Back pressure measurement?
 

Has anyone else besides me done this? I welded in some fittings right behind the headers allowing 1/8" steel tubes about 6" long off of the head pipes. I then attatched flexible lines to the interior of the car and attatched a Vacuum guage that also showed positive pessure 0-10 psi.

At idle I got .5 psi and a max of 2.5-3.0 psi at 5500 RPM. The guage actually vacillated alot at that point making a definite reading improbable. I would say 2.75 psi @5500 RPM.

Anyone else ever done this? I think anything under 3.0 psi should be OK. Any comments / opinions welcome.

Rev

Nice work - I've considered doing this myself. you have chosen the right spot in the system. Now, you'll have to switch exhaust componanats to see the affects on power and back pressure.

The reason I did it...
 

The reason I wanted to measure the back pressure in the first place, is because I noticed that the resonator exhaust tips that I'm using (Pace Setter Monza) actually restrict my 2.5" tailpipes down to 1.75" to allow room for the glass pack material. I figured that must hurt power by increasing back pressure. I have new Hooker non resonator unrestricted tips ordered fron Jeg's that should be here Friday.

First thing I'll do is retest the back pressure. Second thing I'll do is do a G-Tech run to see if there's any difference. Eventually, I'll get back to the track for definitive tests when the weather is cold and dry. I'm hoping for a few more ponies at the wheels. Might dyno it again if it looks like there are any gains.

Rev

Car Craft just did an article on what you did. They said back pressure should be between 2-4 psi.

I'd like to hear your results. The smaller diameter that far back may have less effect than you think - you'll know for sure soon.