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  1. #46
    14 PSI Boost
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    I searched but I didn't see it stated. What is responsible for the 36lb increase in the 1986 model?

  2. #47
    Administrator SVOeric's Avatar
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    Mar 2002
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    SVO's: 86-1C & 86-1E
    dual exhaust.
    Eric C
    SVOCA Webmaster

  3. #48
    OVER-BOOST!! GAboySVO's Avatar
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    Dec 2002
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    Acworth, GA
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    SVO's: 2 - 9Ls
    84s and 85s I believe had the green top 30lb/hr injectors and horsepower was reported as 175. in 85.5 and 86, they changed the intake, the injectors to brown top 35 lb/hr, and the computer programming to bring it up to 200 HP. The extra fuel was needed to support the added power.
    Mike S

    '86 SVO 9L Leather
    '86 SVO 9L Road Warrior
    '96 300ZXTT

  4. #49
    14 PSI Boost
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    @svoeric
    Noted. Is there any performance potential in the dual exhaust or is it primarily cosmetic? If the exhaust is 2.5", I suppose you could run larger pipe with a knuckle reducer at the split to keep the same pressure.

    @GAboySVO
    According to my calcs, 36lb/hr injectors should support 320bhp with complete burn if these are "squirt" type injectors. Has anyone on this forum upgraded their injectors to the "misting" type of the same value and noticed smoother running? As an aside, would anyone be interested in blueprinting their current squirters so that they match output? Having the injector output profiles matched is supposed to make a smoother engine and a bit more power efficiency. All we would need is 25 members to make this service affordable, how does the forum feel about group buys?.
    Last edited by yldouright; 07-16-2018 at 12:43 AM.

  5. #50
    Administrator SVOeric's Avatar
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    SVO's: 86-1C & 86-1E
    It's slightly more than cosmetic, but any reduction in exhaust restriction helps, and the 85.5&86 exhaust is a bit better. The Biggest gain is a 3 inch down-pipe, and simplest system is a full 3 inch, single system.
    The stock dual system is a ~ 2.25 inch down-pipe, into 2 2.25 inch duals.

    so, your math is close , and so are your numbers
    SVO's (85.5 & 86) use 35# low impedance injectors. not 36 (which are high imp).

    The math does work out fairly close (think the actual math works out to 325hp) IF you up the fuel pressure to about 90 psi. -- I know this for a fact, as I've done it. remember you can't reach 100% duty cycle.

    I have a dyno pull where I fell just shy of 300 hp (290 range @ 20 psi) because of an electrical issue, the fuel pump wasn't quite keeping up. (that's at the wheels)

    no need for a 'group deal' as we have a vendor who provides this service for club members (not forum members) at a discount. Typically the suggestion is to send in ~6 injectors, and pick the ones that map the closest.
    Eric C
    SVOCA Webmaster

  6. #51
    Pimpin Pumpkin Carver Laredo's Avatar
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    Aug 2006
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    Stillwater, MN
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    1,174
    SVO's: 86 2R
    Quote Originally Posted by yldouright View Post
    If the exhaust is 2.5", I suppose you could run larger pipe with a knuckle reducer at the split to keep the same pressure.
    Or not.

    Quote Originally Posted by yldouright View Post
    Having the injector output profiles matched is supposed to make a smoother engine and a bit more power efficiency.
    Not necessarily. You are assuming everything else being equal as well (intake airflow speed and density per cylinder, fuel dispersion, temperature across cylinders, exhaust scavenging, etc, etc). The injectors on an SVO are batch fired (30 year old technology - the fuel sits in the intake "waiting" for the intake to open, and an unequal amount of time), and the airflow efficiency among cylinders is FAR from equal (relatively speaking). Worrying about minutia of injector imbalance is kinda like putting a Band-Aid on a broken leg or using a scalpel to cut down a tree. There are so many other issues to improve and/or correct on these engines to gain power before nit-picking injectors.
    Last edited by Laredo; 07-16-2018 at 02:24 AM.
    "If there's no plan, what can go wrong...?"

  7. #52
    14 PSI Boost
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    Jul 2018
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    Brooklyn NY
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    @Laredo
    Fuel and air are interrelated and ideally we need to balance both but you're right, there's no point in shaving if you're losing your head so how do we insure even/balanced air flow? Is it just a matter of trial and error porting on the manifold or is there more to do like precision facing and valve work? Is there a way to quantify the result without a dyno? Where do you see the biggest bottleneck? How much control do we have over mapping with the stock ECU? As I've mentioned earlier, I'm fearful of losing low end torque by opening it up too much. Has anyone blueprinted their engines (equal piston mass, etc)? I know, I have so many questions but I'm inspired and hungry to learn. I think Alan and I finally have a deal on the Brooklyn SVO. We should close and take delivery this week. I'm afraid the questions are likely to increase going forward even though I will now see things for myself in person

    @SVOeric
    Well, I'm guessing we could get closer set matching from 100 injectors but doing so would be much more inconvenient than just sending in 6. I would be happy with 290whp with 15lbs. of boost which translates to ~145whp NA. With modern fuel mapping and EGR delete this should be achievable without screwing up the nice SVO torque. Has anyone here achieved that?
    Last edited by yldouright; 07-16-2018 at 08:22 AM.

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