Nems NA to TT conversion, with an added suprise ;)

Discussion in 'Member's Garage' started by SRB-2NV, Jan 22, 2014.

  1. IB

    IB ?????

    In my experience, when the CAS is all the way anti clockwise, the crank is normally out by one tooth.
  2. SRB-2NV


    Thats what i thought, i wont know for sure till i pull it apart but before it was 3/4 of the way over for 15° and now its all the way.

    I've also redone the vac lines and the 3584 is spooling much quicker now.. car is all round going a fair bit harder now and even ~13psi yesterday felt great. Previously the car did 266rwkw at 12-13psi on only the factory turbos and it definately feels like it has that power back. I do however need to get new plugs and gap them down fairly tight as ~24psi is blowing the spark out.
    Harts likes this.
  3. SRB-2NV


    Got my CF dipped centre panel from RGS performance. Just need to get a double din headunit now. Also looking at getting other bits dipped.

    ivan129 and IB like this.
  4. SRB-2NV


    Better daylight pic.
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  5. SRB-2NV


    More cf dipped parts are on the way from RGS. Also my new powertune digital dash arrived, will hopefully have it installed tomorrow. 20210820_234545.jpg
  6. SRB-2NV


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  7. SRB-2NV


    Well i must say ive had an eventful week. If anyone remembers i had 38mm EWG welded into my dump pipes a few years ago as my internals were weak and barely held 14psi.


    Like that.
    Now this worked very well, even for how crappy it looked i managed to get 24psi out of the stock turbos in the midrange and 20psi at redline like this. However i always had the stock internal gates in place and functioning. This gave me a supercharger like boost curve with 6psi initially to 11psi at redline on wastegate pressure.

    Now when i installed my compound setup, i had basically just added the rearmount on and hoped for the best...

    Once the rearmount was on, the car still had a rising boost curve and the original dinosaur gt42 made 7psi or so at 4500rpm-ish depending on which gear you were in. Fast forward and i buy a GTX3584RS DBB turbo, install it and make a few changes. What i had done is connect ONLY the internal wastegates to the EBC and left the externals on their own connected to the charge piping. I was amazed at how much better it was, to test i set the stock turbos to 16psi and by 4300rpm the gtx35 was online and making 13psi.. the stock turbos were running around 3psi once the big turbo came on(16psi total boost). Setup worked well like this and made all the right noises, minimum total boost like this was 13psi(big turbos wg spring)

    So a few days ago i decided to reconnect the external wastegates to the EBC(teed with the internals like they were on the stock setup) and the car changed completely, for the worse. It still made decent power however now my lowest boost setting gave me 16psi total boost... hmm strange? And my GTX35 was laggy, like GT42 laggy and only made 6-7psi

    Turns out im an idiot, when i changed turbos i disconnected the Externals from the boost control system and had them just on manifold pressure... so when i would run boost controlled only by the internal gates the externals would start to crack at lower pressure and obviously send exhaust energy to the big turbo.

    When i reconnected the external gates to the boost control system, the EBC held the gates shut till the stock turbos boost reached a set point.. which in turn caused the rising boost curve to return and stuff all exhaust energy to go to the big turbo which = crap spool.

    I again disconnected the externals from the boost control system and the car is back to normal. Another interesting note it 4300-4500 seems to be the earliest i can get the big turbo to spool... but the funny thing is its the same RPM whether its 13psi or 20psi out of the big turbo, 43-4500rpm is the earliest.

    I think what is happening is because the stock turbos make their full boost (say 20psi) from 4-4200ish rpm and thats when their wastegates open to give the rearmount enough energy to hit a decent boost level. Basically i could have spooled the GT42R at the same RPM and to the same boost level... its my boost control strategy that stuffed me and pretty much a mechanical limit to how early i can spool any big turbo is how quick i can spool the small turbos.

    Now Things to note about this setup:

    On the stock turbos ONLY the car made 20psi at 3500rpm.

    With the rearmount added thats now 4000rpm for 20psi... breathing through 10ft of 2.5" tube doesnt seem to help.

    When it was on stock turbos only(300rwkw) it had GREAT low end power, 275rwkw at 4500rpm and 300rwkw by 5200rpm. After that it felt pretty flat.

    On the same boost with the compound setup, low end power has dropped more than id have liked it too. Definately weaker to 4500rpm but once that point is passed the car hauls ass.

    Now for future plans for the setup:

    Currently the car is running in "sequential mode" which is basically having the stock turbos boost drop as the big turbo comes on. This does work however what happens is the stock turbos pressure ratios drop "off the map" and blowing boost through a turbo that is only making 1.1:1PR at some points along with the single 2.5" charge pipe to the front may not give me the results i want.

    What i will be doing next is to run the car in "true compound mode"... basically the big turbos boost is added to the external wastegates TOP port. In this boost control scheme boost pressure numbers are added together, so 13psi of pressure added to the top port of a wastegate with an 11psi spring will be 24psi of total boost...on wastegate settings! However the externals SIDE port will still only be connected to the charge piping, no boost control. In this setup i will have the only internal wastegates connected to the EBC as they will blow open once the big turbo comes in and itll be upto the external gates, now also receiving pressure to their top ports to control total boost.

    This seems to be a more efficient way of going forward, as having both turbos do a more "even" amount of work and instead of having the GTX35 trying to push through a compressor thats at a low or no pressure ratio it will have the stock turbos pulling their weight.

    I may put a MBC on the big turbo, but even at 13psi the GTX35 still flows 70+lb/min so it may be enough.

    Comp-Map-GTX3584RS (3).jpg

    And the stock zed turbos are still on the map at super low pressure ratios.

    images (86).jpeg

    Im dumb.

    This setup is super sensitive to how vacuum lines are connected.

    I could have spooled my big GT42 at the same RPM as my GTX35.

    Setup is going to be better, i have ideas how to bring the stock turbos back to their original spool times and how to make this setup be more efficient.

    Would have been easier to just fill my nitrous bottle(kits been in the car for 4 years) and throw in my built RE4R03A + billet flexplate and go for a low 11/high 10..

    I will do that once i test this setup in proper compound mode and make sure everything plays nice.
    Harts likes this.
  8. SRB-2NV


    Note that i tried "true compound mode" ONCE and i hit ~40psi on one of my higher boost settings but since i dont have the injector or pump for that much boost i put it back. Next time i try it ill make sure my EBC is on its minimum setting .
  9. SRB-2NV


    Well, vac lines are hooked up in compound mode. Drove fairly well, kept boost around 20-22psi.

  10. SRB-2NV


    Also had some goodies show up from RGS performance received_167015578786950.jpeg
  11. SRB-2NV


    Well, i got the response a lot better for the GTX3584. The screamer opens at 4300ish in 2nd gear now. Im going to heat wrap the last section of exhaust piping before the turbo and hook my EBC upto the big turbo to try and bring that back down a bit more. Im also going to get a bit more agressive with the tune at lower boost levels to try and get the stock turbos to spool a bit quicker.

    All in all, this out of the box stuff works... just it takes forever to get right.. but 23psi in 2nd gear at 4300RPM is a win for me! I'm going to gradually up the boost now till i get to the limit of my fuel system.
  12. SRB-2NV


    Bought this for a quick test, haven't driven it yet but i do think it'll make a big difference.


    0.83 turbine housing vs the old 1.01.
  13. SRB-2NV


    So obviously the smaller housing works, with this setup the big turbos response is directly linked to how much boost you run out of the factory turbos. The smaller housing is letting me hit full boost without having the small turbos maxed out to get best response. Another thing to note is exhaust heat, in the first 10-20 minutes of driving the car is fairly doughy due to the exhaust being cold. After that though the car is an animal. I wrapped the last meter or so of exhaust pipe as i didnt have a lot of wrap but i will be doing the entire exhaust now, it makes world of difference once the exhaust is hot.

    Also the cars midrange power has improved a fair bit, my next step is to put an ordinary MBC on the stock turbos and have them at 20psi and up the GTX35 boost for a total of 30psi or so.
  14. SRB-2NV


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  15. Harts

    Harts Active Member

    Beasty build, looking forward to seeing the dyno of this, especially how the power actually hits in the compound set up. I expect the shape of the curve should have a far plateau and maybe a step in it too mid range, so interesting!
  16. SRB-2NV


    Back when it was on stock turbos only, the car made full power(300rwkw) at 5300rpm and after that the curve was dead flat. Now boost at the time showed 18.5psi peak at 4000rpm and it had dropped to 15psi by 7000rpm.

    Now the boost curve is the opposite and rises towards redline. I'd expect it to make less than before below 4000rpm and a fair bit more above that simply due to the higher boost pressures.

    I'm tossing up whether to put the built auto in yet or not, i'm not sure if my 4.11 GTR diff will be too short.
    Harts likes this.
  17. Harts

    Harts Active Member

    Auto for drags or you just prefer the slushbox to a manual?
  18. SRB-2NV


    For drags, i picked up a built RE4R03A a year ago and i have a billet flex plate sitting on my shelf. Next step is a fully manualised valvebody and ratchet shifter.

    I could run a tight converter due to the factory turbos and still put 30-40psi into it. Id say that would be a 10 second capable setup.
  19. SRB-2NV


    Well here we are, i just ordered a bead roller for the cooler piping on the rearmount. Right now i have tack welds on the ends of the piping to stop it from slipping off which im pretty sure wont hold up to 20psi+ from the rearmount.

    I expect once the boost is upped via the rearmount is when the setup will show its true potential. Two more rolls of heat wrap are also on the way for the front pipes so fingers crossed i can get everything ready soon.
  20. SRB-2NV


    This just showed up today, i'll be buying a pipe bender aswell in the near future. Hell i need to learn how to weld, so we can get some more custom stuff going 20211007_175243.jpg
    MagicMike and IB like this.

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