Flame propagation and the tooth fairy
02-21-2005, 01:22 PM
#106
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Why do I state the laws of physics are on my side in reference to water injection? Hmm... because they are? Just a guess.
Still after hundreds of dyno hours there was no measurable power gain to be found!
Without having any proof I'll bet my money on lowering the backpressure.
Bengt
02-21-2005, 03:16 PM
#107
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Originally Posted by Bengt Sweden
...and I guess I deserved that for not checking first.
Still after hundreds of dyno hours there was no measurable power gain to be found!
Without having any proof I'll bet my money on lowering the backpressure.
Bengt
Still after hundreds of dyno hours there was no measurable power gain to be found!
Without having any proof I'll bet my money on lowering the backpressure.
Bengt
Hopefully it will end with, "to be able to run with a 993tt, remove the spark plugs, take a hammer and a centre punch..."
02-21-2005, 06:37 PM
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Originally Posted by TurboTommy
FSAEracer is right,
that when water evaporates (or fuel, for that matter), the molar count of the air increases (there is a net gain in air molecules available to burn fuel. When evaporation occurs there is an increase in air molecules in a given space. Yes, when the liquid water turns into gas it takes up more space, but it uses up only 20% of the gain in density in order to take up this space.
This is why the water should be evaporated quite a bit earlier before it gets to the intake ports.
If WI is installed and tuned correctly (read: less is better) a slight increase in power can be achieved even without increasing boost (providing there is already a good healthy amount of boost).
Bengt is correct, however, that timing must be optimised to achieve this. Otherwise, there will probably be a net loss.
that when water evaporates (or fuel, for that matter), the molar count of the air increases (there is a net gain in air molecules available to burn fuel. When evaporation occurs there is an increase in air molecules in a given space. Yes, when the liquid water turns into gas it takes up more space, but it uses up only 20% of the gain in density in order to take up this space.
This is why the water should be evaporated quite a bit earlier before it gets to the intake ports.
If WI is installed and tuned correctly (read: less is better) a slight increase in power can be achieved even without increasing boost (providing there is already a good healthy amount of boost).
Bengt is correct, however, that timing must be optimised to achieve this. Otherwise, there will probably be a net loss.
Originally Posted by Bengt Sweden
TurboTommy, I am not sure what you mean by a "healthy amount of boost" and how that would influense. We ran stock boost levels with stock boost control system. This also means that the density gain from cooling was supported by increased flow from the turbo, and still power was down.
Originally Posted by FSAEracer03
Besides have a cork on the exhaust (like a cat converter... or a potato ) gains seen from lower exhaust backpressure are low. That's what I was trying to say above, so this is my an addendum. Yes, as the valve raises off it's seat and pressures equalize, gains will be seen with slightly lower pressure resistance and reduced concentration of residual gases. But I'd argue that besides extreme cases, the gains are minimal. Exhaust tuning based on primary lengths and pulse resonance can give much more effective gains... and with turbo motors, I'd really only aim to get backpressure drops for turbo spooling, wouldn't you? Also, with an NA motor, a decent backpressure can be a vital part of your power curve depending on what you're looking for: top end power or lower end torque? Many times gains in one will compromise the other.
FSAEracer03, when you talk about backpressure I get the impression that you only mean pressure after the turbine? When you state that slightly lower backpressure gives minmal gains, are you aware that on our engins it's possible to have backpressure of at least 3 times the boost pressure? I think that you can obtain more than slight reductions in backpressure on our cars and the gain will be more than minimal.
I even go so far that I think that most of the gain seen in a turbo upgrade, is due to lowered backpressure. Yes you will need a bigger compressor to be able to flow more air but without a VE increase from reduced backpressure the engine would not flow that much more air regardless of what compressor you change to.
Originally Posted by hally
what about if we inject heavy water, increase the compression a little.. of course we would have to beef up the cat converter, on the upside knock detection could be simplified.
Tomas
02-21-2005, 06:47 PM
#110
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Bengt,
healthy amounts of boost, like over 1 bar
When boost gets higher, there will always be quite some heat left in the charge air, even after it went through the IC. Taking this residual heat out (density increase) and being able to keep with good spark advance is where the slightly extra power potential could come from. At lower boost levels this gain potential is simply not there and anything that's left on the table can easily be taken care of by the fuel itself.
Interesting findings you have with your WI research. How much water did you use?; this might be key
healthy amounts of boost, like over 1 bar
When boost gets higher, there will always be quite some heat left in the charge air, even after it went through the IC. Taking this residual heat out (density increase) and being able to keep with good spark advance is where the slightly extra power potential could come from. At lower boost levels this gain potential is simply not there and anything that's left on the table can easily be taken care of by the fuel itself.
Interesting findings you have with your WI research. How much water did you use?; this might be key
02-21-2005, 06:59 PM
#111
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Tomas,
the idea is to achieve the density gain before the intake valve closes.
In general, somebody correct me, but I believe this to be true:
highest VE and density with the least amount of cooling during the compression stroke will yield the highest power potential but the greatest likelyhood to detonate;
more cooling during compression will decrease power and lessen the likelyhood to detonate.
Balancing this will yield the greatest safe power
the idea is to achieve the density gain before the intake valve closes.
In general, somebody correct me, but I believe this to be true:
highest VE and density with the least amount of cooling during the compression stroke will yield the highest power potential but the greatest likelyhood to detonate;
more cooling during compression will decrease power and lessen the likelyhood to detonate.
Balancing this will yield the greatest safe power
Last edited by TurboTommy; 02-21-2005 at 11:23 PM.
02-21-2005, 07:21 PM
#112
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Originally Posted by TurboTommy
Tomas,
the idea is to achieve the density gain before the intake valve closes.
the idea is to achieve the density gain before the intake valve closes.
Originally Posted by TurboTommy
In general, somebody correct me, but I believe this to be true:
highest VE and density with the least amount of cooling during the compression stroke will yield the highest power potential but the greatest likelyhood to detonate;
more cooling during compression will decrease power and lessen the likelyhood to detonate.
Balancing this will yield the greatest save power
highest VE and density with the least amount of cooling during the compression stroke will yield the highest power potential but the greatest likelyhood to detonate;
more cooling during compression will decrease power and lessen the likelyhood to detonate.
Balancing this will yield the greatest save power
I also think that this explains why Bengt didn't get any increase in power with water injection. If the Volvo engine had sufficient margin against detonation at it's stock boost level so that it could be run with an ignition setting that was optimum for power, then water injection would not yield any gain. If the boost level would have been raised then the result might been different.
Tomas
02-21-2005, 10:23 PM
#113
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Since this is a turbo forum I'll only comment on turbo applications.
FSAEracer03, when you talk about backpressure I get the impression that you only mean pressure after the turbine? When you state that slightly lower backpressure gives minmal gains, are you aware that on our engins it's possible to have backpressure of at least 3 times the boost pressure?
FSAEracer03, when you talk about backpressure I get the impression that you only mean pressure after the turbine? When you state that slightly lower backpressure gives minmal gains, are you aware that on our engins it's possible to have backpressure of at least 3 times the boost pressure?
Should we inject natural uranium also? But the nead to fill the block with lead radiation shielding may slow us down a little... We also need a higher pressure radiator cap, boiler reactors use around 80 bar pressure.
Tomas
Tomas
Yes, but if that's all we want we would definately be better of with a larger intercooler.
02-22-2005, 02:43 AM
#114
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When boost gets higher, there will always be quite some heat left in the charge air, even after it went through the IC.
Anyway the results regarding power from these tests discouraged me and I instead focused on Nitrous injection for my Hot-Rod. No detailed measurement were needed there to detect the power gains
Bengt
02-22-2005, 03:42 AM
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The engine we used for the tests was not equipped with an intercooler so there was plenty of heat to take out. Perhaps the result would have been different if the water injection was done further upstream. The testing was part of my graduation work at the university 1986 and the conclusion was that water could replace fuel enrichment at top loads to enhance emission control.
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I am not as experinced nor have I as much turbo knowledge as some of you here so I am not trying to disagree but I had a 76 930 that had no intercooler. Looking into water injection, I found out from the Buick Grand National crowd, that on the earlier GN's, wich came without intercoolers, waterinjection had been used as a method of cooling the intake charge.
I have the aquamist 1s for my 951 but have not gotten a chanse to fully test it due to difficulties,posted on here.
Anyway , I will post results as soon as I get my new Vitesse dme chip. I am running on 91 oct in Ca and plan on a daily driver with 330 rwhp at 16psi to a hopefull 350rwhp at 18 psi,but I want at least the timing won't retard if not advance.
I have a very well built vitesse TO4E with the SMT5 unit.bosch 550 cc.Tial 38. no cat. an more ...will add the 3inch exhaust after smog test with stright out wg dump,no cat,and plan in water injecting right at the beginning of the intercooler to throttle body pipe using .5mm nozzle first than .6mm for more than 16 psi.
I was going to use the windshield washer fluid but the location itself is hot....looking for a place under the lights where to place a small tank without soaking engine heat.....I want the water to be as cool as possible. I think WI is most beneficial in hot California summers that my car has to endure and traffic where the engine really gets hot.
Question: are the goals I stated above attainable ? what about if I use 50/50 water methano?l
PS : W/M injection did awesome for Buick GN's!! Ended up buying one...those are fast!! can have a daily driver do 11 no problems and not even change tires!!Best part is that it had MORE room in the back than a taurus,camry or accord,twice..yes twice the trunk space,,,do I need to mention driver's comfort? hmmmm........only 2 doors..... future family/business 10 sec coupe??
Bengt Sweden
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I am not as experinced nor have I as much turbo knowledge as some of you here so I am not trying to disagree but I had a 76 930 that had no intercooler. Looking into water injection, I found out from the Buick Grand National crowd, that on the earlier GN's, wich came without intercoolers, waterinjection had been used as a method of cooling the intake charge.
I have the aquamist 1s for my 951 but have not gotten a chanse to fully test it due to difficulties,posted on here.
Anyway , I will post results as soon as I get my new Vitesse dme chip. I am running on 91 oct in Ca and plan on a daily driver with 330 rwhp at 16psi to a hopefull 350rwhp at 18 psi,but I want at least the timing won't retard if not advance.
I have a very well built vitesse TO4E with the SMT5 unit.bosch 550 cc.Tial 38. no cat. an more ...will add the 3inch exhaust after smog test with stright out wg dump,no cat,and plan in water injecting right at the beginning of the intercooler to throttle body pipe using .5mm nozzle first than .6mm for more than 16 psi.
I was going to use the windshield washer fluid but the location itself is hot....looking for a place under the lights where to place a small tank without soaking engine heat.....I want the water to be as cool as possible. I think WI is most beneficial in hot California summers that my car has to endure and traffic where the engine really gets hot.
Question: are the goals I stated above attainable ? what about if I use 50/50 water methano?l
PS : W/M injection did awesome for Buick GN's!! Ended up buying one...those are fast!! can have a daily driver do 11 no problems and not even change tires!!Best part is that it had MORE room in the back than a taurus,camry or accord,twice..yes twice the trunk space,,,do I need to mention driver's comfort? hmmmm........only 2 doors..... future family/business 10 sec coupe??
02-22-2005, 03:57 AM
#116
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Darius, 50/50 is actually the extreme limit for injection, really. Water injection developers will tell you 10-20% methanol is a good amount. Beyond that you're hurting yourself rather than helping.
02-22-2005, 03:22 PM
#119
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Originally Posted by TurboTommy
FSAEraser,
"more than 20% methanol, your hurting yourself rather than helping"
That information is totally false!
"more than 20% methanol, your hurting yourself rather than helping"
That information is totally false!
From a theoretical standpoint, water has a slightly higher latent heat absorbsion than methanol when the state change is made (with respect to entropy and enthalpy).
If there's something I'm missing, and was missed in testing (fuel loads were kept good, so I'm not quite sure what it would be) please share.
02-22-2005, 06:28 PM
#120
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FASEraser,
I obviously don't know what this test is that you're talking about, or how good it was.
All I know is that I don't need a test (well, I did a test: on my own car) to tell me that methanol will achieve denser mixtures, decrease detonation tendencies, and do this without slowing combustion.
Yes, water has higher heat absorption; but only to the condensation point. With too much water, your charge air density can actually get less. A little hard to grasp, at first.
In general, only when the boost really gets up there, is when the water starts to become beneficial.
I obviously don't know what this test is that you're talking about, or how good it was.
All I know is that I don't need a test (well, I did a test: on my own car) to tell me that methanol will achieve denser mixtures, decrease detonation tendencies, and do this without slowing combustion.
Yes, water has higher heat absorption; but only to the condensation point. With too much water, your charge air density can actually get less. A little hard to grasp, at first.
In general, only when the boost really gets up there, is when the water starts to become beneficial.