compressor fitting
- Thread starter rag231
- Start date
- Joined
- May 26, 2001
Not all turbos have this brass 90* elbow. I believe all of PTE's compressor cover castings have this brass elbow. You can drill and tap most other compressor covers to accept this hose barb, but the location is pretty critical. I prefer to tap off the intake manifolds' vacuum distribution block lines, for a boost signal reference when it comes to boost controllers, as you want the controller to see a pure signal. Pure signal meaning, the actual PSI amount that is making it into the intake. The actual output psi from the turbo almost always differs slightly than what actually makes it to the intake, because of the pressure loss across your intercooler core.
Ex: Your turbo might be putting out 20psi, but your intake may only see 16psi due to these losses. A more efficient IC core will help reduce this loss in pressure. Also, the more efficient your IC core is, the less stress is put on the turbo to make a given amount of boost.
Let's say your turbo has to put out 25psi of boost, in order to make 20psi of boost at the intake due to a very inefficient intercooler core. Now, I would much rather have my turbo breathing easy, rather than maxing it out to make such a moderate amount of boost. Now, let's say you change the intercooler core so that you only have to make 22psi to reach 20psi at the intake. Over time, that 5 psi difference from the turbo will give it a longer life span. In general, 1-2psi pressure drop across the intercooler core, is considered acceptable in street and racing applications.
This is also a very important thing to remember when determining a source for a MAP sensor, as well as the fuel pressure regulator. They have to know true psi as well for proper fueling. If you tap into one of the vacuum lines from the top of the t-body, make sure that you split the line equally between the two branches. IE: an equal amount of pressure will go to both sources. FWIW, that brass elbow is a standard 90* hose barb fitting with 1/8" NPT threads. Available at most competent hardware stores.
Hope this helps.
Patrick
Ex: Your turbo might be putting out 20psi, but your intake may only see 16psi due to these losses. A more efficient IC core will help reduce this loss in pressure. Also, the more efficient your IC core is, the less stress is put on the turbo to make a given amount of boost.
Let's say your turbo has to put out 25psi of boost, in order to make 20psi of boost at the intake due to a very inefficient intercooler core. Now, I would much rather have my turbo breathing easy, rather than maxing it out to make such a moderate amount of boost. Now, let's say you change the intercooler core so that you only have to make 22psi to reach 20psi at the intake. Over time, that 5 psi difference from the turbo will give it a longer life span. In general, 1-2psi pressure drop across the intercooler core, is considered acceptable in street and racing applications.
This is also a very important thing to remember when determining a source for a MAP sensor, as well as the fuel pressure regulator. They have to know true psi as well for proper fueling. If you tap into one of the vacuum lines from the top of the t-body, make sure that you split the line equally between the two branches. IE: an equal amount of pressure will go to both sources. FWIW, that brass elbow is a standard 90* hose barb fitting with 1/8" NPT threads. Available at most competent hardware stores.
Hope this helps.
Patrick
Syclone0044
Full Street Trim
- Joined
- Apr 7, 2002
Hey Patrick I can really appreciate what you said about the pressure difference from the turbo to the manifold. Would it be worth it to do a boost gauge off the turbo fitting, and another in the manifold? I happen to have an extra boost gauge sitting on the shelf and I'm wondering how much drop I'm getting on my stock "Garrett Air to Water" intercooler core on my mid-11 second 91 Syclone. The inlet is only 1.75", I'd have to think it's a bottleneck.
- Joined
- May 26, 2001
Yes, definitely do that if you are suspecting a high pressure loss.
One boost gauge reading true intake pressure, and the other boost gauge directly from the compressor cover hose barb. My bet is you will see somewhere between 2 - 2.5psi pressure loss on that factory Garrett core. I would also advise you to use two of these as well. Doing so will leave no doubt.
Autometer PN# 3230
Auto Meter 3230 - Auto Meter Blower Memory Kits - summitracing.com
This is Autometer's Blower Memory kit, that is compatible with any boost gauge. It will hold the pressure in the line until you press the release button to relieve the pressure. This way, you can put both gauges side by side and be able to see the difference. I would also recommend marking the gauge for the intake as P1 and the gauge for the turbo as P2, with either a piece of tape, or small felt tip pen.
Just remember, that when you run these inline check valves, the gauges will stay pegged at whatever boost they see when you let off the gas. This can be a bit unnerving the first couple of times you lift off the throttle under WOT. But you'll get used to it. It's just a poor mans boost datalogger setup that works. But, it will only work if both gauges are accurate. Test them both with the same pressure amount before installing and going. Otherwise, this test is futile.
HTH
Patrick
One boost gauge reading true intake pressure, and the other boost gauge directly from the compressor cover hose barb. My bet is you will see somewhere between 2 - 2.5psi pressure loss on that factory Garrett core. I would also advise you to use two of these as well. Doing so will leave no doubt.
Autometer PN# 3230
Auto Meter 3230 - Auto Meter Blower Memory Kits - summitracing.com
This is Autometer's Blower Memory kit, that is compatible with any boost gauge. It will hold the pressure in the line until you press the release button to relieve the pressure. This way, you can put both gauges side by side and be able to see the difference. I would also recommend marking the gauge for the intake as P1 and the gauge for the turbo as P2, with either a piece of tape, or small felt tip pen.
Just remember, that when you run these inline check valves, the gauges will stay pegged at whatever boost they see when you let off the gas. This can be a bit unnerving the first couple of times you lift off the throttle under WOT. But you'll get used to it. It's just a poor mans boost datalogger setup that works. But, it will only work if both gauges are accurate. Test them both with the same pressure amount before installing and going. Otherwise, this test is futile.
HTH
Patrick
Syclone0044
Full Street Trim
- Joined
- Apr 7, 2002
Wow, what a great suggestion! Sounds much easier and more accurate than trying to eyeball two boost gauges at WOT. Do you have to go under the hood to "reset" these check valves every time?
