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Low Boost 03 Cobra???

  • Thread starter Thread starter xtreme02stang
  • Start date Start date Aug 29, 2010
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xtreme02stang

New Member
Jun 25, 2007
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0
Orlando
Aug 29, 2010
#1
  • Aug 29, 2010
  • #1
Just purchased a 03 Cobra with jlt cai, t/b with elbow, 2.8 pulley, stock eaton, and boost/air fuel gauges. My problem is I'm only pulling 8lbs of boost with this setup. I hear other people making more with the same pulley. Is 8 lbs normal? Thanks for your help.
 

wmburns

SN Certified Technician
Aug 14, 2009
5,892
514
204
Houston Texas
Sep 2, 2010
#2
  • Sep 2, 2010
  • #2
What are the results of a compression test? What is the base condition of the motor? Any vacuum leaks? What about the exhaust system? A blocked/restricted exhaust will raise boost.

FWIIW, there is a possibility that you are missing the mark if focusing too much on the amount of boost. Isn't this about making HP?

There are tons of reasons why one motor makes more boost than another. Differences in stock cam timing being very near the top of the list. In fact, it may not be a bad thing to have less boost.

Sacrilegious you say?

Take two motors. One flows better than the other. All other things being equal, the better flowing motor will have LOWER boost and will most likely make more HP. Boost is partially the by product of the resistance to the flow of air.

Check out the KB WEB site. There are several tech articles talking about boost and why one motor could make more/less than another.

If you still want more boost, try crimping the exhaust. The extra exhaust back pressure will raise the boost level showing on the guage. However, I doubt if the over all results will please (note this is an attempt to make a point).
 

Three50won

10 Year Member
Jul 11, 2010
1,135
64
69
Sep 29, 2010
#3
  • Sep 29, 2010
  • #3
+1 on wmburns comment...also check the size of the crank pulley, it might be smaller than stock in which case you'll have less boost. Maybe the previous owner had a bigger supercharger on it and altered both pulleys for a specific boost/hp amount to tune it properly and prevent belt slippage.
 
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