Supercharger boost help

OK this is a very rare setup and very not working properly :emb

i just completed my project and have a problem i have a pulley rated a 7psi but im only getting 4 psi if even that at WOT and so far this is what ive got

1.i am sure that there is no boost leak as i just fixed it

2.i have a 2.5" pulley boy pulley and my crank pulley is 4.15" in diameter so you do the math i got 7.76 PSI

3.dose not have a proper tune as i cant afford it

4.the highest i got it is barely 4psi at WOT if even that

5.pretty much the vid boost gauge is the same while driving

6.i tried taking off the air filter but still the same

7.i have no BPV but that shouldn't effect the boost

8. it dosent look like it is slipping unless i really pound the pedal fast..faster than a normal launch

9. i checked if the boost gauge will go over 5 psi and it did so the gauge is good


SO whats the problem???????

some vids that maybe can help you out MAYBE no one has yet to figure it out ???

http://i354.photobucket.com/albums/r...h_ASF_0007.jpg


http://i354.photobucket.com/albums/r..._ASF_0g003.jpg

http://i354.photobucket.com/albums/r...h_ASF_0002.jpg

BTW the cars a 3000gt SL 91

How did you arrive at 7.76psi of boost? What formula did you use?

Also, which model Eaton supercharger are you using? A little more information on the blower itself may prove helpful in narrowing down the problem.

Not sure about that math but my chart shows a small eaton with those pulley sizes making 3.21 psi. I show a 6.21" crank pulley producing 6.75 psi.

Quote:

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Originally Posted by speedytang

Not sure about that math but my chart shows a small eaton with those pulley sizes making 3.21 psi. I show a 6.21" crank pulley producing 6.75 psi.

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If that's the case, then I think Cyote has his answer: get a larger crank pulley.

Careful if you change the crank though as your oil pump etc will turn faster and may not work correctly, Is this a home made kit of off the shelf? Maybe the volume is just too big to fill with that size blower