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P73 PR3 or P30 pistons?

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P73 PR3 or P30 pistons?

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    P73 PR3 or P30 pistons?

    Ok i have p73Ao pistons on my ls block i read somewhere that the pr3 or p30 pistons are better for compresion if so why??????? dont the type r pistons have better compresion??????

    #2
    http://www.c-speedracing.com/howto/c...c/compcalc.php

    Plug in all your information, you'll see that the setup yields higher compression, thus creating more power.
    With a higher compression, you will have a stronger engine, refer to the TEG Tips about rebuilding an engine, it talks about what compression is too high for pump gas, etc.
    In other words...

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      #3
      Your ITR pistons do have better compression than stock, but not as high as some others:
      This info is from another G2IC member:
      here is a list of the different 81mm bore oem b series pistons. In order from highest compression ratio, to lowest.

      1) PCT
      2) P30
      3) PR3
      4) P73-00 (jdm itr)
      5) P73-A0 (usdm itr)
      6) P72-00 (jdm gsr)
      7) P61
      8) P72-A0 (usdm gsr)
      9) PR4


      So, Here are the compression ratios of these pistons in the LS. I'm sure you'll note this already but i'm calculating for a stock head, if yours is milled, obviously it'll be different.

      b18a with:
      PR4: 9.2:1
      P72-A0: 9.6008:1
      P61: 9.6987:1
      P72-00: 10.135:1
      P73-A0: 10.3438:1
      P73-00: 10.807:1
      PR3: 10.8179:1
      P30: 11.015:1

      out of all of those the pr4, p61, pr3 and p30 will fit stock LS rods w/o modification. All of the b18c pistons will require the rod shaving modification....any machine shop can do this.

      This info was posted recently by a G2IC member, I am sure whoever you are will recognize your handy work, but I copied this into my Teg Notes, and I didn't copy the author's identity, my bad.

      Comment


        #4
        wow coo thanx this help out alot and also put me in check i kinda figure that the type r pistons give u more Compresion that the b16 ones.Well my next question is that my mechanic gots 2 P30 pistons and he order 2 more but they send him the PR3, but on the box they came out of it says P30 so we got confused we called honda and they said that its the same thing its that the numbers change in time for inventory reasons.Well i look at the P30 pistons we have and the 2 new PR3 and the look excactly the same so i dunno what do ya think? And can someone pleaseeeeeeeee put picks of PR3 and P30 pistons that also may help pleaseseeeee.

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          #5
          And also with what rods ya think will go best with the P30 pistons should we stick with the Ls rods or the SI or Type R rods if so wich vtec rods are the best. And wich crank is better the ls or the si or type r.And this is going all in a B18b block im going all motor ls.

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            #6
            any help please

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              #7
              All motor, just have the rods shot peened. unless you've got a fat pocket and money isnt an issue. Get some Crowers. ?

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                #8
                I still need help on these question........Well my next question is that my mechanic gots 2 P30 pistons and he order 2 more but they send him the PR3, but on the box they came out of it says P30 so we got confused we called honda and they said that its the same thing its that the numbers change in time for inventory reasons.Well i look at the P30 pistons we have and the 2 new PR3 and the look excactly the same so i dunno what do ya think? And can someone pleaseeeeeeeee put picks of PR3 and P30 pistons that also may help pleaseseeeee.

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                  #9
                  they say on the top of the piston either "pr3" or "p30"

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                    #10
                    well the new ones we got say PR3 on top of the piston but on the box they came out of it says P30 and they look sooooooo alike to the P30 we already and on those it says P30 on top of the piston and i dont know what to look for, like i said when my mechanic order them they told him that its the same thing and something about damm i forgot, i want to say invantory reasons or something about time changing lol i dont know lol. Well we are in the process of installing them now but dont want to mix it up with 2 diff pistons if the are really different please help.

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                      #11
                      what does it say on the top of the piston?

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                        #12
                        PR3 on the 2 new ones we order and in the box they came out of it says P30 and on the ones we already have it says on top P30.

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                          #13
                          then they're pr3's. i'd to with the actual product over what the box says, they're going to look very similar, but they are in fact different.

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                            #14
                            i'd to with the actual product over what the box says........??????? on that part retype please.

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                              #15
                              what happends if we do decide to put them in anyways will it work and will i loose compresion...........

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                                #16
                                help

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                                  #17
                                  um, yeah, you don't really want to do that. that's going to mess with all sorts of things that you don't want to get into. don't waste your time and money by rushing it and doing this, get the other two p30s.

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                                    #18
                                    yea ur right let me talk to my mechanic tomorrow and see if i can talk to the guy to let me know if the PR3 he send me are the same as my P30 that i have in my hands. Its weird that the PR3's came in a box that say P30's, so my next question is can i tell them apart by just looking at them besides that stamp number on top. Are the P30 pistons more doomy than the PR3's?
                                    Last edited by ZeroCool; 29 Dec 2004, 03:16:29.

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                                      #19
                                      yes, the p30s are a little more domey, but i'm not sure if you're going to be able to tell. but once again man, they are pr3's if that's what it says on the piston, regardless of what it says on the box. someone messed up.

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                                        #20
                                        i scanned the posts.. didnt see anyone answer your question about what rods to use..
                                        you have to use LS rods as you have an 89mm stroke.. if you use the GSR/ITR (b18c1/5) rods, your pistons will be hitting the head and valves as they're longer by almost a millimeter. the b16 rods are way too short as is the b17 rods..


                                        the best thing you can do with a stock LS rod is have ARP rod bolts installed and have them "resized" at a good machine shop (any good machine shop will know what resizing the rod is) and have them balanced.
                                        i'm not a believer in shotpeening.. my old lsvtec had balanced/resized LS rods with arp rod bolts.. i revved that thing to 8200 no problems.. the rod bolts are the weak point on the stock LS rods... the rod itself is strong.

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                                          #21
                                          he never aksed a question about rods . it didn't matter in this case anyway as the pr4's, pr3's and p30's all share the same wrist pin.

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                                            #22
                                            Originally posted by ZeroCool
                                            And also with what rods ya think will go best with the P30 pistons should we stick with the Ls rods or the SI or Type R rods if so wich vtec rods are the best. And wich crank is better the ls or the si or type r.And this is going all in a B18b block im going all motor ls.
                                            hmm.. looks like he asked about rods right there


                                            also for to answer his crank question.. he can either use ITR/GSR rods and itr/gsr crank in LS block or he can keep his LS rods and LS crank (second choice is best bet) you cant mix and match

                                            edit:
                                            the b18 series blocks and b20b/z blocks have same deck hight... meaning you can interchange the internals between any of them (well the b20 has 84mm pistons so cant interchange them ) the b16 and b17 have the same block, just different internals ... same deal applies.. u can put b16 internals in the b17 block and visa versa.. altho if u go with b16 internals in b17 block, u got a b16, not a b17
                                            Last edited by 93integraRS; 31 Dec 2004, 21:57:02.

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                                              #23
                                              whoops, accept my apologies. i'm blind today

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                                                #24
                                                LOL np, i missed the part about the crank didnt see that till i read it a second time

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