The Twin Screw Thread
12-14-2016, 11:07 AM
#2701
Nordschleife Master
My logic says that one should spray water/meth downstream of the intercooler.
12-14-2016, 12:34 PM
#2704
Rennlist Member
Much easier with a turbo or centrifugal s/c to inject water/meth with one injector, but as Hans said, for it to be truly effective you need to do it at the individual ports on a roots/twin screw type s/c.
Was just wondering what others are doing, because on lots of various boards I've read when Googling the subject there are people that swear by injecting before the s/c which seems odd. You'd think that you'd want to do it after to help with heat from the s/c, but some are saying it still works if you inject it before. Sounds strange, that's why I asked what the E55 guys are doing.
Was just wondering what others are doing, because on lots of various boards I've read when Googling the subject there are people that swear by injecting before the s/c which seems odd. You'd think that you'd want to do it after to help with heat from the s/c, but some are saying it still works if you inject it before. Sounds strange, that's why I asked what the E55 guys are doing.
12-14-2016, 01:03 PM
#2706
Rennlist Member
If you sprayed before the SC how would that work with water, water doesn't compress right?
Sounds to me after and as said port injection would be the best, I would think the same applies to N2O.
Sounds to me after and as said port injection would be the best, I would think the same applies to N2O.
12-14-2016, 02:46 PM
#2708
Nordschleife Master
Same holds for oil, too. You don't want excessive amounts of oil being puked from the breather system into the twin screw compressor. I think some twin screw compressors have internal bypass valves for this scenario.
12-14-2016, 09:02 PM
#2709
Rainman
Rennlist Member
Rennlist Member
Was just wondering what others are doing, because on lots of various boards I've read when Googling the subject there are people that swear by injecting before the s/c which seems odd. You'd think that you'd want to do it after to help with heat from the s/c, but some are saying it still works if you inject it before. Sounds strange, that's why I asked what the E55 guys are doing.
12-15-2016, 12:41 AM
#2710
Many guys in the community are spraying just a bit before the sc (just water) to cool the air pre-sc and help the rotors seal a bit. This is argued about quite a bit.
Then they also also spray after the intercooler as you don't want it pooling in there. This is the place for water and/or meth. Placement has taken up many threads.
You want it to cool the air before it gets to the chamber. Obviously this has many benefits.
Spray at the ports and you are technically doing something different. You will not give the water time to evaporate as much in the ports to cool the charge air- you are now "chemicaly" changing what happens in the chamber and the combustion process to reduce knock.
What i I have read really separates these two techniques.
Methanol itself is a fuel and with enough you are changing the octane of the mixture.
Then they also also spray after the intercooler as you don't want it pooling in there. This is the place for water and/or meth. Placement has taken up many threads.
You want it to cool the air before it gets to the chamber. Obviously this has many benefits.
Spray at the ports and you are technically doing something different. You will not give the water time to evaporate as much in the ports to cool the charge air- you are now "chemicaly" changing what happens in the chamber and the combustion process to reduce knock.
What i I have read really separates these two techniques.
Methanol itself is a fuel and with enough you are changing the octane of the mixture.
12-15-2016, 09:05 AM
#2711
Nordschleife Master
Thermodynamics say that the water spray works to cool the charge because of the latent heat of the vaporization. As long as the water vaporizes, it pulls out a given amount of heat regardless of the charge temperature. This is in contrast with the intercooler. The intercooler cooling effect depends critically on the temperature difference between the coolant/cooler and the charge. Larger the temperature difference, greater the intercooler cooling effect. Putting these two together, you ideally want to spray the water downstream of the intercooler. Anything you do upstream of the intercooler to cool the charge will reduce the effectiveness of the intercooler and offset some of the benefits of the additional upstream cooling.
12-15-2016, 10:33 AM
#2712
Captain Obvious
Super User
Super User
Why does it matter where the air is cooled, before or after the IC? Cold air is cold air.
As for the water/alcohol injections, you need to flood the blower in order for it to hydrolock and that's a crap load of water.
As for the water/alcohol injections, you need to flood the blower in order for it to hydrolock and that's a crap load of water.
12-15-2016, 03:13 PM
#2713
Nordschleife Master
Thermodynamics say that the water spray works to cool the charge because of the latent heat of the vaporization. As long as the water vaporizes, it pulls out a given amount of heat regardless of the charge temperature. This is in contrast with the intercooler. The intercooler cooling effect depends critically on the temperature difference between the coolant/cooler and the charge. Larger the temperature difference, greater the intercooler cooling effect. Putting these two together, you ideally want to spray the water downstream of the intercooler. Anything you do upstream of the intercooler to cool the charge will reduce the effectiveness of the intercooler and offset some of the benefits of the additional upstream cooling.
The water spray cools about the same regardless of where you spray it. But intercooler cools more if water is sprayed downstream of it.
