Boost gauge

[Jcg_3v94]

Long story short, i have a saleen blower series 6 on my 07 gt. Im running a 3.4 pulley thats rated anywhere between 8-9 psi. The shop i went to hooked up a boost gauge in the fuel rail pressure line, would that be accurate? I know the correct spot is in front passenger side of the manifold. He did it for a quick reading. Im just not to sure if my blower is having issues since im only getting 6psi which is stock boost, or if the location of the gauge was not good.

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[teeje]

Long story short, i have a saleen blower series 6 on my 07 gt. Im running a 3.4 pulley thats rated anywhere between 8-9 psi. The shop i went to hooked up a boost gauge in the fuel rail pressure line, would that be accurate? I know the correct spot is in front passenger side of the manifold. He did it for a quick reading. Im just not to sure if my blower is having issues since im only getting 6psi which is stock boost, or if the location of the gauge was not good.

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I believe you and I just talked about this. The correct spot to put the boost gauge would be in the vacuum line going to the FRPS. So yes, that is in the right spot. You can move it to a different positive pressure side of the manifold, but where you have it now will work just fine. I believe you and I were talking about low boost in my thread about low boost on my kennebell. My solution is to put a smaller pulley on. I had a 3-78ths pulley going to a 3.5. I haven’t put it on yet because fedex is a joke and didn’t deliver it today, but I’m almost 100% positive a smaller pulley will fix my problem as well as yours. What exhaust do you have? Do you have cats? Did you put the blower on or did you buy it used?


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[Jcg_3v94]

I believe you and I just talked about this. The correct spot to put the boost gauge would be in the vacuum line going to the FRPS. So yes, that is in the right spot. You can move it to a different positive pressure side of the manifold, but where you have it now will work just fine. I believe you and I were talking about low boost in my thread about low boost on my kennebell. My solution is to put a smaller pulley on. I had a 3-78ths pulley going to a 3.5. I haven’t put it on yet because fedex is a joke and didn’t deliver it today, but I’m almost 100% positive a smaller pulley will fix my problem as well as yours. What exhaust do you have? Do you have cats? Did you put the blower on or did you buy it used?


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Yea that was me, ill probably purchase a smaller pulley then as well. The car came with it when i purchased it. Oem headers, oem hpipe. Everything is pretty much oem besides supercharger.


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[teeje]

Also sorry for the second post but I wouldn’t have the vacuum line at that tight of an angle. No zip ties are needed on the fuel rail. You can zip tie the vacuum line farther back. Here’s how I have mine....I don’t have a picture but I will explain it to you...I have a vacuum line coming from the PS on the manifold that goes to a T. One side of the t goes to the bypass valve and the other to the frps. The line that goes into the frps I have a brass T that I put the boost gauge on. I used a brass t so I could use small hose clamps so the vacuum line doesn’t come off the T


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[teeje]

Yea that was me, ill probably purchase a smaller pulley then as well. The car came with it when i purchased it. Oem headers, oem hpipe. Everything is pretty much oem besides supercharger.


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Measure the pulley first and see what you have. You don’t want to go to a really small pulley. You will probably need to get a tune. I know Lito told me not to do anything until I datalog it after I put that pulley on.


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[Jcg_3v94]

Also sorry for the second post but I wouldn’t have the vacuum line at that tight of an angle. No zip ties are needed on the fuel rail. You can zip tie the vacuum line farther back. Here’s how I have mine....I don’t have a picture but I will explain it to you...I have a vacuum line coming from the PS on the manifold that goes to a T. One side of the t goes to the bypass valve and the other to the frps. The line that goes into the frps I have a brass T that I put the boost gauge on. I used a brass t so I could use small hose clamps so the vacuum line doesn’t come off the T


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Sweet ill go ahead and try that, just hoping my blower isnt taking a shit.


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[teeje]

Sweet ill go ahead and try that, just hoping my blower isnt taking a shit.


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Take the belt off and spin the pulley. Check for excessive backlash. The couples can go bad


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[Jcg_3v94]

Take the belt off and spin the pulley. Check for excessive backlash. The couples can go bad


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Will do, any certain noise i should hear?


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[Laga]

That location will not give you an accurate reading. I believe the Saleen is a similar setup to the Edelbrock , which is what I have. I originally had mine setup as yours and then discovered this explanation from Edelbrock,

CAUTION: Never cut into the vacuum lines leading to the fuel rail pressure sensor and bypass actuator, on the driver's side of the manifold, for the purpose of tapping in a boost gauge. Interruption of the vacuum signal to the fuel rail pressure sensor can affect the fuel pressure reading to the PCM, which can result in engine failure! Furthermore, this port reads pressure before the intercooler, and therefore is before the inherent intercooler pressure drop. Readings from this port will always be approx. 20% higher then what the engine actually sees.



Mine was reading higher than actual. Once corrected, I was able to go to a smaller pulley. You might have a leak giving the lower reading. Either way, Thats not a good place to measure.

 

[Jcg_3v94]

That location will not give you an accurate reading. I believe the Saleen is a similar setup to the Edelbrock , which is what I have. I originally had mine setup as yours and then discovered this explanation from Edelbrock,

CAUTION: Never cut into the vacuum lines leading to the fuel rail pressure sensor and bypass actuator, on the driver's side of the manifold, for the purpose of tapping in a boost gauge. Interruption of the vacuum signal to the fuel rail pressure sensor can affect the fuel pressure reading to the PCM, which can result in engine failure! Furthermore, this port reads pressure before the intercooler, and therefore is before the inherent intercooler pressure drop. Readings from this port will always be approx. 20% higher then what the engine actually sees.



Mine was reading higher than actual. Once corrected, I was able to go to a smaller pulley. You might have a leak giving the lower reading. Either way, Thats not a good place to measure.

Sweet thank you! Leak as in a vacuum leak?


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[Laga]

If you are getting a lower reading than expected than, yes. That would be my guess.

 

[teeje]

That’s conflicting information then. Kennebell Lito, and many others have said putting the boost gauge where undid is perfectly fine and now all of a sudden I hear tapping into the frps line isn’t ok? I’ve never heard of such a thing


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[Jcg_3v94]

That’s conflicting information then. Kennebell Lito, and many others have said putting the boost gauge where undid is perfectly fine and now all of a sudden I hear tapping into the frps line isn’t ok? I’ve never heard of such a thing


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Ill just connect it where they recommend me connecting it on the saleen blower which is here

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[Laga]

That’s conflicting information then. Kennebell Lito, and many others have said putting the boost gauge where undid is perfectly fine and now all of a sudden I hear tapping into the frps line isn’t ok? I’ve never heard of such a thing


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Originally, when I installed my SC, I made the mistake of tapping into the FRPS vacuum line. I was reading 8# of boost which was high from the pulley that came with the kit. Lito said that is the limit to my setup. After discovering that warning from Edelbrock, which is not in the installation instructions but in the online FAQ section, I called Edelbrock tech and was told that the pulley I had would put out a max of 6# in most applications. I installed 2 boost gauges, one mechanical and one as part of the Areoforce Interceptor to double check and be sure. They both read 6#. I informed Lito of the change and was able to go to a smaller pulley and now read 8-9#.
Boost measured before an Intercooler will differ from afterwards because of the restrictions. This happens on all designs. Do a google search for “ Boost drop from intercooler “.
Plus, as stated in other threads here, you don’t want to tap into that line because it increases chances of a leak, which can cut fuel at WOT and cause big problems.

 

[teeje]

Originally, when I installed my SC, I made the mistake of tapping into the FRPS vacuum line. I was reading 8# of boost which was high from the pulley that came with the kit. Lito said that is the limit to my setup. After discovering that warning from Edelbrock, which is not in the installation instructions but in the online FAQ section, I called Edelbrock tech and was told that the pulley I had would put out a max of 6# in most applications. I installed 2 boost gauges, one mechanical and one as part of the Areoforce Interceptor to double check and be sure. They both read 6#. I informed Lito of the change and was able to go to a smaller pulley and now read 8-9#.
Boost measured before an Intercooler will differ from afterwards because of the restrictions. This happens on all designs. Do a google search for “ Boost drop from intercooler “.
Plus, as stated in other threads here, you don’t want to tap into that line because it increases chances of a leak, which can cut fuel at WOT and cause big problems.

Use a brass T and small hose clamps and you’ll never have a problem. Using the cheap plastic Ts? Sure they definitely cause leaks but that usually isn’t something people think about when they put a boost gauge in. They usually use what is included then the t breaks and they have issues


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