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Thread: Martini RSR engine build

  1. #1

    Martini RSR engine build

    I know a few of you have been following the story of the car over on the DDK forum since it arrived here in the UK from Gib's care in Arizona, so now I've started the engine build I thought I run a thread with some details.

    Just spent the last week with Neil Bainbridge at BS Motorsport helping put the motor together. We decided to do a full competition RSR engine, the level of Neil's attention to detail is incredible and the tolerances he works to are unbelievable. The cases are 930 which are homologated for the RSR, they have had the usual mods for oil bypass and so on, together with extensive windage work for the gas flowing. Black coated with a low friction protective Formula 1 engine finish only 20 microns thick.

    The Carillo rods went onto the 70.4 crank beautifully confirming it's in great standard/standard condition, we only had it polished and then balanced with the flywheel, clutch and bearings.

    The inter-gear is a bit special in that the chain drive gears are lightweight aluminum racing ones, and the main drive gear is a lightweight straight cut version.

    The picture below shows the shuffle pinned cases with the crank, rods and lightweight intergear in situ with the high flow GT3 oil pump with a modified scavenge pipe and strainer so as to keep a flat early sump plate, like an original RSR. Even the sleeve which connects the intergear to the oil pump is modified, instead of the usual circlips to keep it in place which are unreliable and can break in race engines, the sleeve is pinned inside to stop it from sliding, no nasty bits to fall off!

    Cases go together and the final view of inside before the pistons and cylinders go on.

    For the DDK thread:
    cheers, Mike
    1972 911 S/RSR to Martini Prototype specification

  2. #2
    After originally buying a set of Mahle barrels and RSR pistons, when tested they didn't come near to the 10.3:1 compression ratio the factory 'werks' cars ran, so as Neil insisted on forged pistons instead of CNC'ed billet like JE's, we went with Wossner who are a German Motorsport supplier. Porsche themselves use their pistons for some of the factory race engines apparently. They claim 10.5:1 and when we cc'ed them with my heads and ran the figures through the computer we got 10.1 but more of that later.

    The Mahle barrels go on with the RSR 'tinware' between, RSR because it's aluminum, and in this case anodised.
    Right is a temporary race filter housing, the right one arrives soon. This replaces the engine oil cooler the road cars have.

    Couldn't resist resting on the chain boxes for the oil fed cams and fan housing at this stage, and you can see the bracket for the mfi pump support bracket top right sticking up.

    cheers, Mike
    1972 911 S/RSR to Martini Prototype specification

  3. #3
    Just realised you might prefer this thread in technical, if so moderators please feel free to move it!
    cheers, Mike
    1972 911 S/RSR to Martini Prototype specification

  4. #4
    Very very nice Mike!!!
    Wossner pistons are the best!!!

  5. #5
    VERY COOL STUFF! Thanks for the pics. Very nice engine!

  6. #6
    A lot of work has gone into the heads over the past 6 months, from the original machining of decking and twin plugging, to then the fitting of seats and guides and the porting and polishing. It's been a long journey to get them to the stage of finally fitting the valves.

    The man who did all the work is a very well respected head engineer now in his seventies who has worked in the past with Formula 1 teams and knows Porsche heads inside out. He has a mass of data from all his past efforts and charts and graphs galore mapping the various permutations, I didn't realise how much of a 'black art' all this is, but after going on his flow meter for the final time and doing the calculations he pronounced them the best flowing heads he's ever done!

    Maybe that's something to do with the fact they have the correct RSR porting of 43mm both inlet and exhaust.

    Fitting the valves was another example of the accuracy used doing this kind of stuff. Using Schrick racing springs with titanium collars you have to measure their individual heights given the maximum and minimum lift required, then machine the spring seats to the nearest couple of thou to give you the optimum operating timing and balance between them all. This involved about 12 hours between the micrometer and the machining lathe then back again, measure then machine and again, and again to get the right sizes, so about a hour each one then!

    cheers, Mike
    1972 911 S/RSR to Martini Prototype specification

  7. #7

    Your commitment to detail and seeking the Nth degree of perfection is humbling for the rest of us. Most on this Board are not aware that you have spent many hours with Neil working on this engine and the assembly (also stripping) work on your Martini re-creation doing much of that work yourself. Plus, you have spent the last 2 years finding the right parts and schlepped them from everywhere to build this very authentic RSR prototype. It will be an amazing car when it hits the road.

    Gib Bosworth
    EarlySReg 434
    R Gruppe 17

  8. #8
    Excellent work! I am subscribing for the details.

    Max_911S_fahrer, on Flickr
    1971 911S, 2.7RS spec MFI engine, suspension mods, lightened
    Early 911S Registry Member #425

  9. #9


    There are real hp losses to be found in valves that are not set up properly (height). A thousandth here and there adds up.
    Cylinders not getting complete fill due to valves being out of spec. makes for an engine that cannot "be all it could be".


    "Be who you are and say what you feel because those who mind don't matter and those who matter don't mind." - Dr. Seuss
    "Experience is the mother of wisdom" - idiom
    "Let them that don't want none, have memories of not gettin' any"- Brother Dave Gardner

    Early S Registry #235
    rgruppe #111

  10. #10
    Senior Member CamBiscuit's Avatar
    Join Date
    May 2006
    Adelaide, Australia
    Thanks for sharing Mike.

    Can't wait to see the output when its done
    Looking for engine # 6208151
    '74 RS 3.0 Replica
    '70 911E Bahia Red (SOLD)
    '71 911 S/T Replica 2.3 Twin plug BEAST (SOLD)
    Australian TYP 901 Register #78
    Early S Registry # 1076

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