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Thread: Medusa

  1. #3101
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    Flying Phil is offline
    Well done Robert.....80 odd mph must feel like flying!....and of course on your private test track officer.

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  3. #3102
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    Top work, as usual Robert. Love the photos, the B&W ones make it seem so "of an era".

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    Or could that be ERA ?

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    WELL..

    Latest stuff to happen , is , i went to bicester scramble in April , got worse mpg than last time ,around 5 to 6 mpg , although i will admit i was going a lot faster with my outrider simeon on his dirt bike as company .nice to hear from him that the car looked very planted around the corners .

    had some nice conversations with a lot of people at the scramble ,as usual had no idea of where to park, so just went where i was told and ended up in the brooklands museum area next to a Fraser Nash . A new phenomenon was people asking me to start the car , little did they realise that probably used a quid of fuel each time !(allowing for the most marginal of exaggeration)

    later on i got too cold ,so moved the car to the sunnier areas , it was surreal cruising through the crowds faced with a wall of phones and cameras .....modern life eh.

    in other news , i have had to use the car for my weekly shopping in witney the last couple of weeks due to the astra dying 80 miles away , and having to be relayed home , (by auto aid who did a brilliant job)...turns out its ecu fried a transistor , so that's getting fixed when the part for me to solder in arrive .


    in the waitrose car park..









    in lidl's car park ...




    had some nice convo's with people at both places ...it was nice to use the car for a purpose , not just driving it around .



    something i tackled the other day , a little bit anyway , was the seam in the bonnet . i always wanted it to be smooth , and there was an idea of welding it and smoothing it , however i was concerned about the bonnet being distorted by the heat , so i had a bit of a bash at it with a hammer ,i think it looks a little better , ,,



    how it looked before ..









    how it looks now ..









    not perfecto , but a incny wincy improvement




    Work continues on the economy of the car , i will,now i have my new clutch working ok , and the hub not slipping ,focus on the thorny problem of trying to get the same amount of fuel in each cylinder , i have pretty much concluded that the longer the copper pipe , the more fuel goes to that cylinder , so have fitted little taps to each cylinder on engine no2 , and will try to improve things by measuring the exhaust gas temperatures , and adjusting my taps ....time will tell.




    taps...










    exhaust temperatures ...









    you can see on the rhs graph i did manage to get no5 ,the black line to respond just by richening the car , however that then sends the other cylinders super rich .




    thanks for reading .

    regards
    robert
    Last edited by ivanhoew; 17-05-2019 at 08:57.
    Bicester scramble ,Medusa enjoyed the trip.https://www.youtube.com/watch?v=Q-7I7-nA19U

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  8. #3105
    Official RnS Addict ivanhoew's Avatar
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    guten morgen !


    well i did a pivotal experiment in the batcave the other day .

    i set the car running at 2000 rpm steady with the tickover screws , ,then, whilst logging the exhaust gas temperatures , i only went and turned on the overhead cooling fans , mounted in the ceiling above the car ...yes i did !

    The idea was to see what sort of an effect the airflow past the bellmouths was having on the gas flow from the mixers in each trumpet .

    The result ?

    well the result was the engines dropped by 1200 rpm to around 800 , and staggered and stuttered until i turned off the fans.


    conclusion was , ,whilst a venturi mixer system works well on a common plenum , on seperate open bellmouths ,not so much .

    oh ,heres the logging graph.... it's very interesting for a few reasons ..






    at the start you can see , all 6 cylinders are working , notice how the red line cylinder no 2 , is now lower than the black no5 this is because the car is set very rich ,and its now too rich on no2 ..

    then i turn on the fans and its all goes haywire , different cylinders are going rich and lean and the lines are all totally random as they all try to fire a massively varying mixture .

    the car then runs out of gas , and you can see the 4 cylinders going hotter again , this is because they are so rich the lack of fuel leans them momentarliy to a better hotter mixture before they too fall off the grid ,the cylinders that were a bit lean fall immediately , our old friends no 5 and 6 .



    Solution :


    well i have decided , the car is pretty much unusable on my lack of income at 5mpg , and the thought that a lot of that lpg may well be being sucked out of the trumpets as i go along has brought me to only one solution .....


    fuel injection .



    i have a megasqirt ecu i bought as a kit several years ago for the tvr , ,and it was expertly constructed for me very kindly ,so that is going to be repurposed for medusa .

    i have 8 injectors , and have managed to find 6 more on ebay for 30 quid , so i am now in the construction side of it all .



    found out the old jag toothed wheel..







    took off the front of the car yet again and popped the pulley off and bolted on the wheel ...







    checked that the ms2 could do staggered ignition timing i can adjust to cater for the 45 degree difference engine to engine ,here is the ignition signal on the scope ...







    here the orange is one engine ,the purple the other ,and they are split by 15 degrees .


    i could also log cranking speed , and make a graph showing how the speed slows when the engines reaches compression on each cylinder ..





    found some nice old gauges for the lpg pressure on the injector rails ..






    a bit of panel beating and polishing and they look ok ..






    out with the old reducers in with the new ..






    these are needed to run 1 to 2 bar gas pressure .



    i am struggling at the moment to find a way to hide these in there somewhere subtle ,






    since i will be keeping the old copper snakeyness of course .




    the gas will be fed in in pulses into the old vacuum tub take offs on the inlet stubs , right next to the head ,at 20 odd psi , so will be far less affected by air flow past the bellmouths ...also i can run two maps on the ecu , each running closed loop from its respective wide band sensor on the exhaust .

    this was each engine will have its own unique map , and its own timing since i can vary the offset to cater for the link varying .



    i hope to sell the parts i have removed , and that will cater for the costs , and then hope to have far greater mpg .





    regards
    robert
    Last edited by ivanhoew; 26-05-2019 at 08:41.
    Bicester scramble ,Medusa enjoyed the trip.https://www.youtube.com/watch?v=Q-7I7-nA19U

  9. #3106
    Rods 'n' Sods Junkie Austin Martin's Avatar
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    You've probably considered the option, but a joggled joint may be the answer, as joggling one side of the joint stiffens the panel edge.
    Just a passer by as you might say.

  10. #3107
    Official RnS Addict mygasser's Avatar
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    hi robert,
    had you considered using small bore copper pipe from the distribution blocks to the injectors instead of the usual black plastic? they could all hide in plain sight then.
    or had you considered knocking up an airbox (temporarily) for each engine (as is) to put the trumpets out of the airflow and then see what effect that had on the fueling?
    neil.
    need a job done on your project? i may be able to help.

  11. #3108
    Off the Xmas card list kapri's Avatar
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    Back to basics ...what would a single original engine do MPG wise around town?

  12. #3109
    Official RnS Addict ivanhoew's Avatar
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    Quote Originally Posted by Austin Martin View Post
    You've probably considered the option, but a joggled joint may be the answer, as joggling one side of the joint stiffens the panel edge.

    do you mean for th bonnet join austin?

    Quote Originally Posted by mygasser View Post
    hi robert,
    had you considered using small bore copper pipe from the distribution blocks to the injectors instead of the usual black plastic? they could all hide in plain sight then.
    or had you considered knocking up an airbox (temporarily) for each engine (as is) to put the trumpets out of the airflow and then see what effect that had on the fueling?
    neil.

    i did consider an airbox then thought no it would not be viable lookswise , so went to the ultimate solution .re the injectors its not the piping its the inj themselves ,but i think i have a plan.




    Quote Originally Posted by kapri View Post
    Back to basics ...what would a single original engine do MPG wise around town?

    in a jag Kev ? generally i think they do 28 motorway low 20s town. however , they do weigh twice my car , masses more frontal area, automatic, and lower gearing and much more tyre drag .also that's on petrol so might be 26/18 on lpg.


    regards
    robert
    Bicester scramble ,Medusa enjoyed the trip.https://www.youtube.com/watch?v=Q-7I7-nA19U

  13. #3110
    Rods 'n' Sods Junkie Austin Martin's Avatar
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    Yep for the bonnet.
    Just a passer by as you might say.

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