Intercooler Too BIG or Too SMALL???

Posted by 4g63telantra, Nov 12, 2005
Newbie Forum - Beginner/newbie/general DSM modification questions. First mods, how to run 10's when you haven't run 12's yet, any tech question that doesn't fit in another tech forum.

  1. 4g63telantra

    4g63telantra Proven Member

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    Just wanted to know, How can you tell if a Intercooler is too big or too small for a turbo?
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  2. brute

    brute Proven Member

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    if the intercooler is too small to handle the boost, you will get heat soak. and if the intercooler is too big you will have boost spikes
    #2
  3. fwdturbobov1996

    fwdturbobov1996 Proven Member

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    I thought you would also experience slow spool up if the intercooler is too big. Buddy got his fmic before his turbo and t25 spooled 1500 rpm later LOL. LOL .
    #3
  4. 420aonboost

    420aonboost Probationary Member

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    yes thats correct...if your intercooler is too big then you will get more lag from your turbo
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  5. 96bmwm3

    96bmwm3 Proven Member

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    This is not necessarily true. Spool is a function of exhaust flow.
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  6. tstkl

    tstkl Proven Member

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    THIS IS NOT NECESSARILY TRUE

    if you dont know, dont speak....

    think about it, a larger intercooler has a larger volume, which means the turbo charger has to fill your larger intercooler with pressurized air before it starts filling the uicp, then the intake manifold, then the engine, if you increase the volume of your intake system after the turbocharger, the spool WILL decrease, doesnt matter how unnoticable it is to you, it will... thats why people ask, Will a 3 inch uicp give me too much lag? and why i went with short route piping over long route... saves a lot of piping, cutting down on volume...
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  7. Slipstream

    Slipstream Proven Member

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    In addition to the other replies please also note that turbos should have a rating for how many cfm of air they'll push...good intercoolers also have cfm ratings. Keeping this in mind when shopping for an ic will help you pick one that will at least flow enough air to keep up with your turbo, but not so much air that you're overbuying. (how well an ic actually cools the charge air is another matter entirely) but for volume sake this should get you started.
    #7
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  8. 96bmwm3

    96bmwm3 Proven Member

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    Ok, then I'll speak. Spool WILL NOT necessarily decrease.

    Check your definitions. Spool does NOT = lag. I will admit that 420aonboost did say "lag" and not spool. But the poster before said that an intercooler would decrease spool.

    Spool refers to a turbo's spinning up to speed and creating boost. This is a function of exhaust flow, geometry, etc. In fact you might even say the more volume in the system the faster the turbo will spool (probably shouldn't say this, I don't know for a fact, but looking at the decrease in back pressure I suppose you could argue that).

    Lag actually refers to how long it takes to spool the turbo when you're already at a sufficient engine speed to create boost. This can be affected by piping, intercooler, etc. But is usually not noticeable unless the componets you have added increase the pressure drop through your system considerably.

    Oh, and just because people wonder about the affects of certain parts and because you installed short route piping doesn't make that theory a fact.
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  9. brn2race96

    brn2race96 Proven Member

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    this is a usefull thread.... i have a 2g 6bolt with a 14b turbo. I was in the market for a intercooler, any suggestions as to what will be best for moi. I wanted to go fmic, will that be too big?
    #9
  10. JessesTalon

    JessesTalon Proven Member

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    If its heat soaking its too small.....

    just get a evo fmic... good cheap decent cooling and will handle at least 16g's no problems
    #10
  11. talonkid420

    talonkid420 Probationary Member

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    What about a GT30? I know that I will need a bigger on then the on on my stock GSX
    #11
  12. ericbev

    ericbev Proven Member

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    You all need to read this... its big but has alot of information

    http://www.are.com.au/techtalk/intecoolersMR.htm
    #12
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  13. tstkl

    tstkl Proven Member

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    ok lets go through this peice by peice... your right spool is not lag, but looking at spool is like looking at hp output and trying to nail down performance, a 400hp truck isnt faster than a 200 hp car,... what am i getting at? all that really matters is the final, noticable result, aka lag... why care how long it takes your turbo to create pressure if you cant use it?

    i dont even know what your talking about when you say the more volume in the system the faster the turbo will spool, are you talking about exaust or intake? either way i think its a false statement, since exhaust gas velocity is a lot more important the overall volume, (think if you had 500 liters of gas moving at 0 m/s, fast spool right?)

    i believe you arent familiar with modern physics, and the absolute gas equation:pv=nrt

    or for those of you that dont understand, (pressure) x (volume) = (number of molecules) x (some constant i forgot the name of) x (temperature)

    pressure drop is not caused by the components of your intake system, the reason why your intercooler has a lower pressure at its outlet than at its inlet is due to the fact that n, and r are constant, and v cannot change at the same rate as t is, so p changes as well as v, (colder air is denser, right? thats why you get a decrease in v with t, but p also drops some as well)

    and the reason why i said people wonder and i did install short route piping is because, like the concept that a bigger exaust pipe will flow more gases, some true facts make their way to the modern uneducated public, (and they feed off that info, which is why you have 5 inch mufflers on the back of civics, which doesnt help, but in there warped and twisted ways of looking at exhaust, it does)... and i installed short route piping because the lower volume will decrease lag, theres no way to get around physics... it will decrease lag, while my fmic will increase it since the volume of that is about 3 times as great as my old intercooler...

    im done, if i forgot anything, tell me...
    #13
  14. 96bmwm3

    96bmwm3 Proven Member

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    I think you've made my point for me, thanks. You just lost all credibility with those comments. BTW, R is the universal gas constant (8.31 J/mol x K). I've used it a few times.

    As intake temperature decreases (through your intercooler), your volume doesn't change it's just more dense. Pressure lose IS due to the components in your intake system. Energy is lost through your intercooler and piping due to friction - this is why you see a dP across your intercooler.

    Hey everyone, if you don't add an intercooler to your cars you'll see the same pressure at your intake that you did at the outlet of your turbo!!!!
    #14
  15. DSM BEEYACH

    DSM BEEYACH Proven Member

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    You Sir are totally correct i'm glad to see someone that knows what there taking about. :thumb:
    #15
  16. CanadianTSi

    CanadianTSi DSM Wiseman

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    Kingston, ON_Canada

    Your friend had a boost leak.

    People make too big of a deal about Intercoolers being to big, its just not that big of a problem in reality, maybe a couple hundred rpms of extra lag but that's it.
    #16

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