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BMW M12/13 F4t

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  • BMW M12/13 F4t

    OK guys, I am hoping I don't get flamed too hard for asking this question, but I am trying to find out more info on the F1 M12/13 F4t head. I did a couple of searches and found nothing, but I am sure the topic has been discussed before. I am just waiting for Searchy to prove me wrong. Anyway, I thought I had heard somewhere that the m12/13 head had a lot of similarities to the s14 head. All I know is that is is a DOHC mounted to an m10 block. I also know that 2002 guys are retorfiting s14 intakes onto their m10's. Was the s14 head an evolution of the m12/12 head? Someone please fill me in and tell what an idiot I am for asking this question. By the way, I did manage to find two pics of the motor, the first is from the 1982 edition in a Brabham BT 49D and the second from a 1986 Benetton B186


    Edit: This is the one other thread I can find and it doesn't really explain anything
    Last edited by greateratlanta; 07-20-2004, 11:33 AM.

  • #2
    Visit and search for m12. There have been discussions about it, several pics have been shown. There have been no internal, or chamber shots that I know of. It would be really interesting to see a cross section of the heads layout.

    I am pretty sure there was a German technical paper written about the motor in the early 80's. If you ever come across it, please post about it. I could shoot myself for not writing down the reference when I saw it. Now I can't fricking remember what paper it was a reference for.


    • #3
      since you have an E36, and are worried about flamming, I bet you frequent and bf.c

      we here at are rather friendly, and unless you a compleate wood post (aka rob) you will probably get along pretty well

      edit: any and all pictures or info on that motor is good with me.

      Karl Kraus --Education is a crutch with which the foolish attack the wise to prove that
      they are not idiots.


      • #4

        you are correct about my posting on other forums like bimmerforums and dtmpower etc. I realize most everyone on this site is mild mannererd and more interested in learning and discussing cars than flamming. I figured I would put a disclaimer just in case my topic was a repost and had been talked about many times before. Well I've been looking for some more info and here is what I've got so far. It is basic, but it is a start:

        The actual engine code is S10B15
        1985 spec:
        Engine: 4-cylinder, turbocharged M12/13 72 degree left
        Valve linkage: DOHC
        Displacement: 1499 cc
        Bore x stroke: 89.2 mm x 60 mm
        Power output: 800 horsepower at 10,500 rpm
        BMW took the and m10 1.8L block with over 100,000 miles on it, de-stroked it to 1.5litres in order to comply with then-current FIA rules and regulations. The engine, when it was finally completed, ran 62.5psi of boost for races, and 85psi for qualifying. The racing fuel used a mixture of 84% toluene which has an octane rating of 114.

        I also found out that the cylinder head of the M49 engine (6 cylinder, 3453cc 24V Motorsport twin cam), used in the group 5 racing BMW 3.0CSi, is almost similar to the M12/2 formula II engine. There was gear drive for the double overhead camshafts, the same hemispherical combustion chambers; titanium connecting rods (first born in the 1.6-litre Formula 2 days) and the same cast alloy Mahle pistons. The nitrided steel crankshaft was different. This engine first raced and won at Salzburg in March 1974, when it developed around 435 bhp at between 8000 and 8800 rpm. Theoretically the heads, with the same valve angles and the same dimensions as the Formula 2, should have been able to provide more than 9000 rpm as well, but the length of the six-cylinder crankshaft prevented this. The single slide fuel injection and leightweight pump from Kugelfischer were retained.

        New Pic:

        That's all I have for now.........

        Last edited by greateratlanta; 07-22-2004, 05:22 PM.


        • #5

          I want to revive this old tread.
          We are starting project to remake M12/13 engine.
          We have full capacity to use 5-axis cnc-mill and cnc-lathes.
          We start project by redesigning cylinder head and crankshaft.
          We have access to local foundry where blocks are casted and then machined.

          If someone is interested about hearing more about this engine project, or
          is interested to buy one of these cylinder heads please email me at:


          • #6
            Very cool project^^^


            • #7
              very interested in this project. please post some pictures and details of you progress.


              • #8
                Wow back from the dead

                I have a bmw engine book that documents the different versions pretty well I will have to scan it one day.

                One interesting note was the engines were swapped in dealers, so essentially if you had a 100k + m10 they would give you a new engine for free then they would then season the block by placing it out side of the factory in a field for a year.

                Shes sold now :(


                • #9

                  The heads are not like an s14, the inlet and exhaust are reversed and the timing gear is my a solid wheel. The s14 is more like a schtinzer 16v head from the pre 75 group 2 2002's.

                  And the m12 is still a very popular engine in historic single seater, cost about 50k these days, and Henri might get a bit upset if you copy his engine




                  • #10
                    It amazes me to see F1 using an iron block and a distributor....even back in the '80s....


                    • #11
                      While both M12 and S14 are made by BMW, let's not forget that Alpina and Schnitzer had a major influence on BMW (not yet) Motorsport. The S14 is a reduced version of the M88, which was built around a very different layout from the then M12/X motors. I'd say that the 16 valve Schnitzer head must be closer to the M88 and S14 motors than BMW's own M12 engines, which, as e21 Jason noted, had reversed intake and exhaust.

                      As a 2002 owner, I clearly see the S14 as the legit son of the 16v Schnitzer motor. The M12 being a distant uncle...


                      [email protected]

                      1969 2002 racecar
                      1989 M3 racecar
                      e39 Touring


                      • #12
                        there is a guy in Arizona that has an M12 in his garage, just sitting there. My buddy saw it a year or so ago, guy wanted something like $20k for it.

                        I think he still has it for sale. It looked like an incredible piece.


                        For Aftermarket Engine Management, Visit Electromotive Store:

                        Own a shop and need a better website?
                        PM me or Visit


                        • #13
                          We have a Chevron B36 in our shop with the M12/7. Actually, we just ran it at CMP in the club race (rather slowly, unfortunately, as she hadn't been to the track in 5 years and we just wanted to shake her down). Yes, intake and exhaust are opposed to S14 configuration. It doesn't make power until ~7k, though she will rev to ~10k. Torque lacks, just as with the S14. While dropping one into an E30 M3 would be cool, it just isn't designed to propel 2400+ lbs with OE gearing. You really need tight gearing to make use of the narrow power band, and even the OE dogleg's gearing is far too broad. You would think that 330hp out of 2L would be enough to overcome these issues, but not really. The M12/7 was designed for 1000lb F2s and 1300lb sports racers. In the end, you can make more power AND torque with the S14 for the same $$$ as a fresh M12/7. I think the last rebuild on our M12/7 at Radlinger was ~$25k. The engine was in running condition when it was sent to them. $25K will get you a rather impressive S14, I would think. Oh yeah, a fresh M12/7 will go ~15 hours before sending it back for a refresh.



                          • #14

                            This thread is way too cool to die in obscurity! Surely there is someone else who can contribute.


                            • #15
                              Originally posted by coreyabraira View Post
                              This thread is way too cool to die in obscurity! Surely there is someone else who can contribute.


                              WE have been working hard last couple of years....
                              We did build our own dyno and couple of other project too.
                              But now we are focusing back to BMW engines.
                              Currently we are building our M10(8V ohc) engine to rev over 10000rpm.

                              Now I got time to design M12/13 head.
                              So design is on the way.
                              It will be different than orginal, here are some specs:

                              Desined for 91mm piston.
                              intake valves 2 x 41mm
                              exhaust valves 2 x 32mm
                              combustion chamber 48cm3

                              Here is couple of pictures:


                              We expect that designs, tool paths and simulations of heat and port flow will be ready at spring.
                              It is good change that we will test firsts heads at end of 2012.
                              My email is still same mentioned in older message.
                              Here is my companys website
                              It is not ready yeat, but will be up at end off this year.