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B20 Pistons for Low Compression Setup

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  • #46
    Good luck! I am ready to pull the trigger on the Wisecos, $140 a hole, but I already have a set of Millenia rods. Never did find any floating piston options, or shop willing to cut circlip groves, in the low compression (1998) B20 engine pistons, which as it turns out have a tad lower compression height than the later ones.

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    • #47
      Originally posted by Mike 99 View Post
      ...Never did find any floating piston options, or shop willing to cut circlip groves, in the low compression (1998) B20 engine pistons, which as it turns out have a tad lower compression height than the later ones.
      The Honda pistons that I have -are floating pin and have spiral locks.
      Success is a measure of determination!
      Bonneville Dreamer-(AKA Purple Pimp Mobile)
      $500 Gas-Electric-Gas Reconversion/Restoration
      Mini-me & 500k "Old Gal" RIP
      Restoration of a legend

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      • #48
        The ebay turbo ones? They look really good, but as you said they require different rods or re-working the milli rods. The early (pre-1999 Honda USDM) factory-style lower-compression height and dished B20 pistons may have just squeaked by.

        I thought about the connecting rod options, as well as using milli rods, B20 turbo pistons, and EngineTech 0.030" head shims, but I don't have a lot to work with locally for machine shops and by the time I either paid for the work on the rods - milli or 5.4 ford - or monkeyed around with variable cam timing/intake alignment, I would probably be right there in cost with the Wiseco's.

        However it sounds like you have a good working relationship with a machine shop and have been down this road a time or two, looking forward to reading how it comes together!

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        • #49
          Do Vr6 pistons work with our rods? Same bore and pin diameter. I need to learn how to use the calculator to figure out the compression but I was researching and wondering of this has been tried before. I searched the forums but couldn't find anything. Compression on the pistons I'm looking at is 8:5.1 je pistons.

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          • #50
            I remember looking at the Vr6 awhile ago. Check the compression height, I seem to recall it was way off. Also being a German part it cost more than custom pistons.

            I pulled the trigger on Wiseco's. I have a new (yes new) block, so I went with 84.5mm pistons (stock bore, not oversize), -11 cc, 0.030" offset wrist pins. Wiseco part number WD-04479.

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            • #51
              Originally posted by Mike 99 View Post
              I remember looking at the Vr6 awhile ago. Check the compression height, I seem to recall it was way off. Also being a German part it cost more than custom pistons.

              I pulled the trigger on Wiseco's. I have a new (yes new) block, so I went with 84.5mm pistons (stock bore, not oversize), -11 cc, 0.030" offset wrist pins. Wiseco part number WD-04479.
              Yeah I checked and asked wouldn't work. How much the wisecos cost you? I've been meaning to fill out custom forms for piston companies to see prices.

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              • #52
                $144 per cylinder

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                • #53
                  Originally posted by KLZE Porsche View Post
                  The Honda pistons that I have -are floating pin and have spiral locks.
                  Hey,

                  I'm looking to do the same thing with these pistons, how have you got on with them so far?

                  I'm wondering if we could get away with just using a thicker head gasket to take into account the taller piston? lots of people run positive piston / deck setups by using this method...

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                  • #54
                    I'm guessing you already noticed that the honda rods are 0.935 wide on the pin end and the kl rods are 0.835, does this concern you? thats quite a large increase in clearance. the bending load on the pin will be increased because of this.

                    going back to my comments on gaskets, i'm sure you've also heard of using solid copper head gaskets, this would seeminly be an ideal solution as you can choose many thicknesses.

                    if copper isnt your thing, aluminium is widley used for decompression plates for alloy block / head engines along with a single head gasket.

                    so if we used a 1mm thick decompression plate and a stock head gasket then i think we might have solved the compression height issue...

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                    • #55
                      Originally posted by jimmy hotrod View Post
                      I'm guessing you already noticed that the honda rods are 0.935 wide on the pin end and the kl rods are 0.835, does this concern you? thats quite a large increase in clearance. the bending load on the pin will be increased because of this.

                      going back to my comments on gaskets, i'm sure you've also heard of using solid copper head gaskets, this would seeminly be an ideal solution as you can choose many thicknesses.

                      if copper isnt your thing, aluminium is widley used for decompression plates for alloy block / head engines along with a single head gasket.

                      so if we used a 1mm thick decompression plate and a stock head gasket then i think we might have solved the compression height issue...
                      Hey Jimmy!

                      I got the block bored -but I have another engine on the stand at the moment. As soon as I complete the current build -that one is next up.

                      As for the rod width difference -I don't consider it to be a significant issue (unless I was going to be pushing 500+ hp ...Not on this one!) -as this is only .05" per side

                      As for the head gasket idea (or actually spacer with the large difference) -I would rather shave the block to the desired height to avoid having to possibly use two head gaskets per bank (block/gasket/spacer/gasket/head). I don't like the idea of having more than one variable thickness void on a torqued surface -where the torque method is goofy anyway (torque/90deg/90deg). I think no matter which way I choose -there may still be complications.

                      Shaving the block to the desired height may end up causing loss of gasket sealing surface. That is one thing that I will be measuring when I mock it up. I plan to put one stock KL piston in one TDC cylinder and then in an opposed TDC cylinder -the Honda setup -to compare measurements.

                      It may be entirely necessary to shave the block -as well as using a thicker copper head gasket to get the desired deck height.
                      Last edited by KLZE Porsche; March 15, 2017, 09:33 AM.
                      Success is a measure of determination!
                      Bonneville Dreamer-(AKA Purple Pimp Mobile)
                      $500 Gas-Electric-Gas Reconversion/Restoration
                      Mini-me & 500k "Old Gal" RIP
                      Restoration of a legend

                      Comment


                      • #56
                        That's good to hear about the rod thickness.

                        The comp height of the Honda piston is 30mm and the comp height of the kl is 29mm, if using a Milli rod or K1 etc then the piston will stick out the deck 1mm more than the kl piston right?

                        The solid gaskets can be used without a conventional head gasket or if using an aluminium decompression plate, it is recommended that you use only one gasket but use a sealant on the metal to metal seal.

                        ---------- Post added at 04:33 PM ---------- Previous post was at 04:33 PM ----------

                        How do the valves line up with the valve pockets?

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                        • #57
                          Originally posted by jimmy hotrod View Post
                          ...How do the valves line up with the valve pockets?
                          That is my largest concern. The Honda pockets are a smaller diameter. I really do not want to machine the tops of the pistons for valve clearance -and thus losing the benefit of the teflon cop coating (or whatever it is). I figure if these are supposed to be turbo pistons for Honda's -the H guys would be installing larger valves. And the pistons should be designed to allow for this.

                          So I won't actually know until I mock up and put some silly putty on top of a piston and rotate it through the movements.
                          Success is a measure of determination!
                          Bonneville Dreamer-(AKA Purple Pimp Mobile)
                          $500 Gas-Electric-Gas Reconversion/Restoration
                          Mini-me & 500k "Old Gal" RIP
                          Restoration of a legend

                          Comment


                          • #58
                            Hurry up and putty that thing so I can order my pistons hahaha!

                            I was talking with a work colegue who has made a cutting tool from a valve before, dummy built the head onto the engine and used the valve guide to control the tool location! You just need a drill to drive the valve / cutting tool!

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                            • #59
                              Originally posted by jimmy hotrod View Post
                              Hurry up and putty that thing so I can order my pistons hahaha!

                              I was talking with a work colegue who has made a cutting tool from a valve before, dummy built the head onto the engine and used the valve guide to control the tool location! You just need a drill to drive the valve / cutting tool!
                              I did very similar to make a valve seat surfacing tool. It actually works quite well! Sometimes the Jerry-rigging (or red-necking) method makes sense!

                              I have some NASCAR 6mm stem TI valves that would make a good KL piston valve relief cutting tool. You just have to make sure that there are no micro machined bits-n-pieces present when you move the piston in the bore! The only major drawback to cutting your own reliefs this way -is that there is no real good way of cutting the reliefs to a high tolerance depth. You can end up with varying compression from cylinder to cylinder.
                              Last edited by KLZE Porsche; March 15, 2017, 09:57 AM.
                              Success is a measure of determination!
                              Bonneville Dreamer-(AKA Purple Pimp Mobile)
                              $500 Gas-Electric-Gas Reconversion/Restoration
                              Mini-me & 500k "Old Gal" RIP
                              Restoration of a legend

                              Comment


                              • #60
                                Originally posted by dammitcam View Post
                                sucks we dont have better aftermarket support
                                That is simply because probe owners in general are cheap bastards who does not want to pay for parts. If there a market here, it would be filled
                                Mazda 626 GT - 2.5 V6 - KL31
                                Mazda RX-7 FD - EU spec

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