Boost drop after cam swap question
Boost drop after cam swap question I went from running 5psi max boost with a 208/216 .500/.500 113lsa cam to running 3psi max boost with the new installation of the '02LS6 cam (204/218 .555/.551 117.5lsa) Is it usual to lose that much boost from a cam swap??? I was thinking boost pressure should have gone up because the decrease of valve overlap going from 113lsa to a 117.5lsa.
Even if the '02LS6 cam was a lot more efficient than my old cam at getting air in/out of the motor, I would think that a cam would only make like a half psi difference? Just to be sure, I checked everything else -no leaks and the bypass valve seems to be closing at WOT like it should.
What boost changes have you guys seen with cam swaps?
Thank you for the help.
Ryan
Even if the '02LS6 cam was a lot more efficient than my old cam at getting air in/out of the motor, I would think that a cam would only make like a half psi difference? Just to be sure, I checked everything else -no leaks and the bypass valve seems to be closing at WOT like it should.
What boost changes have you guys seen with cam swaps?
Thank you for the help.
Ryan
TECH Resident
Joined: Aug 2003
Posts: 948
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From: orlando, florida
.050 more valve lift will move alot more air. I also think with the 113lsa cam you were getting some reversion that was letting spent exhaust gases back into the cylinder before the exhaust valve closed. Which inturn means less avalible space to fill on the next combustion stroke, higher intake pressure(Boost), higher cylinder temps and less efficent. I may be wrong but this is my theory.
Teching In
Joined: Dec 2003
Posts: 12
Likes: 0
From: Marietta, GA
I would be interested to know if your power dropped along with the reduction in boost.
Sometimes when a process becomes more efficient, the boost level will decrease and power remain the same or better.
Seat of the pants is not a true measure....
Sometimes when a process becomes more efficient, the boost level will decrease and power remain the same or better.
Seat of the pants is not a true measure....
8 second mod
iTrader: (37)
Joined: Nov 2002
Posts: 17,879
Likes: 1
From: East Side Performance! mASShole
The 117 is good, other mods would help answer this questin.
engin size,specs ect, But just because you swap cams means that is the reason. Ive learned my lesson!! Check all the easy **** first, it might be somthing so simple!!! hapens everytime.
The ls6 cam is a decent cam for psi aps, so id look else where, or try dyno, it might answer all.
Good luck.
engin size,specs ect, But just because you swap cams means that is the reason. Ive learned my lesson!! Check all the easy **** first, it might be somthing so simple!!! hapens everytime.
The ls6 cam is a decent cam for psi aps, so id look else where, or try dyno, it might answer all.
Good luck.
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