DAZ

can any one tell me how water injection works?

what equipment do you need to do it?

is the same as a charge cooler?

cheers

daz

[This message has been edited by DAZ (edited 29-10-1999).]

leestudd

Hi Daz,

Water injection isn't the same as a charge cooler.

Water injection is just that, water injected as a very fine spray into the intake. This causes the air charge temperature to be lower and reduces the risk of knock (bad).

Where you inject the water is another matter. You could inject before turbo, before intercooler or directly into the intake plenum. Depends on your needs.

A chargecooler is similar to an intercooler. An intercooler has an air/air interface. I.e. outside air flowing over radiator fins causes the air inside to be cooled. Simple and no moving parts.

A chargecooler is similar. The air in the intake system (Air charge) is passed through a radiators fins. However, the fins themselves are cooled by water which is pumped around the system. The water itself is usually cooled by another radiator at the front of the car, in the air flow. System is much more complex, more weight, more moving parts (that can fail). However, much more efficient than an intercooler. Water has a greater latent heat than air.

How effective a chargecooler would be on a Scooby, I don't know, even if you could find room to fit it. However, many cars that have intercoolers (air/air) gain big gains with chargecoolers (air/water). E.g. Ford RS Turbos get something like 20 - 25 bhp gain. (IIRC).

If you want more info. on water injection take a look at the following site:

Mike Tuckwood

Daz, Hi.

Jay has water injection fitted let's sort out a pub meet one evening in the week or next week and you can have a look at his.

Any joy with that contact that you were going to source for me?

Mike.

DAZ

cheers lee interesting concept never thought of it that way

using thermo induction to dicipate detination temps (cool)

like to see maths round calculation in exactly how much gains you can get before water affects combustion properties

mike
i have had a chat they are geared for mass production of units

would need to see costs to see if it would be economicly viable

also quantities (dont they all) :-)

lets get this meet organised and we can chat then

also got my oz on now they look the b*******


later

daz

steve McCulloch

DAZ

I thought you needed to remove the ABS to get the water spray, that why the Type R's dont have ABS.
Interesting dicussion on charge/intercoolers.
Chargecoolers are OK as long as your not heavily modding cars, in which case intercoolers are ALWAYS better. Reason being that chargecooler involves water - in Subaru's engines can get very hot - the heat actually raises the temparature of the water, so that on repeated track days you have nothing to cool the engine as charge cooler water is boling. Intercoolers are less efficient but dont suffer from above problems.

My cossie was modded heavily and I had to go the intercooler route. The guy in Scotland with a 480hp subaru also thinks charge coolers are crap.

DAZ - I would'nt bother, good gimmick though that water spray.

AlexM

Steve,

A properly engineered chargecooler can be very efficient, with the possibility of more than 100% efficiency (i.e. exit temps lower than ambient), although this isn't normally acheivable in most installations. I think the main problem people introduce with aftermarket systems is that they underestimate the water flow rate water needed to avoid the problems you describe.
When the car is moving, and provided you have sufficient area on your front heat exchanger, the water will always stay cool enough. It is a question of weight, cost and space.

The main problem is that a non-moving car will heat the water up as you describe. Once you have moved off, the high heat capacity of the water in the system means that the temperature won't drop as quickly as it would for an air-air intercooler that had been heated by an equivilent amount.
Heat soak is a considerable problem because of the heat capacity of the system.

They can still be a very good solution for cars with packaging problems as the heat exchanger cores are smaller, and would help to reduce lag compared with a front mounted I/C on an Impreza by reducing the length of presurised pipework.

Cheers,

Alex.

leestudd

Hi All,

The arguement over chargecoolers (air/water) and intercoolers (air/air) will rage forever.

However, I am sure that a properly designed and installed chargecooler will be more efficient than an intercooler with the same flow rate.

However, as was pointed out in earlier posts, a chargecooler doesn't work very well in a car that is crawling in traffic, the whole water system (which *is* seperate from the engine coolant system) will just heat up due to heat soak.

However, on the open road, the chargecooler brings down the air charge temperature much better than an intercooler (read lower temperature). This is a good thing. The cooler the air, the denser it is (even after being pressurised by the turbo(s)), and hence the more fuel (oxygen) you get into the cylinders.

Drive your turbo car on a hot day and then drive it on a cold night, notice the difference ?

The only real problem with chargecoolers is the additional weight and complexity, i.e. additional front-mount radiator, water pump, level sensors, pipe work, coolant.

-----

Water injection is a great invention in my book. In its normal road use, the water is injected into the intake system after the turbo and intercooler. This charge full of suspended water droplets (very fine) is pushed into the cylinder. Here it cools the cylinder down due to waters large latest heat. Not only does it reduce the risk of knock (likely as you up the boost) but means your engine actually runs at a lower temperature (but not much I guess). It has also been proven to 'clean' (over time) the cylinder bore, removing carbon deposits that can form hots spots. Steam clean the inside of the engine for you sir ?

Best bit, once fitted, it is very cheap to run ;-) Until the Gov. start taxing water you put in your car.

Cheers

Lee S.

leestudd

Hi All (again),

Now, I'm sure you guys are not confused, but just in case, Do not get the water spray (some Scoobys), confused with water injection. Different game altogether.

Setting up water injection is fairly complex with no real rule of thumb.

You start with a high pressure water pump (say 6 bar). You then use a jet, say 0.5mm tapped into the intake system. This gives you abour 225 cc/min water flow (v. fine spray). You next have to decide when to start spraying and when to stop. Say you set it up to start spraying when boost in the intake is above 8 psi. Fine.

You wil find that each car is different, you may need more water (change the jet to a larger size). You may find you need to start pumping earlier, say 6 psi. Or you may find you need to start pumping earlier with more water (bigger jet) etc. Oh, and all possibilities in between.

This is where a good rolling road place is a god-send. You can test again and again and keep an eye on exhaust gases, power output etc. as you change the settings.

If you are serious about water injection (not sprays, which are for the outside of the intercooler) look at the ERL stuff. it is the biz.

Cheers

Lee S.

Paul Wilson

steve,
I think the two are totally separate (ABS and Water Spray) It was just that there was this handy hole for a water bottle after Subaru had taken out the ABS. The water spray system(external on to intercooler) is very simple, the tank which sits where the ABS would be, can go anywhere on the car

firefox

Hi you lot....

Great day at the Pod... although I didnt run... Bloody freezing though...

I was gonna write a long paragraph on the principles of water/air/spray/injection.

I feel I have quite a bit of experience.... because of the following:

I have run with the standard top I/C, with an STI top I/C...water spray on both. I have used water injection, my car was used to develop the pace charge cooler system. I have used a front mounted I/C.

So...as you can see.... I have tried most methods of cooling the intake air temp down... lol

Anyways...

I gotta run... job to do.

J.

ps - The placement of the water nozzle on the injection system is important. It serves different needs dependant on where it is fitted.

DAZ

has any one used both systems on a car
using the intercooler for standard driving and using both systems when required

using this type of system the air would be cooled first by the intercooler and then water injected before it hit the charge cooler.

would this optimise the air cooling ?

or would it be the air was to cold and would cause freezing problems with parts and sensors.

next step on is that if you know what the required air temp was. you could run a closed loop system to control the air temp by using both systems when required.

has this been done?

cheers daz

johnfelstead

i use water injection on a full group A spec saphire cosworth in forest rallies.
Water injection is used to allow high boost to be maintained when the intake temperature is rising. It is essential when an anti-lag system is operating as intake charge rises quickly.
The ECU is programmed to switch the WI on at a preset intake temperature and boost level, if the WI does not reduce the intake charge temp sufficiently then the boost is reduced to stop detination.
We use a modified boat bilge pump at 3 BAR pressure to inject the water into the inlet plenum via a high mist spay nozzle.
to give you an idea of how essential this is, we use approx 2 litres of water in 5 stage miles. When the system fails, it can loose us 2 seconds per mile in performance.
If the system you use is not mapped to boost/air charge temp then its a waste of time.