only showing 5lbs boost?

[Qkhorse]

well i got the sn93 paxton running last night. ( Love the sound of it!!!!!) on the boost guage is see 5lb at 5500-6000 rpm on almost wot. I have on it a 9lbs pulley? fuel presure is set at 35psi with vaccum off. I 'm running the FMU with the silver unit.

I'm wondering why i'm only seeing 5lbs boost?? any suggestion.

[root]

Well it could be a few things..

- Check the gauge
- Do you have heads / cam / intake / intercooler
- Are all the clamps around your blower tight

Ian

[Qkhorse]

yes all the clamps are tight, trick flow upper and lower intake, world product race heads, compression 9.3 to 1, e303 ford camshaft, Guage seems to be correct, no intercooler, timing at 8 degrees BTDC.

[root]

Well you have a 9lb pulley which means it will make that on a stock engine. You have mods and so your boost will fall. The blower may also be a little tired.

Ian

[Qkhorse]

Tahnks for the info i'll be looking for a pulley that will make 9 lbs of boost with my setup.

[Hustler]

Yep as Ian said Qkhorse, your motor will show less boost because your motor is capable of moving more air than a stock motor. While you are actually moving the same amount of air as 9lb's of boost on a stock motor your vacuum/boost gauge will show less boost because the air path through your motor is larger due to your intake/heads and cam, therefore creating less resistence/backpressure "boost"

[Hustler]

Just make sure you don't overspin the sn93. Boost is basically a reference number, but you shouldn't always use it to compare one motor to another.

[root]

If you try to get 9lbs on your motor that will spin the blower much too fast IMHO.

Ian

[90redpony]

been there done that, i smoked my s/n93 in minute by too small of a pulley, if you are changing to a smaller pulley, make sure you have an oil cooler on it!

[speedytang]

Your inlet and outlet are to small to get much more boost than you are showing without cooking the ball drive. Are you using the 3.75" or the 3.5" now to get 5psi