Water Injection in Turbos?
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  1. #1
    Fellow Frogger!
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    Water Injection in Turbos?

    Hi Guys,

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    does anyone know much about water injection for turbo cars. As I understand it, it is used to remove some of the heat in the combustion chamber? a sort of charge cooling? I'm not sure but I think I have read that it is a second rate mod for turbo cars not setup properly- any thoughts?

    On my 18 turbo I have an intercooler spray (switchable), should I alter this to be a boost operated spray just before (inside the intercooler pipe) the carburettor?- or should I have both mods?


    Cheers Ben

  2. #2
    Guru davemcbean's Avatar
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    Ben,

    I don't think I would call water injection second rate, because from a thermodynamic point of view it is capable of taking much more heat out of the airstream than any intercooler. The problem is, if the water injection puts in any more water than is strictly necessary it will loose you horsepower and possibly cause steam induced corrosion of the valves. There are some electronically controlled water injection systems around, but it is possible to build a pretty effective and low cost system using only boost pressure to inject the water. This means you don't need any electric motors or electronics and the amount of water injected will be proportional to the boost pressure. I'll scan some chapters on water injection from some hot-up books and send them to you.

    Regards,
    Dave
    NZ Fleet
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  3. #3
    Fellow Frogger!
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    Reault17,

    Water injection was first used in WW1 Supercharged fighter planes to control detonation
    They believed that the water injection gave them a edge in battles
    So i wouldn't call it second rate listen to dave as he knows what he is talking about
    The trick as dave pointed out is using just the right amount of water in a very fine mist to suspend it in the air
    We were driving turbo cars with water injection 18 years ago well before most people even new what a turbo was it was very effective in my car to combat detonation at around 11 psi
    The best systems i have seen are electronically controlled and mappable to gradually spray a very fine mist
    We simply used windscreen washer bottle with a 50/50 water/methanol mixture that used a hobbs pressure switch to spray the mixture at 7 psi we had a little usefull light inside the car in the dash to let us know if the motor was operating very crude system but worked fine in battles against $12.000 clevelands & chevs

    Murat

  4. #4
    Fellow Frogger!
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    Thanks Guys,

    looking forward to those articles Dave. One of the things that I am not sure about is that the motor I have has a knock sensor that automatically retards ignition (and therefore less power) when it senses detonation. How do I figure out when this detonation is occurring? Is it to put the thing on a dyno so that you can accurately see when the ignition is retarded - ie high boost only or under any engine load.... (Most of my other measurements (at this stage) have been seat of the pants stuff- acceleration times etc etc.

    It does seem to be be a little 'rough' under high boost- 13psi plus, which gives me doubts about the knock sensor working at all really. I'm asking these questions for the future as I will be rebuilding the motor at some stage (once the 17 is finished!) and want to do things properly! However it all to be done on a budget- not cutting corners, but just not endless amounts of cash on aftermarket ignition systems etc....

    Cheers Ben

  5. #5
    1000+ Posts Damien Gardner's Avatar
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    I wouldn't mind a copy of the water injection articles please Dave, my supercharged 16TS powered R10 has a lot of heat generated by the compression of the inlet charge & as the system is suck thru the blower, an intercooler if used would be a potential bomb, waiting for the first back fire. A point to watch with Turbo's or blowers is the increased compression ratio and the potential increase in engine knock unless higher octane fuel is used. I assume as water is injected this raises the compression further and would thus increase the knock factor. My last purchase of AVGAS cost $1.50 p/lt with an octane rating of 145 i have no knock problems.
    I hope this provokes some discussion.
    Damien
    Health and good fortune always,
    Damien.

    We rode on the winds of the rising storm,
    We ran to the sounds of thunder.
    We danced among the lightning bolts,
    and tore the R10's assfromunder.

    Robert Jordan & memyself&I

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  6. #6
    Guru davemcbean's Avatar
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    Damien,

    What's your email address? If you don't have any pinging problems, then you don't need water injection, because it would just loose you power. Water injection is only used to stop detonation (due to the cooling effect of the water or even better water/methanol mixture). Water or water/methanol injection can allow you to use more boost or compression without detonation problems. That is the only reason people use it. Any more water than the minimum necessary to stop detonation or pinging, will loose you power. The articles, which I have, explain this better.

    Regards,
    Dave
    NZ Fleet
    1976 504 Ti
    1984 205 GT twin carb
    1991 205 SI 1.6GTI motor
    1994 106 Xsi
    1996 Mondeo V6
    Aus Fleet
    1955 203C
    1997 Civic Cxi (great allrounder- revy, flexible, nimble, comfortable , economical, simple and durable )

  7. #7
    1000+ Posts Damien Gardner's Avatar
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    Thanks Dave Addy is [email protected]
    My interest is purely to cool the inlet charge as the pipe from blower to plenhem chamber get to hot to put your hand on, after several laps at 6200 rpm. My theory being 10lb of cold air has more volume the 10 lb of hot expanded air therefore more horsepower generated per detonation from the greater mass of air.
    A tip for anyone using water/methanol injection seek out speedway super sprintcar drivers & or drag racers that use methanol as it goes of after several weeks left sitting & no longer gives max Hp as a raw fuel it still has the cooling power required when mixed with the water as well as the octane boost i'm told a 60% water 40%methanol is the usual mix. I have some pages on water/toluene injection if anyone is interested i could scan them it also explains a simple method of acheiving the injection.
    Damien
    Health and good fortune always,
    Damien.

    We rode on the winds of the rising storm,
    We ran to the sounds of thunder.
    We danced among the lightning bolts,
    and tore the R10's assfromunder.

    Robert Jordan & memyself&I

    1/48th Scale Alpine A310,
    N-scale 1/160th Renault & Citroen, Advert. Signs & Billboards

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