-water Injection-
08-31-2003, 07:46 AM
#36
Senior Member
Join Date: May 2002
Location: Okinawa, Japan
Posts: 4,928
Originally Posted by 1Revvin7' date='Aug 31 2003, 02:54 PM
Chill out, you could have just pm'd him. He is here to learn like everyone else.
08-31-2003, 01:11 PM
#37
Senior Member
Join Date: Sep 2002
Posts: 2,550
I haven't read the first page, but here is some information that should be helpful to some of you...
11-11.2:1 is a relatively safe a/f ratio, peak power is somewhere around 11.7-12:1 or so, but you GREATLY increase the chance of blowing your **** up for a measly 10-20hp if you run toward the lean side. The reason a rotary needs to run rich is actually for two reasons.
# 1. Poor atomization of fuel due to the design of the rotary engine and the fact that the combustion chamber where the air and fuel needs to be when it ignites is moving. The atomized fuel is burnt, but their is some left over that isn't atomized that gets kick out with the exhaust causing a rich reading on the O2 sensor.
# 2. The extra fuel is also needed to cool the rotor. This helps eliminate hot spots that can cause predetonation.
if you run too lean you will get very hot ex temp, however if you run too rich you will also get very hot ex temps due to the left over fuel burning in the ex manifold. The way we used to tune prior to getting our kick *** wide bands was to tune rich to start and watch the ex temps drop as we took away fuel until the ex temp wouldn't go any lower. If you continued to take away fuel it would start to rise again and you knew you were getting too lean.
Here is what air/fuel ration is. I.e. Stoic. Say you have 1 gram of fuel, in order to burn all that fuel efficiently you will need a mass of 14.7 grams of air for it to oxidize with during the combustion process. This gives you the 14.7:1 ratio. When you run a richer a/f ratio you are basically giving the engine more fuel than the air to be had can burn. This extra fuel evaporates in the engine and removes heat. Another benefit from this and also from the water injection is that when a fluid evaporates taking away heat it also expands and will create more tork and can also aid the spooling a turbo faster since the exhaust pressure will be increased and be more dense.
11-11.2:1 is a relatively safe a/f ratio, peak power is somewhere around 11.7-12:1 or so, but you GREATLY increase the chance of blowing your **** up for a measly 10-20hp if you run toward the lean side. The reason a rotary needs to run rich is actually for two reasons.
# 1. Poor atomization of fuel due to the design of the rotary engine and the fact that the combustion chamber where the air and fuel needs to be when it ignites is moving. The atomized fuel is burnt, but their is some left over that isn't atomized that gets kick out with the exhaust causing a rich reading on the O2 sensor.
# 2. The extra fuel is also needed to cool the rotor. This helps eliminate hot spots that can cause predetonation.
if you run too lean you will get very hot ex temp, however if you run too rich you will also get very hot ex temps due to the left over fuel burning in the ex manifold. The way we used to tune prior to getting our kick *** wide bands was to tune rich to start and watch the ex temps drop as we took away fuel until the ex temp wouldn't go any lower. If you continued to take away fuel it would start to rise again and you knew you were getting too lean.
Here is what air/fuel ration is. I.e. Stoic. Say you have 1 gram of fuel, in order to burn all that fuel efficiently you will need a mass of 14.7 grams of air for it to oxidize with during the combustion process. This gives you the 14.7:1 ratio. When you run a richer a/f ratio you are basically giving the engine more fuel than the air to be had can burn. This extra fuel evaporates in the engine and removes heat. Another benefit from this and also from the water injection is that when a fluid evaporates taking away heat it also expands and will create more tork and can also aid the spooling a turbo faster since the exhaust pressure will be increased and be more dense.
08-31-2003, 01:22 PM
#39
Senior Member
Join Date: Sep 2002
Posts: 2,550
Just found this.. 
http://www.zaxjax.com/Air%20Fuel%20Ratio%2...cal%20Paper.pdf This will help you understand what a/f ratio is
08-31-2003, 07:20 PM
#40
Member
Join Date: Aug 2002
Posts: 65
Does anyone have any experience on what happens to EGTs in the presence of water injection? Dragon's post implies that they are considerably lower which is what you'd expect.
But I'm not sure that this is good for spooling a turbo. I've heard many times how the drive for the turbine comes from both the difference in pressure and temperature accross it, not the pressure difference only. On piston engines running antilag the pre-turbo EGT's are huge.
I have no personal experience with this, but I'm just trying to consider any downsides to water injection.
But I'm not sure that this is good for spooling a turbo. I've heard many times how the drive for the turbine comes from both the difference in pressure and temperature accross it, not the pressure difference only. On piston engines running antilag the pre-turbo EGT's are huge.
I have no personal experience with this, but I'm just trying to consider any downsides to water injection.