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Thread: Spec Class for '64-'65 911s

  1. #21
    I would imagine you could build a car from a SWB 912 chassis so long as it meets the spec? Has this been done in the 2.0L series?

    Erich
    Early 911S Registry #263

  2. #22
    Quote Originally Posted by Frank Beck View Post
    I don’t see the 39/35 valve size as a problem at all. What’s the port spec?

    190hp out of a 2.0? That would qualify you in the back of the pack in U.S., everything else being equal. Are ti parts free? Compression? Fuel? How about flywheels and clutches?

    As far as 9k with 906 cams... me thinks that’s a fairy tale. 906 cams simply won’t do that.

    We were testing to 9500 several years ago and wearing the valve guides out every 5 hours. Now we cap at 8500. A strong 2.0 easily makes 230+hp. But just as important is getting reciprocating/rotating mass way down.
    The guys in Europe are not messing around. Given the spec of the series rules and the difference in dynos, they are building engines comparable to any where...
    Matt Hart
    @the_escape_road - Instagram
    RHD 914
    1980 911SC (sold)
    69' T (sold)
    Early 911s reg # 994

  3. #23
    Quote Originally Posted by 304065 View Post
    Anyway check this one out at 1:00 in-- https://youtu.be/OB2geR45yqk that is a Bosch BLUE coil my friends, no way is that going to support full spark energy at 7000 rpm, even if you were using a Pertronix or Hot-spark electronic ignition. The primary resistance and inductance are simply too high to allow charging between ignition events.

    The Bosch points can handle about four amps before they melt particularly at high RPM. Solid-state drivers can pass at least seven amps, allowing you to charge the coil fully between ignition events. But you would use a low primary resistance coil in that case.

    Anyway it looks like the Appendix K rules say you must use a coil with a minimum of three ohms.



    The Delta Mark Ten is out, made too late.

    I think the best solution would be an original coil with 2,1 ohms primary resistance and the 0,9 ohm ballast resistor. That would easily satisfy the rules and get you the minimum resistance possible for max spark energy while at the same time not burning the points.
    There are certainly issues with both Bosch 2-piece points used in the Cast Iron Dizzies and Bosch Coils and neither seem to work well.

    By changing the base plate and using the one-piece 'Tiger Stripe' breakers produces a better and more reliable performance but these breakers are also difficult to find now and the latest versions are not as good as the older stock.

    We bought about 50 NOS sets about 6 years ago and still havea few sets in stock but as described in an earlier post we are trying to develop a base plate to use some high performance Lucas points that are being re-manufactured to a high standard. I also wonder if any of the Mallory Breaker sets may be worth trying?

    It may also be possible to use a Mallory Dual Point type system which could help with heating and wear problems?

    We always use BERU ZS106 coils which work well and are reliable.

    What about a Judson Electronic Magneto - which I think was available from the late Fifties?

    I have heard stories of concealed CDI boxes with a programmable advance curve being used but couldn't be confident that this is really happening.
    Last edited by chris_seven; 06-12-2018 at 05:16 PM.

  4. #24
    Chris that is interesting information about the Tiger Stripe Bosch 009 points- the higher spring pressure is said to allow them to work to 8000 RPM. Elsewhere here you can see my tribulations with the early two-piece points although this is more of my personal Karma than a failing of the engineers at Bosch. http://www.early911sregistry.org/for...mand+attention

    I think with the ZS106 you may be leaving some ignition energy on the table at high RPM when you need it most. While the Beru catalog doesn't specify, elsewhere I was able to locate the primary resistance specifications:

    ZS106 blue 3.3 ohms
    ZS109 red 1.5 ohms

    At 3.3 ohms and a nominal 12V system voltage, that is only 3.63 amps of coil current. As such, the coil ignition energy will be less at the first time constant. I don't have one to measure but if we know the primary coil impedance it's possible to simulate the ignition energy. I think it will be very similar to that of the Bosch Blue, slightly worse than the original SWB setup (3.0 ohms). I plotted out the coils I had on hand a few years back in this thread: http://www.early911sregistry.org/for...d-NOS-SWB-Coil



    Now obviously you cannot run the ZS109 coil by itself without a supplemental primary resistance or the points will be destroyed. But this was originally designed for the Mercedes W114/115 chassis (the "stroke eight" series) which used a solid-state electronic ignition and ceramic resistors in various colors (Red, 1.8 ohm; Blue, 0.4 ohm; Silver, 0.6 ohm; Gold, 0.9 ohm)

    So maybe using the ZS109 with the appropriate resistor can deliver more spark energy at high revolutions and not burn up the ignition.

    I have no experience with magneto ignition except in airplanes, where I only touch the switches!
    1966 911 #304065 Irischgruen

  5. #25
    That's very useful - I have tired to find impedance data on this coil but without success.

    Way back we used to use Lucas DLB105 Sports Coils which were 3 Ohm and they worked well with high revving Ford and other competition engines. There is also the DLB110 which is 1.5 Ohm used with a 1.6 Ohm Ballast resistor.

    The current offerings of these coils seem very variable and I am not confident that they are consistent.

    I wonder if a Pertronix Flame Thrower would work as I have never really tried out these coils.

    The Judson Unit isn't really a Magneto as it isn't a rotating machine just an electronic coil.

    I think they used to be fitted quite Commonly to Beetles and 356 Race Cars.

    http://mgaguru.com/mgtech/ignition/ig210.htm

  6. #26
    Senior Member uai's Avatar
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    Quote Originally Posted by 304065 View Post
    Anyway check this one out at 1:00 in-- https://youtu.be/OB2geR45yqk that is a Bosch BLUE coil my friends, no way is that going to support full spark energy at 7000 rpm, even if you were using a Pertronix or Hot-spark electronic ignition. The primary resistance and inductance are simply too high to allow charging between ignition events.
    I think it does look blue and it has a sticker, but it doesn't look bosch to me.

  7. #27
    Quote Originally Posted by uai View Post
    I think it does look blue and it has a sticker, but it doesn't look bosch to me.
    Quite right UAI, that color Blue is really BERU blue and the coil sticker isn't an original anyway.

    Chris, the Pertronix Flamethrower series of coils looks like it will suit-- the 40611 is an epoxy filled coil with a black case with a 3.0 ohm primary resistance, 80:1 turns ratio, 10.0mH inductance and a 55mm diameter, all of $41 from the usual stockists.

    But as the attached data suggest the ignition energy falls off precipitously below 6000 rpm, not even 10MJ.

    No wonder that er, "non-standard" ignitions have been creeping their way in! At high RPM there is very little time to charge the coil with conventional points ignition.
    Attached Images Attached Images
    1966 911 #304065 Irischgruen

  8. #28
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    Yes you could easy , but that will not invite you too any of these races , like pete´s 2L cup , Spa etc , prefered are 300/ 301 cars clean with title
    even heard a rumor that they scan the VIN before you enter so NO FAKES are invited... I am speaking often with Mark Bates of EB motorsport running the white car with red center stripe
    I will try to make him chip in and offcause we have Phil from Tech9 in UK on the forum here also running the series , speak up Phil



    Quote Originally Posted by ErichW View Post
    I would imagine you could build a car from a SWB 912 chassis so long as it meets the spec? Has this been done in the 2.0L series?

    Erich

  9. #29
    Hey Marek, I'm here

    Phil Hindley
    Tech 9 Motorsport
    United Kingdom

    www.tech9.ms

    Early S registry membership #2207

    65 911 Racecar
    66 912
    69 911S
    77 930 3.0
    82 911 SC Coupe
    84 3.2 Carrera
    88 928 SE ex Porsche/AFN Tony Dron racecar
    88 928 SE
    91 944 Turbo

  10. #30
    Congratulations Phil on your 2nd place at last weeks race!!

    Looking forward to seeing some footage of the race.

    Last race of the series is in Aug i believe? Good luck

    Mark

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