Hi all I am looking at installiing a water/meth injection system on my 1998 f150. Has anyone done this? Any thoughts? Thanks

 

What for?

 

The only "good" reason to add water injection is as a last resort to control detonation. Any other reason is a bad reason..

 

.....This is an old carburation and supercharging trick where there is not much control over fueling but what the airflow through the carb does.
.....In a stock FI motor application, everything is controlled by sensor feed back to within a narrow set of limits.
.....What can happen if a "cooling" agent is introduced into the air stream ahead of the mass air sensor is the cooling of the air stream the intake air temperature sensor can detect and richen up the fuel.
.....The mass air meter is a hot wire type. The meth/water can cool the bridge element and change the signal to the PCM as if it were more air (by cooling) and again richen the fuel in response 'with less air' being passed except for the change in air density tending to counter it. (Same effect as winter time temps.)
....In the combustion chamber it can cause the temps to run cooler and may or may not help power by the time all the other effects are factored in and delt with by the PCM.
....In the exhaust, the OX sensors detect the effects of extra oxygen from meth and call for more fuel to counter the extra oxygen.
....Question is how is the cats affected by a cooling agent (water)? Water passes through the motor with only a phase change to steam.
....Then throw in the changes in ignition timing that will occur.
....Who knows what the overall effect would be when all these actions are brought togather.
....It would be interesting to see what happens to the fuel tables "LTFT/STFT" under these conditions. Likely move over a wide range and see a large varying effect on fuel mileage.
...My guess would be lower fuel mileage from the accumulated effects of richening and possibly feel a little more torque, but you would pay for it.
....This is what's wrong with being forced to buy gas with ethonal in it.
....Difference with it added in the gas is no effects in the intake tract before fuel injection and use of more fuel caused by the added oxygen detected after combustion.
....Best indicator of what it would be like is to note the weather vs performance under times of very high humidity and cool temperatures that would come close to same attempt as your introduction of a water vapor to the intake air stream.
....Only difference is it's all moisture at this point without the effects of meth.
Good luck.

 

yeah, really not worth the trouble unless you are already pushing 1000 hp and having detonation issues

 

Meth injection is really popular with the tuner crowds. I have two friends that run it..one in a 2006 Cobalt SS and another in a 2004 Subaru WRX-STi. Cobalt has about 250hp and the Suby has about 400..and they use it great. But then again both of them are built up.

Water injection was common in WW2 on fighter aircraft engines. It greatly increased power for WEP for about 5-10 minutes. Not sure I would recommend it for a stock truck engine, however.

 

Fairly popular for boosted applications, but not much use with a basically stock truck.

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http://forums.corral.net/forums/supe...cated-etc.html

http://forums.corral.net/forums/supe...devilsown.html

 

I have 4.6L with a php chip. Ever since I installed the chip I have to run 89 octane or I get pinging. I really like the chip and really don't want to have him change anything.

 

Is the tune set up for premium fuel?

 

The pinging issue is the tune has adjusted the timing tables with some ignition advance in an effort to increase low end torque.
Firing the cylinders with some ignition advance requires the gas be higher octane.
What the higher octane gas is doing is slowing down speed of combustion so peak cylinder pressures do not occur to near to top dead center.
If that happens, the rod to crank relationship is too much in alignment and cannot respond to the higher pressures fast enough.
Since the rod/crank can not move fast enough in that alignment position, the sudden combustion shock "rings the pistons, the cylinder walls and the heads.
You hear this as ping.
If it gets bad enough it is heard as a loud knock. At this point, head gaskets, piston crowns and cylinder wall are at risk of cracking/breaking as well as rod bearing pounding.
You can see now why the change in gas grade has to slow the combustion down with a change to performance tune.
The same would be true if the compression ratio were raised high enough.
Good luck.

 

the tune was supposed to be 87 octane. Thanks for all your input. I will just 89 octane.