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Thread: 15g spoolup questions

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    Man vs 3/S verified Feedback Score 6 (100%) R/T93's Avatar
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    15g spoolup questions

    With my stock 9b's, in 5th gear, from 2000 rpm roll, I am at 14.5 psi at around 2500 rpm.

    How much slower would 15g's do the same thing. I am still going to autocross this car but even the 9b's have really upset me in the spoolup dept. There is lots of on/off throttle in autocross and I dont like waiting even the quarter second it takes for the engine to make any boost, but I definately want more power. I have to get used to it, might do more left foot braking while keeping a bit on the throttle to keep the motor loaded.

    I also do lapping days at Pacific Raceways, where a powerful car can make up a lot of time, I know around 400-450 whp would make a very formidable vehicle at that track. I already have all supporting mods for that amount of HP: fuel, EBC, IC's, clutch, exhaust (E-cutout), suspension, wheels/tires, instrumentation, logging capability, WB02.

    I have a used set of 15g's I can get rebuilt and I would have them for 1200 total. Thats less than half of the new billet turbo's that came out last year.

    I need some real world data on the 15g. I can find hundreds of dyno #'s, thats not what I'm looking for. I want to know HOW they boost. If I am at 3000 rpm in 2nd and I floor it, how long until full boost, less than a second? I dont want to be like the modded EVO's and STI's at the autocross where they are only hitting a few psi every time they accelerate cuz they have to slow down in 1 or 2 seconds.

    The only thing I have found is TT Erik doing his 0-25 psi in 3rd gear, but he has DR-750's. That is the kind of data I am looking for.I know 15'g arent titanium whizbangs but they are a lot smaller, would spoolup be similar?

    I am not sure I am going to get methanol injection, and we have pretty crummy gas in my county, and no E-85. I dont want to get a turbo where I can only use 60% of its potential.

    If someone could make a vid for me, go into 4th gear at around 50 mph and floor it till full boost and then tell me the rpm, I want to see the boost gauge.
    93 R/T - Modded, Full Suspension, Full Exhaust, Quaife Diff, Turbo brakes, Alpine/Boston Sound One of 25
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    Forum User Feedback Score 0 JasonY's Avatar
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    A 15g car i drove had a very noticeable delay from when the throttle went down until you felt the surge of power. They built boost very quickly, but were not very progressive in doing so. Very in/off and not as responsive as i expected them to be. My DR650's were very progressive in onset of boost/power and same for my HL wheeled 19T's i have on the 99 now.

    Jason

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    Now with more poop-smear Not Verified Feedback Score 8 (100%) IPD's Avatar
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    i think it also has to do with your intercooler setup to an extent. granted, it's a more minor role, but it still factors in. draw through vs. blow through is probably another factor.

    p.s.

    i'll also add that dr750's have better spool up than 9b's; as demonstrated by STM's dyno sheets vs. DR's. afaik, nothing else has that kind of spool up in td04's. the next closest is probably 13g's.
    Last edited by IPD; 01-30-2011 at 01:34 AM.

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    Man vs 3/S verified Feedback Score 6 (100%) R/T93's Avatar
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    HKS sidemounts, hardpipes, stock MAF.

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    Pass Me Another Hooker Feedback Score 0
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    also curious on spool up time, but i have a fmic and ams, and non maf intake's . car isnt done yet. mine where converted from 9bs.

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    I'd definitely save up and get Billet turbos if I were you. The billet DR650 would be perfect for your needs.

    But if you don't want to spend that much, I'd get 13Gs or 16T/19Ts. The 19t has more power and spools quicker than a 15g. And a 13g beats both of them in the spool up dept., but not nearly as much power potential. 16T is somewhere in the middle (still more power than a 15g and spools quicker). See this site for turbo upgrades: http://midwestturboconnection.com/

    With billet turbos, the spool up is like a 9b or better and well over 500whp potential. Best of both worlds.
    Last edited by Nytron; 01-30-2011 at 09:23 AM.

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    Just a thought... what if you ran a sequential setup? like a 9b 15g combo or something.


    Kurt S.
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    Man vs 3/S verified Feedback Score 6 (100%) R/T93's Avatar
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    I have no idea if a 15g/9b combo would work. This is my first turbo car, most of the mods were already done, just needs turbos

    I am not going to make a decision unless I see video or a detailed description of how they boost. I want full boost by 3000 rpm on a long gear highway pull. Turbo compressor maps dont tell me this, dyno runs dont tell me this.

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    Member Not Verified Feedback Score 7 (100%) mb3000's Avatar
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    I can try to get you a video of my 15g's after I get my new boost gauge installed if nobody posts up a video before then.

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    Man vs 3/S verified Feedback Score 6 (100%) R/T93's Avatar
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    Sweet. I made these today, haha 9b's rock.

    Stupid shit isnt embedding properly.

    http://www.youtube.com/watch?v=D1xcL0Hg9_8

    http://www.youtube.com/watch?v=Q5jqxpjJUn0

    Sorry for the shakiness.

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