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Thread: Medusa

  1. #3121
    Rods 'n' Sods Junkie Austin Martin's Avatar
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    I know it looks like I'm not paying attention, but going back a page, who the fck solders their own ECU's?

    On the subject of airflow (which admittedly I know very little about) maybe the idea of a temporary airbox is worth a try; using the tried and tested Sherlock Holmes theory, that being, when you have discounted everything plausible, then what remains, however implausible, is the truth?
    Just a passer by as you might say.

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    Official RnS Addict 28Chevy's Avatar
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    Brilliant my dear Austin, Meerschaum pipe shaped trumpets are the obvious answer!
    Whirrr whirrr chuff chuff de chuff........chuff......BRUMMMM!

    My Chevy thread: https://www.rodsnsods.co.uk/forum/sho...y-coach-403745
    Rugged Robin 2/3rd track: https://www.facebook.com/Rugged.Robin.tracked/

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    Official RnS Addict ivanhoew's Avatar
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    holy smokes , look at all this new chat !!!! love it , thank you everyone ,


    Quote Originally Posted by mylesdw View Post
    Great work Robert; I love the way you just get on with things in the time that I would still be thinking about it.

    It's a shame that forum traffic is waning. For projects with a subject and a timeline forums are a much better format than horrid facebook.

    Thank you myles ,i am a bit impatient to find out a solution and be able to afford to use it more ...re forums ,I agree myles ,i had thought of bringing all the threads on the car over to my blog .,and might still do , its much much nicer when a bit of conversation goes on .



    Quote Originally Posted by 28Chevy View Post
    Seems to me that when in forward motion the airflow across the trumpets fights the inflow of air.

    So maybe sticking a bend in to turn them forwards might help a tad, having them alternatively pointing up and down to miss each other would look mighty Meduser-ish too..

    i can see what you mean Bernard , i will think about that , maybe keep my eye out for some ally 50mm bends so i can try it , ,, however i do like the parallel trumpets denoting order and rigid correctness third reich stylee , then the engines transform that into a bohemian unbridled chaos in the exhaust pipes , i like contrast like that .




    Quote Originally Posted by chaley View Post
    Robert,
    You’ve broken my brain, I don’t know how you do it?? But I’m glad you do.

    Chaley

    hey now ! you know very well it was broken long before me !

    Quote Originally Posted by Paul L View Post
    Robert - I liked your car park photos.

    There is something about being parked next to a 'normal' car that always makes me smile.

    Sorry I can't help on the technical side of your fuel injection solution, but I certainly hope it works.

    If your set backs are getting you down, please take a step back and look at the magnificent beast you have created.

    You've built a straight 12 by joining two engines together and are having a few issues getting them to run perfectly.

    I think most people would have no idea how to get them to run at all!

    Keep up the great work you and hold your head up high while you are doing it.

    Take care, Paul.


    WELL ! that's a nice bit of motivational nosity , thank you Paul , i do have a bad habit of looking forward and completely forgetting where i started .It is brilliant fun to park in the shopping car park , and walk off .



    Quote Originally Posted by drseg View Post
    awesome work!

    I know you want the 12 air intake look BUT I think you should try a temporary air box to confirm that's whats playing up the system.

    could it actually cause suction? thinking like a cheap airbrush a stream of air over a tube sucks the paint up

    could the airflow from the grill create strange effects over the intakes as well giving different pressures to draw air in
    if it still does odd stuff when injected must be something in that area

    seem to remember a Ferrari with stacks out of the centre of the bonnet with a Perspex cover wondering of that could be a similar issue?




    i am quite certain Drseg ,as i said earlier , the airflow is making all sorts of pressure differential changes over the inlets, you only have to look at a curtain sider lorry on the motorway to see the high and low pressure areas . if i had desired to continue with the venturis , a flow steadying plenum would i think have been necessary ...don't get me wrong the car is fast and totally driveable as it is , just very thirsty , its got such light weight compared to engine size and particularly torque output , with over 300 lbs/ft from 1500 and around 400 lbsft at max , and a weight of 900 ish kilos ,that it can run very inefficiently ,and still hoon on ...should be a different animal if all 12 cylinders work together as one .





    Quote Originally Posted by watahyahknow View Post
    the airflow thing over the inlettrumpets from the car itself kindah makes sense i wonder if it helps to connect all those inlets together with a copper plumbing tube/pipe (parallel so one tube with 12 branches to a connection after the butterfly inside the trumpets ) so the vacuum along all of them equalizes automaticly , that still lets you keep the look you have now

    hmmm thought about it some more , you already have that with the two sferes and all the piping going to the trumpets maibe connct the sferes together to equalize between the two engines


    yes i had thuogt of connecting all the trumpets together near the throttle bodies with a lateral copper 28mm pipe , but hey, i had a ecu, so thought i woulb try this .


    Quote Originally Posted by Austin Martin View Post
    I know it looks like I'm not paying attention, but going back a page, who the fck solders their own ECU's?

    On the subject of airflow (which admittedly I know very little about) maybe the idea of a temporary airbox is worth a try; using the tried and tested Sherlock Holmes theory, that being, when you have discounted everything plausible, then what remains, however implausible, is the truth?


    Definitely true Austin ,for an ideal , even, steady airflow , it does need a plenum over all 12 ..hopefully the injection ,where the gas is injected at 15 to 30 psi , 1/2 " from the inlet ports , will make it viable as is .Time will tell !




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

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    Official RnS Addict ivanhoew's Avatar
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    Quote Originally Posted by 28Chevy View Post
    Brilliant my dear Austin, Meerschaum pipe shaped trumpets are the obvious answer!


    NOW that's an idea
    Bicester scramble ,Medusa enjoyed the trip.https://www.youtube.com/watch?v=Q-7I7-nA19U

  7. #3125
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    I know you are going for injection, which will be more fuel efficient, but have you thought of an air filter in the trumpet? - would having a small block of stationary, low pressure air pull the gas through more evenly, allowing better adjustment?

    May I also ask what pressure the new injection manifold runs at? - does it not have to be fairly high to get enough volume of gas into the chamber in the needed time, and to overcome the pressure in the chamber?

    Edit to say thank you for the replies to others given above!
    Last edited by Peanut Gallery; 31-05-2019 at 08:21.

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    Official RnS Addict ivanhoew's Avatar
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    Quote Originally Posted by Peanut Gallery View Post
    I know you are going for injection, which will be more fuel efficient, but have you thought of an air filter in the trumpet? - would having a small block of stationary, low pressure air pull the gas through more evenly, allowing better adjustment?

    May I also ask what pressure the new injection manifold runs at? - does it not have to be fairly high to get enough volume of gas into the chamber in the needed time, and to overcome the pressure in the chamber?

    Edit to say thank you for the replies to others given above!


    Hi PG , yes i had thought of a small k and n cone filter in each inlet , but that would cost more than using an ecu i already have





    the gas is injected into the inlet tract of each cylinder , so does not experience any pressure to speak of , however it does have a time constraint related to getting enough gas in there in a short enough space of time to feed that cylinder per revolution ...to calibrate the amount of gas going in , you have a) the pressure feeding the injector ,typically 15 to 30 psi ...and you have the size of the hole in the injector , typically 2 to 4mm , and you have the amount of time the injector is help open per revolution measured in milliseconds .

    the injector opening time is controlled by the ecu , which in this case is a megasquirt 2 . the ecu takes reading of rpm, manifold vacuum , air temp, lpg temp , throttle position,battery voltage , and calculates the openning time ,referring to the ve map which looks like this ..





    making the numbers bigger means more fuel.



    you also have a similar map for the ignition timing .




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

  9. #3127
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    Quote Originally Posted by ivanhoew View Post
    What a kind lovely message thank you mark , with forum traffic being so low , and few comments , any comments of an encouraging nature mean even more , so thank you again , i feel motivated , from feeling a bit burnt out .


    regards
    robert
    Robert, not having a project of my own, (well actually I do but it's a series 3 Land Rover, which isn't particularly enthralling and I'm rubbish at taking photos and posting stuff), I tend to be more of a lurker. Threads like yours are brilliant and, even though I don't really understand half of what you do, I love all the techie stuff.

    Keep up the good work, I'm hooked.

    regards,

    Mark.

  10. #3128
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    Thank you! - yeah, my mind was stuck on direct injection, rather than inlet tract injection which makes more sense for gas!

    Thats still a fair bit of gas to get in in the millisecond that the intake is happening! - my mind cannot work out how engines work at so many thousand rpms.

    Thank you!

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    Official RnS Addict ivanhoew's Avatar
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    my pleasure PG ,

    i don't actually get the gas injected all on the intake stroke for each cylinder , that would require sequential injection timed to the intake pulses , and costs a fair bit more , what i am doing is injecting twice per rev on all 6 injectors ..which isn't perfect , and you will hear people saying it must be sequential or it wont work , however i have been running my astra 1.4 8 valve turbo for 5 years like his and its fine .

    Direct injection would be nice , then i could probably inject liquid lpg , which is a whole step up in performance ,but very pricey if possible at all .



    well.. re the car , i now have the ecu all modified to give two separate ignition channels , and also take in 2 separate wide band ex gas signals ,so i can get to wiring it all up .



    i also sussed out how to mount the injectors nicely on engine no1 ...so onwards and upwards !



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

  12. #3130
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    so you have 12 pulses per rotation divided by 3 across the 6 injectors
    or do you just have 2 pulses per rotation at the same time no matter wat cilinder ?
    the last would mean that 2 cilinders injects perfect at one of the two pulses while the others are about a thirth of a rotation to early or too late
    with a log style manifold that should be ok as the gas stays inside the plenum to be sucked in when needed , with the trumpets it might cause the gas to blow out the trumpet and be lost running 4 of the 6 lean \
    in that case it might actually be better to inject 6 times per rotation no matter wat cilinder that way you get it right on time out of 6 on each cilinder
    as for hining the injectors , you could T in in the copper pipes from the back near the inlet run the goses along the back of those same pipes and hide the gasmanifold behind the sferes , think if you mount the gasmanifolt under the trottlebodies you whont notice them either but the feed lines would show
    Last edited by watahyahknow; 31-05-2019 at 20:39.

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