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I dont know of ANY water/meth injection company that uses a 40 PSI checkvalve.
Ours is 22 lbs, DO is 16, Aquamist is 15 (I think). I would love to know the source of this mystical "40 PSI" valve. |
Edited
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For the record:
Originally Posted by SnowTech
(Post 4963412)
Well it looks like I may be mistaken. It wasn't in fact a 40 psi check valve. Apparently it was a 22 psi check valve.
It was taken out of a diesel kit. The instructions that came with the kit don't specify the cracking pressure. I guess the more important thing here is that a check valve with a 22 psi cracking pressure reduces pressure by 40 psi. Consider for a moment that a diesel truck might make 50 psi of boost. A 150 psi pump can only make 110 psi because of a 22 psi check valve. With 50 psi of opposing force working against the pump output the net pressure is now only 60 psi. This means little to no progression and half the amount of flow that is actually required to support a diesel making this much boost. Check valves: {thumbdwn}
Originally Posted by SnowTech
I personally tested a readily available checkvalve that is offered by a company that has been mentioned in this thread. I did the EXACT same test that Richard did except that I used 100% water and not air. I tested pressure before and after a 40 psi checkvalve. No I don't have any cool pictures and no I don't have any cool videos so I guess you'll just have to take my word for it:
I witnessed a 40 psi drop across a check valve with a cracking pressure of 40 psi. 150 psi going in and 110 psi going out. Those of you that aren't agreeing with the fact that there is a pressure drop across a ball-type check valve should just try it yourself and see. You can't refute real world test results.
Originally Posted by SnowTech
I'd like to see Richard conduct his test again using water.
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Edited.
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My unedjucated guess on this topic is that a system with a spring loaded obstruction inline will have a greater preasure drop across it in proportion to the flow (nozzle) while keeping the pressure constant.
I wonder if one can make up for this pressure drop mearly by mounting a nozzle in a venturi (I think it's called that) section fitted on the charge. If the section is streamlined enough there will be little or no drop in air flow or pressure accross it, but most importantly will reduce the charge pressure in that section. Anyone done that yet? |
This thread has been a very good read and contains lots of good input and test data. I would like to add my 2 cents to maybe put the final nail in the coffin and put this horse to rest.
The tests done by Abner clearly show a pressure drop across a CV. Whether it is air, water or photons traveling though the CV does not matter. All three materials are made of particles with the density of these particles being the major difference. The laws of fluid dynamics clearly states that a pressure drop will occur as a fluid passes though a medium. Whether that medium is a hose, CV or nozzle orifice, all contribute to a pressure drop. The basic fluid laws (or Darcy’s law in this case) are analogues to those used in other fields: Ohms law for electronics or Fourier’s law for heat conduction. Pressure, Voltage, or a Thermal Source the laws are very similar. Work is required to move something across a medium. If the medium is a CV, electrical resistor or convection point, the more work done the more something will flow; fluid, electrons or heat. With fluid flow, when you add in a CV you have a pressure drop on the outlet, but at the same time you have an increase in the velocity of the fluid as it goes from high pressure to lower pressure, Bernoulli's principle. The inverse can also be seen by the CV data charts posted earlier in this thread. For example on the 4CP check valve, as fluid flow increase we see an increase in the amount of pressure drop across the CV. The point to be understood is that for fluid flow to increase, requires an increase in pressure or work done by the pump. So with a PPS system, CV or not, fluid flow still increase as pump pressure goes up. On the specific 4CP posted, significant drop does not occur until about .4 GPM or 1500ml/min. That’s a lot of fluid for a W/M system and most setups. Free Beer!!! Ok now that I have you attention again lets apply this to a water injection system. The main point about nozzle outlet pressure is that it has to be high enough to create enough shear force on the fluid to get the smallest water partials as possible. The reason being the smaller the particles the greater the surface area and the more heat they can take out of the inlet air charge. This translate to about 40-60psi at the nozzle outlet for good atomization of the water. Yes you have to subtract off manifold pressure and pressure drop from the CV from the pump pressure. But it is incorrect to take max boost pressure and subtract it from the low speed pressure of the pump. Since we are talking about PPS, the output pressure or work from the pump will be lower at lower manifold pressure and increase with manifold pressure. So much like your FPR, the fluid flow increase with the pump pressure as it goes up significantly faster then manifold pressure resulting in higher fluid flow at higher boost. Remember the medium is not changing so the resistance is fixed. Higher pump pressure = more fluid flow though a fixed restriction and at higher velocity. If the system starts at 7psi of boost with 80psi of pump, 80 – 10 (CV) – 7 (boost) – 1 (all the other unaccounted for’s) leads to 62psi at nozzle. 150 psi at 30psi boost: 150 – 10 – 30 – 1 = 109 at nozzle. Either case you have good atomization at the nozzle. So the CV does affect the system behavior, but manifold pressure is more of a restriction. So ok, why use a CV or a solenoid in the first place? Main issue is to prevent fluid siphoning out of the nozzle during engine vacuum. Other issue is to keep fluid in the line so that the onset of injection is sooner when boost reaches the Start point to activate injection. The main trade off to consider is reliability of the system when choosing a CV or a solenoid. To increase reliability you need to reduce the number of failure points. A CV has a higher mean time between failure then a solenoid so would be a better choice to increase the reliability of the system and still gain the benifits listed above. At the end of the day all that matters for a W/M system is that it is tuned properly and that A/F is held constant. The small flow rate drop though a CV is inconsequential if the vehicle is tuned properly. A failed solenoid can be catastrophic. It will running your race weekend if you use a cheap one from someone that claims to be an expert and never tested the damn thing on their own car. Sorry for the long post, but hope someone finds it to be a useful read. Best regards, Dan |
Originally Posted by Labonte MotorSports
(Post 4964439)
This thread has been a very good read and contains lots of good input and test data. I would like to add my 2 cents to maybe put the final nail in the coffin and put this horse to rest.
The tests done by Abner clearly show a pressure drop across a CV. Whether it is air, water or photons traveling though the CV does not matter. All three materials are made of particles with the density of these particles being the major difference. The laws of fluid dynamics clearly states that a pressure drop will occur as a fluid passes though a medium. Whether that medium is a hose, CV or nozzle orifice, all contribute to a pressure drop. The basic fluid laws (or Darcy’s law in this case) are analogues to those used in other fields: Ohms law for electronics or Fourier’s law for heat conduction. Pressure, Voltage, or a Thermal Source the laws are very similar. Work is required to move something across a medium. If the medium is a CV, electrical resistor or convection point, the more work done the more something will flow; fluid, electrons or heat. With fluid flow, when you add in a CV you have a pressure drop on the outlet, but at the same time you have an increase in the velocity of the fluid as it goes from high pressure to lower pressure, Bernoulli's principle. The inverse can also be seen by the CV data charts posted earlier in this thread. For example on the 4CP check valve, as fluid flow increase we see an increase in the amount of pressure drop across the CV. The point to be understood is that for fluid flow to increase, requires an increase in pressure or work done by the pump. So with a PPS system, CV or not, fluid flow still increase as pump pressure goes up. On the specific 4CP posted, significant drop does not occur until about .4 GPM or 1500ml/min. That’s a lot of fluid for a W/M system and most setups. Free Beer!!! Ok now that I have you attention again lets apply this to a water injection system. The main point about nozzle outlet pressure is that it has to be high enough to create enough shear force on the fluid to get the smallest water partials as possible. The reason being the smaller the particles the greater the surface area and the more heat they can take out of the inlet air charge. This translate to about 40-60psi at the nozzle outlet for good atomization of the water. Yes you have to subtract off manifold pressure and pressure drop from the CV from the pump pressure. But it is incorrect to take max boost pressure and subtract it from the low speed pressure of the pump. Since we are talking about PPS, the output pressure or work from the pump will be lower at lower manifold pressure and increase with manifold pressure. So much like your FPR, the fluid flow increase with the pump pressure as it goes up significantly faster then manifold pressure resulting in higher fluid flow at higher boost. Remember the medium is not changing so the resistance is fixed. Higher pump pressure = more fluid flow though a fixed restriction and at higher velocity. If the system starts at 7psi of boost with 80psi of pump, 80 – 10 (CV) – 7 (boost) – 1 (all the other unaccounted for’s) leads to 62psi at nozzle. 150 psi at 30psi boost: 150 – 10 – 30 – 1 = 109 at nozzle. Either case you have good atomization at the nozzle. So the CV does affect the system behavior, but manifold pressure is more of a restriction. So ok, why use a CV or a solenoid in the first place? Main issue is to prevent fluid siphoning out of the nozzle during engine vacuum. Other issue is to keep fluid in the line so that the onset of injection is sooner when boost reaches the Start point to activate injection. The main trade off to consider is reliability of the system when choosing a CV or a solenoid. To increase reliability you need to reduce the number of failure points. A CV has a higher mean time between failure then a solenoid so would be a better choice to increase the reliability of the system and still gain the benifits listed above. At the end of the day all that matters for a W/M system is that it is tuned properly and that A/F is held constant. The small flow rate drop though a CV is inconsequential if the vehicle is tuned properly. A failed solenoid can be catastrophic. It will running your race weekend if you use a cheap one from someone that claims to be an expert and never tested the damn thing on their own car. Sorry for the long post, but hope someone finds it to be a useful read. Best regards, Dan |
Damn he's smart. All the arguing we did in here and he just explained it scientifically but yet still easy to understand.
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Dan,
Its good to see someone posting real world data with scientific explanations behind it. Maybe in the spring after the snow melts, others will read this and get it as well. Good job. |
It took 8 pages just to get the checkvalve message through !!!
But this is nothing compared to two years on varies forums, putting a simple message about the effect of Checkvalve on PPS system. Still a great deal of work to do. I will move onto the PWM valve very soon. Before that - take a closer look at the pump used on the PPS controller - is it really that linear to PWM control pulses as it claimed ? Anyone would like to make a start? |
PPS system #1:
on-demand aka pulsing shurflo set @100psig w/ Hago M5 nozzle PPS system #2: on-demand switch on shurflo disabled w/ Hago M15 nozzle system #1 - http://img2.putfile.com/thumb/9/25400594779.jpg system #2 - http://i240.photobucket.com/albums/f.../AAPPSflow.jpg |
Abner,
I believe alkycontrol (system#2) is the only company that disconnected the demand switch after activation. This eliminated the "low frequency pulsed" that everyone hates. |
Originally Posted by Richard L
(Post 4966076)
Abner,
I believe alkycontrol (system#2) is the only company that disconnected the demand switch after activation. This eliminated the "low frequency pulsed" that everyone hates. |
The system #2 test you did gave pretty good results for a pump speed controller. Apart from operating outside the pump's allowable maximum pressure - it did stood out to be a better system than the system #1.
It does help me a great deal on studying a PPS system with a "demand switch" in circuit. This will further reduce the PPS system's operating pressure range. The system #2 's progressiveness performance is compromised by the action of the "demand" switch. I gather the "demand " switch has a hysteresis of 20psi. Once trigger, the 150psi pump pressure will spike between 130psi and 150psi. |
is it even possible to get good atomization AND flow range out of a progressive pump speed system...??
good atomization requires lots of pressure behind the nozzle, ~40psig behind a small M5 and ~60psig behind a M15 for a nice misty spray. good dynamic flow range requires varying pump speed/line pressure http://i240.photobucket.com/albums/f...IX/MMWHago.jpg seems that the progressive pump speed injection idea is a compromise between good flow range and good atomization |
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