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Thread: What am I doing wrong?

  1. #1

    What am I doing wrong?

    2 weeks ago tomorrow, I blew both head gaskets.



    2 days ago, I finished replacing both gaskets with Felpro replacements.

    I decided to take the TGP to class today in Indy. About 10 miles outside of Indy, some dude in a Mazda wanted to get his ass kicked. Middle of second gear, 50% throttle (too afraid to get on it all the way because I don't want to blow it up). 4psi of boost after a couple of seconds, into third. Smashed his ass.

    Then dude starts flashin me. I see in his headlights a shit ton of smoke. I pull it over, shut it off, and sure enough, theres a lot of smoke coming out the exhaust, and under the hood. So I pop out the dipstick and the oil level is normal, a little low maybe. Last time this happened, coolant mixed with oil and the radiator exploded from the added pressure when the gasket blew. This time, I didnt even realize it blew. But I'm sure it blew because I can see pulses of smoke coming up out of the valve cover.

    So I start it up and turn around to drive the half a mile back to the nearest gas station. Lots of smoke, running on 5 cylinders. I pull in and check the oil level again. 1 qt low. Still no coolant in the oil.

    I figure I blew a gasket again, but I don't know where all the oil is going. Is the oil burning off in the combustion chamber and that's where all the smoke is coming from? Did a piston ring blow and I'm getting some serious blow-by?

    The AFR was about 11.5, the coolant temp was 200*, I pulled 5* of spark timing after the first gasket blew. I was running 4psi when it happened.

    The car is sitting in Indy right now. Tomorrow I'll tow it back home.

    Are the factory gaskets (and replacements) really so weak that they are unable to handle 4psi of boost?

    1990 ASC/McLaren Turbo Grand Prix 3500 swap GT3076R turbo 40lb/hr injectors FMIC LX9 coils Megasquirt2 v3.0

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  3. #2
    Quote Originally Posted by Jonpro03 View Post
    2 days ago, I finished replacing both gaskets with Felpro replacements.
    Your problem is right in your first sentence. My felpro HG lasted ~300km also. You can find a lot of horror story about felpro HG on this forum also.

    Go with 04+ GM graphite gasket or cometic with arp head studs and you will never have to worry about HG anytime soon.

    If you plan to run around 10-12psi, there is no reason the stock graphite gasket won't work, unless you have something else terribly wrong.

  4. #3
    Car is finally back in the garage. Tomorrow I'll tear it down and find out what happened.

    1990 ASC/McLaren Turbo Grand Prix 3500 swap GT3076R turbo 40lb/hr injectors FMIC LX9 coils Megasquirt2 v3.0

  5. #4
    Bisong eater :P CNCguy's Avatar
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    If you lost the middle cylinders again, my guess would be lean or too much timing. From my understanding, the center cylinders tend to run leaner due to plenum design. With Aaron blowing the same cylinders, it would seem to make sense. Does MS allow you to do cylinder skewing?

    At some point I want to verify this with some engine dyno testing/tuning with individual EGTs.

  6. #5
    Here is what I'm running for a individual cylinder knock control: http://www.jandssafeguard.com/

    I'm also running MS3+MS3X

  7. #6
    Sorry, MS2 here. That means batch fire. I've been running it very rich though. Maybe I should go even richer?

    I don't know, I'll wait and see what the problem is before I do anything.

    1990 ASC/McLaren Turbo Grand Prix 3500 swap GT3076R turbo 40lb/hr injectors FMIC LX9 coils Megasquirt2 v3.0

  8. #7
    I'm running batch fire also. No problem running the J&S safeguard with batch fire if that's what you were thinking. 11.5 AFR is just fine, how many degree of timing ?

    I have a feeling your problem is more then HG then the tune, but as you said we will see

    Just trying to help there
    Last edited by 90BlueZ; 04-23-2011 at 10:55 AM.

  9. #8
    I appreciate the help. There's not a lot of MS 3x00 guys around.

    Here's the spark table I was using when it happened.



    Are you running a boosted engine? Care to share your tables?

    1990 ASC/McLaren Turbo Grand Prix 3500 swap GT3076R turbo 40lb/hr injectors FMIC LX9 coils Megasquirt2 v3.0

  10. #9
    I pm'ed you my MSQ. I'm running a 3400 with 10lbs boost. Lot more advance too... about same afr around 11.6 at 10psi...

    More info here: http://www.v6z24.com/registry/91z24

  11. #10
    Turbo3500.zip

    Here's the AFR and Spark maps I'm using now if you want to go over them.

    I'll have a looks see at yours! Thanks!

    1990 ASC/McLaren Turbo Grand Prix 3500 swap GT3076R turbo 40lb/hr injectors FMIC LX9 coils Megasquirt2 v3.0

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