Water/meth injection: a theoretical and practical discussion

[dazzz]

So how can you be sure your reading o f the inlet temps is correct? Do you see my opinion with regards to the moisture collecting on the probe.

I'm no expert when it comes to car engines and injection systems but I am an expert in testing and measurements.

I don't have any evidence that it is 100% correct but I seem to be the only person in the discussion bringing any evidence at all, what we do know is that methanol engines run very cold in general and the freezing temps I recorded were when injecting around 2L per min of methanol (still with 250cc of H20 mixed in) which does not really surprise me.

I cant see what water would remain as liquid after passing through the turbo (pre compressor inj) so this argument would seem irrelevant in that scenario, phase change happens before the liquid even reaches the turbo, even if it wasn't there would be explosive vaporisation at the tips of the compressor, temperature of the inlet is reduced due to latent heat of vaporization.

So you're adding the water before the turbo. But the Water only cools when changing from a liquid to a gas. If there's no water vapour left after the turbo, how is it cooling the compressed air after the turbo.

You also say your injecting at 2l per min. When you go for a drive for half an hour, how much methanol/water are you having to carry. Surely you can't have a 60l tank onboard


If what you're saying is true, I can't understand why the likes of Audi, Merc, and even Bugatti haven't used wi to reduce the weight and complexity of there intercooler systems.

Do any super / hyper cars use them?

I just can't see liquid cooling the airflow at such a rapid rate in such a short distance to offer any beneficial inter cooling effect to the air charge temperature.

In the 15 years you've been installing surely you know some real boffin who could explain the ins and outs.

[T.F.S.]

What do you guys make of this paper?


http://turbolab.tamu.edu/proc/turboproc/T34/t34-06.pdf


Dazz your last post was empty?

[dazzz]

I pressed submit without typing.

[dazzz]

What do you guys make of this paper?


http://turbolab.tamu.edu/proc/turboproc/T34/t34-06.pdf


Dazz your last post was empty?

I'm gonna have to read that at least 3 times.

[T.F.S.]

So you're adding the water before the turbo. But the Water only cools when changing from a liquid to a gas. If there's no water vapour left after the turbo, how is it cooling the compressed air after the turbo.

You also say your injecting at 2l per min. When you go for a drive for half an hour, how much methanol/water are you having to carry. Surely you can't have a 60l tank onboard


If what you're saying is true, I can't understand why the likes of Audi, Merc, and even Bugatti haven't used wi to reduce the weight and complexity of there intercooler systems.

Do any super / hyper cars use them?

I just can't see liquid cooling the airflow at such a rapid rate in such a short distance to offer any beneficial inter cooling effect to the air charge temperature.

In the 15 years you've been installing surely you know some real boffin who could explain the ins and outs.

Sometimes I was, sometimes I wasn't...I played with this and that, changed things around etc.

If the water does not turn to vapor I do not expect it to cool, this is when you need to add another chemical.

The liquids are only ever injected on boost so I would take say 10 Liters in the tanks and then have another 10 with me, in the end I started using the washer bottle as well but I never injected more than say 5 liters in one night even during hard repeated testing which was a bit of an excuse for driving like an utter madman, the logs are a testament to this..

The freezing point figure was taken with the boost cracked open at about 3psi and a lot of meth, the rest of the night it was 40c on boost.

The temp drop is very real, we have a stock engine MR2 running silly boost on a big turbo and stock paper head gasket and no intercooler, if inlet temp was not as low as it was the engine would not have survived the utter abuse that it did, it was even sold on afterwards and as far as I know is still being raced now?

The thing about having a car mapped like this is that the car will go bang if you remove the water/meth mix (apart from a list of other drawbacks) that is why cars are not mass produced like this.

I have spoken with many people who have experienced lower inlet temps, customers and dealers, designers etc, all of them apart from Bob have experienced it.

[T.F.S.]

What do you guys make of this paper?


http://turbolab.tamu.edu/proc/turboproc/T34/t34-06.pdf


Dazz your last post was empty?

I'm gonna have to read that at least 3 times.

There appears to be a couple of places where it seems to be well documented that inlet air temp was reduced by evaporate cooling of water.

[dazzz]

I've read the document.

It relates to land based gas turbines where the hot gases, usually natural gas, are saturated to 100%. This then only still reducing the temp from dry to wet values.

Doesn't really apply to car turbo chargers IMO. They are talking about creating a stable efficient compressor setup in land based applications.

I don't know how much air flows through the mr2 or at what temps. I don't know how much coolant your injecting or at what pressure. I still don't think the charged air could be cooled that quick though.

What sort of saturation levels are you actually getting?

[T.F.S.]

So "inlet air" is natural gas?

[dazzz]

So "inlet air" is natural gas?

No

Natural gas is 95 per cent Methane (CH4)

Plus four other hydrocarbons:

Ethane (C2H6) - 2.5%, Propane (C3H8) - 0.2%, Butane (C4H10) - 0.06%, Pentanes Plus (C5H12 + C10H22) - 0.02%

It also contains small amounts of:

Nitrogen (N2) - 1.6%, Carbon Dioxide (CO2) - 0.7%, Hydrogen Sulphide (H2S) - trace, Water (H2O) - trace

It also much lighter than air.


What happens to the effective octane of the fuel when you injecting methanol. Does it increase? If so by how much per unit?

I understand you may be getting good results but I don't think it has much to do with the air inlet temps.


I cant see any real evidence of inlet temps being dropped significantly. Im not saying it doesn't happen, if you inject cold water into hot air it will reduce the temp.

[raptor95GTS]

WWII aircraft used WI in the inlet of the supercharger, achieved 100degF air intake temperature drops. I'd guess those engineers used the right equipment to measure their data

[ashley]

WWII aircraft used WI in the inlet of the supercharger, achieved 100degF air intake temperature drops. I'd guess those engineers used the right equipment to measure their data

Not necessarily, technology has moved on "slightly" in the last 60 years or so...

[2mad]

When I was running water/meth I could hammer the car for an hour no drop in performance get home and touch the pipe running from the intercooler to the throttle body (intake manifold too) and it would be cool, if I tried that w/m off I would have got 3rd degree burns.
If the metal pipes and manifold are cool does that not mean the air flowing along them would be cooled too, like an intercooler.
How can the pipes and manifold be cool if the air is still hot

I still have no answer to taking the air temp without the the iat being cooled also (if that indeed is what is happening), maybe borrowing cerns large hadron collider might help


Kev.

[dazzz]

WWII aircraft used WI in the inlet of the supercharger, achieved 100degF air intake temperature drops. I'd guess those engineers used the right equipment to measure their data

The pilots also used to eat carrots to help them see in the dark

[Danbob]

One way to test the theory is to to find a members car which has wi fitted just after the IC and has an after market ECU. Set the ignition timing to a fixed conservative value and boost low enough to be safe without WI, then run a back to back dyno run with and without WI switched on.

If the benefit of the theoretical cooling effect outweighs the power loss from the air that the water displaces, then the wi dyno run will produce more power and we can all go home happy

If it doesn't gain power when WI is on then the discussion continues because WI might still be having some cooling effect, and car could still be seeing a benefit from installing post IC rather than directly at the ports.

To avoid dyno expense one of the phone based or ignition basd dyno programs could be used, not as accurate but will be consistent and should show the difference..

[bobhatton]

So how can you be sure your reading o f the inlet temps is correct? Do you see my opinion with regards to the moisture collecting on the probe.

I'm no expert when it comes to car engines and injection systems but I am an expert in testing and measurements.

I don't have any evidence that it is 100% correct but I seem to be the only person in the discussion bringing any evidence at all, what we do know is that methanol engines run very cold in general and the freezing temps I recorded were when injecting around 2L per min of methanol (still with 250cc of H20 mixed in) which does not really surprise me.

I cant see what water would remain as liquid after passing through the turbo (pre compressor inj) so this argument would seem irrelevant in that scenario, phase change happens before the liquid even reaches the turbo, even if it wasn't there would be explosive vaporisation at the tips of the compressor, temperature of the inlet is reduced due to latent heat of vaporization.

I think the problem we have here is that I am talking about water injection systems and you are talking about fuel injection, two totally different subjects.

As soon as another fluid is added to the water, this is then no longer a water injection system.

It is very well known that fuel can ice up carburettors, that is why manufactures fed warm air into the air filter.
So injecting petrol or methanol into an engine is a fuel injection system and has nothing to do with adding water.

[T.F.S.]

No

Natural gas is 95 per cent Methane (CH4)

Plus four other hydrocarbons:

Ethane (C2H6) - 2.5%, Propane (C3H8) - 0.2%, Butane (C4H10) - 0.06%, Pentanes Plus (C5H12 + C10H22) - 0.02%

It also contains small amounts of:

Nitrogen (N2) - 1.6%, Carbon Dioxide (CO2) - 0.7%, Hydrogen Sulphide (H2S) - trace, Water (H2O) - trace

It also much lighter than air.


What happens to the effective octane of the fuel when you injecting methanol. Does it increase? If so by how much per unit?

I understand you may be getting good results but I don't think it has much to do with the air inlet temps.


I cant see any real evidence of inlet temps being dropped significantly. Im not saying it doesn't happen, if you inject cold water into hot air it will reduce the temp.

I know what natural gas is, my point is that they said quite clearly that they cooled the inlet air with water injection via evaporation.

Kev your hand is not a calibrated piece of equipment that is traceable to the national mass so according to the experts that info does not count

[T.F.S.]

Bob we seem to be talking about multiple scenarios on this thread but for the purposes of WI discussion do you not agree that if the water is injected before the turbo which obviously results in total evaporation of the liquid does this not reduce the inlet air temp?

[bobhatton]

Bob we seem to be talking about multiple scenarios on this thread but for the purposes of WI discussion do you not agree that if the water is injected before the turbo which obviously results in total evaporation of the liquid does this not reduce the inlet air temp?

How and why will it have total evaporation? It is still water until it boils, then there is a very large increase in its volume that will displace a lot of air

[ashley]

Does it need to boil to evaporate? What about when we sweat and the sweat evaporates off of our skin, so cooling our skin...the sweat isn't boiling off us is it? Or is it? Confused!

[Draven]

Just chiming in.. no water does not need to boil to evaporate. It is evaporating all the time just at room temperature. Just not at a noticable rate.