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    forced induction question

    do you guys recommend doing a cam with forced induction?

    #2
    Yes, you should have a cam.

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      #3
      absolutely. a good N/A cam is also going to be a good turbo cam.
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      Bimmerlabs

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        #4
        what do you recommend for a good cam? mine is worn and broke a rocker

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          #5
          A new stock replacement cam should be fine for a while.And fix the broken rocker ofcourse.Upgraded valve springs should go in with the new cam.

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            #6
            Stock cam is the best unless you find a company that makes a turbo cam cause an aftermarket N/A cam will NOT work well
            First: 1984 318i
            Second: 1987 325
            Third: 1987 325is
            Current: 1990 325i (Soon To Be 335i)

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              #7
              Originally posted by Spinning Tires View Post
              Stock cam is the best unless you find a company that makes a turbo cam cause an aftermarket N/A cam will NOT work well
              again, not true.

              convention wisdom pwns j00.
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                #8
                Most companies making an N/A came make the lobe separation too big causing the built up exhaust pressure to back feed through the intake
                Last edited by Spinning Tires; 03-19-2009, 02:51 PM.
                First: 1984 318i
                Second: 1987 325
                Third: 1987 325is
                Current: 1990 325i (Soon To Be 335i)

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                  #9
                  if you have that much exhaust back pressure then your exhaust is too small.

                  look at what the guys in scandanavia are running. there is a reason people here struggle to produce 300whp and people over there do 500whp in their sleep.
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                    #10
                    Originally posted by StereoInstaller1 View Post
                    Yes, you should have a cam.
                    Turbocharging is a little outside of my scope of expertise but I must agree here always have a cam in your engine, I don't think they will run at all otherwise.

                    I have been told by a power-plant wizard that big overlap is not your friend with turbocharged engines and delaying intake opening is the trick (this is hearsay, take it with a grain of salt then go research it thoroughly).
                    I'm Not Right in the Head | Random Rants and other Nonsense1st Order Logic Failure: Association fallacy, this type of fallacy can be expressed as (∃xS : φ(x)) → (∀xS : φ(x)), meaning "if there exists any x in the set S so that a property φ is true for x, then for all x in S the property φ must be true".

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                      #11
                      what duration of cam do you recommend?

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                        #12
                        what kind of motor is this for?
                        First: 1984 318i
                        Second: 1987 325
                        Third: 1987 325is
                        Current: 1990 325i (Soon To Be 335i)

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                          #13
                          Originally posted by nando View Post
                          if you have that much exhaust back pressure then your exhaust is too small.

                          look at what the guys in scandanavia are running. there is a reason people here struggle to produce 300whp and people over there do 500whp in their sleep.
                          exhaust pressure before the turbo is always going to be more then intake pressure
                          First: 1984 318i
                          Second: 1987 325
                          Third: 1987 325is
                          Current: 1990 325i (Soon To Be 335i)

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                            #14
                            Originally posted by Spinning Tires View Post
                            what kind of motor is this for?
                            1990 325i so m20b25

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                              #15
                              heh, for some reason I thought you were building a 24v motor.

                              I still would reccomend a decent cam. what are you using this for? I'd look into what blacktrail69 used, he was making over 300whp at 10psi with a 280 degree or so duration catcams. The shrick 288 would also be a good choice if it's more of a race/fun car than a DD.
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