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Water Injection, declined in popularity, why??


Chris Wilson

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Stock bottom end

 

Most people are running stock bottom ends, greg's supra was running on a stock bottom end??? Yours only has about 70k iirc??

1.4 not be ok?

Again, sorry for the hijack, please delete when i have have a time to read lol

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Most people are running stock bottom ends, greg's supra was running on a stock bottom end??? Yours only has about 70k iirc??

1.4 not be ok?

Again, sorry for the hijack, please delete when i have have a time to read lol

 

Gregs Supra isn't exactly a daily driver. I need mine to start every day, on the dot, run fine in heavy traffic and also be able to handle 1 hour long high boost motorway runs (late night runs back to the west country at very silly speed). Above 1.2 its going to be pushing the old girl to manage that and 15k miles a year.

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I just had my system installed today. Right now it is only running off a boost activated switch. I have 2 leds on my dash, one tells me when the fluid is low and the other tells me when the system is injecting.

 

It is currently set to come on at 10psi, I will raise this to 1bar and see how fast the fluid gets used, I have a 1.5 gal tank so it should last a fair bit. I am running a 30% meth/water mix right now.

 

I did not get much time to play with it as it was dark and wet out and with the power I am pushing it is hard to give it some when wet.

 

I'll take some pictures of the installation tomorrow when I go to the RR. Everything has been installed in the boot as it is a bit handy having the extra weight of the 1.5gal to offset the weight of my battery which is also in the boot on the passenger side.

 

Apart from the 3 settings I currently have on my boost controller which are:

 

Off - Wastegate 0.8bar

Chan 1 - 1.2bar

Chan 2 - 1.5bar

 

 

I will have Dan map me two more settings. One will be 1.6-1.7bar or higher depending on how good the WI can suppress det.

 

The other setting will be a race fuel map so I can use it at the track or at a RR day on good fuel.

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Great post Chris, that explains the benefits and reasons for WI clearly.. at least on an engine thats designed to deliver maximum power.

 

One thing thats not clear is why someone with a 'more than sufficient' fuelling setup and map, plus running low boost on a 2JZ would require one. If the EGT and AFR measures are within safe limits then why add WI, surely there's no need?

 

I have been running water injection for the last three years, on my S14 and now the Supra, and to answer your question, quite simply it will allow you to fine tune an engine to get the best possible power for the state of tune, if you are BPU and in either sequential or TTC like me, you will find that the fuelling and timing are not ideal, very rich on boost and higher RPM, which only saps power, i use WI in conjunction with emanage ultimate to tweak things to get better performance and economy, and provided you use some sort of fail safe device with WI so should you have a problem with water supply then either the boost is cut or timing pulled, there is nothing to worry about:)

My S14 was capable of over 350 BHP with surprisingly few big mods, just careful mapping and WI.

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Anything that cools the intake charge further than the I/C can manage on a given day is free power, so adding WI will lower charge air temps. At a trackday at an airfield my pretty much bone stock mazda FD-3S rotart engine saw 68 degrees C charge air temps on a stinking hot UK summer day. With WI turned on (same airfileld, same day, same LAP) charge air temps went down to 42 degrees C and it felt like someone in a Group C car was giving me a push, so much powwr did this cooled charge give. I don't suggest it to give the ability to run the most aggressive ignition timing possible on fuel "X", more to maximise charge air cooling on any given day.

 

Someone asked about costs, i don't rate mappable systems for road cars, too complex, and no one here uses an engine dyno anyway, which you'd really need to get the best out of it. I recoomend, and use myself, a basic ERL 1s switched system coming on line at .9 bar So whatever they currently cost and i charge about 75 quid to fit it (properly). That's using the stock screen washer bottle to feed the WI and the screen washer pumps.

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Great info as always Chris.

 

So thats the WI sorted. One thing I'm not clear on is how adding methanol to my screenwash improves the windscreen wash function?

 

I have been that route, and it really dose not enhance screen washing properties ;) i now run a dedicated tank for WI so methanol can be added, then you can add a decent screen wash and not screw the WI pump up.

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So, on a BPU car would this mod increase power without any other mod's (fancy ECU's etc), or does it just help protect the engine from detonation at it's current boost level?

How do you go about selecting the correct jet size, location and pressure for the system? I take it this needs assessment on a dyno?

 

Sounds almost like a free lunch!! What's the down side, other than having too much water at the wrong time and killing the engine?

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I spoke about using WI to a guy who used to be an engineer for Richard Burns' car.

When I suggested it, he gaffawed at it. He said that you shouldn't be using it as part of a safety set-up as the engine should be mapped to be safe without it. What if the water ran out? You wouldn't map your car to deliberately run with knock, and rely on the knock sensors to permanently retard the ignition would you?

So I then said, well OK, but what about the potential performance gain?

He then launched into an explanation of how it's actually a really inefficient performance gain, as you're now lugging a load of water around....

By this time I was feeling a little foolish....

What he did suggest was that instead of using WI, he suggested using a spray bar for the intercooler, as you could use less water, and the effectiveness of it was much greater.

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So, on a BPU car would this mod increase power without any other mod's (fancy ECU's etc), or does it just help protect the engine from detonation at it's current boost level?

How do you go about selecting the correct jet size, location and pressure for the system? I take it this needs assessment on a dyno?

 

Sounds almost like a free lunch!! What's the down side, other than having too much water at the wrong time and killing the engine?

 

 

The short answer is no! no performance gains to be had just running water injection, but it can help protect from det high EGTs, in fact Aquamist do produce systems that are included in specialist cars as std!

TLicense, everybody seems to have their own opinions about WI some good some not, it has actually been used with great success in rally cars over the years, anyway if anybody seriously wants to get hard facts, and lots of info and tips regarding water injection, then go here, http://www.aquamist.co.uk/phpBB2/

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TLicense, everybody seems to have their own opinions about WI some good some not, it has actually been used with great success in rally cars over the years,

 

Just repeating what I was told, by someone who I have a LOT of respect for. I was all pro for it until he persuaded me otherwise.

I guess it's a Marmite thing....

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You will not get the same charge temp reduction effects from waterspray on an intercooler to a correctly specced water injection system. The heat removed is far greater with true WI.

 

To some extent I agree you wouldn't want a motor that was only "safe" when injecting water as well but there's no reason not to map a different boost level that requires WI. For instance you could run 1.0bar daily, 1.2bar bax on road fuel and then the fuelling for 1.4/1.5bar could be mapped in conjunction with the WI playing a part. This would drastically reduce the potential for problems as you'd choose upfront to run 1.5bar knowing your WI tank must be full and ready. Also some of the Aquamist warning systems for flow are pretty good now.

 

I have the fully mappable Aquamist 2s system sat in the garage waiting to be fitted when I get a spare morning...

 

Just my 0.02p

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I think it all depends on your perspective.

A rally car needs to be ultra reliable and receives tremendous punishment. They're highly tuned anyway so as that chap said, the small performance gain that WI would give isn't something they'd consider.

I quite agree that I'd feel uncomfortable using WI to the extreme where you're relying on it to work to support the ignition advance you've set.

 

There's tuning the ECU to take advantage of WI, and there's using it to simply keep things cool.

 

Using it to reduce charge temps seems like a cheap and sensible thing to do to me for the summer - we all know how the increased temp zaps performance then.

 

Running BPU you're limited to 1.2 bar anyway by your standard tubbies, so no extra performance gain to be had, expect when it's hot out there.

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Great info as always Chris.

 

So thats the WI sorted. One thing I'm not clear on is how adding methanol to my screenwash improves the windscreen wash function?

 

My guess is either:

 

a) methanol evaporates at a lower temp than water and so will clear your windscreen quicker, or

 

b) methanol will dissolve grease and grime which would just repel water based solvents

 

or both?

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Chris W fitted mine for me a long time ago.i stopped using the washer bottle and had a tank for methanol/water

 

bought 2 20liter tubs of methanol to use.

 

would a mix of 50/50 be fine or what about more methanol?

 

pure methanol supposed to eat away at alloy if i remember correct

 

just ok for a safety feature and peace of mind

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