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  • B20 Pistons for Low Compression Setup

    I'm looking to upgrade with higher strength Millenia rods and lower compression pistons to allow more boost. Wiseco forged pistons are a good option, lots of great info already posted on Vitera pistons as a low cost option with somewhere around 8:1 comp. This little exercise is looking at readily available B20 pistons.

    Others have pointed out that the B20 piston has the correct pin diameter for the Millenia rods, and I think there are members who have done this swap for NA. I have a question on the use of B20 pistons turbo pistons with Millenia Rods for a low compression setup. Pricier than the Vitera pistons, but perhaps less than custom pistons and may be available off-the-shelf.

    The B20 pistons for this example - although there are several suppliers - are the Manley Platinum Series, forged 2618 alloy, with floating pins, a 11.9 cc dish, and 84.5 mm. The B20 pistons have a compression height of 30 mm (1.181") vs. stock KLDE pistons with a compression height of 29 mm (1.142") (or 28.75mm in some references, verification here would be great!!).

    The Millenia rod specs I have pulled from old threads is 5.4' length, 21mm small ends, full-floating, versus 5.427-inch and 20mm for stock.

    The deck height with stock KLDE rods and pistons is 0.013" (I think, not verified from a shop manual reference). Add 0.027" for the Millenia rods (5.427 - 5.4), then subtract 0.039" for the difference between the compression height of the B20 and KLDE pistons (1.181"-1.142") and the remaining deck height above the piston top is 0.001", or diddly squat.

    KL03 head chamber volume is 39cc, stroke is 2.921". Compressed head gasket is 0.026". Plugging the all info for the KLDE/Millenia Rod/Manley B20 turbo piston into the Summit Racing compression calculator tool,

    http://www.summitracing.com/expertad...ion-calculator

    comes up with a grand total of 8.6:1 compression ratio, or a nice happy number for a turbo while not killing it when not on boost. For comparison, STIs run 8.2, Evos 8.8.

    Putting it out there to see what the issues may and see if anyone else has taken this to the next step.

    I will get the ball rolling with some of the obvious stuff:
    - may create interference engine, valve relief for a B20 may be all wrong for a KL
    - the 0.001" piston clearance from the deck seems sketchy.
    - The connecting rod/KLDE piston compression height/deck height numbers above may be off
    - the piston wrist pin offsets may be wrong

    Thanks!

  • #2
    OK, problems above, the Millenia rod length is same as stock, so this would require using 5.4" 347 stroker rods, but cost for rods and additional shims and machining goes up. Bummer. Also dug deeper on the compression heights, looks like slightly less difference from the KL to the Honda that the first cut (29.6 mm Honda - 28.9 mm KLDE, 0.7 mm or 0.028").

    Soooo, deck height: 0.013" stock plus 0.026" from rod length change minus 0.28" for difference in compression height between Honda and Stock piston =0.011". OK in theory, but for the cost may as well go Wiseco or something similar. Or 8:1-ish with the Vitaras.

    Ah well.

    Comment


    • #3
      Custom piston sets for milli s rods are like 130 a piece roughly too sucks we dont have better aftermarket support
      1995 Probe GT. Colt 218* cams, Tein SS Coilovers with EDFC, K6F trailing arms, CZT traction bars, ZE Intake Manifold, Milly MAF/OBDII swap, GReddy SP1, Probe Addiction Strut braces, RX8 Seats, PRD STS, PRD door sills, ACT 6puck, MFactory LSD,Built trans, Euro tails and corners, Walbro 255, and more to come
      Stage 3 Audi S4 pushing about 425awhp

      Comment


      • #4
        Agree. I have been looking at another Suzuki option, but very little information available. The 2007-2009 SX-4 also had the J20, which (hard to verify) had a compression ratio of 10.5:1, up from the earlier engine 9.5:1 ratio. What is really unclear is whether this was from different heads or from a smaller dish piston. The part numbers for these pistons is different than the 2003 and earlier pistons, so it is possible this is how the compression change happened - if it did. Did I mention good specification data is hard to find? The 2007-2009 pistons are 84 mm stock, so 0.020" oversize (84.5mm) should be the ticket. The wrist pins are floating like the earlier models, and 21mm, so should fit my Milli rods. If the piston dish is the source of the higher CR, this piston may - possibly - result in a CR of somewhere between 8.5 and 9:1 with milli heads and KLDE heads, if there are no fatal flaws like sticking up above the deck.

        2010 and later SX4's went to a VVT design called the J20b, same bore/stroke dimensions but many other changes and flat top pistons, maybe different deck height? Unlikely to be a go.

        I did call an aftermarket manufacturer who makes pistons for the SX to see if they had specs available on dish volume and compression height but keep getting routed to a dead-end voicemail. Try, try again.

        So my connecting rod upgrade is on hold for now, in any case I will wait until I tear down the engine - or build a different one - to see if I need to go another 0.020" over on the pistons if the block needs a bore.

        Until then, I would be immensely grateful if anyone on PT who may have access to the 2007-2009 SX4 piston specs would check it out and pass the info on!

        Comment


        • #5
          You can always pray for a bulk buy.

          I want to buy some pistons soon. I will approach the admins about it.
          ¡Renewed Vigor!

          Comment


          • #6
            I will light a candle under the bulk buy shrine.

            I did get half the info on the SX4 pistons using a secret squirrel phone number given to me by a distributor. Same compression height as the earlier J20 pistons. Listed specifications differences are compression ring widths are narrower on the SX4 and the pistons appear to have a coating/heat treat. No specs available from the manufacturer on the dish volume, so I would need to pony up and buy a set to get an answer. Given the low cost, I may do this. The pistons may be cast from the same mold used for the older J20 with different ring grooves cut, or may be a different casting. This was the problem with the J18 swap as pointed out by others here, the factory dish volume would have been ideal for the probe but the aftermarket sells just the J20 piston dish to save making a different casting, and factory (non-oversize) pistons are 84mm. No way to tell on the 2007-2009 SX4 aftermarket piston without getting my hands on one.
            Last edited by Mike 99; April 24, 2016, 12:24 PM.

            Comment


            • #7
              I don't know how well people have investigated into Nippon racing pistons for Honda -but these look like a very good piston for the money and supposedly good to 600 hp:

              http://www.ebay.com/itm/161564228393

              85mm is .020 over for a KL if I am correct? That is just about perfect for an overbore rebuild without going too far.
              Last edited by KLZE Porsche; April 23, 2016, 03:20 PM.
              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


              • #8
                Last I spoke with Ross, they wanted around 800 for 6. They have measurements already, but still recommended I send them a sample.

                Diamond wanted about a grand.

                These Nippon Racing ones are about half that price. I'm just not brave enough to be the guinea pig.
                ¡Renewed Vigor!

                Comment


                • #9
                  Originally posted by KLZE Porsche View Post
                  I don't know how well people have investigated into Nippon racing pistons for Honda -but these look like a very good piston for the money and supposedly good to 600 hp:

                  http://www.ebay.com/itm/161564228393

                  85mm is .020 over for a KL if I am correct? That is just about perfect for an overbore rebuild without going too far.
                  It's a 21mm pin, but a pressfit. Would that make any difference for using the millenium rods ?

                  Also; I don't fully understand their compression ratio.

                  85mm B16A BLOCK AND HEAD 11:1
                  85mm B18A/B BLOCK W/ PR3 HEAD 12.9:1
                  85mm B18A/B BLOCK W /P72 HEAD 13.1:1
                  85mm B20B/Z BLOCK W/ PR3 HEAD 12.9:1
                  85mm B20B/Z BLOCK W /P72 HEAD 13.1:1
                  85mm B18C BLOCK W/ PR3 HEAD 11.9:1
                  85mm B18C BLOCK W P72 HEAD 12.1:1
                  Mazda Mx3- Panther black, Kosei 18", custom hood, cleaned, new pakfeifer front, customized pakfeifer rear

                  KLZE highcompression, Pippercros Viper intake, kl31cams, MS1 v3, Aasco fly, CM st3 clutch, cai, ss headers, ground wirekit, srd bushings, msd window switches, nitrous

                  Comment


                  • #10
                    Originally posted by Whitefinish View Post
                    It's a 21mm pin, but a pressfit. Would that make any difference for using the millenium rods ?

                    Also; I don't fully understand their compression ratio.
                    That information would be irrelevant to us. Those combinations are using different block and head combinations (varying head chamber volumes and block deck heights).

                    For us -the only thing that would matter would be the piston compression height -which isn't given. I have sent the seller a message to see if he/she can provide this information. But -yes the pin size is the same as Milli "S" rods.

                    OK -I did a little bit of investigation and the results are not set in stone. But in using Rock Auto to find compression heights on pistons from a Ford Probe and from a Honda CRV (B20B engine) -EngineTech brand gives compression heights. They gave 1.150" for the Probe and 1.165" for the B20B. This is a difference of .015 (shorter for our Probe). This might be able to be compensated for in head gasket thickness (if you can find a head gasket that is .015" thicker than stock). This can also be compensated with 5.400" rods and a minimal shave on the heads. I think there is potential here.
                    Last edited by KLZE Porsche; April 24, 2016, 05:18 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


                    • #11
                      Considering the price of custom, I am very interested.
                      ¡Renewed Vigor!

                      Comment


                      • #12
                        My main concern is that these pistons are designed for an inline engine, don't V engine pistons have to be made a certain way? I'm sort of a novice at building engines lol
                        1995 Probe GT. Colt 218* cams, Tein SS Coilovers with EDFC, K6F trailing arms, CZT traction bars, ZE Intake Manifold, Milly MAF/OBDII swap, GReddy SP1, Probe Addiction Strut braces, RX8 Seats, PRD STS, PRD door sills, ACT 6puck, MFactory LSD,Built trans, Euro tails and corners, Walbro 255, and more to come
                        Stage 3 Audi S4 pushing about 425awhp

                        Comment


                        • #13
                          Originally posted by dammitcam View Post
                          My main concern is that these pistons are designed for an inline engine, don't V engine pistons have to be made a certain way? I'm sort of a novice at building engines lol
                          Not having the proper off set would affect longevity. You side load the piston more.
                          ¡Renewed Vigor!

                          Comment


                          • #14
                            I know there were issues with one build on here I forget the member but he had 2 of the same bank made, there was a VR6 build on audizine as well where they placed the pistons backwards lol. It really got me contemplating doing my own engine work haha
                            1995 Probe GT. Colt 218* cams, Tein SS Coilovers with EDFC, K6F trailing arms, CZT traction bars, ZE Intake Manifold, Milly MAF/OBDII swap, GReddy SP1, Probe Addiction Strut braces, RX8 Seats, PRD STS, PRD door sills, ACT 6puck, MFactory LSD,Built trans, Euro tails and corners, Walbro 255, and more to come
                            Stage 3 Audi S4 pushing about 425awhp

                            Comment


                            • #15
                              Originally posted by KaedenKy View Post
                              Not having the proper off set would affect longevity. You side load the piston more.
                              I found out not too long ago -that piston offsets are not always used. I will have to check with the seller to find out.
                              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

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