Patrick's Twin Turbo 350 Build Thread

Discussion in 'Small Block Tech' started by patwhac, Apr 8, 2019.

  1. sean Buick 76

    sean Buick 76 Buick Nut

    Nice fab work!
     
  2. patwhac

    patwhac Well-Known Member

    Thanks all!! Only a few more things left before I fire it up!
     
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  3. sean Buick 76

    sean Buick 76 Buick Nut

    Once you feel the boost kick in you will be addicted.
     
  4. patwhac

    patwhac Well-Known Member

    Well I'm almost at the precipice. Stayed up late last night finishing all of the wiring:

    [​IMG]

    [​IMG]

    Planning to fire it either this weekend or the next!
     
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  5. Buick#455

    Buick#455 Well-Known Member

    I say fire it up this weekend
     
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  6. patwhac

    patwhac Well-Known Member

    If I'm not mistaken, you run a twin turbo 455 right? Any tips for boost haha?
     
  7. sean Buick 76

    sean Buick 76 Buick Nut

    His is a turbo 350 as well... I sold him some nice ported iron heads that should work well.
     
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  8. Buick#455

    Buick#455 Well-Known Member

    What kind of tips you want? Any questions, just ask. Glad to help out anyway I can
     
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  9. patwhac

    patwhac Well-Known Member

    Awesome thank you!

    Here are some off the top of my head:

    1. Are you running an intercooler and/or meth injection? I plan on running both which some say is overkill for my tame (6-8psi) boost level. I say it can't hurt. If intercooled, are you running two singles or one 2-1. How did you mount it in a Skylark? In the grille area in front of the radiator?

    2. Are you running an oil cooler? If your car is a street car I could see not running one. But since I plan to track mine (road course and drift) I was planning on it. If so, where did you fit it and what size do you recommend? Also, is it best practice to run the oil cooler pre-turbo or independently of the turbo oil lines?

    3. I'm worried my exhaust will be rather quiet with turbos. What are you doing for exhaust and how does it sound?

    4. Did you heat wrap your downpipes? Any other areas that need attention to heat shielding? (Was planning on shielding booster/master cylinder and starter at least)

    Sorry I know that's an essay of questions, but there aren't too many of you boosted 350 guys around! I appreciate guys like Sean that have paved the way for people like me!
     
  10. dr

    dr Well-Known Member

    Just found this thread "I got some reading to do"
     
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  11. Buick#455

    Buick#455 Well-Known Member

    1. No intercooler, I'm just running meth
    2. No oil cooler either, it's a street & strip car.
    3. Pretty quiet thru the mufflers, but still sounds good.
    4. Downpipes are wrapped & I need to shield my brake booster...... after 5 in a row strip runs, I'm pretty sure the brake fluid was bubbling Lol.
    If you want, PM me your cell #, I'll send you a video of the car running.
     
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  12. dr

    dr Well-Known Member

    Buick#455 Can you snap some pictures of the exhaust to and from the turbos. Maybe a side shot? My simple brain is struggling.
     
  13. sean Buick 76

    sean Buick 76 Buick Nut

    This pic may help. The first is the single turbo setup from Porto Rico. Second is mine.
     

    Attached Files:

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  14. dr

    dr Well-Known Member

    Helps a little I have to see the "path of the exhaust gas". If I can't see the picture by now I should stay in my lane. lol
     
  15. patwhac

    patwhac Well-Known Member

    Thanks so much! PM on it's way!

    Also, thanks Sean for the pictures, I will make sure to document how I set up my cold and hot piping.
     
  16. sean Buick 76

    sean Buick 76 Buick Nut

    Here. And a wastegate simply re routes exhaust energy around the turbo to keep boost levels from spiking too high.
     

    Attached Files:

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  17. dr

    dr Well-Known Member

    Thanks You.
    LOL. I get that part, I just have a hard time seeing the whole picture. I have a simple mind
     
  18. patwhac

    patwhac Well-Known Member

    Well, I did it this weekend!! The camshaft is officially broken-in!! :):):)

    I am working on editing the video and will post it once I'm done. In the meantime, at least I can at least share with you the post break-in compression test numbers:

    #1 135
    #3 130
    #5 135
    #7 135

    #2 135
    #4 135
    #6 140
    #8 135

    Compression test, engine as purchased (copied from first post):

    150psi in every cylinder except 148psi in one (can't remember which, I think it was #2).

    I am very happy that my numbers are still consistent across all cylinders, but I am wondering what caused them to drop over all. Did I mess up the rings by not cleaning the bores well enough? Or the valves? Or is this just testing variables? Things like place, time, weather, different intake, different carb, thicker head gaskets (was 0.020" now is 0.040") etc?

    I am very stoked that it's running though!
     
  19. sean Buick 76

    sean Buick 76 Buick Nut

    You asked about the dual intercooler idea so here is my input:

    1. An air to air intercooler is great if its not too tough to install.
    2. A water/meth injection kit works very well however requires refills and it is one more thing that could fail. I still use it, works great.

    My advice though is to wait to try the water meth until you have some tuning and driving success. Adding the spray drastically changes to the tune up requirement. For now limit the amount of tuning variables. Unless in case of just using water meth, then of course its vital for the tune no way around it.

    I wouldn't be concerned about the low numbers at all. There are so many variables and the bottom line is that as long as the engine is healthy it will morph into a monster on 8 PSI.

    I was involved with the deal where Jefferson Bryant used a Burton kit on a stock 74 350 that wasn't even opened up for a cam or valve-springs. The engine had well over 150,000 miles on it. The compression tests showed 115-125 PSI but it still ran great on boost posting 350 HP up from 174 HP factory.

    https://www.hotrod.com/articles/hrdp-1206-100hp-bolt-on-addition-the-buick-350hp-turbo-kit/
     
    Last edited: Apr 5, 2021
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  20. patwhac

    patwhac Well-Known Member

    Thanks so much Sean, this is all super helpful! It's relieving to hear that my compression numbers seem ok. I was always told consistency across cylinders was the most important thing, regardless of the actual number.

    Ok, so I will mount the meth injection but maybe not run it at first until I get some tuning time. My general plan is to get it tuned at a dyno once the turbos/FI are installed. I wonder if I should tell them to tune without the meth for the first few sessions?

    Here's the intercooler I was thinking of using, it's a 2 into 1 setup that seems similar to what you and Mark Burton may have used. Only problem is I'll probably have to modify the upper radiator support for clearance, but not a huge deal I suppose.

    https://www.treadstoneperformance.c...ler,-chevy,-corvette,-gm,-viper-968hp/p104560
     

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