Project Nissan Sentra Spec-V Part 7: Installing a Turbo System

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 Project Nissan Sentra Spec-V Part 7: Installing a Turbo System
Mike saws off our old T25 flange in a bandsaw.
 Project Nissan Sentra Spec-V Part 7: Installing a Turbo System
He then grinds the flange area flat on a belt surfacer.

To meet our power goals we called upon Garrett Turbochargers for a mid range responsive turbo. The good folks at Garrett supplied us with a GT30R turbocharger.  The GT30R is a mid frame size turbo with a low friction for less lag, ball bearing center section.  It is capable of easily producing power levels in the mid 400 range and can produce more on larger displacement engines.   The GT30R is blessed with super efficient compressor and turbine wheels that are a good match for our motor.  We used a GT3071 version of the GT30R which has a 56 trim 71 mm compressor wheel in a .50 a/r TO4S compressor housing mated to a 76 trim 60mm turbine with a .82 a/r turbine housing.

 Project Nissan Sentra Spec-V Part 7: Installing a Turbo System
Mike welds the new flange to our manifold using a TIG welder.  TIG stands for Tungsten Inert Gas.  The welder’s electrode is made of tungsten a super hard metal and the welder’s torch has a nozzle that dispenses inert argon gas to shield the weld area from air, prevent the molten metal from absorbing oxygen which weakens the weld.
 Project Nissan Sentra Spec-V Part 7: Installing a Turbo System
After a quick fit check, the flange is ported to the manifold’s runners for better flow.

This turbo can produce considerably more power than the GT28RS Disco Potato that we were intending to run at this point.  The GT30R will have about 1000 rpm more turbo lag which we think is a fair trade off, our long stroke QR25DE will have plenty of low end torque anyway and long stroke engines make powerful exhaust impulses that spool turbos quickly. 

 Project Nissan Sentra Spec-V Part 7: Installing a Turbo System
Now it’s time to make the downpipe.  Considering how tight it is around the turbo, this is a very difficult task.  We used a section of 3” doughnut to make the first part of the downpipe.
 Project Nissan Sentra Spec-V Part 7: Installing a Turbo System
Mike welds the flange to the doughnut.

For simplicity, we wanted to retain an internal wastegate, the trouble is until recently there were no mid frame internal wastegate exhaust housings on the market for the new GT series turbos.  ATP came to our rescue with their new internal wastegate GT series exhaust housing.  The ATP housing has a large flapper valve that can flow as well as some external gates.  The housing has a built in diffuser which flairs to a full 3” for superior exhaust flow.  The housing also divorces the wategate flow from the turbine discharge, another trick that helps boost turbine efficiency.

 Project Nissan Sentra Spec-V Part 7: Installing a Turbo System
321 Stainless tubing is hard to cut as its is a very tough metal.
 Project Nissan Sentra Spec-V Part 7: Installing a Turbo System
The tubes are test fitted.  Since we used a very thin 321 tube, the mitering must be very precise and the fits exact as we have to use a very fine electrode and filler rod.

 

4 comments

  1. Mike, how is the time attack coming? For years I’ve been toying with the idea of a primarily off the shelf parts V12 with enough capability to be worthy of the investment. Sure anything V12 would be cool but for genuine interest, I need two things. For larger displacement, (the impossible find! Every OE is making baby bores for economy) that 87mm is the absolute “sweet spot” for single sparkolator flame front propagation, meaning lowest possible chance of detonation while still having room for valves. For displacement and having a minimal chance of detonation, I need a dual plug 4.5 inch bore. I’ll have to compromise with a single plug at 4.150-4.185 bore. Nissan has a 4.41 bore space, Mopar has a 4.46 bore space. The Mopar 3.5 SXT and 4.0 R/T Nitro have SOHC 60 degree blocks. Beefier than the Nissan with closed deck design. VQ37HR or VK56 heads oughta do.
    The point is, I found your T/A build here searching for QR25 bore spacing, wuuuh waaah, too small. This is an awesome build! Can’t wait to see it go. I’m thinking of a LS mid sleeved VK56 for a 94 Sentra rwd conversion!! Lotta work, but cool factor off the charts. Wheel well and opening hackery for to the Nth degree to get any decent size diameter tires.
    When is this thing gonna make some runs?

    1. We scrapped the car mostly because the QR engine is a piece of trash and there was no interest in the car besides maybe 50 people in the world which made sponsorship impossible. Basically what you are planning isn’t really possible and your assumptions of bore size and understanding of bore spacing are not correct either. Your considered build won’t have any sponsorship or fan interest either. It is also several hundred thousand dollars to do what you think you want to do. I suggest sticking to cars that have more interest and technology that is off the shelf.

  2. Well I’m interested in what you have to say about my following comment…

    I’ve already poured a couple thousand dollars into my qr25 build with over two years of research and it might very well be a waste of money but it’s one I’ll see through. I just got my stage4 clutch from 2j-racing, they have been a big help to fill in some of the gaps. I to am aiming for 400hp-450 safely but for street, still taking the massive extra steps to make my bearings happy and oiled. my last piece of the puzzle “was” going to be sleeve the block but I see you used a different method, one that I only heard of a couple weeks ago. Now, I read you didn’t finish the project but how do you think the engine would have held up with the aluminum filled epoxy resin?

    1. Hows your build coming Emily D?

      I’m in the middle of my turbo build, shooting for 280hp on my 02′ with 34k miles and still running strong. Concerning your block try reaching out to VisionRacing, or better yet you can do a VQ swap with Nissformance kits.

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