Boosted Cam Question
07-20-2016, 08:54 AM
#1
Boosted Cam Question I am wondering how well my current cam will work with a pair of Precision 6766 CEAs .96 A/R. Was originally specced for NA + spray.
I don't have an issue with getting a new cam if I need it, but since the cam only has 1 summer on it if I can keep it I would like to lol.
Engine - 402 LS2 CNC LS3 heads, 11.07 c/r
235/250 .620/.596 115+4
IVO 6* BTDC
IVC 48* ABDC
EVO 64* BBDC
EVC 6* ATDC
ICL 111.0*
I don't have an issue with getting a new cam if I need it, but since the cam only has 1 summer on it if I can keep it I would like to lol.
Engine - 402 LS2 CNC LS3 heads, 11.07 c/r
235/250 .620/.596 115+4
IVO 6* BTDC
IVC 48* ABDC
EVO 64* BBDC
EVC 6* ATDC
ICL 111.0*
07-20-2016, 12:11 PM
#2
Well, I'm new to turbos as well and have gone through this same deal with cams. One, your duration is really big. Your valve overlap is going to be about 65 degrees which is a lot and will need to turn higher rpm to be in the power band. Your at 12 degrees at .050 which my TU2 cam was as well. The power band will also be narrow as well.
The TU2 had 226/226 at .578 lift. But overlap was at 65 degrees. I dropped down to a 224/224 112 . And this is actually a big cam for SBE 370ci engines. Your bigger ci may allow a bigger cam, but most turbos actually run well on stock type low duration cams from what I have been told.
Also you need to get your CR down to about 9-1 . 10-1 seems to be a safe max, but you start running into heat issues and not being able to add as much boost pressure to higher base CR, so you end up with less power in the end. 11-1 is really high for turbos.
Others with more experience will chime in as well. Its just what I have learned so far and might be of use. The real turbo guys will be able to judge backpressure as well, which I am still learning.
The TU2 had 226/226 at .578 lift. But overlap was at 65 degrees. I dropped down to a 224/224 112 . And this is actually a big cam for SBE 370ci engines. Your bigger ci may allow a bigger cam, but most turbos actually run well on stock type low duration cams from what I have been told.
Also you need to get your CR down to about 9-1 . 10-1 seems to be a safe max, but you start running into heat issues and not being able to add as much boost pressure to higher base CR, so you end up with less power in the end. 11-1 is really high for turbos.
Others with more experience will chime in as well. Its just what I have learned so far and might be of use. The real turbo guys will be able to judge backpressure as well, which I am still learning.
07-20-2016, 01:49 PM
#3
I was too lazy & cheap to buy/swap out my current cam (236/246 .612/.612 110lsa) when I built my turbo set up. I really couldn't get a good enough answer to warrant the extra $.. Some said might cause back pressure problems others said it would bleed off boost etc. So I went ahead with my cam, had it tuned with a 12lb spring in the gate, which actually made about 13.7psi & made over 700rwhp.. Car feels like a monster, with the 4k stall its not laggy at all. Need to step down to a 3.42 or 3.23 gear as it blows through the 3.90 pretty quick. My point is, try your cam, it may surprise you.