"Best" mixture for port water injection?.
I`m currently running a 6 0.3(75cc) jet setup on my V6 Twin Turbo, the jets are approx 3 inches away from the intake ports. At the moment I`m running a 30%methanol 70% water mixture and I`ve leaned the fuel out slightly to suit (net 12:1 afr).
I`ve been reading up on different mixtures and I`ve heard a lot of conflicting information. My goal is soely knock control, any inlet air temp cooling is a bonus. a 50/50 mix seems to be the best starting point, but then I hear that straight water is better due to it`s higher cooling capacity, but then methanol evapourates quicker and can aid cooling.. Cost is another factor, a 30m70w mix is twice as expensive for me than straight water and I get through 16l to a tank of fuel if my right foots itchy! I don`t mind spending the extra if the methanol is really benificial but then again I don`t want to pour money down the drain!. Water is 20% by volume of the fuel injected (2200cc/min of fuel at peak flow). Anyone care to shed any light on my situation, would like to here from people running direct port setups but there doesn`t seem to be many around for some reason?, any comments are welcome. |
A few people have settled down experimentally to around 70water/30meth as a compromise of in-cylinder cooling and atomisation/octane booster.
Your water/fuel ratio is higher than average and you shouldn't have any cylinder distribution issues (where methanol helps) so I guess ambient temperatures would be another deciding factor for your mix. In the summer maybe a bit more meth (for the extra charge-cooling effect) Have you ever seen any hint of detonation with your setup? |
Hello John, thanks for the input.
Originally before any water I had bad detonation and had to pull 6 degrees of timing which really dampened the engine down, I then tried injecting the water before the throttlebody and still had detonation problems (I'm assuming that was down to my log style manifold). With my port setup and 30meth/70water I`ve been able to add back the 6degrees of advance and it isn`t detonating, think I`m just going to leave it be at 30m/70w as it seems to be doing the job. The methanol is pobably more use as an octane booster rather than charge-cooler in my setup. |
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This isn't as crucial in port injection, but it helps. :smile: 20% of 2200cc/min is 440cc/min. Are you sure your pump configuration can support this much? If so, then you're having roughly 140cc of methanol mixed with 2200cc of fuel under those conditions - percentagewise it isn't very dramatic and neither will be the octane rise. But it's nice to have under boost anyway :smile: |
Hello John, I`m running a race pump with primer and 6 75cc/min jets. I tested it with battery voltage at 12v and was getting 450cc/min into a jug, may be more with the car running and the voltage up to 14v but there`s the boost pressure at the nozzle which would porbably cancel that out.
Wideband looked like the meth was making the afr`s 1/2 a point richer, will have to have another look into that, as you say the amount of meth injected is a drop in the ocean compaired to the fuel going in!. If I ran pure meth it`d only be 20% meth to fuel ratio, I`d need to pump a litre/min in to make any real dent I suppose!. |
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Yeah, if I had a mitsubishi TT I'd definately go for port WI, it's the only way to keep it from misbehaving under high boost :D Left alone, the cyl bank next to the bulkhead does feel a bit hot under the collar, doesn't it? :shock: |
Yeh the rear bank does get toasty warm after a hard run!, they`ve also got a tendancy to let go on number 6 cylinder which is the last in the line for fuel supply.
Port injection`s worked very well with it, I`m leaving it be for the time being but if I go for bigger turbo`s I`ll be looking into higher volume port injection, Shurflo pump with Aqamist fittings I think. I was a bit dubious going for port injection, but it was worth the effort. The primer pump is an amazing upgrade for the Erl pumps, before 330cc/min was it`s limit and it can flow 600cc/min after the primer depending on jetting.. |
I realize this is an old topic, but I wanted to get a little input.
I have 2003 Dodge SRT-4, with a 2.4L turbocharged engine. I'm currently running an Aquamist HFS-5 system, with a 4-scroll 0.3mm nozzle (98cc) at each intake runner, and a .5mm nozzle just after the intercooler. I'm running 680cc fuel injectors. With this setup, I'm still getting some knock running a 50/50 mix of water/methanol and 91 octane fuel. Unfortunately, that's the highest octane I can get here, other than race gas. Would it make sense to increase the nozzle sizes at the ports, and reduce the one for the air charge? |
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0.4mm nozzles are less prone to blockages as well. I wouldn't think that the post-intercooler nozzle adds much under these conditions, yet lowers the available pressure for the other ones! (they need the pressure for good atomisation). |
I found after a bit of testing 75%methanol - 25%water mix was best for my engine to control knock (flowing 1.2l/min), I changed to a Shurflow pump. My engine must be octane limited by the looks of it, I run BP Ultimate petrol - 97 ron or slightly higher. 10psi and under it needs no det control, after that I need something to stop knock or else I have to retard timing 6 degrees which kills the power/ engine responce.
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