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JD's Turdo

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  • JD's Turdo

    My turbo SL2 thus far:

    New 2.5" exhaust

    Pulled the engine. It was in pretty good shape for 354k KM. Seals were all leaking.

    Old block was cleaned, machined and painted. 0.5mm overbore and .007" decked.
    New pistons, rings, main bearings, rod bearings, cylinder head alignment pins, water pump, oil pump, head gasket, rubber seals (all of them), thermostat, oil filter relocation adapter, and timing kit.

    Next will be the cylinder head. I still have to clean it up and flatten it out, weld up the EGR holes, paint, port, polish, install new guides, lap the valve seats, order/find a 3rd gen DOHC camshaft bearing cap bolt (it's stupid... don't ask), and reassemble. Phew!

    MegaSquirt-II V3.0 ECU is on the table ready for wiring, which is where I came to a grinding halt. The amount of information on here is so plentiful, it is unnavigable by a novice like me.

    A few things I've noted while working/browsing the thread that I would like to clarify here:

    1: Ring gaps have been checked and are good for NA, but gaps for turbo applications are 20% to 40% greater. After running the NA engine with MSII to ensure functionality, will I have to disassemble the engine once again and re-gap the rings?
    2: The oil pump pressure regulator has a valve in the TTC, and I only just came across someone's thread recently saying that it needs modifications. What is this modification and why is it necessary?
    3: I know there are oils for turbo applications that have an "SN" designation. Does the weight of the oil stay the same, or should it be heavier? I've heard a couple different opinions on this.
    4: Torque-to-yield head bolts should not be reused. I've heard people saying they reuse them a couple of times. For the purpose of running the engine naturally aspirated for a while, am I safe reusing the old head bolts for now until I am sure it runs fine. I plan on purchasing studs when I can find some and when I'm ready to install the turbo.
    5: Valve springs. Earlier, I posted a question on another part of the forum about springs. Any input here would be of use (reusing old ones vs. finding a set that will work for my application vs. custom springs???)

    There will be many more questions to come, maybe a few more pictures (heck, I might even make a video). Really, this is my first foray into building cars and I want this to be fun for me, so I will take my time to do things right and accept as much input and/or criticism that comes my way.

    Thanks for reading, and sorry for the lack of pictures so far.

  • #2
    I can help answer these questions best possible

    1) i would gap rings as you intend for turbo applications. a good ring seal by proper break in will affect consumption more than too big a gap. I ran .017" on a stock motor (which is outside of the factory limit) and it burned no oil for quite some time.
    rule of thumb for forced induction is gap = .006" x bore diameter (quoting A. Graham Bell's book "Forced Induction Performance Tuning")

    2) I've beat the piss out of a stock 3rd gen and never had lubrication issues over the 100k miles of daily redlining and abuse, including road course racing. but your bearing loads will be higher at lower RPM with forced induction so i would wait for one of the experienced folks to answer this one

    3)If you want a higher viscosity you may need to change clearances for proper flow rate of oil If you are run factory bearing clearances i would stay with the factory spec 5w30 in full synthetic, and monitor oil temperatures. . avoid over 220*F, ideally hover between 190-210*F. That being said, i have ran 0w-40 mobil 1 for some time without issue. if you run a cooler get a thermostat or a way to control air flow over the cooler. cold oil is bad bad bad for an engine especially if you are street driving a lot. if you intend to put sticky tires on the car and take corners fast i would fab an oil pan baffle to keep oil at the pickup tube, rather than sloshing away. a horizontal piece with a hole cut out for the pickup tube is what i've used-

    what is your rod / piston combo ? FYI Wiseco can make some pistons for not too much money. Mine were only a 1 month lead time.

    4) torque to yield means use ONCE. buy new bolts, they are cheap. You may as well not assemble the engine if you cant replace the head bolts. why throw your effort away to save $50 of head bolts?

    5) 99% of builds on these engines use stock springs. you can check their free length and conduct a visual inspection for defects that may be stress risers. if you are so inclined you could test their spring rate and make sure they are within spec as well. unless you are running significantly more RPM's than stock, running larger valves that have a significant weight difference from stock or are running a radical cam profile stock meets the needs.


    • #3
      That's a lot of great information. Thanks! My pistons are EngineTech .5mm oversized and the rods are the original Saturn ones. I debated buying new rods, but they are really hard to come by and quite expensive if you do find them.


      • #4
        Originally posted by Jooshmeister View Post
        I debated buying new rods, but they are really hard to come by and quite expensive if you do find them.

        If that's too expensive I've got some bad news for you.... Owner
        2016 Honda Fit
        2002 Saturn SL1 - RHD
        2002 GMC Sierra 2500HD Duramax


        • #5
          Holy shit thats a cheap set of Rods... dude why are you not buying those. i spent way more on crower rods for my NA build


          • #6
            For forged rods, that's pretty good. I was looking for forged internals a month or so ago and they were all around $1200 for a set. That's why I kinda forgot about it. I'll probably order these before putting the turbo on.


            • #7
              Just a quick update. Over the summer I had the engine rebuilt and promptly seized it. Ended up installing an oil filter relocation kit incorrectly and starved the bearings of oil. Tore it apart again and rebuilt it a second time, but this time with those forged connecting rods that I was trying to convince myself to buy back in June (Christmas present to myself). Runs great now. Currently I'm working on the Megasquirt and wiring harness so that I can play around with the fuel and spark before ploughing ahead on the turbo. I need to get my hands on an exhaust flange to mock up a manifold ASAP, so if anyone knows of a source for a 2D CAD drawing of the exhaust flange, hit me up so I can get it made (I can do one myself but I'm lazy and if there's already one out there than I'd hate to waste so much time)

              As usual, any input or pointers for a first-timer are appreciated and I'll post some updates as they come.


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