Just another turbo miata
03-22-2011, 10:23 PM
#22
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03-22-2011, 10:41 PM
#23
However, I'm intrigued by what you're doing. Do you have any plans to do some before and after data collection to show us how it works?
Also, Fae, pre-turbo gives faster spool? First I've heard of that. Why does that work? I wouldn't think it would do anything for spool.
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03-22-2011, 10:46 PM
#24
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http://n54tech.com/forums/showthread.php?t=7304
"1. Pre-Turbocharger/Centrifugal Injection
By placing the water methanol injection nozzle or nozzles pre-turbocharger or centrifugal supercharger and injecting a fine precise amount of water methanol into the air inlet of the compressor can have a dramatic positive effect on compressor efficiency (particularly with turbocharger systems and high boost centrifugal applications) while substantially lowering discharge temperatures at the source of compression. On 8-25 psi applications, users can expect to see a 70-160+ degree drop in compressor discharge temperatures. While reductions of 160-240+degree's can be had on 25-60+ psi high boost applications such as diesels.
How is this possible?
When water methanol is first injected, we're able to begin slightly cooling the incoming air entering the compressor. This air is already relatively cool in relation to the ambient temperature of the day as it has yet to be compressed and heated. Depending on the temperature of the day and how the air inlet is plumped and where the air is being drawn in from, the incoming air entering into the inlet of the compressor commonly ranges between 5-20 degree's above ambient. Only minor cooling of the air charge occurs at this stage before it enters into the compressor. More importantly, we are about to dramatically cool the air that is being compressed and heated within the turbocharger.
It's important to understand it is here that the heat is being generated.
A turbochargers impeller can spin at an astonishing speed between 100,000- 150,000 rpms. While centrifugal supercharger impellers spin between 40,000-65,000+ rpm. Between each pair of blades on an impeller exists a wedge shaped open space which the air fills in. As the impeller is spinning, this wedge shaped air pocket is subjected to tremendous centrifugal forces and is forced outward away from the center of the impeller to the outer edges. It is here where the air begins to stack up and compress against the compressor housing forming the heat as it makes it way into the scroll.
As the compressed air heats up, it tries to further expand, making it now more difficult for the heated compressed air to pass through and exit the compressor thereby lowering the compressor efficiency. In addition, this compressed air is taking up more space within the compressor limiting new incoming air from being processed. Furthermore, the hot compressed air exiting the turbocharger is less dense as it has been heated significantly. Therefore, containing less power producing oxygen while making the engine considerably more prone to detonation.
By cooling the air as it's being compressed within the turbocharger or centrifugal supercharger, the compressed air is now substantially cooler, more dense, taking less space and moves more efficiently through the compressor allowing us to pack and process more air through the turbocharger or centrifugal supercharger. This leads us to our second benefit. Improved compressor efficiency.
All of this results in improved compressor efficiency. Because of this improved efficiency the compressor does not have to work as hard to produce the same amount of boost as without the water methanol injection. In turn it raises the maximum mass air flow of the compressor. Thereby, making a smaller turbocharger or centrifugal supercharger now perform like a larger turbocharger or centrifugal supercharger with the addition of the water methanol injection.
Lastly, as already mentioned above, pre-compressor injection substantially lowers the discharge temperatures exiting the compressor. The engine is now less prone to detonation through this reduction in air charge temperatures. Furthermore, the use of an intercooler is dramatically reduced and in some applications no longer needed as it may not offer substantial further cooling effects in return for the pressure drop caused by it. Removal of the intercooler could now offer a further increase in boost pressure at the engine as well as compressor efficiency.
While all of this sounds very exciting. To do this properly requires proper sizing of the nozzles in relation to the compressor size and output. Additionally, the type fluid being used also effects the size of the water injection nozzle selected. When done properly, very little of the water methanol mist injected into the inlet of the compressor survives the process. Thereby, discharging a much cooler air charge with a relativity high humidity with very little or no water methanol droplets present.
When injecting water, we can quickly over saturate the air charge and have an excess of fluid discharging the compressor. Water has a much higher latent heat of vaporization, nearly double that of methanol, and does not flash (instantly evaporate) like that of methanol or other alcohols when injected into a hot air stream. Therefore, a smaller nozzle must be used when spraying pure water.
A better choice for pre-compressor injection is a greater concentration of methanol vs. water or pure methanol. Methanol instantly flashes (evaporating) as soon as it enters into a hot compressor and meets the heat within it. By using an alcohol, this dramatically reduces the amount of actual fluid exiting the compressor due to it‘s fast evaporation. Additionally, methanol offers much greater cooling effect then water. Furthermore, methanol is also less dense then water thereby having a softer impact on the impeller. The specific gravity of pure methanol is .792 @ 68° F compared to water which is 1.00 @ 64° F.
One major concern associated with pre-compressor injection is erosion of the impeller. This is only likely to occur when injecting solid stream of water at the impeller of a turbocharger or using an excessively large nozzle. Impeller erosion is highly unlikely with centrifugal supercharger as they spin at a considerably slower speed then turbochargers. Impeller erosion is of little concern with centrifugal superchargers."
"1. Pre-Turbocharger/Centrifugal Injection
By placing the water methanol injection nozzle or nozzles pre-turbocharger or centrifugal supercharger and injecting a fine precise amount of water methanol into the air inlet of the compressor can have a dramatic positive effect on compressor efficiency (particularly with turbocharger systems and high boost centrifugal applications) while substantially lowering discharge temperatures at the source of compression. On 8-25 psi applications, users can expect to see a 70-160+ degree drop in compressor discharge temperatures. While reductions of 160-240+degree's can be had on 25-60+ psi high boost applications such as diesels.
How is this possible?
When water methanol is first injected, we're able to begin slightly cooling the incoming air entering the compressor. This air is already relatively cool in relation to the ambient temperature of the day as it has yet to be compressed and heated. Depending on the temperature of the day and how the air inlet is plumped and where the air is being drawn in from, the incoming air entering into the inlet of the compressor commonly ranges between 5-20 degree's above ambient. Only minor cooling of the air charge occurs at this stage before it enters into the compressor. More importantly, we are about to dramatically cool the air that is being compressed and heated within the turbocharger.
It's important to understand it is here that the heat is being generated.
A turbochargers impeller can spin at an astonishing speed between 100,000- 150,000 rpms. While centrifugal supercharger impellers spin between 40,000-65,000+ rpm. Between each pair of blades on an impeller exists a wedge shaped open space which the air fills in. As the impeller is spinning, this wedge shaped air pocket is subjected to tremendous centrifugal forces and is forced outward away from the center of the impeller to the outer edges. It is here where the air begins to stack up and compress against the compressor housing forming the heat as it makes it way into the scroll.
As the compressed air heats up, it tries to further expand, making it now more difficult for the heated compressed air to pass through and exit the compressor thereby lowering the compressor efficiency. In addition, this compressed air is taking up more space within the compressor limiting new incoming air from being processed. Furthermore, the hot compressed air exiting the turbocharger is less dense as it has been heated significantly. Therefore, containing less power producing oxygen while making the engine considerably more prone to detonation.
By cooling the air as it's being compressed within the turbocharger or centrifugal supercharger, the compressed air is now substantially cooler, more dense, taking less space and moves more efficiently through the compressor allowing us to pack and process more air through the turbocharger or centrifugal supercharger. This leads us to our second benefit. Improved compressor efficiency.
All of this results in improved compressor efficiency. Because of this improved efficiency the compressor does not have to work as hard to produce the same amount of boost as without the water methanol injection. In turn it raises the maximum mass air flow of the compressor. Thereby, making a smaller turbocharger or centrifugal supercharger now perform like a larger turbocharger or centrifugal supercharger with the addition of the water methanol injection.
Lastly, as already mentioned above, pre-compressor injection substantially lowers the discharge temperatures exiting the compressor. The engine is now less prone to detonation through this reduction in air charge temperatures. Furthermore, the use of an intercooler is dramatically reduced and in some applications no longer needed as it may not offer substantial further cooling effects in return for the pressure drop caused by it. Removal of the intercooler could now offer a further increase in boost pressure at the engine as well as compressor efficiency.
While all of this sounds very exciting. To do this properly requires proper sizing of the nozzles in relation to the compressor size and output. Additionally, the type fluid being used also effects the size of the water injection nozzle selected. When done properly, very little of the water methanol mist injected into the inlet of the compressor survives the process. Thereby, discharging a much cooler air charge with a relativity high humidity with very little or no water methanol droplets present.
When injecting water, we can quickly over saturate the air charge and have an excess of fluid discharging the compressor. Water has a much higher latent heat of vaporization, nearly double that of methanol, and does not flash (instantly evaporate) like that of methanol or other alcohols when injected into a hot air stream. Therefore, a smaller nozzle must be used when spraying pure water.
A better choice for pre-compressor injection is a greater concentration of methanol vs. water or pure methanol. Methanol instantly flashes (evaporating) as soon as it enters into a hot compressor and meets the heat within it. By using an alcohol, this dramatically reduces the amount of actual fluid exiting the compressor due to it‘s fast evaporation. Additionally, methanol offers much greater cooling effect then water. Furthermore, methanol is also less dense then water thereby having a softer impact on the impeller. The specific gravity of pure methanol is .792 @ 68° F compared to water which is 1.00 @ 64° F.
One major concern associated with pre-compressor injection is erosion of the impeller. This is only likely to occur when injecting solid stream of water at the impeller of a turbocharger or using an excessively large nozzle. Impeller erosion is highly unlikely with centrifugal supercharger as they spin at a considerably slower speed then turbochargers. Impeller erosion is of little concern with centrifugal superchargers."
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03-22-2011, 10:49 PM
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OK, for the record, it is most effective to atomize with a high-pressure pump in the heated charge post-turbo. That's how I'm going on my build.
However, I'm intrigued by what you're doing. Do you have any plans to do some before and after data collection to show us how it works?
Also, Fae, pre-turbo gives faster spool? First I've heard of that. Why does that work? I wouldn't think it would do anything for spool.
However, I'm intrigued by what you're doing. Do you have any plans to do some before and after data collection to show us how it works?
Also, Fae, pre-turbo gives faster spool? First I've heard of that. Why does that work? I wouldn't think it would do anything for spool.
A turbocharger only knows 2 important properties of the gas it is compressing. The density of the gas at the compressor inlet and the pressure ratio it is operating at, which is determined by the rotor rpm and the gas density. If you increase the pressure or reduce the temperature at the inlet you will modify both of those parameters. In both cases (increased inlet pressure, or lower inlet temperature) you increase the apparent density of the gas passing through the compressor. At a given rotor rpm with a given gas density you will flow a very specific volume of gas and it will be compressed to a specific pressure ratio on exit. That is what the compressor map is based on. If you change the inlet conditions (gas density) you in effect slide the compressor map left and right. This is the "corrected flow" of the turbocharger.
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03-23-2011, 11:31 AM
#26
http://www.aquamist.co.uk/vbulletin/...34&postcount=8
A turbocharger only knows 2 important properties of the gas it is compressing. The density of the gas at the compressor inlet and the pressure ratio it is operating at, which is determined by the rotor rpm and the gas density. If you increase the pressure or reduce the temperature at the inlet you will modify both of those parameters. In both cases (increased inlet pressure, or lower inlet temperature) you increase the apparent density of the gas passing through the compressor. At a given rotor rpm with a given gas density you will flow a very specific volume of gas and it will be compressed to a specific pressure ratio on exit. That is what the compressor map is based on. If you change the inlet conditions (gas density) you in effect slide the compressor map left and right. This is the "corrected flow" of the turbocharger.
A turbocharger only knows 2 important properties of the gas it is compressing. The density of the gas at the compressor inlet and the pressure ratio it is operating at, which is determined by the rotor rpm and the gas density. If you increase the pressure or reduce the temperature at the inlet you will modify both of those parameters. In both cases (increased inlet pressure, or lower inlet temperature) you increase the apparent density of the gas passing through the compressor. At a given rotor rpm with a given gas density you will flow a very specific volume of gas and it will be compressed to a specific pressure ratio on exit. That is what the compressor map is based on. If you change the inlet conditions (gas density) you in effect slide the compressor map left and right. This is the "corrected flow" of the turbocharger.
"You also change the pressure temperature profile inside the compressor wheel itself. You probably actually change the shape of the compressor map. As the gas moves outward and is compressed, heat that would have gone into heat and increased pressure is absorbed by the WI mist and so the compressor has less work to do since it is no longer fighting this temperature driven pressure increase, it can achieve more mass flow at that pressure ratio. The cooling should also modify the speed of sound in the gas and the mach number of the compressor blade tips should also change. This should change the choke flow characteristics of the compressor but I don't have the information to comment in detail on that."
The above jives with Technosalvagers explanation too.
To put it more simply, by injecting pre-turbo, the compressor ingests a mixture of a gas and a liquid.
The amount of cooling that happens before the compressor depends upon how much of the liquid changes phase. This will be negligible -- could be a little in Pheonix, there won't be any in New Orleans -- this is the field of "psychrometrics," look it up.
However, once it is in the compressor being heated (remember p = rho x R x T), the liquid changes phase to a gas while removing heat . . . a LOT of heat . . . which lowers pressure . . . which has an impact on compressor characteristics.
Note that some of this effect would also be seen with post-compressor/pre-throttle body water injection because that would also lower the pressure at the compressor discharge, although I wouldn't expect the effect to be as dramatic.
Interesting.
Note that the cited articles talk about the importance of atomization to prevent compressor erosion. I'll be interested to see what your results are long-term with the pumpless injection.
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04-22-2011, 10:26 AM
#27
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Sorry. Don't buy this quote. However, in the exact same post (2 paragraphs down) is the real mechanism, namely:
"You also change the pressure temperature profile inside the compressor wheel itself. You probably actually change the shape of the compressor map. As the gas moves outward and is compressed, heat that would have gone into heat and increased pressure is absorbed by the WI mist and so the compressor has less work to do since it is no longer fighting this temperature driven pressure increase, it can achieve more mass flow at that pressure ratio. The cooling should also modify the speed of sound in the gas and the mach number of the compressor blade tips should also change. This should change the choke flow characteristics of the compressor but I don't have the information to comment in detail on that."
The above jives with Technosalvagers explanation too.
To put it more simply, by injecting pre-turbo, the compressor ingests a mixture of a gas and a liquid.
The amount of cooling that happens before the compressor depends upon how much of the liquid changes phase. This will be negligible -- could be a little in Pheonix, there won't be any in New Orleans -- this is the field of "psychrometrics," look it up.
However, once it is in the compressor being heated (remember p = rho x R x T), the liquid changes phase to a gas while removing heat . . . a LOT of heat . . . which lowers pressure . . . which has an impact on compressor characteristics.
Note that some of this effect would also be seen with post-compressor/pre-throttle body water injection because that would also lower the pressure at the compressor discharge, although I wouldn't expect the effect to be as dramatic.
Interesting.
Note that the cited articles talk about the importance of atomization to prevent compressor erosion. I'll be interested to see what your results are long-term with the pumpless injection.
"You also change the pressure temperature profile inside the compressor wheel itself. You probably actually change the shape of the compressor map. As the gas moves outward and is compressed, heat that would have gone into heat and increased pressure is absorbed by the WI mist and so the compressor has less work to do since it is no longer fighting this temperature driven pressure increase, it can achieve more mass flow at that pressure ratio. The cooling should also modify the speed of sound in the gas and the mach number of the compressor blade tips should also change. This should change the choke flow characteristics of the compressor but I don't have the information to comment in detail on that."
The above jives with Technosalvagers explanation too.
To put it more simply, by injecting pre-turbo, the compressor ingests a mixture of a gas and a liquid.
The amount of cooling that happens before the compressor depends upon how much of the liquid changes phase. This will be negligible -- could be a little in Pheonix, there won't be any in New Orleans -- this is the field of "psychrometrics," look it up.
However, once it is in the compressor being heated (remember p = rho x R x T), the liquid changes phase to a gas while removing heat . . . a LOT of heat . . . which lowers pressure . . . which has an impact on compressor characteristics.
Note that some of this effect would also be seen with post-compressor/pre-throttle body water injection because that would also lower the pressure at the compressor discharge, although I wouldn't expect the effect to be as dramatic.
Interesting.
Note that the cited articles talk about the importance of atomization to prevent compressor erosion. I'll be interested to see what your results are long-term with the pumpless injection.
Got my LS2 coils the other day. Need to make a bracket get them mounted. Ordering a bigger nozzle for my pre turbo injection and adding another nozzle for extra water pre throttle body.
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06-21-2011, 10:18 AM
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not pictured.
950cc Haltech injectors and a 949 fuel rail
should fix my issue of running out of spark and injector from the last dyno. 260whp on stock ignition was pushing it pretty hard imo.
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06-21-2011, 10:46 AM
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What do you think Faeflora, 300 whp ? Wonder how long my rods will last before they decide they need fresh air.
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06-21-2011, 11:40 AM
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It has a 3" divorced downpipe from artech, with full 3" exhaust to a 11x18x22 magnaflow muffler.
Last edited by PatrickB; 06-21-2011 at 01:38 PM.
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06-21-2011, 01:42 PM
#36
Nice looking build.
Next time you are on the dyno please make some pulls comparing no water injection to all three possible injection scenarios (pre-turbo, pre-tb, both) if time and money allows. It'll give the pre-turbo haters something to chew on and provide some real data as well.
Good luck!
Next time you are on the dyno please make some pulls comparing no water injection to all three possible injection scenarios (pre-turbo, pre-tb, both) if time and money allows. It'll give the pre-turbo haters something to chew on and provide some real data as well.
Good luck!
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06-21-2011, 02:38 PM
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15psi it was on dyno dynamics, the owner of the dyno says that it reads %18 lower. However we know that every car has read atleast 15% lower on the dynamics then it does on the dynojet. My plot is uncorrected it did 227/220 so a 15% correct gives it 261hp. I am going to be taking it a dynojet soon. I ran out of injector(rx7 460's) and spark(stock) at the last session.
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06-21-2011, 02:46 PM
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Nice looking build.
Next time you are on the dyno please make some pulls comparing no water injection to all three possible injection scenarios (pre-turbo, pre-tb, both) if time and money allows. It'll give the pre-turbo haters something to chew on and provide some real data as well.
Good luck!
Next time you are on the dyno please make some pulls comparing no water injection to all three possible injection scenarios (pre-turbo, pre-tb, both) if time and money allows. It'll give the pre-turbo haters something to chew on and provide some real data as well.
Good luck!
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