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what ratio pistons???

Discussion in 'Forced Induction' started by bvtec, Jan 15, 2004.

  1. bvtec

    bvtec Senior Member

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    hi
    here i am again with a question for u honda professionals. i wanted to know what ratio of low comp pistons do i need for my project civic b16a2 turbo,i am wanting to run abt 350 whp and approx 15-17 psi,i was gonna settle for the 9.01 when a friend said id need at least 8.5.1 the lower the better he was suggesting 8.0.so im now confused???
    so can u resolve the issue plz what ratio is best .???
    thanks for ure help :D
     
  2. pissedoffsol

    pissedoffsol RETIRED

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    to run 17 psi, you're going to need a 3-bar map sensor, as the oem one tops out at ~ 10psi
    to run a 3-bar map, you need a hondata or other EMS unit.

    you have a goal of 350 whp- thats fine. but don't make psi a goal too. use psi to reach a goal. you build a motor for a power level, not a pressure lelvel. a normal t3/t4 (like the one found in the drag and revhard kits) will get you there on about the 17 psi you mention, give or take motor setup... but a larger turbo could easily get you there on 10.

    What ratio is best, is really user preference. the higher the compression you go, the less lag and more off-boost (vacuum) power you will have.

    IMO, 9:1 is well suited for higher horsepower cars (400+)
    with 9.5:1-10:1 being great for street setups in the 250-350 range.

    the lower compression you go, the more boost you will have to run to make the same power as a higher compression motor. But- too much compression = no room for boost to get in. so, generally, i'd say low 10's is the highest you want to go- but again, there's boosted ITR's on 11:1 making 300+ whp off 5-6 psi t3/t04e's.

    So really, its your own choice- but in a torque=-starved b16, i'd be looking at 9.5:1 pistons, a hondata, and some 550-720cc injectors
     
  3. bvtec

    bvtec Senior Member

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    hmm.. thx pissedsol
    how much boost can i run on the standard engine without damaging it i think the comp on these b16a2 is something like 10.4.1.
    because im gonna buy the pistons and rods in abt 1-2 month so im thinking in the mean while i just put the turbo on..
    thx
     
  4. mjfubar

    mjfubar Member

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    some people say u can run 10 to 12 but i think they are fucking crazy i had stock internals on my turbo b16 with t3t4 and i ran 7 or 8 max. but pissedoffsol is right shoot for a hp goal not a psi i myself am goin for at least 350 hp. i went with 10.1 JE pistons and eagle rods. with hondata and 550cc injectors. i just had a problem with my aem fuel regulator where the diaphram broke and fuel was all fucked up but its getting fixed now
     
  5. turbocrx2.0l

    turbocrx2.0l Member

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  6. NotUrAverage_Si

    NotUrAverage_Si Senior Member

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    :werd:

    B's right about the bigger the turbo, the less you'll have to boost to reach your goal. the turbo I'm using is pretty big and as soon as I figure out how to brace it and the manifold just right for the installation on Saturday, I hope to have pictures up. btw, stock b16 rods are fine to use.
     
  7. bvtec

    bvtec Senior Member

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    so you reckon that a t4 turbo will be better than the t3/t4 turbo,i heard that with t4 you suffer alot of lag.
    and by the way whats a ball bearing turbo,i have the option on one of those ??? ;)
     
  8. pissedoffsol

    pissedoffsol RETIRED

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    i dont think you need a t4, no.

    you're missing the point that theres 32312 kinds of t3/t4's

    theres t3/t04b .48/.63 turbos that are tiny.
    then, theres t3t04s .70/1.2 turbos that flow close to what a garett t66 is capable of.

    ball bearing option, IMO, is overrated. it will incraese your spool time by about 400 rpms. for the extra $1000 that they cost (real ball bearing turbos, like the garret gt35 center), its so not worth it. you're below your spool point in- 1st gear. thats it. if you fall far out of boost on shifts- you have the wrong tranny, or the wrong tire size, or simply just don't know how to drive.


    all taht said, on a b16, a 350 whp goal is pretty easy to get.... but i wouldn't be doing it on stock internals- tuned or not. not in a daily driver. but that's me. i hate the idea of cracking a sleeve and getting stranded. so i sleeved my block.

    basically, it all comes down to this:

    your budget
    how much risk are you willing to take
    and the give and take back and forth between the two.

    me, i risked next to nothing, and blew 15 grand in the process.

    others have spent 4, and probably make similar power.


    but whos going to blow up... i mean, we all do :) its just a matter of time... but how MUCH time. thats a decision on you can make.
     
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