm just wondering if anyone else has run into this. The pics of other installs available seem to have the senders placed just about anywhere there's a flat spot cast so I wouldn't think it matters BUT this is my first turbo install.