Water Injection 2007
3.0 BAR
Joined: Oct 2006
Posts: 2,330
Re: Water Injection 2007
Originally Posted by fe3tcourier
we are arguing at cross purposes.
i say "it will be cooled some small but real amount"
then you say "it wont be cooled enough to matter"
...
i say "it will be cooled some small but real amount"
then you say "it wont be cooled enough to matter"
...
i strongly believe that it will cool that charge some potentially substantial amount. it may even drop pressure in the process and end up inducing the same mass of air, but there will be a temperature drop from such an activity...
IE you are proven wrong and are now simply beating a dead horse.
1.5 BAR
Joined: Jul 2007
Posts: 752
Re: Water Injection 2007
no, i still think its some appreciable difference. jd still thinks its not, but keeps stating that its not happening at all. which it is.
dont worry, i wont back down unless i see a good reason to. i was just trying to explain why he feels that way...
dont worry, i wont back down unless i see a good reason to. i was just trying to explain why he feels that way...
1.0 BAR
Joined: Sep 2005
Posts: 199
Re: Water Injection 2007
[quote=Joseph Davis ]
No, measurements aren't difficult to take. If the intake charge was cooled appreciably then power would come up measurably as cooler denser air fills the combustion chamber with more airmass.
[/quote}
How do you figure? The water/meth cools the air by turning to steam. The steam then takes up space that cannot be filled by more air.... The temp drop is supposed to outweigh that factor though.
No, measurements aren't difficult to take. If the intake charge was cooled appreciably then power would come up measurably as cooler denser air fills the combustion chamber with more airmass.
[/quote}
How do you figure? The water/meth cools the air by turning to steam. The steam then takes up space that cannot be filled by more air.... The temp drop is supposed to outweigh that factor though.
0.0 BAR
Joined: Feb 2003
Posts: 0
Re: Water Injection 2007
Liquid is incompressible, and displaces air, but have you ever calculated the amount of liquid we are talking here? Its inconsequential. Compare the large amount of exhaust coming out of the tailpipe when you rev your engine to 5K for 5 minutes during which time the gas needle doesn't move. Do you know how many cfms it takes to consume a gallon of gasoline?? Further, there IS NO STEAM until the mix meets the chamber. The only thing cooled enough to ideally increase VE is the intake valve face, but Vizard's work on detonation only showed an increase in knock limit from controlling intake valve temps. That cooling simply happens too late in the tract to create real world VE gains.
1.0 BAR
Joined: Sep 2005
Posts: 199
Re: Water Injection 2007
Charts and dyno from water injection :
http://www.flyinmiata.com/tech/water_injection.php#
Anyways the larger gain from it is tuning for it (advancing timing/boost). Also using it just before the intake manifold keeping everything internal much cooler as its moving across it can be a big help for someone with cast iron pistons (such as myself). Compression maybe 7.5:1 but forged pistons are exactly available for my car......
http://www.flyinmiata.com/tech/water_injection.php#
Anyways the larger gain from it is tuning for it (advancing timing/boost). Also using it just before the intake manifold keeping everything internal much cooler as its moving across it can be a big help for someone with cast iron pistons (such as myself). Compression maybe 7.5:1 but forged pistons are exactly available for my car......
Thread Starter
1.0 BAR
Joined: Mar 2007
Posts: 247
Re: Water Injection 2007
Datalog (will open in a new window)
The graph on the left is a run through 2nd, 3rd and 4th gears without water injection. The graph on the right is a run through 3rd and 4th gears with water injection turning on at about 4psi. The important traces are the dark blue trace for the intake air temperature (A Temp on the graph) and the light blue trace, close to the bottom, indicating ignition advance (IADv). Other parameters on the graphs are knock (red, showing simple engine noise in both graphs), MAP (manifold absolute pressure) and RPM.
Both traces for the intake air temperature start above 60°C, typical for a non-intercooled setup such as this one. Once in boost the run on the left shows the intake temperatures climbing to 96°C. With the water injection, the run on the right shows the temperature dropping and then leveling out at about 46°C. We can also run a lot more timing with the water injection thanks to the lower intake temperatures.
The graph on the left is a run through 2nd, 3rd and 4th gears without water injection. The graph on the right is a run through 3rd and 4th gears with water injection turning on at about 4psi. The important traces are the dark blue trace for the intake air temperature (A Temp on the graph) and the light blue trace, close to the bottom, indicating ignition advance (IADv). Other parameters on the graphs are knock (red, showing simple engine noise in both graphs), MAP (manifold absolute pressure) and RPM.
Both traces for the intake air temperature start above 60°C, typical for a non-intercooled setup such as this one. Once in boost the run on the left shows the intake temperatures climbing to 96°C. With the water injection, the run on the right shows the temperature dropping and then leveling out at about 46°C. We can also run a lot more timing with the water injection thanks to the lower intake temperatures.
