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    m20b25 turbo questions, almost done!!

    Alright, guys so here I am after a year or so of collecting parts I'm almost done with my build. I have done a lot of research and am doing my best to search forums to find the correct info but if you guys could help me fill in the gaps I would appreciate it.



    GT35 Turbo:
    - 4" Air Inlet, 2.5" Compressed Air Outlet
    - Oil and Water Cooled
    - .70 A/R Compressor, .63 A/R Turbine



    List of Questions:


    I have one more question. I set my timing to 0 on tuner studios and checked it with a timing light(only can see the cam gear).... it still was 1.5 teeth off about. How do I edit that in tuner studios so my ecu is reading the correct timing?



    Answered

    1. My 45mm wastegate spring is 15lbs and my blow off valve spring feel like half that. How do I measure my spring rate and if I want to run around 8-10 psi am I okay to rely on my diverter valve with such a strong spring on my wastegate?

    2. I bought a cx racing oil sandwich, running my oil feed line from that sandwich the top of my turbo, do I run the line from either inlet on the sandwich, there are 2(my return line just going to the oil pan).
    example: https://www.cxracing.com/OIL-SW1?search=oil%20sandwich

    3. Do I just run breather hose from the back of my valve cover into the intake with a catch can? ill plug the throttle body where it originally would hook up to. Do I need to worry about any other breather hoses under boost blowing my gaskets? is my brake booster okay under boost?

    4. Fuel and fuel regulator, both are stock, what power figures will they be okay with before I need to upgrade? Can i just add another inline pump on the line and keep my oem pump in the tank?

    5. Has anyone used these wide bands? Megasquirt seems to have preset options in the ecu, should I just get one of those listed? this just seems like a good deal.

    http://www.wide-band.com/WB-D2-wideb...-p/wb_d2b2.htm

    Also, I have an undiagnosed draw and have been unplugging the battery alot, do i need to recalibrate the wideband every time that happens?



    I know this is a lot to drop on the forums and I appreciate all you guys so much. Been living on here... girlfriends pissed.

    I've been an Audi guy forever and this project is by far the deepest I've gone. Done a lot of 1.8t and 2.0t turbo nonsense, but starting from scratch on a turbo build has proven to be quite the journey. If I was going to do it again I would have just done itb's an called it a day lol.


    thanks again!
    Last edited by Yuri; 05-09-2019, 10:15 PM.

    #2
    Assuming the sandwich is for a cooler? If you're not drawing from a loop, you'll need to use the "outlet" or "supply" and plug the return.
    Edit, I didnt see the link. Looks like it doesnt matter which one you take off.

    Your fuel system is going to be your biggest hold back. I dont know what stock maxes out at, but cant imagine it supports more than 250-300whp.

    Sent from my SM-G960W using Tapatalk

    Comment


      #3
      Turbo is a bit big IMO; might be a bit of a dog out of boost, but who knows you might like it.

      1. Your BOV spring rate is not a factor of what your wastegate is doing. It isn't meant to bleed pressure to achieve the psi target. If you want to run 8-10psi, you need a wastegate spring lower or equal to your target psi and a boost controller for adjustment assuming your system wont creep pressure past the target. So being your WG spring is 15psi, you're at stuck at a minimum psi of 15psi without creep/spikes right now.
      To measure the spring rate, calculate the load applied divided by the distance traveled. You don't need this though.

      2. The ad states all the inlets are 1/8 NPT; use any. Use which ever one is less prone to kink when routing.

      3. Yeah - you can run it to a can, then from the can to your turbo intake or just to atmosphere. Make sure the hose you're using isn't cheap and won't kink.
      In my experience of being on the dyno with both setups, run the hose to your intake and do some pulls. Then remove it; let it vent to atmosphere and then do some pulls again and ask your tuner if anything changed.

      4. You should tell us what your power goals are first to answer this. I'd change the pump anyways, they aren't expensive. Leave the stock reg alone.

      5. Reputable and highly used companies such as Innovative and AEM have them for roughly the same price. I'd go with the tried and true. Much more support online as well.


      Unplugging the battery is fine; nothing needs to be done. Youtube how to check for draws with a multi-meter.

      Also, I know you said you've done your fair share of Audi projects, but remember don't go hooning in the car without getting it tuned after your install is done.
      Drive it out of boost to the dyno.

      Have fun and share some pics!

      1991 325iS turbo

      Comment


        #4
        Brake booster should be fine with the factory 1 way valve installed. If your shooting for over 300whp IMO the factory fuel will get you there but not much past it.

        Comment


          #5
          With larger injectors of course.

          Comment


            #6
            Speaking from experience: Find a different oil feed solution, or buy an in-line filter to protect your turbo. The sandwich plate is sending unfiltered oil to your turbo, if any crud in your engine gets sucked up by the pump it could wind up in your turbo and ruin it. Been there, done that. Also, upgrade the stock pump. My old turbo M42 setup was too much for the stock pump at 12psi, this was readily apparent when I needed to completely re-tune the boost portion of my VE table when I replaced the pump, that means the pressure was dropping because the pump couldn't provide enough fuel at standard pressure.
            @turbovarg
            '91 318is, M20B25, T3/T04E 60 trim (15psi), megasquirt, coilovers, Z3 rack, cold AC
            [b u i l d]
            [Car of the month: April 2018]

            0c8b7c9527af628a346878feb14bf757

            Comment


              #7
              Originally posted by cream_e30 View Post
              Assuming the sandwich is for a cooler? If you're not drawing from a loop, you'll need to use the "outlet" or "supply" and plug the return.
              Edit, I didnt see the link. Looks like it doesnt matter which one you take off.

              Your fuel system is going to be your biggest hold back. I dont know what stock maxes out at, but cant imagine it supports more than 250-300whp.
              I was planning on running the line to my turbo not an oil cooler... :/

              ended up upgrading the fuel pump.

              Originally posted by ak- View Post
              Turbo is a bit big IMO; might be a bit of a dog out of boost, but who knows you might like it.

              1. Your BOV spring rate is not a factor of what your wastegate is doing. It isn't meant to bleed pressure to achieve the psi target. If you want to run 8-10psi, you need a wastegate spring lower or equal to your target psi and a boost controller for adjustment assuming your system wont creep pressure past the target. So being your WG spring is 15psi, you're at stuck at a minimum psi of 15psi without creep/spikes right now.
              To measure the spring rate, calculate the load applied divided by the distance traveled. You don't need this though.

              2. The ad states all the inlets are 1/8 NPT; use any. Use which ever one is less prone to kink when routing.

              3. Yeah - you can run it to a can, then from the can to your turbo intake or just to atmosphere. Make sure the hose you're using isn't cheap and won't kink.
              In my experience of being on the dyno with both setups, run the hose to your intake and do some pulls. Then remove it; let it vent to atmosphere and then do some pulls again and ask your tuner if anything changed.

              4. You should tell us what your power goals are first to answer this. I'd change the pump anyways, they aren't expensive. Leave the stock reg alone.

              5. Reputable and highly used companies such as Innovative and AEM have them for roughly the same price. I'd go with the tried and true. Much more support online as well.


              Unplugging the battery is fine; nothing needs to be done. Youtube how to check for draws with a multi-meter.

              Also, I know you said you've done your fair share of Audi projects, but remember don't go hooning in the car without getting it tuned after your install is done.
              Drive it out of boost to the dyno.

              Have fun and share some pics!
              All this info was so helpful thank you so much! very informative!

              Regarding the tuning, my plan was to purchase the below and use the auto tune feature to get started. is that not sufficient?

              https://www.efianalytics.com/registe...=TSULTRA_MLVHD


              Also, I've decided to purchase an 8lb/10lb spring instead, not sure what I was thinking with 15lb. In doing so, do I just use this alongside my ms2 for boost control? seems resonably priced.

              https://www.diyautotune.com/product/...-solenoid-kit/


              Originally posted by turbski View Post
              Brake booster should be fine with the factory 1 way valve installed. If your shooting for over 300whp IMO the factory fuel will get you there but not much past it.
              good to know on those lines, I was confused about that. Does the one-way valve hold up to 400hp?

              also just bought a Walbro 450LPH Fuel Pump, hopefully that will fix things up.

              Originally posted by varg View Post
              Speaking from experience: Find a different oil feed solution, or buy an in-line filter to protect your turbo. The sandwich plate is sending unfiltered oil to your turbo, if any crud in your engine gets sucked up by the pump it could wind up in your turbo and ruin it. Been there, done that. Also, upgrade the stock pump. My old turbo M42 setup was too much for the stock pump at 12psi, this was readily apparent when I needed to completely re-tune the boost portion of my VE table when I replaced the pump, that means the pressure was dropping because the pump couldn't provide enough fuel at standard pressure.
              I have the e36 m50/52 something or another oil pump in there(bought the motor 2nd hand). I'm not sure how much of an upgrade that is, but I'm hoping that will be okay. Can I put an oil pressure sensor in the sandwich to keep an eye on it? what pressure ranges are safe? DO people ever add inline oil filters in the turbo oil feed line, or would that bogg thing down alot.

              Comment


                #8
                Yuri, I meant that part is for an oil cooler before I looked at the link. Just pick a line and toss it on the turbo feed. Dont forget the orifice or you'll be in some trouble with oil pressure.

                Good that you upgraded fuel pump. If your goal is 400, you'll need at the very least 40# injectors. Pump you bought will get you there. I would get a new FPR, one that can work with boost pressure to maintain fuel pressure.

                Sent from my SM-G960W using Tapatalk

                Comment


                  #9
                  Originally posted by cream_e30 View Post
                  Yuri, I meant that part is for an oil cooler before I looked at the link. Just pick a line and toss it on the turbo feed. Dont forget the orifice or you'll be in some trouble with oil pressure.

                  Good that you upgraded fuel pump. If your goal is 400, you'll need at the very least 40# injectors. Pump you bought will get you there. I would get a new FPR, one that can work with boost pressure to maintain fuel pressure.

                  Sent from my SM-G960W using Tapatalk
                  Awesome, those lines should be simple enough.

                  I got the TRE PNP 60lb Fuel injectors, so i think those should be fine as long as I stick with gas. I'm in Minnesota where e85 grows rampant so ive been toying with the idea, but ill probably start gas.

                  Comment


                    #10
                    Originally posted by Yuri View Post
                    I was planning on running the line to my turbo not an oil cooler... :/

                    ended up upgrading the fuel pump.



                    All this info was so helpful thank you so much! very informative!

                    Regarding the tuning, my plan was to purchase the below and use the auto tune feature to get started. is that not sufficient?

                    https://www.efianalytics.com/registe...=TSULTRA_MLVHD


                    Also, I've decided to purchase an 8lb/10lb spring instead, not sure what I was thinking with 15lb. In doing so, do I just use this alongside my ms2 for boost control? seems resonably priced.

                    https://www.diyautotune.com/product/...-solenoid-kit/




                    good to know on those lines, I was confused about that. Does the one-way valve hold up to 400hp?




                    I don't think its a matter of hp but rather boost pressure. The one 1 way will only see one or the other. Mine is connected in the stock location with factory valve and around 12+ psi with no issues. Im sure someone with more knowledge can put this in technical terms

                    Comment


                      #11
                      Right, that makes sense. If I just run one line from the throttle body to the brake booster, will my brake booster still function properly?

                      Comment


                        #12
                        Mine does. I think it works as a venturi. Hence the one way valve. Someone pls correct me if I'm wrong

                        Comment


                          #13
                          Perhaps I didn't understand the question, but you need manifold vacuum for the brake booster. The 1 way valve is to keep vacuum in the booster and "replenish" the vacuum for when you need it.
                          '84 318i M10B18 | 93whp/90ftlbs | 147- Safari Beige | MS2E w/ LC, 2-Step

                          Comment


                            #14
                            Originally posted by Jaxx_ View Post
                            Perhaps I didn't understand the question, but you need manifold vacuum for the brake booster. The 1 way valve is to keep vacuum in the booster and "replenish" the vacuum for when you need it.
                            For some reason it didn't click the first couple times I read it. Im not sure how much pressure "boost" the one way valve will take on a turbo set up but when not in boost, it is under vacuum from air being sucked into the engine.


                            I think the OPs question was how does the brake booster hold up to boost. I guess the answer is as long as the valve is installed it should never see boost in the brake booster?

                            Comment


                              #15
                              the spec will differ for any one-way valve. I've seen some that handle upto 150psi against the valve.

                              Well, the reason you want a check valve is that you can have assisted brakes even if you're on the power, or the manifold still has pressure(under boost). You could run without a check valve, but you would have a stiff brake pedal relative to the manifold pressure.

                              The brake booster would probably hold up to boost just fine for modest values--at idle it's close to 10psi on the seals, but the opposite direction. Maybe it's not designed for pressure in the "wrong" way... the kind it would experience under boost.

                              In a simple way to explain it, booster works on differential pressure between atmosphere (brake pedal side) and vac(booster side). Hope that helps clarify things
                              '84 318i M10B18 | 93whp/90ftlbs | 147- Safari Beige | MS2E w/ LC, 2-Step

                              Comment

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