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Ls Turbo Sizes????

Discussion in 'Forced Induction' started by jtornado, Nov 4, 2007.

  1. jtornado

    jtornado New Member

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    I'm sure you guys know me for how many threads I have posted. I tried to find some specs on what turbo size is good for my goal. This is gonna be DD.
    Here is my setup:
    B18a 81.5mm 9:1 CP Pistons with Eagle H-Beam Rods
    Walbro 255 Fuel pump
    10psi
    Hondata S200
    3" Exhaust Everything else is stock
    I hear turbo lag is good for traction???? Tell me if this size is good for my goal. .60trim .63 A/R???? To be honest I have no idea what these number mean. I know that the .60 trim is the size of the wheel but I have no idead what the .63 A/R means nor the turbine size. Could someone help me understand what I wanna be looking for and what everything means??????
     
  2. R.E.Developement

    R.E.Developement Import King of Irvington

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    ok you are correct about the 60 trim being the compressor wheel and for knowledge the .63 ar is for the turbine side. thats a nice size turbo but it depends on your goal which you didnt tell. if you are going for a simple setup but very effective ill go with a either a 50 or 57 trim turbo because the turbo lag may help for traction but not for this setup unless you are going to put some srings and retainers in the head for more rpms. if it was my setup and i was using a 60 trim with a .63 ar turbo i would put some afrte market srings and retainers in (skunk2 and protech are good)and in some precision 400cc injectors as well. this would help keep the combustion chamber cooler with would allow you to get more power with your tuning. speaking of tuning i would also upgrade from that s200 to a s300.;) its alot easier to tune. with what i just mentioned your setup should be a beast. as a matter of fact im doing a simular setup for this kid around my way but his ls motor is completely stock and hes not using injectors and running 8 psi. i think that it should be a nice setup too so just imagine yours.
     
  3. jtornado

    jtornado New Member

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    Alright I think I'm understanding this now. When people say the 60 trim, they are referring to the compressor wheel but why don't they mention the turbine wheel. Is the compressor wheel trim more important than the a/r of the compressor? Is the turbine a/r more important than the wheel trim? Anyways I heard a 50 trim with a large a/r such as .63 is a good setup. So basically my compressor(cold side)is 50mm and which will make it reach 10 psi faster and my turbine(hot side) is .63 a/r which will give me the top end power correct?????
     
  4. silver

    silver Senior Member

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    Slow down there. Start here: TurboByGarrett.com - Turbo Tech101 and read through all the tech sections. That should get you started.

    The "trim" has nothing to do with the actual size of the compressor wheel--e.g. the "50 trim" is actually a 54mm/76mm compressor wheel.

    Also, a .63 a/r T3 housing is not really that big. It's sort of the compromise between really fast spool (like a .48) and more top end (like a .82).

    The answer to your other question is much more complicated, but in a nutshell
    1. Your compressor wheel is the primary determinant of choke (max) airflow.
    2. Your turbine wheel will only partially determine your spool times, because your compressor wheel has a big affect on this as well.
    3. Everything you just said in reality deals with both the compressor and turbine wheels, as well as the housings.
     
    Last edited: Nov 29, 2007
  5. Briansol

    Briansol Admins Admin VIP

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    the LS head flows like crap and doesn't rev out like the vtec's do, so you're going to need a smaller turbo than a gsr would to get a powerband sooner.

    i'd recommend this:

    Garrett T3/60-1 w/ .48 a/r

    fast spool (mid 3500's i would imagine it starts kicking in some power) and a good top end that WILL die off at 8k due tot he .48, but not at 6800... it will be perfect there :)
     
  6. R.E.Developement

    R.E.Developement Import King of Irvington

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    thats a good size but i still love them 50 trims. ive just done a 50 trim with 63ar stock ls turbo setup for this kid this saturday and it runs excellent and its on only on 8 psi
     
  7. jtornado

    jtornado New Member

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    So how do I calculate the trim???? Do I take the trim from both wheels and put it into a formula. How did you calculate the trim???
     
  8. honda801

    honda801 New Member

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    i am also interested someone, anyone?
     
  9. silver

    silver Senior Member

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    Forgot to keep up with this. The formula is:

    Trim = Inducer^2/Exducer^2 x 100%

    Thus, for the "50 trim", the calculation = 54^2/76^2 x 100% = 50
     
  10. jtornado

    jtornado New Member

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    I tried to calculate that with other turbos and im getting different answers. Why times it by 100% and the inducer is always bigger than the exducer. Does mayor mean the same thing as inducer????? Here go to this link and try to calculate out the trim and yes I already know they tell you the trim but I wanna figure it out myself. Also do you calculate the trim from the compressor wheel???????
     
  11. silver

    silver Senior Member

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    You have that backwards. Inducer is the outside "inducing" portion of the wheel.

    Wait what the hell, were you using that for turbine trims? That was only for compressor wheels.

    Also, this isn't really that important. The actual wheel dimensions mean infinitely more than "trim".
     
  12. jtornado

    jtornado New Member

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    I got this from that Garrett site
    Example #1: GT2871R turbocharger (Garrett part number 743347-2) has a compressor wheel with the below dimensions. What is the trim of the compressor wheel?
    Inducer diameter = 53.1mm
    Exducer diameter = 71.0mm


    [​IMG]
    Also wouldn't this turbo have a big trim????
    Garrett T3/60-1 w/ .48 a/r
     
  13. silver

    silver Senior Member

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    That's exactly what I wrote above.

    The 60-1 is 60mm/76mm, meaning the trim would be 60^2/76^2 x 100 = 62 trim.
    The turbine wheel is a T31 "stage 3" wheel, which is 65mm/57mm. Turbine wheels are calculated backwards, so 57^2/65^2 x 100 = 77 trim (it's commonly called the 76 trim because that is what you get if you use inches instead of mm).

    Like I said though, "trim" means jack shit. The T66 wheel is a "52 trim", but you can bet your ass that it flows a crap ton more than the "50 trim wheel" aka 2.123/3.000 compressor.
     
  14. jtornado

    jtornado New Member

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    So what are the things I should be looking for on a turbo?????
    Or just tell me if Im right.
    I want a large Compressor A/R(does this mean it can hold about 15 max psi or so but can flow more) and small-medium Turbine A/R(does this mean more low-end torque) to spool a little quicker, possibly around 3500.
    The head will be stock so I will not be going over 6800.
     
    Last edited: Dec 1, 2007
  15. silver

    silver Senior Member

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    Spoolup is determined by the turbo as a whole basically--compressor wheel, turbine wheel, and turbine housing.

    The housing VOLUTE size will play just as big a role as the A/R, meaning that since a T4 inherently has a bigger volume to fill up, it's going to spool that much later than a smaller T3. A/R can only be used to compare between the same type of housing--e.g. a .48 T3 will spool sooner than a .63 T3.

    Compressor housing A/R means next to nothing as far as I'm concerned. Garrett turbos have a much more limited set of compressor housings.

    Compressor wheel is the single most direct determinant of your turbo's airflow characteristics (makes sense, doesn't it?). The general train of thought is that the bigger the wheel is, the more air it will flow. Minute differences in wheel size actually have huge impacts on flow characteristics, so keep that in mind.

    The turbine wheel is what actually turns this whole assembly. In general, the bigger the turbine wheel, the less boost you will have to run to make the same power--a given the same 60/76mm 60-1 wheel and say 14.7 psi boost (PR=2), same everything else, the T31 turbine wheel will make less power than say a T350.

    As far as which turbo you should go for, I believe B answered that 10 posts ago. If it were me though, I would ask for at least the stage 5 turbine wheel if it doesn't cost much more.
     
  16. jtornado

    jtornado New Member

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    So the T3 is smaller(faster spool and smaller volume) than the T4(slower spool and bigger volume). If my goal is around 300hp then I want a bigger turbine wheel to get more hp than a smaller wheel and a smaller turbine a/r to spool quicker and the bigger the compressor wheel the more air it can flow. Well wouldn't that mean more air it can flow at one time. Example if I wanted to be running lets say 30psi(I actually run 10psi but this is just an example), I would wanna be looking for a big compressor wheel to suck a lot of air at 1 time but I would also want a smaller turbine wheel to run more psi and than finally use a T4 because of the large volume of air?????????
    I'm sorry if I'm making it really difficult for you but I'm doing my best to understand.
    I heard that the bigger the down pipe the faster it spools, is this true?????
    Also could you tell me the differences in wheel stages????
     
  17. silver

    silver Senior Member

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    Less exhaust backpressure (more free flowing/bigger exhaust) = easier for exhaust gas to move across the turbine wheel = faster spool.

    Jesus I don't even remember what they call stages anymore. All I know is that there's the T31, T350, T4-69, and the T4-P trim (lowest to highest). If I had to take a guess, it would be stage 3, stage 5, "69", "P-trim".

    The whole part where you start getting into mass air flow per unit time is when I get really lost. At the risk of misunderstanding your questions and then sounding like a douche by giving you bad/wrong ones, read these links instead:

    TurboByGarrett.com - Turbo Tech102
    TurboByGarrett.com - Turbo Tech103

    In case you still want my input though--
    -The T3 vs. T4 thing is a moot point. You will not be using a T4 turbine housing for your power goals, end of discussion.

    -The two common turbine wheel choices you have, assuming you don't go with a custom job and shove a T4 turbine wheel into a T3 turbine housing (which can be done, and works well btw--I'm on a .55 A/R Mitsubishi flanged housing running a Borg-Warner turbine wheel roughly the size of a P-trim), are the T31 (stage 3) and the T350 (stage 5). I would recommend going with the T350 though, as the extra lag is worth the efficiency increase, ESPECIALLY if you're going with a much bigger compressor wheel.

    Edit: I think I'm wrong about the 69/P-trim in a T3 thing. Either way though it is up to you, but I would still go with a T350.

    -Compressor wheel selection is much more finicky given that I'm not too familiar with Honda turbo sizing. I do know that short of going with an advanced EMS system, you will be stuck at roughly ~10 psi of boost (I've also heard 12, so I don't know). Common choices seem to be the T4 60-1 wheel, and the T4 T61 wheel. B already recommended the 60-1 wheel above, so I'd just go with that.
     
    Last edited: Dec 4, 2007
  18. jtornado

    jtornado New Member

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    Okay I have 1 problem. My tuner does not think I will get to 300 hp with this setup:
    B18a 81.5mm 9:1 CP Pistons with Eagle H-Beam Rods
    Garrett T3/60-1 .48 A/R
    Walbro 255 Fuel pump
    10psi
    Hondata S300
    3" Exhaust
    Mild P&P Head
     
  19. LS_VTEC

    LS_VTEC you get the BRAKE

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    You won't get 300whp out of that. A gsr with that same setup utilizing the stock bore dimensions only made 295whp. AND that was with bigger injectors and a tune on crome-pro and was actually 11psi.

    Do Ls-vtec turbo. get a b16 head, build it in moderation... you dont wanna spin that LS bottom end higher than 8k built or not if your using the LS crank. Its not meant to be spun high, thus the longer rod stroke. go ls-v, do a mild port job and valve job on the b16 head, go with an itr manifold/tb, do valve springs/retainers, rc 550's and tune it accordingly... you should make over your goal of 300whp easily and have reliability.

    All this talk about boost is making me want to go back to it :[
     
  20. jtornado

    jtornado New Member

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    So even with RC 440's or Precision 440's I still will not be able to reach this goal??? My tuner did say I will need 16+psi possibly to reach 300. What could my number look like that you would think with this setup and I know it might vary on different tuners. I was hoping atleast 250whp out of this setup.
     
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