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Thread: turbos and timing

  1. #1
    what is the best way to go on a twin turbo innercooled set up locked or not

  2. #2
    How much boost and compression?
    Pump Gas?

  3. #3
    sorry info you need more info
    8 to 1
    hyd roller
    12 to 14 lbs inner cooled
    pump gas
    twin carbed
    alum heads
    forged everything
    looking for 900 hp

  4. #4
    84 camaroturbo
    on my twin turboed camaro i bought a msd box that will retard the timing a curtain degree for every pund of boost. at full boost you will want about 18 degrees. but mine is intercooled with meth injection.

  5. #5
    on my twin turboed camaro i bought a msd box that will retard the timing a certain degree for every pound of boost. At full boost you will want about 18 degrees. but mine is intercooled with meth injection.
    Were you getting detonation that prompted you to cut the timing back that far?
    I bet those headers really glow with that retarded timing.
    Optimizing the timing curve is one of the areas where the EFI really shines. I've got it so that at a crusing speed of 3500 rpm and 10.5 " vaccuum it's at 42 degrees advance and the timing decreases as the manifold pressure increases. It reads the MAP sensor and adjusts to whatever you program it to.
    I run 32 degrees advance at 20# boost / 7000 rpm.
    Unless you're getting detonation you'll want as much timing as the motor can take for max power.
    Some EFI systems tie into a knock sensor and keep the timing advanced as far as possible just below the detonation threshhold.

  6. #6
    Unchained is right. At part throttle, being low compression, turbo motors like a lot of advance, but can't handle it as the boost comes on. When I did my last turbo boat, I used a GM HEI, and I used a vacuum advance can (79 chev p/u with 350 I think) that actually was a retard unit. I locked out the centrifugal advance and set the timing at 40deg. As long as the motor was pulling vacuum it would stay there but when it went to 0 and then on to boost it would pull the timing back to about 28. It was a bit hard to start when warm though.... The only down side I can see is that when you back off the throttle the timing will come back up instantly which could spell trouble. You may have to go the parts house with a vacuum pump in hand to get the right part but it does work. MSD is still the way to go, but I think retarding back to 18 degrees will be putting fire out the exhaust.
    On my turbo VW sandrail, I run locked out 22deg. with 10psi.

  7. #7
    set it at 30 and lock it out

  8. #8
    Did you move to North Carolina ?

  9. #9
    84 camaroturbo
    The map on my car is only a one bar so it wont read boost. before i had my meth injection i would melt the pistons and rings out of it. so the people on have some crazy turbo cars said to retard it to 18 at full boost. now with my meth and intercooler it is at 29 and pulls like hell.

  10. #10
    I'm happy with a MSD 6BTM. The cat's meow for carb setups. My distributor is set at 8 BTDC and curved to 38 BTDC at 3500 RPM. You will want the advance to get the turbos spooled and good performance off of idle. The BTM cuts from 0 to 3 degrees per psi of boost with theturn of a knob on the dash. I pretty much keep it at 1 deg/psi with good fuel and more with pump gas. Read the plugs to find where it's happy.

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