Roush Boost Gauge Install and Boost

Roush Boost Mechanical LED Boost Gauge

The instructions from Roush are extremely poor. The gauge comes with a "T" shaped plastic fitting and the instructions only say "plug it to boost/vacuum line". No one has any idea at all which line is that.

The best way to install the boost gauge is to tap into the opening on the manifold's passenger side, just above cylinder 8. There is a hexagonal bolt that Roush plugs in at factory to seal the port.

Buy a 1/8 NPT to 1/8" Barbed fitting for $2. Remove the factory bolt, wrap the NPT fitting with a line of Teflon sealant and plug it into that hole. Attach the boost gauge hose to the barbed fitting. Done.

I finally managed to get my Roush gauge to work yesterday. To my big surprise, it was only reading about 7-7.5psi boost and -16/-18 in.Hg at idle. Vacuum reading was perfect but I was surprised with the boost. 85mm pulley normally is rated at 8.5psi.

VMP tuning wrote me and explained that the manifold boost eventually depends on the tune and how the TVCT settings are calibrated. Normally a Ford Racing or Roush tune would show up more boost in the manifold whereby VMP's tune actually reduced it by close to 1 psi, yet still making 661hp at crank!

The boost kicks in at around 5psi from low rpm and immediately climbs to 7psi as of 1500rpm. Stays steady all the way to red line.

I will install the 82mm pulley today which is supposed to increase the boost by 1 psi. I hope to read about 8-8.5psi at the gauge.