injecting hot side

[stevieturbo]

Pretty dead forum, so will have a go anyway.

We typically use WI to cool both charge and chamber as well as using that to help prevent detonation.


In a setup using good fuel, detonation isnt a problem, but charge temps do rise higher than is desirable, more so on hot days.

Would injecting a small amount of water on the hot side be better ?

ie between turbo and intercooler ?

As a state change will take place here with water, surely that would remove more heat than injecting post IC which only sees circa 50-70degC at most ?

This is mainly as a supplement for hot days. On the road and track temps are generally ok as there is decent airflow.
It's just sitting about then 1/4 runs things can get heat soaked

[Richard L]

This forum is more liken to "read-only" than technical discussion type. People just post their experiences instead of discussions. Most just read the results and form their own opinions.

There are no specific rules or a definitive route to arrive at a best result. WRC engines use it purely for inlet and in-cylinder cooling.

[stevieturbo]

But from a charge cooling point of view, is the theory sound ?

ie injecting water into air above 100degC will remove more heat than injecting the same amount of water into 70degC air ?

Because in the cooler air, the water will stay as a fine spray, and no state change will take place ?

[mrx79]

I would follow RICE's approach of pre-compressor injection if post-compressor temps is what's your concern.

For sure it's true that injecting in hotter air is more efficiant, but you also inject in a high pressure environment, which makes it harder for the air to change it's state. This is easier with pre-compressor because it is low(er) pressure.

With 14psi of boost post compressor, water will not boil at 100?c.

With pre-throttle injection you will have the same / worse problem, but there you have a short path inside the combustion chamber which has very high heat and pressure and water can work there.

With your post-turbo injection, water will not benefit from the low pressure before turbo and has a long path inside the chamer.

It can of course work, so feel free to try it, but just from a physical point of view i would say i'ts not the ideal position to inject water. But i never tried it by myself. So if you try and have some results, feel free to post them up... i would be curious. Sometimes reality is a bit different then simplified phyics.

[stevieturbo]

Never thought about the pressure aspect.

Would likely be seeing around 40psi in the hot side, although might push for more soon.

Chamber temps are less of an issue, as already running methanol in the fuel, so dont see any point of injecting closer to the intake valves

[mrx79]

just out of curiosity, what kind of fuel are you running because you saied Meth in fuel?

[stevieturbo]

97RON pump with 20% methanol mix

[mrx79]

How does this effect your tune compared to pure 97RON fuel?
despite of the fact that you have to inject more fuel due to the differen stoic ratio.

But i mean in terms of pre ignition / knock, etc.
i've heared that it is difficult to tune when mixing pumpgas with methanol.

[stevieturbo]

It provides much improved resistance to detonation allowing more timing where knock may have been a problem before.

And as you say, your fuel system does need to be able to accommodate the extra flow requirements.

Certainly nothing difficult using it, and tuning with it is no different to pump fuel.

It's quite popular with some guys here in the UK, although Ive only tried it recently on a few cars.
Personally I feel it is wasteful, as no matter what the driving style, the methanol is getting used.
But on the flip side there is no risk of a methanol injection system not working, because it's always there.

[jontysafe]

Hello there, I still haven`t pulled the trigger on my HFS3 install but I was thinking exactly the same as Stevieturbo. I was going to go for one pre-intercooler jet and one post intercooler jet. In an ideal world 100%water pre and 50/50 water/meth post, but more than likely 60%Water40%Meth in both or it gets complicated.
A stated the boiling point of water is affected by pressure:

http://www.engineeringtoolbox.com/boiling-point-water-d_926.html

From what I understand though not enough on the hot side to be a problem?

If we take 14.69psi as atmospheric pressure, do I understand this correctly, in a turbo charged engine running 20psi I should read graph across at 35psi? Then the boiling point is 126 degrees C. Hardly an issue?

[stevieturbo]

If you are only using pump fuel and because of this are severely knock limited, then I would just go with the typical WI setup and inject between the IC and intake valves.

I only posted the question to deal with charge air temperatures only. Nothing as to what might happen in the chamber, which is a key aim of a more typical WI installation.

Good info there though. Even at 40psi boost, water would still boil off at 130degC. So water should remove a fair chunk of heat if injected hot side.

[jontysafe]

Would then it not be beneficial for me, who is under endowed in the intercooler area, to inject both pre and post? First for IAT and second for in cylinder benefits?
Ideally I`d have a massive garrett cored air to air intercooler but just don`t have the room.
Thanks for your input Stevie, you`ve offered advice for me here and PH now!

[stevieturbo]

Have you actually established what your charge temperatures are yet ?

For most normal applications, injecting after the IC is the done thing and I see little reason to change that

Especially when using methanol.

I'd say the hot side is simply too hot, and it would take large amounts of methanol to actually do anything.

But it as all speculation. I'd like to find out what pre-IC charge temps are actually like in this instance. Hopefully can do that soon

At the minute he is just working on allowing cool air actually into the air filter to see if that helps matters. After that, may change current core to a Garrett core.
Allegedly they are supposed to be fantastic.