This is topic Supercharger boost in forum Tech Talk at Northern California Ford Owners  .


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Posted by castor (Member # 2765) on :
 
Is it correct to say that if my boost guage is connected to the vacuum tree on the firewall right behind the steering wheel, that's "intake boost" and it reads lower than connecting it to the outlet of the unit itself?
If so, then connecting to the output will give me a more accurate reading?

Thanks in advance.
 

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Posted by 5LVENOM (Member # 2282) on :
 
Any manifold vacuum source will give an accurate reading.
 

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Posted by white1990stang (Member # 2307) on :
 
i connected mine to the fitting on the tb. you know where the hose from the valve cover oil fill to the tb went. i used an adapter like the one used right behind the gauge to connect the line and a 2 inch piece of rubber hose.
 

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Posted by 66 AC COBRA (Member # 904) on :
 
yeas and no, if u had 500 90's bends iun ur system, and the blower saw 50psi, but the intake only saw 8psi, what would u tune the car for
8psi

obviously that is exagerated but it demostrates my point

boost is not power, just a restriction, so where do u want to measure that, where the motor is sucking it in or where the blower is spitting it out

and think of it think way, either u will make 352rwhp at 8psi referenced at the manifold or 352rwhp at 11psi referenced at the blower
 

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Posted by castor (Member # 2765) on :
 

quote:

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Originally posted by 66 AC COBRA:
yeas and no, if u had 500 90's bends iun ur system, and the blower saw 50psi, but the intake only saw 8psi, what would u tune the car for
8psi

obviously that is exagerated but it demostrates my point

boost is not power, just a restriction, so where do u want to measure that, where the motor is sucking it in or where the blower is spitting it out

and think of it think way, either u will make 352rwhp at 8psi referenced at the manifold or 352rwhp at 11psi referenced at the blower

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Thanks for the great info. Only reason I'm asking is because from the tree, I only see about 3 1/2lbs. of boost at about 5k plus RPMs. My blower is older, rated from the factory at 5-6lbs of boost, but when it was rebuilt, the modified impeller was added at a rating of 1-2lbs of additional boost, if memory serves me correct. The unit in question is a Paxton SN2000.
Thanks, all.
 

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Posted by Fostang (Member # 3752) on :
 

quote:

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Originally posted by castor:

quote:

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Originally posted by 66 AC COBRA:
yeas and no, if u had 500 90's bends iun ur system, and the blower saw 50psi, but the intake only saw 8psi, what would u tune the car for
8psi

obviously that is exagerated but it demostrates my point

boost is not power, just a restriction, so where do u want to measure that, where the motor is sucking it in or where the blower is spitting it out

and think of it think way, either u will make 352rwhp at 8psi referenced at the manifold or 352rwhp at 11psi referenced at the blower

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Thanks for the great info. Only reason I'm asking is because from the tree, I only see about 3 1/2lbs. of boost at about 5k plus RPMs. My blower is older, rated from the factory at 5-6lbs of boost, but when it was rebuilt, the modified impeller was added at a rating of 1-2lbs of additional boost, if memory serves me correct. The unit in question is a Paxton SN2000.
Thanks, all.

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quote:

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Originally posted by Fostang:

quote:

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Originally posted by castor:

quote:

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Originally posted by 66 AC COBRA:
yeas and no, if u had 500 90's bends iun ur system, and the blower saw 50psi, but the intake only saw 8psi, what would u tune the car for
8psi

obviously that is exagerated but it demostrates my point

boost is not power, just a restriction, so where do u want to measure that, where the motor is sucking it in or where the blower is spitting it out

and think of it think way, either u will make 352rwhp at 8psi referenced at the manifold or 352rwhp at 11psi referenced at the blower

---

Thanks for the great info. Only reason I'm asking is because from the tree, I only see about 3 1/2lbs. of boost at about 5k plus RPMs. My blower is older, rated from the factory at 5-6lbs of boost, but when it was rebuilt, the modified impeller was added at a rating of 1-2lbs of additional boost, if memory serves me correct. The unit in question is a Paxton SN2000.
Thanks, all.

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Yup thats the right amount of boost your seeing. 3.5 pounds possibly 4 just because of the boost not getting efficiently read from the vacuum tree.

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Thanks...anyone else?
 

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Posted by 66 AC COBRA (Member # 904) on :
 
i never said that the vaccumm tree was a good place for reference

i woulkd want that gauge directly off the intake manifold
 

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Posted by PurpleNotch (Member # 2902) on :
 
i use the vacumm tree on the firewall and i have seen almost 13 pounds on the guage when i was on the dyno so i believe that the spot is ok.
 

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