more intercooler power

[Warpspeed]

The Autospeed article is a good one.

The biggest problem is using the water efficiently. If you spray on heaps it just runs down the cooler onto the ground, and you need gallons of the stuff. If you just mist on a pissy little bit, it is not going to do much.

Probably the best and most efficient way to use water is with a water injection setup. This will help with detonation, but it is not going to increase power potential much, if at all.

If you are happy to cart around a couple of gallons of water, a air/water setup has some real advantages on a street car.

[GTRman1992]

The power of Water injection isn't if you just install it. As you said it will help with detonation and thats it. Where you win is that with it you can wind up the boost and forward the ignition timing. As I said above, on my Starion I got 50rwhp with it.

Your right with the intercooler sprayer, it is great for street use, my mate runs the circuit from AutoSpeed and says it is really good.

[Guilt-Toy]

I stuffed around with water injection. Runs off a 10psi hobs pressure switch and sprays mist into the intake of the turbo

20rwhp from extra timing and boost. Had a small fmic so it spun 285rwhp with a supra fount mount. On very cold nights was best

[GTRman1992]

Only problem with Hobbs switch system is that it runs on boost and does not consider demand. For example, my GTR comes on full boost at 4000rpm and stays that way until 8000rpm. The engines consumption is a lot different between these rpms. The hobbs switch method of tuning only allows for a compromise setup.

I also had this same system on my Starion, hobbs switch spraying water into the turbo intake.

[Sydneykid]

Hi GTRman1992, sorry if I seem to be picking on you but your post "on race tracks you are not allowed to drop fluid, so they cannot be used".. I had better tell the Evo drivers in GTP, because all the teams I have seen run them. We also run windscreen and headlight washers as well, ooops big problem.

The water spray actually doesn't find its way onto the track when we are racing, it tries to blow into the engine bay via the intercooler first and then the radiator. By the time it hits the exhaust manifold there is only steam, no liquid as such.

Oil and fuel droppings are of course another matter.

BTW, we have just received an EVO 8 Ralliart Group N kit and it has a water spray for the intercooler. Seems like it's not a passing phase traffic light GP item for them. The problem we have is that the rally cars spend a lot of time at low speeds on dirt and sideways to boot. As a result there is not anywhere near as much airflow through the radiator. Waterspray helps heaps then, not just intercooler but the engine water radiator as well.

Maybe some of the driftos should look at it, considering the number of over heated and blown engines we have seen lately.

Hope that adds to this interesting thread.

Merry Xmas to all

[Merli]

Only problem with Hobbs switch system is that it runs on boost and does not consider demand. For example, my GTR comes on full boost at 4000rpm and stays that way until 8000rpm. The engines consumption is a lot different between these rpms. The hobbs switch method of tuning only allows for a compromise setup.

I also had this same system on my Starion, hobbs switch spraying water into the turbo intake.

This is a good point... How would you propose to activate the water injection then?

[GTRman1992]

Must have got it wrong, unless the fluid rule only applies to drag racing ???

Your Ralliart kit is as you said for cars not getting enough air flow through the intercooler. This agrees with what I have been saying. It is not needed for track cars getting big air flow through the front mount. I am not arguing with this point.

See the Auto Speed online magazine for a circuit. Else you can have a button on the dash ??

[funkymonkey]

just something I've been curious about... when you grab a hot pan with a wet cloth the heat transfers quicker than if you would have used a dry cloth with air inbetween its threads. Hence proving that water transfers heat quicker than air.

Now... if the ambient temperature is higher than that of the intercooler (as is the case on may hot summer days in aust), would the water assist the intercooler in gaining heat rather than dissipating it?

[Warpspeed]

Thinking about this a bit more, with evaporative cooling in cooling towers and such, you try to keep all the cooled surfaces completely wet. So you spray heaps more water than is actually evaporated.

So how about catching the water under the intercooler and returning it to a storage reservoir underneath, and using a decent pump to really keep evey fin on that cooler seriously wet. Some sort of scavenge pump (like with a dry sump) might also work if it comes on with the main spray pump. I realise this may not be practical for several reasons, but it would be the theoretical ideal. But it would certainly solve the water on the road problem.

As far as water injection goes, what about using a second set of suitably sized fuel injectors, and powering them off the main injectors via a suitable electronic drive circuit. This would keep the petrol/water ratio near constant, and you could easily arrange to switch off these extra injectors below a certain boost threshold. If your aftermarket computer has a spare PWM output you could map the water injection easily enough. This should conserve water as well as get the most benefit.

There might be some problems though with corrosion if you feed water through an EFI pump, injectors, rail and regulator ? It would not surprise me if some of these were made with stainless steel components, but have no idea if this is the case. Anyone know for sure ?

Hey....... I just think up these ideas, it is up to you to make them work.

[GTRman1992]

Hay Warpspeed. Interesting ideas. I don't think you could catch the water dripping off the intercooler as you have to remember you are hammering along while spraying so it will blow through the intercooler. Although while stationary it might be worth a thought. Cooling the core waiting to take off.

I don't think the ambient air will ever be hotter than the air blowing through the intercooler, even on a hot day. When a turbo is pumping the air can easily get over 100deg I believe.

I've had a look into using standard injectors for the W/M system but came up with the same problem with corrosion. Thats why I'm building a system using spray jets and regulating the pump speed to ensure the ideal mix.

If you do come accross some water happy injectors I'd love to know as that is HEAPS easier.

[Warpspeed]

Quite right. At high speed the water is going to be blown all over the engine. But if you are going a million miles per hour, and have a good airstream, you might not actually need the water. Or perhaps you could turn it off at high road speeds, or in the higher gears?

[GTRman1992]

You guys have almost talked me around. I'm starting to want an intercooler water sprayer ! The next debate will definately be the control system. If we come up with something that sounds good, I'll build a prototype.

[GTRgeoff]

OK, almost science degrees aside because I only have a Mech Eng Degree and a Masters of Engineering, here is what I have found by using Autospeed's IC water spray controller on the stock IC with a high resolution high freq temp probe in the post IC airflow, Rigoli modded stock turbo and my home made boost controller @11psi.

On a 35 degree Melbourne day I am maintaining charge temps 20 degrees below standard.

Without the water spray the temps take forever to drop from over 57 deg to 40 deg but with it running with the fuzzy logic from two bimetallic temp elements it is a matter of 30-50 seconds to get to 28 deg or so down from 42-43.

Now I haven't fully applied the 'scientific method' but I am pretty secure with my findings as a definite improvement over an air only IC. I also now run a throttle position induction water spray post IC and find that a positive step as well for suppressing detonation.

My advice...you have the autospeed link, spend $150 and try it out and stop supposing. It works and works well.

Maybe one day I will tell you about oxygen injecting my Lynx to a 7 sec 0-100 machine.

[funkymonkey]

you can buy a Labtronics PICFun2 for 70 bucks from jaycar... what's the diff between the one autospeed sells and the jaycar one?

[Merli]

As far as water injection goes, what about using a second set of suitably sized fuel injectors, and powering them off the main injectors via a suitable electronic drive circuit. This would keep the petrol/water ratio near constant, and you could easily arrange to switch off these extra injectors below a certain boost threshold. If your aftermarket computer has a spare PWM output you could map the water injection easily enough. This should conserve water as well as get the most benefit.

A couple of questions.

Why use fuel injectors at all? Besides all the obvious corrosion problems, they won't finely atomise the water at all, which is a primary goal when designing a water injection system.

The only reason I could see for using fuel injectors like you are talking about is if you were to use 6 of them and plumb them into the runners, secondary set of injectors-style. But this doesn't work either as you need to inject the water far enough up the intake piping for it to absorb the heat from the intake air, heat up as it travels along the intake piping until it hits the cylinders where it turns to steam. Somewhere between "before the turbo compressor", to "just after the intercooler" is best. Injecting it straight down the runners won't work at all.

[GTRgeoff]

MY unit only cost $85 from Autospeed assembled + the watersprays

[GTRgeoff]

Merli

the water spray into the induction limits detonation in the cylinder, not so much by cooling the air but a poorly understood phenomenon that needs more research. The water takes up enough space that it's cooling (compressing) effect is negated by that but it cleans the cylinder and suppresses the dets, and is therefore a good thing.

[GTRman1992]

It does cool the charge a bit, but you have to spray it into at least the runners to each cylinder to get even distribution (discussed above).

As skylinegeoff saif the other effect (as I understand) is that it increases the density of the charge and therefore supresses the pre-ignition (detonation). This allows you to run more boost and more agressive timing.

[Merli]

Merli

the water spray into the induction limits detonation in the cylinder, not so much by cooling the air but a poorly understood phenomenon that needs more research. The water takes up enough space that it's cooling (compressing) effect is negated by that but it cleans the cylinder and suppresses the dets, and is therefore a good thing.

Intake charge cooling is DEFINITELY one of the benefits of water injection, and not taking advantage of it would be quite silly.

Water injection works in three ways. 

Firstly, when the water is injected into the intake system prior to the cylinder head, the small droplets absorb heat from the intake air. Water has a very high specific heat rating (it can absorb lots of energy while only slowly increasing in temperature) and so the intake air is initially cooled. 

Next, the small drops of water start to evaporate. Water has a very high latent heat of evaporation (its change of state absorbs a lot of heat) and so the intake air charge is cooled still further. 

Finally, when the remaining water droplets and water vapour reach the combustion chamber, steam is produced. This acts as an anti-detonant and also keeps the interior of the engine very clean, so preventing the build-up of carbon "hot spots".

As you can see, each stage of the water changing from liquid to gas absorbs heat, and this takes time. There isn't enough time to fully realise the full effect of water injection if you inject the water straight down the runners.

[Merli]

It does cool the charge a bit, but you have to spray it into at least the runners to each cylinder to get even distribution (discussed above). 

As skylinegeoff saif the other effect (as I understand) is that it increases the density of the charge and therefore supresses the pre-ignition (detonation). This allows you to run more boost and more agressive timing.

It increases the density of the charge by lowering the temperature of the air. That's all.

So if you're not taking full effect of the cooling (e.g. by injecting the water down the runners), you're not increasing the density of the charge as much as you could be, in turn you won't be able to increase boost or advance timing as much as you could be.