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Thread: Built motor, big turbo, really slow. Please help.

  1. #41
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Built motor, big turbo, really slow. Please help.

    Thanks for that clarification Todd. I guess they unified the solenoids in 89?

  2. #42
    Moderator Turbo Mopar Staff Vigo's Avatar
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    Re: Built motor, big turbo, really slow. Please help.

    Quote Originally Posted by 94NDTA View Post
    Alright, update time. Pulled the plugs, they looked good,fuel 45psi at idle with vacuum line still plugged in, his MODIS read ~11 for a/f ratio at wot. Vacuum was around 15-16 at idle.

    checked all the piping as best we could, and did not notice any leaks. Also checked vacuum as best we could. Car originally had an engine fire before he bought it, so the wiring harness and all the vacuum lines are new. We looked at the diagrams again and everything appears to be in order.

    He set up the wastegate 2 years ago, and doesn't remember exactly how he set it up except it had a good amount of tension on it when he adjusted it.

    we are wondering if it is not opening up to early. In this video, I swear I can hear it opening as it drops boost. Now, this could be something else, but I can hear it relieving pressure somewhere as it reaches 16 psi.

    VIDEO
    http://youtu.be/G11PcY1Dc7Y

    - - - Updated - - -


    We tried this, and it made no difference. It stayed at 7 or 8, just like in the video I posted when he hits 3rd.
    Couple of points.

    1: the video you just posted isnt EXACTLY the test i had in mind because the engine was still at a low enough rpm that it could not quickly spool the turbo at that rpm. For a more accurate result i would try even higher in the rpms while making sure to go from low-load to FLOORED as quickly as possible. To me it still looks like exactly what i was hypothesizing, that there is a boost spike caused by a delay or restriction in the pneumatic circuit between the intake manifold and wastegate 'can'.

    2. The leaking you hear sounds like a blow off valve or loose coupler. It does not sound like flow out of the wastegate. So i do think you have more than one issue here, but i think the boost spike is more important to diagnose than the leak at this point.

    Dont push the red button.You hear me?

  3. #43
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    Re: Built motor, big turbo, really slow. Please help.

    Quote Originally Posted by Tbird232ci View Post
    It's hard to say you deal with SBC's and then say LT1's. Most LT1 guys (myself included) hate getting compared to the SBC. "Just put a 3/4 race cam in it and dial in the distributor. Worked on my 76 Camura", "I got a Gm Goodwrench tree fitty crate engine from Summit. Makes like fo hunnit horsepower!"
    Funny part of this story is the real LT1 is so 1970! I'm sure plenty of the old school guys turn their noses up on the newer LT1's. Don't confuse LT1 with Type LT Camaro's circa late 72-78 turds. The LT1 was the real deal. It took over two decades for later generation LS SBC's to surpass the original performance of the 1970 LT1.
    Sorry for the hijack. T-bird 232 must have struck a nerve (lol).
    Todd

  4. #44
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    Re: Built motor, big turbo, really slow. Please help.

    Quote Originally Posted by 4 l-bodies View Post
    Funny part of this story is the real LT1 is so 1970! I'm sure plenty of the old school guys turn their noses up on the newer LT1's. Don't confuse LT1 with Type LT Camaro's circa late 72-78 turds. The LT1 was the real deal. It took over two decades for later generation LS SBC's to surpass the original performance of the 1970 LT1.
    Sorry for the hijack. T-bird 232 must have struck a nerve (lol).
    Todd
    Well, since I've seen this debated over the forums a few times, I can tell you that the original LT-1 isn't really a better performer by any means. There was an article a few years back where the compared a LT-1 to the LT1, LT-1 being the original, and the numbers were incredibly close. The LT-1 had an electric water pump on it, where the LT1 did not. Considering that guys have picked up about 8-12rwhp with an electric water pump on LT1 cars, I'd say that is a big factor in the numbers.



    That is from the article in a Corvette magazine comparing the two.

    I understand striking a nerve, but it goes both ways, lol. I get irritated when older guys in muscle cars trash talk newer cars like my 97 Trans Am. They use a similar argument, saying it took all these years to out perform the engines of yesteryear, but you have to consider, in 1970, they had no emissions regulations, no EPA required fuel economy, leaded fuel, and government bearing down financially. Look at the power numbers shortly after. In 75, GM's beloved Corvette dropped to 165 horsepower with a 350.

    So it was only the 2nd generation of SBC to meet/surpass the original LT-1. If the LT1 doesn't do a well enough job for ya, look up the LT4. Same engine with different heads, cam and intake.

    I too apologize for the hijack. I do enjoy a good debate.

  5. #45
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    Re: Built motor, big turbo, really slow. Please help.

    Just to add on my Silverado SS every one calls my motor a SBC. Umm no it is a LS engine. And no offense to anyone here but the lt1 is a horrible motor to build from. The internals are weak. Surprisingly the lt1 only has 2 bolt mains.
    [SIGPIC][/SIGPIC]

  6. #46
    Supporting Member Turbo Mopar Contributor zin's Avatar
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    Re: Built motor, big turbo, really slow. Please help.

    Quote Originally Posted by 94NDTA View Post
    It has an after market adjustable wastegate, the vacuum line goes directly to the waste gate actuator on the fender wall. I was under the impression that the computer was controlling the boost. The tune he had was supposed to be set at 22 psi max. Forgive me if I am getting any if the terms wrong.
    From what I'm seeing here, it sounds like it's a problem with the wastegate solenoid routing (the piece on the fender well). Assuming the solenoid is functioning (the rarely fail), if the cal and the hose routing aren't in agreement, you could easily end up with just the boost the actuator on the turbo will allow (roughly 8psi).

    There are a couple of routing options, TI and TII, unfortunately they are 180* different from each other, and both were used by the factory, but any way you go, the cal and the routing have to be in agreement or you'll not get "what you paid for".

    I'm guessing that you routed it to what was shown on the vacuum routing label, but it's in conflict with the custom tune. Correct that and it'll be a whole other animal!

    Mike
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  7. #47
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    Re: Built motor, big turbo, really slow. Please help.

    Quote Originally Posted by 85boostbox View Post
    Just to add on my Silverado SS every one calls my motor a SBC. Umm no it is a LS engine. And no offense to anyone here but the lt1 is a horrible motor to build from. The internals are weak. Surprisingly the lt1 only has 2 bolt mains.
    The only time the internals are a problem is if you're going forced induction.They have hypoeutectic pistons and 10.5:1 compression. Most don't recommend going above 5psi of boost on stock pistons.. H/C/I guys in the 10's with stock internals. Got a bunch of guys in the single digits with a non-filled block, 383 stroker with nitrous or forced induction. Very seldom do you see someone blow one up without doing something stupid.

    Also, while the LS motor isn't technically a SBC, it still is considered a small block. It's just a different generation.

  8. #48
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    Re: Built motor, big turbo, really slow. Please help.

    Quote Originally Posted by Tbird232ci View Post
    It's hard to say you deal with SBC's and then say LT1's. Most LT1 guys (myself included) hate getting compared to the SBC. "Just put a 3/4 race cam in it and dial in the distributor. Worked on my 76 Camura", "I got a Gm Goodwrench tree fitty crate engine from Summit. Makes like fo hunnit horsepower!"

    Still have the under hood vacuum diagram after the fire? The T1 and T2 cars use a different boost control solenoid and vacuum line routing to it. Wonder if it could be possible that it is stuck.
    I and he work on both, that's why I lumped them together.
    Quote Originally Posted by 4 l-bodies View Post
    Funny part of this story is the real LT1 is so 1970! I'm sure plenty of the old school guys turn their noses up on the newer LT1's. Don't confuse LT1 with Type LT Camaro's circa late 72-78 turds. The LT1 was the real deal. It took over two decades for later generation LS SBC's to surpass the original performance of the 1970 LT1.
    Sorry for the hijack. T-bird 232 must have struck a nerve (lol).
    Todd
    You mean LT-1 I will take getting 30 mpg to the track and running faster times than the old LT-1
    Quote Originally Posted by 85boostbox View Post
    Just to add on my Silverado SS every one calls my motor a SBC. Umm no it is a LS engine. And no offense to anyone here but the lt1 is a horrible motor to build from. The internals are weak. Surprisingly the lt1 only has 2 bolt mains.
    Not all are 2 bolt mains, some years came with 4

    it doesn't matter anyways, as the newest LT1 in the C7 puts them all to shame . Except mine >

    as as far as trouble shooting the motor, it is on hiatus for a bit. I need to focus on getting my car ready for the year.

  9. #49
    Moderator Turbo Mopar Staff Vigo's Avatar
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    Re: Built motor, big turbo, really slow. Please help.

    Oh, well that's good since i guess it means you arent annoyed about people BSing about old chevys in your 'diagnose my dodge' thread.

    Dont push the red button.You hear me?

  10. #50
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    Re: Built motor, big turbo, really slow. Please help.

    Quote Originally Posted by 94NDTA View Post
    I and he work on both, that's why I lumped them together.

    You mean LT-1 I will take getting 30 mpg to the track and running faster times than the old LT-1

    Not all are 2 bolt mains, some years came with 4

    it doesn't matter anyways, as the newest LT1 in the C7 puts them all to shame . Except mine >

    as as far as trouble shooting the motor, it is on hiatus for a bit. I need to focus on getting my car ready for the year.
    The only 4 bolt main lt motors that I knew of was the lt4.
    [SIGPIC][/SIGPIC]

  11. #51
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    Re: Built motor, big turbo, really slow. Please help.

    Quote Originally Posted by 85boostbox View Post
    The only 4 bolt main lt motors that I knew of was the lt4.
    All lt1s in vettes are 4 bolt, and some 97's got left overs with 4 bolt mains.

    - - - Updated - - -

    Quote Originally Posted by Vigo View Post
    Oh, well that's good since i guess it means you arent annoyed about people BSing about old chevys in your 'diagnose my dodge' thread.
    I will talk cars all day long, doesn't matter what kind it is

  12. #52
    Supporting Member Turbo Mopar Contributor
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    Re: Built motor, big turbo, really slow. Please help.

    Any updates on this issue?

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