Dave
05-19-2006, 08:55 PM
I was bored tonight and decided to perform a pressure drop test across the board. For those who might not know what I'm talking about, what a pressure drop test is, is where you messure the manifold pressure (end) versus the compressor pressure (beginning). Real easy algebra here, MAP - CAP = Pressure loss
So I teed into the compressor housing's boost controller line. First I set my manifold pressure to 18.5-19psi... depending on which gear I'm in, it usually increases a 1/3 of a pound throughout each gear.
I go out to Rt. 5, a nice long stretch of road and womp it... bam 18.5psi in 1st and 2nd gear, then a nice steady 19psi in 3rd. Nice having no traction when I pull back 3rd gear and spin the tires. :eyebrows:
Cap off the line for the boost gauge that goes into the intake, and route it into the homemade tee. Take it back on Rt. 5 and, oh what's this? No vaccum is read at the compressor housing? INTERESTING! I nail it, again no traction in 1st gear and little in 2nd, and it reads boost a lot sooner than the manifold! It felt like 5psi but it was reading 10psi. Hmm... So the boost gauge is maxed out, 20+. I guesstimated in 3rd gear I was at 20.5psi.
I had anywhere from a 1.5 to a 2psi pressure drop. Kool! Not bad. My setup is like this, 3.5" cone filter, 3" intake, stock TII Garrett turbo, 2 1/2" intercooler piping, stock TII front mounted intercooler, Blitz BOV, and stock throttle body and intake. I was reading off an Autometer Phantom boost gauge (30/20). Need a bigger gauge, by the way... Mom? Dad? :D
Something else that was interesting was that once I let off the throttle the gauge's needle would flutter and then steadily and slowly drop back down to 0psi. It never went below 0psi. I'm assuming that since the wheel is always spinning it's always causing above-ambient air pressure? Any guesses??
So onto the action. While sitting at a light on the way back home, it turns green and I go to give it some gas and the throttle is stuck to the floor, yet the RPM's are at 800. Whaaaaaat thaaa faaaaak!? Luckily I was on a decent grade of a hill and could roll it down to the middle turn lane. Do that, pop the hood... the entire arm came off the throttlebody. Not the throttle bracket, just the arm. Push it down a hill and hop back in and get it on some side street. Poppa's got come down in the Acclaim so I got a reference to work with. Luckily again I was next to an AutoZone. Walk there and buy a 10mm nut (that's what came off, somehow!)... wrong size, shiat. Go back and get a 13mm, yay! Of course it's course-threaded and not fine. DAMN! Use it anyways!! Haha. Baby it home and found one.
So now I'm out to go cruising. :evil: Just thought I'd share some information with you guys. Everybody likes seeing results.
-Bryan
So I teed into the compressor housing's boost controller line. First I set my manifold pressure to 18.5-19psi... depending on which gear I'm in, it usually increases a 1/3 of a pound throughout each gear.
I go out to Rt. 5, a nice long stretch of road and womp it... bam 18.5psi in 1st and 2nd gear, then a nice steady 19psi in 3rd. Nice having no traction when I pull back 3rd gear and spin the tires. :eyebrows:
Cap off the line for the boost gauge that goes into the intake, and route it into the homemade tee. Take it back on Rt. 5 and, oh what's this? No vaccum is read at the compressor housing? INTERESTING! I nail it, again no traction in 1st gear and little in 2nd, and it reads boost a lot sooner than the manifold! It felt like 5psi but it was reading 10psi. Hmm... So the boost gauge is maxed out, 20+. I guesstimated in 3rd gear I was at 20.5psi.
I had anywhere from a 1.5 to a 2psi pressure drop. Kool! Not bad. My setup is like this, 3.5" cone filter, 3" intake, stock TII Garrett turbo, 2 1/2" intercooler piping, stock TII front mounted intercooler, Blitz BOV, and stock throttle body and intake. I was reading off an Autometer Phantom boost gauge (30/20). Need a bigger gauge, by the way... Mom? Dad? :D
Something else that was interesting was that once I let off the throttle the gauge's needle would flutter and then steadily and slowly drop back down to 0psi. It never went below 0psi. I'm assuming that since the wheel is always spinning it's always causing above-ambient air pressure? Any guesses??
So onto the action. While sitting at a light on the way back home, it turns green and I go to give it some gas and the throttle is stuck to the floor, yet the RPM's are at 800. Whaaaaaat thaaa faaaaak!? Luckily I was on a decent grade of a hill and could roll it down to the middle turn lane. Do that, pop the hood... the entire arm came off the throttlebody. Not the throttle bracket, just the arm. Push it down a hill and hop back in and get it on some side street. Poppa's got come down in the Acclaim so I got a reference to work with. Luckily again I was next to an AutoZone. Walk there and buy a 10mm nut (that's what came off, somehow!)... wrong size, shiat. Go back and get a 13mm, yay! Of course it's course-threaded and not fine. DAMN! Use it anyways!! Haha. Baby it home and found one.
So now I'm out to go cruising. :evil: Just thought I'd share some information with you guys. Everybody likes seeing results.
-Bryan