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Thread: May Prelim question/comment.. Nissan SR20DET in STU

  1. #1
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    Default May Prelim question/comment.. Nissan SR20DET in STU

    Have been contemplating this request for a long time, as Greg and Peter can attest, then I chicken out on doing anything to this car and spend the money on my Prod car.

    I'm glad to see this one on the Prelim notes, however I'm curious why there's a -2mm restrictor limitation on there? Is this in addition to the -2mm that's already there for the RWD cars? (Any chance for a +1mm or 2.5% weight given back for a RWD car with McStrut? )

    Why choke the SR20DET any more than other turbos? Is this just a "cautionary" thing that is subject to update once the powertrain is seen in action, or has there been a proven case that this would create an overdog vs. something like the Solstices that pull away from everything in sight?
    Houston Region
    STU Nissan 240SX
    EProd RX7

  2. #2
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    'Cause JDM. CRB is tacking adders onto anything non-USDM now; turbos get -2mm and everything else gets +2% weight.

    If someone got serious and built one and demonstrated it was not an overdog then I'm confident the CRB would entertain appropriate adjustments.
    Not my circus...not my monkeys...

  3. #3
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    crusty old farts. Just cause it's not "from here" means it gets a penalty?
    Might as well go drive my Chevy to the levee.. But I can't.. it's broken and I'm waiting on parts from Mexico.
    Houston Region
    STU Nissan 240SX
    EProd RX7

  4. #4
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    Crusty old farts is us, brother... Build it, or get someone else to build it. We got it in, we can make it right.
    Not my circus...not my monkeys...

  5. #5
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    You and your funny Furr'in cars. Meanwhile I drive and race cars built in South Carolina.
    STU BMW Z3 2.5liter

  6. #6
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    yea grumpy old guys, after all JDM engines are propelling race cars us motors are not willing to do.
    dick patullo
    ner scca IT7 Rx7

  7. #7
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    Quote Originally Posted by Greg Amy View Post
    Crusty old farts is us, brother... Build it, or get someone else to build it. We got it in, we can make it right.
    I'm trying to see how many people I can piss off first..
    Houston Region
    STU Nissan 240SX
    EProd RX7

  8. #8
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    Does anyone know which SR20DET motor they are trying to get approved for STU.
    Hammer
    CFR
    ITA Nissan 240sx #56
    2009 Nissan GTR
    2010 Nismo 370z
    http://www.ReedNissan.com/

  9. #9
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    Pick your poison; you can run the Blacktop if you want. Just recognize that the TIR is going to pair down the output possibilities while you're generating a lot of heat.

    Focus on maximizing torque.
    Not my circus...not my monkeys...

  10. #10
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    My vote would be S14 blacktop or S15.. You get a better head with the S15 engine, but you also pay a lot more. Both of them have a ball bearing T28 which will help spool and get the torque moving quicker. Plus the T25 on the red top runs out of air pretty quick. Since we're limited to stock turbos, the T25 just can't make the power needed to be competitive whether it has a restrictor or not. Well, at least not at weights attainable by the S14 chassis. (I don't see being able to get the car under ~2600lbs w/ my fat arse.)

    When there's local boys putting down ~400/420 in a 2900lb Pontiac, it's going to be incredibly hard to make the SR20 competitive at 2700lbs with a 31mm restrictor that will give you roughly a max of ~300hp.
    Last edited by Matt93SE; 04-10-2014 at 09:20 AM.
    Houston Region
    STU Nissan 240SX
    EProd RX7

  11. #11
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    Solstice with the LNF has to run 2820# and a 34mm restrictor, and it has to remove -2mm for RWD. That's a 32mm hole; there's no way they're putting out even close to those numbers for STU.

    If you can get the S14/S15 chassis down to 2675#, then you're running a 31mm hole. 1mm down but also 135# down.

    The old SR20DET would be hard-pressed to compete with the technology of the Ecotec LNF, but in general this isn't a terrible pairing. And, if someone builds one and demonstrates it, it has the opportunity to drop that -2mm.

    Build it.
    Not my circus...not my monkeys...

  12. #12
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    If you were starting from scratch in building one, which chassis would you use. I am thinking of building one versus converting my ITA 240sx. I am looking at trying to find a Nissan for a national class for the runoffs at Daytona next year.
    Hammer
    CFR
    ITA Nissan 240sx #56
    2009 Nissan GTR
    2010 Nismo 370z
    http://www.ReedNissan.com/

  13. #13
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    I wouldn't start from scratch- I would buy my S14 that's for sale and drop an SR in it. replace the 8 yr old coilovers, and you'll be well on your way to a competitive car. (I bought an EP RX7 that is/was quite a bit faster for the price it would take me to put an engine and suspension into the 240SX, and EP is quite strong here with national-level competition at every single race. STU is lacking in tough competition, so it doesn't make a ton of sense to me to spend a bucket of money to make it faster with little competition to run against.)

    The S14 chassis is a touch bigger and heavier, but it's also a stiffer chassis and has better geometry in the rear subframe so you can get better corner exits. With the 5-lug hubs, you also get better wheel bearings that last a lot longer than the S13.
    Houston Region
    STU Nissan 240SX
    EProd RX7

  14. #14
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    I will keep your car in mind when doing my research. Distance from Orlando will be an issue

    Initial feedback from friends is the s13 hatch may be the chassis to use.
    Hammer
    CFR
    ITA Nissan 240sx #56
    2009 Nissan GTR
    2010 Nismo 370z
    http://www.ReedNissan.com/

  15. #15
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    Your friends don't have a clue then- the hatch was the softest chassis due to the lack of tie-in around the rear struts. It's a big box, like a small minivan. the sloped rear roof is a touch better for aero, but not enough to make it worth the penalties in chassis stiffness. You can always counteract some of that with the cage, but you have to add more weight in the cage to make up for it, which makes the lighter S13 chassis less beneficial.

    For STU, you also have to put a fuel cell in an S13. The S14 tank is in front of the rear axles, saddlebagged over the subframe (under the rear seat area). it's in a much better location for weight distro, and you have the better suspension geometry. You can also run the stock tank just about dry without starving for fuel. I've run a couple races where my fuel sample port was spitting bubbles after the race, but never had a problem on track.

    Houston to Orlando is 975 miles, so it would be a good 2-day tow. Come up before a race weekend and you can run with the TX boys before you go home. Be sure to bring a big arse trailer cause I got lots of spares with it.
    Last edited by Matt93SE; 04-11-2014 at 12:05 PM.
    Houston Region
    STU Nissan 240SX
    EProd RX7

  16. #16
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    and the hatch is harder to make in plastic, not impossible by any means, but popping a plastic window into a notch is easier. the spec wing works well on the notch, too. not for nothing but I'd be all over the S14 JUST because of the strength and commonality of the hubs / wheel / brake offerings. and as for transport, there's always a transport service (not very expensive) or a trailer with an open spot shuffling things back and forth across our great nation. hell I bet you could have gotten ISC to swing over to Houston after the NOLA majors (I assume they went to the NOLA majors).

  17. #17
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    My friend works at Nissan Motorsports.

    I appreciate all the feedback. Keep it coming. Just looking at all options.
    Hammer
    CFR
    ITA Nissan 240sx #56
    2009 Nissan GTR
    2010 Nismo 370z
    http://www.ReedNissan.com/

  18. #18
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    I have many friends that work for NASA, but that doesn't mean they know how to build a space shuttle.

    If you're truly interested in the car, let me know and I'll work up a current spares list. I'm selling off stuff to make room in the garage, but still have like 3 transmissions, 3.9 4.1 & 4.3 diffs, 6 or 7 sets of 17" wheels, 3 diffs, spare doors, lights, gas tank, subframes, etc.

  19. #19
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    Matt, in my research the S14 and S15 have the same part numbers for the head assembly. I believe the power difference was entirely due to higher boost pressure and ECU tuning, which are open items anyways.

  20. #20
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    I'm very happy to see this even though it is a day (year) late and I'm many dollars short... I still have a bit of sweet spot for Nissan even though it is Honda and Ford for me this year.

    And on less selfish note, I believe that this is a good move for the club.
    Chris Rallo "the kid"
    -- "wrenching and racing" -- "will race for food!" -- "Onward and Upward"

    Independent Motorsports Group: Cars * Competition * Camaraderie

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