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Old 08-09-2013, 11:54 PM
stevieturbo stevieturbo is offline
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Default injecting hot side

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
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Old 09-09-2013, 10:11 PM
Richard L Richard L is offline
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Default Re: injecting hot side

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.
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Old 09-09-2013, 10:27 PM
stevieturbo stevieturbo is offline
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Default Re: injecting hot side

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 ?
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Old 10-09-2013, 07:55 AM
mrx79 mrx79 is offline
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Default Re: injecting hot side

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.
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Old 10-09-2013, 09:35 AM
stevieturbo stevieturbo is offline
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Default Re: injecting hot side

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
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Old 12-09-2013, 02:38 PM
mrx79 mrx79 is offline
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Default Re: injecting hot side

just out of curiosity, what kind of fuel are you running because you saied Meth in fuel?
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Old 12-09-2013, 02:50 PM
stevieturbo stevieturbo is offline
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Default Re: injecting hot side

97RON pump with 20% methanol mix
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Old 12-09-2013, 04:04 PM
mrx79 mrx79 is offline
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Default Re: injecting hot side

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.
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Old 12-09-2013, 04:28 PM
stevieturbo stevieturbo is offline
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Default Re: injecting hot side

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.
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Old 15-09-2013, 12:25 PM
jontysafe jontysafe is offline
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Default Re: injecting hot side

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/bo...ter-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?
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