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  1. #1
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    N52, N54 and N55 EXHAUST Camshafts

    So my interest has been the N52/N55/S55 Valvetronic Intake system and finding a way to increase the intake valve lift on these engines by using my MILVs. (+1mm additional intake valve lift and 2-3* increased duration)

    So the next question is, What about the exhaust cam?

    What I have found out when looking at the Exhaust cam of the N52, N54, N55 and S55 engines.
    -all use the same exhaust camshaft clamshell/bearing ledge
    -all use the same hydraulic lifters
    -all use the same rocker arms, 1.66:1 ratio
    -the N55 and S55 share the same exhaust cam

    What is the actual specifications of these cams? Cam lift and duration?
    Will they interchange? What are, if any, the physical differences?

    I bought 4 different exhaust camshafts that I am sending out to be 'Cam Doctored'.
    Used N52, N54, N55 and a new N52 cam from Russia, reportable an OEM supplier.

    Any guesses as to the specs and differences?
    You would think that the turbo engines would have more exhaust cam lift and duration for the higher power output. Or maybe the N/A N52 will have more exhaust cam lift and duration due to it's higher redline.

    My simple HF digital caliper shows that all 4 camshafts have the same 0.23" cam lift = 9.698mm with the 1.66:1 rocker arms.
    Close enough to BMW's 9.7mm reported value.

    Can I get an additional +1mm exhaust valve lift and 2-3* duration from the Exhaust Cam?
    Is there enough metal on the lobes for a re-grind?

    Any thoughts or comments?
    MILVS- +1mm Increase Intake Valve Lift for N52, N55, S55, N20 Engines
    http://www.bimmerboost.com/showthrea...ift-more-power
    www.bimmerMILVS.com
    Coming soon: +1mm lift Exhaust cam for N52 and N55
    and soon- B58 MILVS with +1mm increase intake valve lift

  2. #2
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    Click here to enlarge Originally Posted by CobraMarty Click here to enlarge
    I bought 4 different exhaust camshafts that I am sending out to be 'Cam Doctored'.
    Where did you send them to?

    This is pretty darn interesting though. Want to see if there is any major difference if any among them.

  3. #3
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    It was tough to find an independent shop that has a 'Cam Doctor' and would even do this work.

    They are going out to SRE in AZ.

    Sure there are Schrick and CAT cams and we know those numbers for the N54, but what is the stock N54 exhaust cam specs, What was the starting point?
    And more importantly, What are the stock N52 and N55/S55 exhaust cams? You can't do a re-grind without knowing where you are starting at.
    MILVS- +1mm Increase Intake Valve Lift for N52, N55, S55, N20 Engines
    http://www.bimmerboost.com/showthrea...ift-more-power
    www.bimmerMILVS.com
    Coming soon: +1mm lift Exhaust cam for N52 and N55
    and soon- B58 MILVS with +1mm increase intake valve lift

  4. #4
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    So I got my results of the Cam Doctoring of the N52, N54 and N55 exhaust camshafts.

    All the cams had the same cam lift- 0.230 +/- 0.002 which is right at 9.70mm.

    Duration of stock exhaust cams is as follows- at 0.020, 0.050 and 0.200

    N52 used- 221.2*, 190.3*, 74.1*
    N52 new Russian- 222.0*, 189.7*, 72.3*

    N54 used- 216.5*, 192.9*, 75.8*
    N55 used- 216.4, 192.9*, 76.9*

    For other aftermarket available N54 cams-

    N54 CAT 239/263 stock- 211* @ 0.020
    N54 CAT 267/266- 216* @ 0.020
    N54 CAT 274/270- 220* @ 0.020
    N54 CAT 282/274- 224* @ 0.020

    Schrick N54 264- ?264* @ 0.020
    Schrick N54 268- ?268* @ 0.020
    MILVS- +1mm Increase Intake Valve Lift for N52, N55, S55, N20 Engines
    http://www.bimmerboost.com/showthrea...ift-more-power
    www.bimmerMILVS.com
    Coming soon: +1mm lift Exhaust cam for N52 and N55
    and soon- B58 MILVS with +1mm increase intake valve lift

  5. #5
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    So the real question is,

    What is the Exhaust Valve to Piston clearance at TDC?

    This is when the exhaust valve is usually fully open and the piston is closest to the exhaust valve.
    MILVS- +1mm Increase Intake Valve Lift for N52, N55, S55, N20 Engines
    http://www.bimmerboost.com/showthrea...ift-more-power
    www.bimmerMILVS.com
    Coming soon: +1mm lift Exhaust cam for N52 and N55
    and soon- B58 MILVS with +1mm increase intake valve lift

  6. #6
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    According to Schrick, their N54 low lift cam, 10.5mm lift, will work with stock pistons.

    According to ABRhouston, the Schrich N54 high lift cam, 11.0mm lift, requires pistons to be flycut.

    So for the exhaust cam with 0.230 inch cam lift which produces 9.7mm exhaust valve lift.
    If add 0.019 inch to cam lift, to 0.249 inch, the total exhaust valve lift would be 10.499mm.

    Now to see if I can get the cam reground to have 0.249 inch cam lift.
    MILVS- +1mm Increase Intake Valve Lift for N52, N55, S55, N20 Engines
    http://www.bimmerboost.com/showthrea...ift-more-power
    www.bimmerMILVS.com
    Coming soon: +1mm lift Exhaust cam for N52 and N55
    and soon- B58 MILVS with +1mm increase intake valve lift

  7. #7
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    1 out of 1 members liked this post. Yes Reputation No
    Got the 4 cams back from their vacation out west getting measured.
    Now to package up the used N52 and new 'Russian' N52 cams and send them to the cam grinder.

    So due to piston to valve clearance at TDC concerns and to stay safe, looking to increase exhaust valve lift +0.8mm, 9.7mm to 10.5mm
    MILVS- +1mm Increase Intake Valve Lift for N52, N55, S55, N20 Engines
    http://www.bimmerboost.com/showthrea...ift-more-power
    www.bimmerMILVS.com
    Coming soon: +1mm lift Exhaust cam for N52 and N55
    and soon- B58 MILVS with +1mm increase intake valve lift

  8. #8
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    the question is does the head even flow more CFM at more lift? or should we have ported head to benefit from the extra lift?

  9. #9
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    Click here to enlarge Originally Posted by CobraMarty Click here to enlarge
    So I got my results of the Cam Doctoring of the N52, N54 and N55 exhaust camshafts.

    All the cams had the same cam lift- 0.230 +/- 0.002 which is right at 9.70mm.

    Duration of stock exhaust cams is as follows- at 0.020, 0.050 and 0.200
    Great data and work!!!

  10. #10
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    Click here to enlarge Originally Posted by CobraMarty Click here to enlarge
    Got the 4 cams back from their vacation out west getting measured.
    Now to package up the used N52 and new 'Russian' N52 cams and send them to the cam grinder.

    So due to piston to valve clearance at TDC concerns and to stay safe, looking to increase exhaust valve lift +0.8mm, 9.7mm to 10.5mm
    Nobody else thought of doing this? You're breaking new ground.

  11. #11
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    Stock lift = 0.38", proposed lift = 0.41"
    According to the stock exhaust flow data from ABR N54/N55 would go from 153/154 to 155/156 on a stock head.
    https://www.bimmerboost.com/showthre...ight=Head+flow

  12. #12
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    And should add 2* duration.

    Cam lift 0.230" x Rocker ratio 1.66 x 25.4mm/in
    stock - 0.230" x 1.66 x 25.4mm/in = 9.6977mm exhaust valve lift
    modified +0.19" cam lift - 0.249" x 1.66 x 25.4mm/in = 10.4988mm exhaust valve lift
    MILVS- +1mm Increase Intake Valve Lift for N52, N55, S55, N20 Engines
    http://www.bimmerboost.com/showthrea...ift-more-power
    www.bimmerMILVS.com
    Coming soon: +1mm lift Exhaust cam for N52 and N55
    and soon- B58 MILVS with +1mm increase intake valve lift

  13. #13
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    1 out of 1 members liked this post. Yes Reputation No
    Valve lift For other aftermarket available N54 cams-
    N54 CAT 239/263 stock- 211* @ 0.020 9.7mm valve lift
    N54 CAT 267/266- 216* @ 0.020 10.0mm valve lift
    N54 CAT 274/270- 220* @ 0.020 10.25mm valve lift
    N54 CAT 282/274- 224* @ 0.020 10.50mm valve lift

    Schrick N54 264- ?degree* @ 0.020 low lift=10.5mm high lift=11.0mm
    Schrick N54 268- ?degree* @ 0.020
    MILVS- +1mm Increase Intake Valve Lift for N52, N55, S55, N20 Engines
    http://www.bimmerboost.com/showthrea...ift-more-power
    www.bimmerMILVS.com
    Coming soon: +1mm lift Exhaust cam for N52 and N55
    and soon- B58 MILVS with +1mm increase intake valve lift

  14. #14
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    1 out of 1 members liked this post. Yes Reputation No
    The cam profile on all N5X cams (intake or exhaust) are asymmetrical. The ramp during opening is more aggressive vs the ramp during closing.

    For the N53 exhaust cam, I can share this info. Cam lift: 0.232" about 0.002" more than the N54 exhaust cam.
    0.005" cam lift = 255 degrees
    0.040" cam lift = 197 degrees
    0.100" cam lift = 152 degrees

    Here is my N54 exhaust cam info:
    0.005" cam lift = 242 degrees
    0.040" cam lift = 196 degrees
    0.100" cam lift = 156 degrees

  15. #15
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    Prefix changed to general as this seems to include all the motors.

  16. #16
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    1 out of 1 members liked this post. Yes Reputation No
    This is some great technical info. Thanks @CobraMarty for the effort in getting the stock cams tested.

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