Water Injection - page 5 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• #60 by Mark(The Miser)UK on 05 Sep, 2006 14:52
• Quote from: BellCityDubber

  Quote from: Benjamin

  Quote

  if you ran a metal tank,you could run a boost line to the tank,so the pressure in the bottle is "equal" to the intake,and voila your 7 psi pump squirts no matter what the boost pressure is

  
  
  Smart  
  
  

  
  
  Hillfolk'r is the man

  [/size]
  Howbig a pipe needed to reduce the lag of charging the bottle? :wink:
  
  What kind of physics required to get a 7psi squirt into 7psi :shock:  :wink:
• #61 by vwgirl82 on 10 Oct, 2006 20:42
• whats the lowest amount of boost you should run with WI..
  
  because i saw people saying for high boost really only?  Mine only runs 25 lbs , could i run WI?  or would my best bet still be the intercooler?
• #62 by HarryMann on 11 Oct, 2006 04:52
• Well I've read all 5 pages of that above...  interesting approaches, of which there are two basic ones
  
  Hill'n'folks and Gregs!
  
  I've been checking this out from across the Atlantic, on the UK and Euro side, remembering that Ricardo himself was probably the first to look into WI for IC engines in any detail, and his graph plot of overfuelling aero engines and then when that reached its limits of detonation suppression, substituting water injection. We're talking 1930's here and that plot still stands and is frequently reprinted to show what benefits are attainable in a spark ignition engine -
  Pratt and Whitney, Rolls Royce and subsequently the Germans were the main champions of this, P&W developing it to a very high level - in fact it was the difference between some of their engines surviving war power settings - or not  :roll:
  
  Applied to a diesel things are a bit different, but not much.
  The difference between Hill'n and Greg is obviously
  1) cost  DIY Vs Pro approach
  .. which cannot be resolved, you're on one side or the other depending on thickness of your wallet;
  
  2) Where and how to inject
  
  Something that hasn't been mentioned, as such, is that 2) is very much influenced by whether short term boost cooling or long term steady state WI is anticipated.
  
  Whilst Hill'n uses it mainly 'just for passing', this is no substitute for an intercooler when a diesel is in a heavier vehicle than a car. Even my AAZ Transporter (vanagon), a draggy shape weighing nearly 2 tons empty, requires 9-10 psi to cruise at the legal limit over here (70 mph).
  
  Long term WI needs to be efficient and reliable at these boost and power levels, and Greg has his figures spot on, between 150 and 300 cc/min to give sufficient equivalence to a good IC.
  
  He also advises higher pressures, better atomising nozzles and some means of ensuring that WI is boost related and cannot inject below a threshold boost - in fact atmospheric pressure would be the minimum, but 7-10 psi makes sense.
  And post turbo injection - this is Aquamist's solution too (and unless for a 'bad' hot underbonnet installation, post intercooler too).
  
  Aquamist in the UK were responsible for supplying the equipment for all the World Rallye car WI systems, so successful they all went that way eventually, and have now been regulated against in that sport.
  
   They are also repsonsible for the WI systems of the recent Diesel World Speed Record 350mph by JCB Diggers (Ricardo, still an important IC engine research outfit, developed the engines). Apparently the tyres ability to transmit more power prevented further spped incraeses, not power.
  
  Their top pump isn't cheap, but the main thrust of their equipment is high pressure, high reliability and nozzles that atomise extremely well under those high pressures. This is Formula One type stuff, the pump designed from scratch as the ultimate WI pump. they do a cheaper higher capacity one too, but their Race Pump is the dog's (about $300). Their control systems and instrumentation also extends to Formula One type levels, but as I say, World Rally Championship regs have now banned these systems (proof of the pudding!)
  
  As Greg says you need at least 10 bar (150 psi) to do the job properly, to keep the flow rates down you need the massive surface area of fine droplets.
  This cools the charge, but there is a lot more going on in the cylinder than a lower charge temperature when 25 to 50% of fuel weight of water is being injected. In fact benefits are still accruing beyond these quantities, if the engine and boost flows are sufficient to utilise them. 100% is possible but eventually the engine will flood, not come to harm, but simply unable to handle that quantity.
  
  One of the main benefits is that the cylinder pressure curve is smoothed out, peak temps come down, but energy absorbed in the early stages of combustion is released later... this can only be beneficial and those having trouble with rod/ring and bottom end strength, as well as head temp issues at high boost levels should really look into this seriously.
  
  Injecting pre-turbo at significant and useful quantities long term has definitely been seen to to erode compressor impellers. For a few seconds here and there, maybe not.
  
  Also, 10% methanol to prevent freezing is probably the best compromise, thats what they tend to use, water has all the other properties required and as a substitute for an intercooler, where WI automatically starts above a certain boost level, 50/50 starts to get expensive as well as a pain in the butt to organise.
  
  But the key to really good WI efficiency, is good control of flow rate, boost dependent and extremely highly atomised before entering the cylinder - you then get charge density benefits + additional in cylinder power enhancement without any risk of overdoing it.
  
  This is not saying Hill'n isn't having great fun developinga and using his  grassroots WI system - it sure sounds like it works, as a quick and cheap way of cooling things down and getting better charge density. But its not the way that the pros have found works best when the chips are really down.
  
  http://www.aquamist.co.uk
  Has some excellent information, but hard to find on their site... look at technical and resources. Here are the JCB diesel World Record breaker links if you are intersted:-
  
  http://www.aquamist.co.uk/dieselmax
  http://www.jcbdieselmax.com/html/home.php
• #63 by greggearhead on 13 Oct, 2006 11:44
• Some really nice points there, and well said.  
  
  Injecting farther away from the intake manifold gives more time for the water to cool the inlet charge if that is what you are after, more than combustion control.  
  
  Also, the higher % of methanol, the more power increase you will see.  We have documente that over and over on larger diesels.  Typically on a 5.9 Cummins, straight water is about 30-40whp, 30% methanol is 50whp and 50% methanol is 70whp.  
  
  The methanol acts like a catalyst to start the burn a little sooner (yep, like advancing the injection timing slightly) and helps to burn the diesel more completely.  Helps a lot with reduciton of particulate matter (black soot)in the exhaust, while the water helps to reduce the NOx emissions.  
  
  Yeah, that streamliner diesel was a very impressive display - I would love to see what the budget was for that car build.  Nice to see everything came together by the end of the week.  
  
  We actually had a couple kits on one or two Freightliners there - one got the record, but of course I can't find the info right now.  Shane called and was all kinds of excited, saying how there was no way they would have gotten the record without the water injection.
• #64 by HarryMann on 13 Oct, 2006 14:20
• Hey, put up a link to that Freightliner record, we could both take this thread even more off topic with that  
  
  JCB are a private non-quoted company, quite rare these days, but well-known for being so, as the British continually bemoan all their famous companies being screwed by the city suits for development cash and then being bought by US and European interests, then the layoffs start the long road to oblivion  :roll:
  
  ... so JCB are heralded as a world apart. Morgan of sports car fame is another company that has for many years held out against pressures to become other than a family owned private company.
  
  So if the Chairman says 'do it' the risk is all his, or the boards, and there's no shareholders to whinge about their dividends being down a penny or a pound.
  
  Whatever the cost, I think it was justified as their normal advertising budget over a period of a year or two, and what a fantastic substitute! And also as a part of the development of their latest engine range - these were fundamentally two of their JCB444 units and so I hear, didn't have to be modified that much at all.
  
  

  Quote

  Sir Anthony Bamford, Chairman of privately owned JCB, is very clear why he wanted to build a JCB record-breaker: “I am passionate about the importance of engineering excellence to Britain and I see using the JCB engine for this record attempt as a fantastic way of showcasing what British engineers can do. The JCB444 has been acknowledged as a remarkable piece of engineering, and this programme to build the world’s fastest diesel-powered automobile is precisely the sort of technical challenge that we should rise to.”
  
  Green, who set the first-ever supersonic world land speed record at 763.035 mph in ThrustSSC on the Black Rock Desert on 15 October 1997, is thrilled to have been given another opportunity to enter the record books. He said: “We will be following in the tradition of British record breakers by running at the sport’s spiritual home, the remarkable Bonneville Salt Flats. I am really looking forward to driving another British entry in the '300 mph Club,' and a diesel-engined, wheel-driven one at that.”

  
  
  PS. Personally, I predict that it will be a long, long time before ThrustSSC's land speed record is broken, if ever. The aerodynamic problems were quite awesome, and even with 2 even more powerful RR Spey engines waiting to be used, Andy Green 'suggested' that they should call it a day - and no one argued!
• #65 by macsdub on 13 Oct, 2006 17:04
• lol i use for more than passing,,i go thru a gallon a week almost
  see my signature,please :wink:
   i feel like the guy that built "the worlds fastest indian",an awesome movie :lol:
• #66 by HarryMann on 13 Oct, 2006 19:07
• Oh yes, watching some of those videos brought back that movie to me - a good'un that. Didn't he go back to Speed Week year after year after that first visit ?
  
  I also like the guy's comment on the JCB video about Bonneville -
  

  Quote

  Well, I don't go to Florida, England or anywhere else on holiday - this place is my holiday - every year

  
  
  Here is Andy Green going up to 725 mph at Black Rock, quite what happens between 350 and 450 is anyone's guess, but it went way off line as the video came back on...
  
  http://www.youtube.com/watch?v=ujJRDwshjbQ
  
  
  And from outside the car, with a good ss bang and chute deployment...
  
  http://www.youtube.com/watch?v=gaGO-we-Fag&mode=related&search=
  
  (The RAF 'lend' him out to these teams on full pay I believe, a fast jet pilot - Good calm commentary - but obvious relief as those chutes deploy   )
• #67 by macsdub on 15 Oct, 2006 11:33
• i liked hi  "offerings to the god of speed"
  and there was a shelf of fragged parts :lol:
  
  
  
  yea vwgirl82
  
  i say if you have a turbo,use water injection :wink:
  you can play games and restrict the flow so you dont get so much water as i do,that will work for lower psi setups,like stock,,or even your 25 psi setup
  eventually if you get an ic,you can still plumb the wi into the intake manifold+use a "boose equalizing line" like described before
  
  as far as the size of that line,im thinkin about the size of 3/8 i.d. hose wouldnt cause any lag issues to pressurize the bottle
• #68 by HarryMann on 15 Oct, 2006 15:24
• A good rule of thumb might be, start the Water Injection as the boost gets to the max boost that the standard setup gives, so for mine that would be 7.5~ 8psi, yours might be 10~12 psi. There's little doubt that above that figure the compressed charge could be doing with a bit of cooling - and the peak combustion pressures and temperatures evening out over the full power stroke too.
  
  A benefit over an IC-less system that hasn't been made much of, or even referred to, is the absence of any pressure losses. These might be 2~4 psi in a tortuous IC system, IIRC, slowing the speed at which boost builds up as much as anything else.
• #69 by macsdub on 15 Oct, 2006 16:42
• oh
  im silly,i see bellcitydubber is runnin a setup
  cool man
  yea i have a switch taped to my shifter knob,and bretty much any time i go WOT,and the boost gets up above 5-10 psi(i run like 35 or more),boom i hit the switch
  and you can pulse it too,if the boost is kinda low
  or just pulse it in certain situations
  
  the other night it wasnt spooled up good+i was injecting water,so i stopped+waited for more boost+then hit it again
  
  
  lol one interesting thing that my setup does
  if i hold the water on in between gears,or even if theres enough built up in the intake
  the revs will hang,like a nasty governor mod gone bad
  so dont hit the water,then let off  wot to stop
  itll still be tryin to make some power
  its a little like a controlled runaway,i guess
  
   :wink: