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B16 Mini 25

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  • B16 Mini 25

    Hi Guys, I have been doing this build for a few years on and off, life got in the way of getting it finished, work, travelling etc etc so I decided to start a build thread and get it finished once and for all so I can have some fun.

    I have owned this particular mini since I was 15, it started life as a mini 25 and has gone through many incarnations over the years, I parked it up about 6 years ago as it needed some work but was never done. The body work is in bad enough condition now and I hope it can be salvaged as this was my very first car and would love to keep it.

    The basic plan is a B16 with a clubman front to make life a bit easier.

    Please excuse some of the poor quality photos as these are from old phones/cameras.

    Here are a couple of pictures of the mini how it stands now all stripped and on a DIY spit ready for rebuild.

    I’ve had a couple of DOHC Vtec’s over the years and was set on a B16 instead of a B18 as I love how they rev and with a nice rebuild I am hoping to make 185-190bhp which I think I’ll be happy with in a mini.

    I bought this 93 EG9 Civic with a rotting back end for easy money, it had an indicated 110k miles on the clock, it had a good engine and a tight gearbox.

    Before full teardown of the Civic I fitted a Hondata S300 to the P30 ECU and got it running to avoid fault finding further down the road.

    A couple of hours on a Saturday had the car striped of all the parts I need for the build

    Once the Civic was stripped I advertised and sold all remaining parts until I was left with a bare shell that I would scrap. This recouped a lot of the money from purchasing the car.

    Time to order some parts, I opted for an allspeed frame with all extras. I’m not 100% set on a clubman front, I might do the extra work and go round nose but I’ll cross that bridge when I come to it.

    With the engine and box out it was time to strip down and rebuild. For my target bhp I would have to add higher lift cams and up the compression ratio a bit.

    I decided to go with ITR cams and springs with a compression ratio of 11:1 as the fuel in the southern Ireland is pants so I didn’t want to push it to much. With this setup and a Skunk 2 intake and exhaust manifold with a good map I should see 190bhp est with a 9k redline.

    To achieve the desired compression ratio I would have to skim the head and deck the block.

    Starting with the head I sent it to get skimmed by 0.1mm and seat the valves, from my calculations this would reduce the combustion chamber volume by 0.5cc. This is before sending to the machine shop. Virgin head.

    Once I had the head back I chemically washed it and fitted ITR valve springs that I got off eBay for a few quid, before fitting I made sure the valve springs were within Honda's tolerance.

    To install the springs I made a valve spring compression tool inspired by the genuine tool that costs about £50, I made mine for free.

    With all the springs installed it was time to do a combustion chamber volume check to confirm the machine shop skimmed the correct amount and that my calculations were accurate.

    I got the burette out and mixed up some methanol with some green food dye. The standard volume of a PR3 head combustion chamber is 42.7cc. When I measured I got 42.2cc this will increase compression from 10.2:1 to 10.3:1. So far all measurements are correct.

    With the volume measurement complete I wrapped the head up and put it to one side as the cams and remainder of parts cannot be fitted until the head is torqued onto the block.
    Last edited by keitht; 10-07-2017, 10:13 AM.

  • #2
    Next up was the block, there was a bit of wear on cylinder 1 so I had to get the block bored out to 81.5mm, I always wanted to use a standard Honda head gasket so I got the block decked to 202.84mm. With this combination of block height, head volume, head gasket thickness, piston and bore my compression ratio worked out at exactly 11:1.

    This is the block just back from the machine shop.

    This is as far as I’ve got with the engine, there has been a delay with my pistons and bearings but there isn’t much in putting it all back together, I hope to have the parts in two weeks.

    In the meantime I have been cleaning and reconditioning all auxiliary parts. The oil pump is first up, I stripped cleaned and checked for wear and tolerances. All measurements are well within Hondas limits.

    Next up was the thermostat housing, I fitted a new stat as well.

    I gave the alternator a quick rebuild all parts were tip top.

    Still no pistons and bearings so I rebuilt the back swing arms with new bearings and hubs and assembled the front hubs and fitted to the sub frame.

    When I get the engine back together I will tackle the S9B gearbox, Once all is together and up and running I will get the shell sorted.

    I have lots of other parts, wheels, tires, seats, suspension, body panels etc etc etc

    I will update as I go, All comments welcome.

    Last edited by keitht; 10-07-2017, 10:15 AM.


    • #3
      Fantastic work, patience and attention to detail. Are you cleaning everything by hand or is there some blasting and plating going on?


      • #4
        Originally posted by Underhauled View Post
        Fantastic work, patience and attention to detail. Are you cleaning everything by hand or is there some blasting and plating going on?
        Thanks Mate, I'll do it once and right. Most parts have been cleaned by hand in a hot water chemical bath some have been blasted but no plating.


        • #5
          Very clean, nice attention to detail


          • #6
            Originally posted by Add_Gee View Post
            Very clean, nice attention to detail
            Thanks, lots more to come.


            • #7
              I've been waiting for my pistons and bearings to come and my crank is still at the machine shop getting balanced, I have all other engine prep done so I decide to double check the deck height as I wasn't 100% happy measuring with calipers. The measurement is exactly the same as the calipers. 202.84mm

              I have been considering spraying the block as well as it looks rough even though it is spotless clean.

              Last edited by keitht; 10-07-2017, 10:16 AM.


              • #8
                Got the crank back from the machine shop today, Balanced and journals micro polished. All measurements are as per Honda spec.

                I still haven't decided to spray the block or not.

                Last edited by keitht; 10-07-2017, 10:16 AM.


                • #9
                  Your on the case hear keitht , I'm suprised you have decked the block without the new pistons and rods on dry build, to see top deck,
                  Or are they all same hight?
                  Just out of intrest to delve into the weird world of Honda
                  "yuck ,more like a 3 r2"


                  • #10
                    Originally posted by ardonfast View Post
                    Your on the case hear keitht , I'm suprised you have decked the block without the new pistons and rods on dry build, to see top deck,
                    Or are they all same hight?
                    Just out of intrest to delve into the weird world of Honda
                    This is the big push to get it finished now that I have a bit of time on my hands.

                    I know I normally wouldn't do any machine work without all of the components but I couldn't order the pistons until I got the block bored as the machine shop wasn't sure how much need to be machined to clear the damage on cylinder 1. I have the drawings and tolerances of the new pistons. The piston to deck height should be 0.15mm and piston to wall should be 0.02mm. I will confirm these measurements when I get the parts.


                    • #11
                      Hoooray these were waiting for me when I got in. Pistons, Rings and bearings. I should get a bit more done over the weekend now.

                      Last edited by keitht; 10-07-2017, 10:17 AM.


                      • #12
                        Very nice!


                        • #13
                          I didn't get much done over the weekend just a few measurements. The piston to wall works out at 0.02mm

                          Last edited by keitht; 10-07-2017, 10:17 AM.


                          • #14
                            I'm not getting much done this week, I decided to paint the block so I've been doing some paint testing to get the best finish I can.

                            I've settled with off the shelf silver Enamel, the finish and colour is far superior to dedicated high temperature aluminum engine paint. I just need to get the workshop nice and warm before painting, hopefully over the weekend.

                            In the meantime I've taken the block into the living room in front of the fire to check some measurements

                            The crank main journals measured at:

                            1. 54.980mm
                            2. 54.984mm
                            3. 54.980mm
                            4. 54.989mm
                            5. 54.987mm

                            My smaller Micrometer got damaged so I can't check the big end journals so I'll have to get a new one.

                            Last edited by keitht; 10-07-2017, 10:18 AM.


                            • #15
                              Wow. Looks like some body know how to rebuild a motor .. Really good shit mate
                              at Pod' ran 11.2 @ 122mph allmotor 1.5 60ft at pod. now building a mini