1. The Turbo Forums - The discussion board for both hard core and beginner turbocharged vehicle enthusiasts. Covering everything from stock turbocharger cars, seriously fast drag racers, boats, motorcycles, and daily driver modified turbo cars and trucks.
    To start posting in our forums, and comment on articles and blogs please

    IF YOU ARE AN EXISTING MEMBER: You can retrieve your a password for your account here: click here.

What makes a cam a "TURBO" cam...

Discussion in 'Turbo Tech Questions' started by 93lxhorse, Sep 21, 2003.

Page 1 of 3

  1. 93lxhorse

    Joined:
    Jun 19, 2003
    What makes a cam a "TURBO" cam...

    What makes a cam REAL GOOD for a turbo?
    What makes it ACCEPTABLE?
    What is an absolute NO NO?

    The reason I am asking is because after 2 headgaskets in 2 weeks, I am looking into other factors, like maybe my compression ratio is not what I thought it would be, or maybe I have the wrong cam, etc.

    The car is back together and runs fine, but still has a hint of detonation unless I use a couple of gallons of race gas.


    Does this sound like a turbo cam to you guys?

    It is a small base circle cam, and it's in my 357 motor.

    ............................INT................EXH
    GROSS LIFT......... 556 ...............556
    Duration at .006..273.................273
    Duration at .050..224.................224

    LSA 114

    If you need the valve timing to be sure, I can provide that too !
     
    93lxhorse, Sep 21, 2003
    #1

  2. Mach1

    Joined:
    Sep 14, 2003
    What makes a cam a "TURBO" cam...

    I would have to say thats a turbo cam. Who built your motor, what cc heads? what pistons? was your block decked?
     
    Mach1, Sep 21, 2003
    #2

  3. JoeSmith

    Joined:
    Aug 3, 2003
    exhaust duration...

    is more duration on the exhaust side not required on a turbo motor??? most engine builders put about 6-8 degrees more on exhaust side on natural applications............

    .....what's the norm with turbos???
     
    JoeSmith, Sep 21, 2003
    #3

  4. turbostang

    Joined:
    Jun 29, 2003
    What makes a cam a "TURBO" cam...

    Chris.. I am still waiting to get my cam card back.. I lean toward the "more duration" on the exhaust side.. I will call ya tomorrow sometime..
     
    turbostang, Sep 21, 2003
    #4

  5. 93lxhorse

    Joined:
    Jun 19, 2003
    What makes a cam a "TURBO" cam...

    Ok, I found mine, so I got all the info.

    Yeah I have always seen turbo cams having a bit more exhaust duration, and sometimes lift, as well.

    I let my engine builder get Comp Cams to recommend one. I may have screwed up by not doing my own research....
     
    93lxhorse, Sep 21, 2003
    #5

  6. turbostang

    Joined:
    Jun 29, 2003
    What makes a cam a "TURBO" cam...


    well.. I did the same.. I went to someone else for advice.. it worked for me.. I do know this.. my cam is nothing like yours.:shocked:
     
    turbostang, Sep 21, 2003
    #6

  7. ShaneH

    Joined:
    Feb 3, 2003
    What makes a cam a "TURBO" cam...

    More exhaust duration does nothing generally for a turbo combo. The trend now for turbo cam grinders is more intake duration and lift with a wide lobe seperation to increase cylinder pressure.
     
    ShaneH, Sep 22, 2003
    #7

  8. TRAXX

    Joined:
    Mar 2, 2003
    TRAXX, Sep 22, 2003
    #8

  9. Jimmy

    Joined:
    Jan 31, 2003
    What makes a cam a "TURBO" cam...

    usually the more intake duration/lift is due to an inefficient top end so they use more duration/lift to fill the cylinder as i am told. The more equal your intake/exhaust pressure ratio is the more your cam will look like a single pattern cam
     
    Jimmy, Sep 22, 2003
    #9

  10. 93lxhorse

    Joined:
    Jun 19, 2003
    What makes a cam a "TURBO" cam...

    Well I have extremely good flowing heads and intake....AFR 205 and TFS R .. so maybe that's why the cam is a single pattern.

    One thing is for sure... the cam gives up at 5800 RPM, but after all, I did specify a cam that would make all its power between 3K and 6K, and that's what I got.
     
    93lxhorse, Sep 22, 2003
    #10

  11. CASTURBO

    Joined:
    Mar 26, 2003
    What makes a cam a "TURBO" cam...

    How do you know the cam "gives up at 5800 RPM" and it's not the turbo running out? What size turbo, what size turbine?

    On the head gasket issue, what is your timing curve look like? I resolved a HG issue once the timing was softened at the torque peak. Making full boost beginning low in the RPM makes for a unique timing curve much UNLIKE a blower or even N/A.
     
    CASTURBO, Sep 22, 2003
    #11

  12. 93lxhorse

    Joined:
    Jun 19, 2003
    What makes a cam a "TURBO" cam...

    When I ran the motor N/A for a few months, that's what the dyno graph showed.

    The turbo is a T66, the A/R is .81.

    And yes, I have gotten a bit more conservative at the torque peak with the timing.
     
    93lxhorse, Sep 22, 2003
    #12

  13. Erik88GT

    Joined:
    Jan 28, 2003
    What makes a cam a "TURBO" cam...

    Here's some specs that Comp Cams lists for a BB chevy turbo cam (part number 11-400-4) to give you an idea:

    Intake @ .050 226
    Exhaust @ .050 218
    Intake Lift .525
    Exhaust Lift .514
    Lobe Sep. 115

    The note for the cam says, "Baseline turbo grind. Short exhaust produces more velocity, helps increase boost."

    I don't know what "helps increase boost" is supposed to mean, but I think the shorter exhaust makes sense on a turbo motor.
     
    Erik88GT, Sep 23, 2003
    #13

  14. JoeSmith

    Joined:
    Aug 3, 2003
    what intake you using?

    just curious.....
     
    JoeSmith, Sep 23, 2003
    #14

  15. 93lxhorse

    Joined:
    Jun 19, 2003
    Re: what intake you using?

    Well I have extremely good flowing heads and intake....AFR 205 and TFS R .. so maybe that's why the cam is a single pattern.
     
    93lxhorse, Sep 23, 2003
    #15

  16. ShaneH

    Joined:
    Feb 3, 2003
    What makes a cam a "TURBO" cam...

    Actually, Ford's have a pretty good intake port and a weak exhaust port. Even so, the trend for a really good turbo cam for the small block Ford is to bias the intake side. This lets the turbo cram the chamber plumb full, which in turn produces higher velocity out of the exhaust port when it opens spooling the turbo easier. From my experience, the cams that bias the intake will spool the turbo faster than the ones that don't.
     
    ShaneH, Sep 23, 2003
    #16

  17. White88GT

    Joined:
    Jan 31, 2003
    What makes a cam a "TURBO" cam...

    I just got my turbo cam from Kenny Duttweiler yesterday. It's for a 383 chevy with a single 80mm. Solid roller.
    intake @ .050 236deg
    Exh @ .050 242 deg
    112 lobe seperation
    has 14 deg overlap.

    The trend to use more intake duration has been around forever. Was used alot back in the days when heads really sucked. I have a 351 W turbo cam from 15 years ago. I'll have to dig it out and measure it.
     
    White88GT, Sep 23, 2003
    #17

  18. white95v6

    Joined:
    Jul 13, 2003
    What makes a cam a "TURBO" cam...

    dang 14 deg of overlap. :shocked: that is a whole lot in a turbo set up. but heck what do i know.:taunt:
     
    white95v6, Sep 23, 2003
    #18

  19. White88GT

    Joined:
    Jan 31, 2003
    What makes a cam a "TURBO" cam...

    Thats what I thought too. But I've had 3 cam people tell me that overlap isnt necessarily a bad thing on a turbo. Guess I'll find out now wont I..LOL
     
    White88GT, Sep 23, 2003
    #19

  20. Jimmy

    Joined:
    Jan 31, 2003
    What makes a cam a "TURBO" cam...

    my cam is a single pattern and it has overlap....the old school of thinking has more overlap

    the new school has none or even negative overlap

    My friends motor didn't have a very common turbo cam and it made 1200hp on pump with 20psi

    www.montygwilliams.com

    too bad car is gone now though, it was a hell of a ride :D
     
    Jimmy, Sep 23, 2003
    #20
Page 1 of 3
Loading...
Similar Topics - cam TURBO cam Forum Date
Seeking Input on Turbo / Cam Turbo Tech Questions Oct 27, 2022
Big cam vs turbo cam for small engine Turbo Tech Questions Sep 15, 2021
Cam recommendation 383 Mopar single turbo Turbo Tech Questions May 30, 2019
Loading...
bridal-shoal