Water meth distribution
11-21-2017, 08:46 AM
#1
Water meth distribution Trying to figure out a better way to decrease my iat temps, this is on a kenne bell 3.6 supercharger. I am currently spraying water meth through the charger with not much affect on iats. I have an option to drill and tap the manifold right where the air comes out of the blower but I am worried about even distribution. I have planned on angling the nozzles back but not sure if the back will catch as much as the front. Is this a huge deal as I am spraying the intercooler instead of directly into the intake ???
11-21-2017, 10:02 AM
#2
A given mass of water has the same heat capacity wherever it is located. So I am curious why you seek to change the position of the spray, it will not change the mass or heat capacity of that water.
for example say you happened to move the spray closer to the IAT sensor and notice a lower IAT as a result.
The final math result will still be the same for the water's mass never changed, thus total energy content absorbed never changed, only the measured scalar quantity of temperature at arbitrary location has changed.
Furthermore, most of the benefit of water/meth injection is not due to the IAT decrease (as I've pointed out it may change at the sensor with little difference overall to the system). For water, the benefit is the enormous amount of energy it carries away when it moves from liquid to gas (which by the way, is 212*F and higher when there is boost, so if you aren't seeing 212*F+ IAT temperatures, the water you are injecting is liquid state wherever it is and hasn't absorbed its massive state-change energy yet). For methanol, the benefit is the high octane fuel quality, and it's lower state-change (liq->gas) which allows some more IAT benefit to show up in the cooling of the compressor and it's product where applicable.
for example say you happened to move the spray closer to the IAT sensor and notice a lower IAT as a result.
The final math result will still be the same for the water's mass never changed, thus total energy content absorbed never changed, only the measured scalar quantity of temperature at arbitrary location has changed.
Furthermore, most of the benefit of water/meth injection is not due to the IAT decrease (as I've pointed out it may change at the sensor with little difference overall to the system). For water, the benefit is the enormous amount of energy it carries away when it moves from liquid to gas (which by the way, is 212*F and higher when there is boost, so if you aren't seeing 212*F+ IAT temperatures, the water you are injecting is liquid state wherever it is and hasn't absorbed its massive state-change energy yet). For methanol, the benefit is the high octane fuel quality, and it's lower state-change (liq->gas) which allows some more IAT benefit to show up in the cooling of the compressor and it's product where applicable.
Last edited by kingtal0n; 11-21-2017 at 10:08 AM.
11-21-2017, 10:24 AM
#4
Think of this,
imagine you setup a tube with air flowing through. The air enters one side and the tube is hollow, and the air exits the other side. Now, imagine the tube is also HOT so that it heats the air as it passes through. The air enters on one side at room temp, and exits on the other side at some higher temp T.
Now, setup water injection somewhere. Imagine it at the front, then in the middle, etc... and try to see if you can imagine/theorize what the temperature of the air going through the tube will look like. If we spray water at the beginning before the air goes through the tube, for example, the temp of the air will be uniform as it passes through the tube, and should also be a lower temperature since we've added the water's heat capacity to the air molecules.
Now, imagine if we inject the water at the halfway point instead. This time, air will rapidly go up in temp as it enters the tube, and will drop suddenly near the place the water is injected. Since the air is flowing ONE WAY, only the downstream portion of the air is cooled, because new mass is constantly entering and pushing out the old mass one way. If the tube is radiant or able to conduct towards the origin of our air, that means the origin of the air is able to absorb heat between itself and the tube, i.e. the starting air will begin to rise in temperature at some distance from the tube due to heating by the tube, so now our starting mass-flow will be lower (since the Temp is higher and nothing else changed) which will reduce power if the origin happens to be a compressor. Presumably this is why injecting methanol pre-turbo increases mass flow, by lowering the temperature at the origin. Compressor wheel has initial say on how much volume flow, which depends on wheel RPM, but not mass flow which depends on temperature
imagine you setup a tube with air flowing through. The air enters one side and the tube is hollow, and the air exits the other side. Now, imagine the tube is also HOT so that it heats the air as it passes through. The air enters on one side at room temp, and exits on the other side at some higher temp T.
Now, setup water injection somewhere. Imagine it at the front, then in the middle, etc... and try to see if you can imagine/theorize what the temperature of the air going through the tube will look like. If we spray water at the beginning before the air goes through the tube, for example, the temp of the air will be uniform as it passes through the tube, and should also be a lower temperature since we've added the water's heat capacity to the air molecules.
Now, imagine if we inject the water at the halfway point instead. This time, air will rapidly go up in temp as it enters the tube, and will drop suddenly near the place the water is injected. Since the air is flowing ONE WAY, only the downstream portion of the air is cooled, because new mass is constantly entering and pushing out the old mass one way. If the tube is radiant or able to conduct towards the origin of our air, that means the origin of the air is able to absorb heat between itself and the tube, i.e. the starting air will begin to rise in temperature at some distance from the tube due to heating by the tube, so now our starting mass-flow will be lower (since the Temp is higher and nothing else changed) which will reduce power if the origin happens to be a compressor. Presumably this is why injecting methanol pre-turbo increases mass flow, by lowering the temperature at the origin. Compressor wheel has initial say on how much volume flow, which depends on wheel RPM, but not mass flow which depends on temperature
11-21-2017, 10:31 AM
#5
The more time the liquid spends in the system the more chance it has to change to gas, which is good/fine depending on the nature of our complaint about the engine. It would be very unlikely for water to go back from gas to a liquid in the flurry of one of our intake systems. There is already water vapor in the air in most places, that isn't what we want though. We want the liquid product, and we want it to change to a gas if possible, but not necessary (it has no choice at the combustion chamber anyways, all will become gas state no matter what), and we want to get it into the system as soon as possible if there is heat trouble prior to the combustion chamber. Water also probably doesn't like to turn corners, which might be something to consider but isn't an issue most of the time.
Pre-compressor isn't ideal because it can damage a compressor wheel. But you don't have to worry about that.
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11-21-2017, 11:00 AM
#8
Something else to consider is that the blower DOES heat the air before it- because it radiates high temperature. In fact the blower is pre-heating everything under the hood for you, just like the exhaust system is. This next is the topic of INSULATION, and how to use insulation effectively should be covered. First, you will wrap, coat, shield the exhaust completely from the intake air path. Next, the lower parts of the engine (like exhaust tubes) must be covered/blanketed to also insulate. It is ok to radiate the temperature down to the ground below a certain point. The temperature reservoirs (radiator/coolers) are radiating their temperature away from the engine of course, and non-insulated so they can fulfill that purpose of energy transfer that every engine needs. Next, consider the blower and the top of the engine, and the area just under the hood. Since we insulted everything below this point, it should not get much hotter here than the head of the engine (220*F~common, regular engine) until a blower is installed. From the moment you turn the engine on, the blower is heating up, and heating everything around it. Keep in mind it is bolted to the head and subjected to highest water temperatures of the engine, so the regular temperature of the surface of the metal there in the blower is going to hit 200-220*F minimum in many applications once steady state.
What can you do to effectively lower air temp:
The blower will generate heat as a byproduct which will cause temperature to increase until the radiative capacity of blower/intake system is balanced. In other words, heat out must equal heat in if you want to stop the increase in temperature. So lets focus on increasing the heat out of the system.
In this application, it is ok to treat the blower and top of the engine like a radiator. If a heat sink could fit, we would use it. We want to suck the energy out of it. We want to blast it with ice cold air from an A/C system while we drive (they have this now for blowers). I'd like a duct or air path to carry heat away from this area. We want to cool the surfaces of the blower, at least to some possible minimum. Maybe reduce the water temperature of the head a little bit. I am giving you the picture of a goal: The same would go for the compressor housing of a turbo or supercharger. I want my compressor as ice cold as I can get it, whether I have to build a box around it and fill the box with ice water, build an A/C system for it, or spray something into it/on it. We are concerned with the entire system, remember we treated the insulation separately, even though it still plays a role in our system under the hood. Also keep in mind the blower surface temperature is more or less capped around a minimum of head temperature, so the goal here should be well defined not to include the surface temperature below a certain point.
Two different GOALS:
1. Cool the blower to it's minimum/head temperature. If coolant is 180*F then a blower sitting on the head would be near that temperature. It will want to go up in temperature from that point as it runs and produces heat- that is the heat we are concerned with.
2. Cool the air going into/through the blower. This is handled separately since the air can be much lower temperature than the head of the engine.
So for #1, for example, an ice water bath around the blower would be a stupid idea since there is no way we can cool the surface of metal touching 200*F head down to reasonable IAT temperatures. It will never be below 180*F in this imaginary example.
Focus on the location of the IAT sensor, and install a second sensor (second opinion) if you are serious about this IAT business. One sensor is not enough.
I would be focused first on injecting enough water to get the end result I needed from the engine to be safe: a low enough EGT. So if you wanted a piece of advice at this stage, it would be install an EGT sensor and get some EGT data to see where you stand on the mass of water injection. You can always inject more water to reduce EGT, but if the EGT is already low you will lose power or the engine will misfire. In other words, water is cheap (I hope you are using distilled water) so lets just inject enough water to get the EGT we want first, THEN look at IAT and handle it separately. Lowering IAT will not always lower EGT but lowering EGT while reducing or not changing the ignition timing is a great way to limit power and make the engine safer to run.
Last edited by kingtal0n; 11-21-2017 at 11:05 AM.
11-21-2017, 11:33 AM
#10
I have water/meth on my Whipple 2.9. I don’t really see a temp change on a quick street hit , but I do on a 1/4 mile run. Why are your temps so high? W2A intercooler? My temps are around 25-30 over ambient with an afco heat x w/ fans with a 2 gal tank . I have heard kenne bells generate a lot of heat, but 180 seems really excessive. Spray the **** out of it with straight meth, and add fans to intercooler.
11-21-2017, 07:04 PM
#16
WOW the supercharger has a closed cooling loop? How does that work? There must be an external pump. If this is true, why not increase capacity of the cooling loop until inlet temp is always ambient? Holy cow. I've never heard of that. I've seen them with internal oil-gear lube all the time, but never coolant. Also I wasn't going to ask but now that we are into it- does the intercooler raise the blower from the head? If so this would all start to make sense, they are trying to get away from the 200*F head temps...
11-21-2017, 10:02 PM
#17
Yea the inter cooler had its own heat exchanger, tank and pump. It's not so much the fluid being ambient, the fluid removes the heat after a pull. But the supercharger heats the compressed air so much its more than the intercooler can keep up with. Most ford kits fit an intercooler 2-3 times as large as the one I have.
11-22-2017, 04:21 AM
#19
9 Second Club
For general coverage, spray evenly into the blower rotors
For guaranteed cylinder distribution, do port injection.
With port injection while you cannot see any cooling taking place via a sensor because of the location, it will still be doing its job, and also a very important job in the chamber.
For guaranteed cylinder distribution, do port injection.
With port injection while you cannot see any cooling taking place via a sensor because of the location, it will still be doing its job, and also a very important job in the chamber.
11-22-2017, 06:21 AM
#20
a bigger tank / more efficient heat exchanger would help a lot . Look at speedway.com in garage sale section . There is always a few discounted ones. Mines an afco pro for a gt500. Picked it up for $500. Canton has a 2 gal tank that fits in battery location .