Water Injection
12-27-02, 08:07 PM
#76
Originally posted by peejay if the car never sees below freezing temps, why not just run pure water?
Water is the key to prevent detonation. That seems to kill turbo rotaries. All the other benefits are just great pluses.
Ken
12-27-02, 08:47 PM
#78
Old [Sch|F]ool
More power from what?
The reason we run such rich A/F ratios under boost is not for more power, it's for detonation resistance. Run a turbo rotary at "max power" A/F and you have a ticking, or to be more precise pinking, time bomb on your hands!
The only advantage I see to adding methanol to the water (besides freezing protection) is that the methanol evaporates at a lower temp than water and therefore pulls more heat out of the intake charge before it gets to the engine. Fine, except that means you have less water injected into the chamber, and it's the water in the chamber that is the anti-detonant, not the reduction in charge temp that is incidental with water injection.
Keep in mind also that at a certain point, making the mixture richer makes detonation even more likely! I am not sure where this point translates on a rotary however.
In other words, we already have too much fuel, what we need is to be able to burn it at the right time without it detonating, because broken engines don't make much power for very long.
The reason we run such rich A/F ratios under boost is not for more power, it's for detonation resistance. Run a turbo rotary at "max power" A/F and you have a ticking, or to be more precise pinking, time bomb on your hands!
The only advantage I see to adding methanol to the water (besides freezing protection) is that the methanol evaporates at a lower temp than water and therefore pulls more heat out of the intake charge before it gets to the engine. Fine, except that means you have less water injected into the chamber, and it's the water in the chamber that is the anti-detonant, not the reduction in charge temp that is incidental with water injection.
Keep in mind also that at a certain point, making the mixture richer makes detonation even more likely! I am not sure where this point translates on a rotary however.
In other words, we already have too much fuel, what we need is to be able to burn it at the right time without it detonating, because broken engines don't make much power for very long.
Last edited by peejay; 12-27-02 at 08:49 PM.
12-28-02, 12:35 PM
#79
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[source of data: The Internal Combustion Engine in Theory and Practice, Charles Fayette Taylor].
1. "Alcohol mixed with gasoline gives anitknock properties," (page 153)
2. "Increasing inlet temp increases the end gas temperature[...], thus increasing the tendancy to detonate." (page 63)
3. "...increasing atmospheric humidity tends to reduce detonation." (page 70)
---------------------------------------------------
So it apears that water/alcohol injection would be
very effective in reducing the tendancy to detonate since it attacks detonation in three ways.
Just my 2 cents.
1. "Alcohol mixed with gasoline gives anitknock properties," (page 153)
2. "Increasing inlet temp increases the end gas temperature[...], thus increasing the tendancy to detonate." (page 63)
3. "...increasing atmospheric humidity tends to reduce detonation." (page 70)
---------------------------------------------------
So it apears that water/alcohol injection would be
very effective in reducing the tendancy to detonate since it attacks detonation in three ways.
Just my 2 cents.
12-28-02, 01:11 PM
#80
Old [Sch|F]ool
My point is that adding more fuel is not the answer. Alcohol is fuel. Yes it has higher octane, but at the levels that water is injected, you'd be also making the mixture highly overrich.
The water acts as a buffer to prevent mass autoignition IE detonation. What matters is that it is an inert material, one that will not burn. Exhaust gas would also work, it is an inert material that will not burn, and in fact this is one reason why EGR valves are used. I certainly wouldn't want to use an EGR valve under boost because of the additional heat, though! So we use water, which has the added bonus of absorbing heat from the intake charge (allowing a denser charge and thus more mass in the chamber) as well as from the chamber itself, further reducing detonation.
Alcohol is a fuel. We have more than enough of THAT already. We don't need to be dumping more of it in.
The water acts as a buffer to prevent mass autoignition IE detonation. What matters is that it is an inert material, one that will not burn. Exhaust gas would also work, it is an inert material that will not burn, and in fact this is one reason why EGR valves are used. I certainly wouldn't want to use an EGR valve under boost because of the additional heat, though! So we use water, which has the added bonus of absorbing heat from the intake charge (allowing a denser charge and thus more mass in the chamber) as well as from the chamber itself, further reducing detonation.
Alcohol is a fuel. We have more than enough of THAT already. We don't need to be dumping more of it in.
12-28-02, 03:20 PM
#81
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peejay is dead on with theory... atleast my 3 years of engineering i've taken can vouch for it... as for practical applications... i'm not sure. i've never tried any water injection.
12-28-02, 05:20 PM
#82
peejay, you have the highest post count that I've ever seen.
Get out much? Jk
What you are saying makes sense. After doing a little bit of research I have concluded that you want to use just enough methanol to keep the water from freezing. I am still unsure of the best injection location. Any input would be appreciated.
Has anyone here been able to build a pumpless water injection system? I read about one guy by the name of garfinkle (or something like that) who used the compresses intake air to run through a hose to a water tank then from the tank through a hose to an injector in the intake. The injection was controlled by a air actuated pressure switch. This seems like a great idea but I would like to hear what you guys think about it.
Get out much? Jk
What you are saying makes sense. After doing a little bit of research I have concluded that you want to use just enough methanol to keep the water from freezing. I am still unsure of the best injection location. Any input would be appreciated.
Has anyone here been able to build a pumpless water injection system? I read about one guy by the name of garfinkle (or something like that) who used the compresses intake air to run through a hose to a water tank then from the tank through a hose to an injector in the intake. The injection was controlled by a air actuated pressure switch. This seems like a great idea but I would like to hear what you guys think about it.
12-28-02, 05:34 PM
#83
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peejay
My claims did not refute yours directly, Your post seemed to imply that methanol was not an antiknock agent. Your post also implied that reduction in intake charge temperature was not a significant factor in reducing detonation.
My claim is that both are significant, to what degree they affect detonation is anyones guess.
But the bottom line is that the water mixed with the intake charge reduces end gas temperature by reducing the initial temp and by reducting the reaction time of the mixture (increased humidity/inert stuff), and a reduced end gas temp means a reduction in the likelyhood of detonation.
As far as the alcohol comment, I neglected to consider its affect on the a/f ratio, please excuse.
jp
My claims did not refute yours directly, Your post seemed to imply that methanol was not an antiknock agent. Your post also implied that reduction in intake charge temperature was not a significant factor in reducing detonation.
My claim is that both are significant, to what degree they affect detonation is anyones guess.
But the bottom line is that the water mixed with the intake charge reduces end gas temperature by reducing the initial temp and by reducting the reaction time of the mixture (increased humidity/inert stuff), and a reduced end gas temp means a reduction in the likelyhood of detonation.
As far as the alcohol comment, I neglected to consider its affect on the a/f ratio, please excuse.
jp
12-28-02, 06:11 PM
#84
Old [Sch|F]ool
Wanklin: Pumpless is a fairly common method. You inject water before the compressor, and you have the water reservoir in free communication with the post-turbo ducting. Free communication meaning a fairly large, short hose with no check valves, so that pressure in the reservoir follows the turbo duct pressure as closely as possible. I'm careful to say turbo duct because free communication with the intake manifold would be a Not Good thing, unless you could design the reservoir/tubing to handle vacuum.
After that, you only need to get a method of holding off water pressure to the injector until the boost pressure in the ducting got above a certain level. A simple popoff valve should work (haven't tried). Mainly this is so if you have the injector lower than the water level it doesn't siphon the water out which would generally be a Bad Thing, but it also allows you to tune the cut-in point. Then you play with restrictor orifices until you get the flowrate you want.
jason, I don't doubt that they're significant, however they are not AS significant. In other words, sure the water injection may lower temps 10-20 degrees but that is not as significant to preventing detonation as the effects in the chamber. Bear in mind that with proper water injection you could lean the mixture out to stoich under boost and not detonate although i would NOT recommend this to anybody just in case the water injection fails or runs out.
After that, you only need to get a method of holding off water pressure to the injector until the boost pressure in the ducting got above a certain level. A simple popoff valve should work (haven't tried). Mainly this is so if you have the injector lower than the water level it doesn't siphon the water out which would generally be a Bad Thing, but it also allows you to tune the cut-in point. Then you play with restrictor orifices until you get the flowrate you want.
jason, I don't doubt that they're significant, however they are not AS significant. In other words, sure the water injection may lower temps 10-20 degrees but that is not as significant to preventing detonation as the effects in the chamber. Bear in mind that with proper water injection you could lean the mixture out to stoich under boost and not detonate although i would NOT recommend this to anybody just in case the water injection fails or runs out.
01-09-03, 02:45 PM
#86
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01-09-03, 05:10 PM
#87
Banned. I got OWNED!!!
Originally posted by wanklin
peejay, you have the highest post count that I've ever seen.
Get out much? Jk
What you are saying makes sense. After doing a little bit of research I have concluded that you want to use just enough methanol to keep the water from freezing. I am still unsure of the best injection location. Any input would be appreciated.
Has anyone here been able to build a pumpless water injection system? I read about one guy by the name of garfinkle (or something like that) who used the compresses intake air to run through a hose to a water tank then from the tank through a hose to an injector in the intake. The injection was controlled by a air actuated pressure switch. This seems like a great idea but I would like to hear what you guys think about it.
peejay, you have the highest post count that I've ever seen.
Get out much? Jk
What you are saying makes sense. After doing a little bit of research I have concluded that you want to use just enough methanol to keep the water from freezing. I am still unsure of the best injection location. Any input would be appreciated.
Has anyone here been able to build a pumpless water injection system? I read about one guy by the name of garfinkle (or something like that) who used the compresses intake air to run through a hose to a water tank then from the tank through a hose to an injector in the intake. The injection was controlled by a air actuated pressure switch. This seems like a great idea but I would like to hear what you guys think about it.
I have a pumpless system, it works great for my application, I stop the water flow through a solenoid in the water line that shuts off the flow when boost pressure drops under 2psi, this cuts the water flow instantly.
For a nozzel I use a special air/atomising unit modified to my spec (for flow rate I require) it is made by spraying systems USA and produces a very fine mist that will not cause impellor wear when injecting in front of the compressor (which is the best way for a performance gain, even aquamist state this in their literature) I believe because you get multiple positive effects, I have never experience a "drop out issue" In terms of corrosion, you cannot use mild steel piping, it will rust, you must get it coated or use a different material that will not rust, once it gets to the Intake manifold this is not an issue.
I will be experimenting with ultra high ratio's of water this year in an attempt to see how far i can go on pump gas, my highest thus far I have tried is just over 22psi with a 12% water to fuel ratio, the a/f was around 13.0 to 13.5:1 at WOT.
From what I have been able to gather from other users in very different fields they are using ratios as high as 30% or more and are in a totaly differnt league in terms of engine "stress" which makes what I have experienced thus far seem tame. My problem is that I need another nozzel to get the flow rate I require to go up to the next level, also what I have experience thus far is that you do need to lean out the fuel ratio to get the performance gain and to a lesser degree to get the motor to operate correctly.
If you are willing to accept the tuning requirements and have a reliable WI system, the results will be a real eye opener and in many cases very unconventional (in terms of operating parameters) to what you are used to if you do a bit of engine tuning.
P.S. I have found you need a bloody strong spark before you attempt to use this technology (especially if you are around the 500rwhp level in a 13B), otherwise you may be disapointed in the results in terms of project power gians for the increased boost available to you.
01-10-03, 01:54 AM
#88
The limit on pump gas, 92/93 octane here with water/alcohol injection I guess would be dependant on application.
I have a buddy with a turbo Buick T-Type that normally run around 16 to 17 psi before knock retard would set in on pump gas. With water/alcohol mix he's now able to run 24 to 25 psi without any knock and have pushed it to 28psi before knock would set in but at a very low rate about 1 to 2 degree of retard. It's fun when you can have a low 11 sec daily driver that runs on 92 octane!
On my race car I'm running 100% methanol and will be experimenting with some water injection later on to see what the results would be. It's not intercooled presently so with a little water I hope it will make a difference for the better.
crispeed
87 Rx-7 TII
9.204@150.47mph
2600lbs
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I have a buddy with a turbo Buick T-Type that normally run around 16 to 17 psi before knock retard would set in on pump gas. With water/alcohol mix he's now able to run 24 to 25 psi without any knock and have pushed it to 28psi before knock would set in but at a very low rate about 1 to 2 degree of retard. It's fun when you can have a low 11 sec daily driver that runs on 92 octane!
On my race car I'm running 100% methanol and will be experimenting with some water injection later on to see what the results would be. It's not intercooled presently so with a little water I hope it will make a difference for the better.
crispeed
87 Rx-7 TII
9.204@150.47mph
2600lbs
un-tubbed
01-10-03, 03:20 AM
#89
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"what the heck. My post about Corky Bell says NO! was on topic
he is very opposed to water injection. Says so in the book im reading right now. I thought that might be something since he is pretty good w/ turbos"
He was referring to water injection instead of an intercooler.
I am sure if it is used on top of tuning kind of like a pop off valve he would consider it a good thing.
GregW
he is very opposed to water injection. Says so in the book im reading right now. I thought that might be something since he is pretty good w/ turbos"
He was referring to water injection instead of an intercooler.
I am sure if it is used on top of tuning kind of like a pop off valve he would consider it a good thing.
GregW
01-10-03, 03:46 AM
#90
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We all know what Mr bells Feelings are about WI. However many formula 1 teams of the 80's used to power their 1.8 liter 1500 hp engines. Also currently all WRC teams use it. These people didn't start working on cars yesterday. So apparantly it has to have some benefits. If i could get around it, then yes. it's one less thing. But right now, temp control under high boost seems to be an issue, and WI is apparantly one possible solution this problem.
01-15-03, 02:56 PM
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I have been using water injection for years on my DSM. I found I would get knock at 17-18 PSI with pump gas no matter how I tuned it, With water injection used to basically raise the octane rating, I now can run 22 PSI exact same setup, My FMIC is very large so intercooling is/was not the primary objective. It was anti KNOCK I was after.
I just retrofitted My FD with a custom system. I use both the windshield fluid tanks. The front one has a bosch fuel pump in it out of a turbo volvo, a low level sensor, and a regulator the rear tank is replumbed to fill the front tank when it's low.
When the level sensor goes low I have a timed relay that triggers the rear tank to refill the front tank for a predetermined time This way I have about 1.5 gal capacity. I never use the windshield washers so I had no problem reusing the stock tanks. I have tested fuel pumps with great results for years. I find that simply running them deadheaded is not good. They need some flow. So I made a regulator to let it run at 65PSI. This way is still has some flow all the time.
I have 2 pressure switches and 2 valves. Stage one is pressure only 8PSI at 8psi thepum turns on,the valve opens and runs water to nozzle one, an aquamist nozzle, can't remember the flow rate off hand. Stage 2 also uses a pressure switch. It gets it's pressure signal from the compressor bypass valve on turbo 2.
This way stage one works untill the second turbo is brought on line at which time stage 1 and 2 run sequentially untill redline. as long as teh boos stays above 8
For now it's not done. I have the hardware installed but still have to install a pressure gauge in the cockpit and wire in the relays and time delays.
I have a time delay on the pump for 10 seconds this way when I'm shfting through the gears, the pump will stay on unless I haven't boosted for 10 seconds.
All my parts were bought through mcmaster-carr except for the pressure switches and nozzles which are aquamist items.
The entire setup has been bench tested and worked real well.
The aquamist nozzles atomize real well over 50 PSI so I run 65. 80psi was too hasd on the fuel pump.
Ill post some pictures of my setup soon.
Greg
I just retrofitted My FD with a custom system. I use both the windshield fluid tanks. The front one has a bosch fuel pump in it out of a turbo volvo, a low level sensor, and a regulator the rear tank is replumbed to fill the front tank when it's low.
When the level sensor goes low I have a timed relay that triggers the rear tank to refill the front tank for a predetermined time This way I have about 1.5 gal capacity. I never use the windshield washers so I had no problem reusing the stock tanks. I have tested fuel pumps with great results for years. I find that simply running them deadheaded is not good. They need some flow. So I made a regulator to let it run at 65PSI. This way is still has some flow all the time.
I have 2 pressure switches and 2 valves. Stage one is pressure only 8PSI at 8psi thepum turns on,the valve opens and runs water to nozzle one, an aquamist nozzle, can't remember the flow rate off hand. Stage 2 also uses a pressure switch. It gets it's pressure signal from the compressor bypass valve on turbo 2.
This way stage one works untill the second turbo is brought on line at which time stage 1 and 2 run sequentially untill redline. as long as teh boos stays above 8
For now it's not done. I have the hardware installed but still have to install a pressure gauge in the cockpit and wire in the relays and time delays.
I have a time delay on the pump for 10 seconds this way when I'm shfting through the gears, the pump will stay on unless I haven't boosted for 10 seconds.
All my parts were bought through mcmaster-carr except for the pressure switches and nozzles which are aquamist items.
The entire setup has been bench tested and worked real well.
The aquamist nozzles atomize real well over 50 PSI so I run 65. 80psi was too hasd on the fuel pump.
Ill post some pictures of my setup soon.
Greg
01-15-03, 09:28 PM
#98
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Nice, and yes MSD has a kit for water craft, I'm wondering what rpm I should turn it on at and what flow rate? got the the MSD site and click on the factory direct then watercraft.....got it for 96 bucks! my mods are in my sig and I don't have a FMIC, I like the throttle response of the tmic........
oh yeah I wanna run 12-15 psi on my stock turbo
oh yeah I wanna run 12-15 psi on my stock turbo
Last edited by BlackRx7; 01-15-03 at 09:32 PM.
01-16-03, 11:10 PM
#99
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Hey Forcefed1
you mean you ran a return line?
Also have you had any problems with corrosion with the EFI pump running water thru it?
Thanks
I find that simply running them deadheaded is not good. They need some flow. So I made a regulator to let it run at 65PSI. This way is still has some flow all the time
Also have you had any problems with corrosion with the EFI pump running water thru it?
Thanks