Laggy and not crazy

Discussion in 'Forced Induction - 5.0L V8 Engine' started by Aussie-up-north, Sep 8, 2019.

  1. sigintel

    sigintel Well-Known Member

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    #16 sigintel, Sep 10, 2019
    Last edited: Sep 10, 2019
    Edit*: Thats a 58/62 0.62 A/R
    it is NOT the 55/61( now called a 5531E)

    Hmmm.
    Some turbos have really large turbine to compressor size ratios to decrease size/cost/need for exhaust bypass/wastegate and blowoff valves.
    Downside is they are exact opposite of what you are after. The 5531E (different sizing schema)was the only current precision unit I could find similar to your 55/62. *edit: you dont have this.
    You have 58/62 previous gen.
    Twin 58/62 would be aimed more at 1200-1400 hp drag strip runs.

    You may want to try contacting precision as they dont provide any maps of compressor or turbine online.
    I suspect a 55/58 0.8-0.55 AR may be way more fun. Consider 55/55-58.
    You may need to spend more money on bypass(exhaust) and blowoff(intake) excess pressure control.
     
  2. OP
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    Aussie-up-north

    Aussie-up-north Well-Known Member

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    That’s some great advice.
     
  3. 3beeps

    3beeps Well-Known Member

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    I'm telling you it's the 9.5:1 compression and the 3C converter. That doesn't seem to be the converter Circle D recommends for turbo cars. They recommended a 2B or 3B to me.

    I have the 5562s and a stock motor with a 2B converter and mine is plenty of fun around town. I often keep it in sport and if I'm gonna get on it any more than normal city driving, I keep it in manual mode. When I keep it in S or D but let it shift itself, it doesn't seem to do what I want if I'm trying to have some fun.

    If you're considering smaller turbos than the 5562s, you'll run into backpressure issues for sure. I'm already running into those issues with the 5562s, as I just had to replace my headgaskets after running only 15 psi max boost.
     
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    Aussie-up-north

    Aussie-up-north Well-Known Member

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    If you stall it on the break upto say 3k, what boost would you see?

    Also if you leave a light at a intersection and say you are not to lazy on the throttle but not hard at all would you come into boost ever?
     
  5. sigintel

    sigintel Well-Known Member

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    #20 sigintel, Sep 13, 2019
    Last edited: Sep 13, 2019
    Hella good info.
    What size/setup exhaust bypass do you have for lowering back pressure?
    Do you know the AR and turbine housing your 5562 use? Kinda interested in those.
    Any chance you have a tack or rpm pickup on either turbo?
    Looking at twin 55/55 up to 60/62 and everything in between.

    Note: the part number he provided is a 58/62 0.62 AR, not a 55/62.
    So he has a higher volume compressor which therefore spins lower rpm (especially at low load) vs your 58 compressor. Your 55 compressor would be an advantage for sure.
     
  6. 3beeps

    3beeps Well-Known Member

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    Without using the transbrake (so just using the footbrake) or the 2 step, I can get it to show 0.0 psi on the boost controller without rolling. Gotta be 110% on the brakes though lol. WITH the 2 step, I can get it to 3 PSI without rolling. With the transbrake AND 2 step, I believe I've gotten it to about 5 psi.

    Here's an example, but I let off as I wasn't in an area where I could safely test.



    To answer your second question, I have some part throttle issues with my trans where it seems to lock, unlock, and lock when it shouldn't. But I haven't spent any time with my tuner getting the trans perfect, especially after having just rebuilt it.

    However, if I put it in sport and control the gears myself, it's a blast. I'm always on a drag radial so I just keep it in 2nd gear and she's always ready to party.
    He has a Hellion kit so he's gotta have the 5562s. They're one of the two included turbo options so I doubt he has some other turbos.

    I have 4-to-1 headers that Hellion offers rather than using the stock manifolds. I imagine that would help lower back pressure.

    Since I blew the headgasket, I've switched to bumper exit exhaust so that should also help with back pressure.

    I don't know the tech specs of these turbos, as Precision doesn't post these turbos for the public; Hellion must have some sort of deal with Precision.

    I HIGHLY recommend these 5562s for a street car. They make more torque than the 6266s and they spool up faster, so you'll have more fun just messing around. If you want 1100+ whp down the road, then go with some bigger turbos.
     
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    Aussie-up-north

    Aussie-up-north Well-Known Member

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    I just took a quick vid, this is is my gate pressure at 9psi and peak boost at 11 and then my duty at 25% in to the two 4port valves.

    Was about 10% throttle then into 50% hard then upto 65% at the end.

     
  8. kent0464

    kent0464 Well-Known Member

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    Nothing wrong with 9.5-1 or a 3000 stahl. My car is 9.0-1 with a 5200 stahl and is bonkers in town. I’ve been running turbos for 30+ years.
    Biggest problem I see with most V8 applications using twin turbos, is that they are geared towards either big horsepower or 1/4 mile times, not for street cars or shorter 1/8 mile tracks.
    To get a better idea of what will work best, you need to think of your motor as 2 4 cylinder motors, since each side will have its own turbo, that’ll make it much easier to size the turbos for your application. Researching 4 cyl turbo forums will show you that there’s really only 3 ways to make power/torque at a lower rpm. Ie: NOS, smaller turbo, or twin scroll turbo with matching manifold......well there is a forth way, compound turbos, but it is much more complicated.
     
  9. OP
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    Aussie-up-north

    Aussie-up-north Well-Known Member

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    What are you driving and what setup
     
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    Aussie-up-north

    Aussie-up-north Well-Known Member

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    Okay guys... did some digging... found out what stall is in here. Do you think this is the cause! DF848A05-D526-42E0-A2BD-C3E30C523504.jpeg
     
  11. OP
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    Aussie-up-north

    Aussie-up-north Well-Known Member

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    This is the stall that’s in here. Do you think this maybe the issue? 029102FE-2CCC-4446-BAEF-7AB189D392DC.jpeg
     
  12. kcc0521

    kcc0521 Well-Known Member

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    That is the right stall for a turbo car. Lots of guys are running great with that one. I have the 258 2B which is just slightly tighter.
     
  13. OP
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    Aussie-up-north

    Aussie-up-north Well-Known Member

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    What rear end gears are you all running behind your a6?
     
  14. kent0464

    kent0464 Well-Known Member

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    Absolutely not. On foot brake you should make some boost and a 2 step should bring the car up on full launch target boost, hell even at part throttle putting around town you should see some boost. 5862’s @9.5 compression should see you in full boost somewhere between 3-4000 rpm.
    I believe you have a different issue. What exhaust set up are you running? From turbo to end?
     
  15. 3beeps

    3beeps Well-Known Member

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    3.15
     
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