Water Injection on an NA 6.2 Diesel
#1
02-27-2018, 10:18 AM
Water Injection on an NA 6.2 Diesel
I know, this is a very old topic that has been discussed a million other times but I'm trying to look at it a little bit differently. I am an engineer so I tend to think outside the box so bear with me. I am not new to diesel in any way and have owned several hundred diesels in my lifetime in addition to having a shop that repaired and modified VW Diesels (TDI's and IDI's both). I am also a certified installer for Kerma TDI although I haven't done a lot in the last couple of years. Although much more power and mileage can be had from a DI diesel, I tend to prefer IDI diesels due to their simplicity.
With the above stated, I have a 1991 Suburban with the old, reliable, economical 6.2 diesel (in addition to a 6.5 in a truck, a 6.2 in an '86 Suburban, and a 6.2 in a Military Police Blazier, a Duramax (LB7) that I have been building from the ground up, and that's not counting my hoards of VW diesels). There's not much to go wrong on the 6.2 diesel due to the simplicity of the design (just like many older idi vehicles). This vehicle is non-turbo. I intend to use the vehicle for family vacations and tend to travel all of the US on these excursions. Reliability is a must for this reason. Also, a '91 6.2 diesel uses a Throttle Position Sensor (TPS) for lockup control and gives a 0-5V signal.
I want to keep the EGT within check but be able to advance the timing (3-5 degrees) and Injection Quantity some (within reason) for a little additional power and mileage. However, that comes with the tradeoff of increased EGT's. In order to help keep EGT's within reason, I intend to put a thermocouple into each exhaust manifold to monitor EGT of each side of the engine. I'm going to hook each thermocouple up to it's own Process Temperature Controller that can be programmed for a Relay (or SSR) output. The relay wired to that can be used to start a pump for Injection as well as open a Flow Valve and the Temperature Controller can be programmed to start the water injection at say 700 degrees F. Now, this can be put into different stages (a 2nd Temperature Controller with another set of Nozzles, etc start flowing at say 900 degrees F) but I'm not looking into doing that at this time. Because I'm not doing anything radical, a 1GPH nozzle should be sufficient I would think.
Question I have for you....
Is it a good idea to consider using a boost controllers to vary the pump output or for a simple NA IDI is a simple on/off based on EGT good enough? I can tie it to the TPS which will be an indication of how hard the engine is being worked and it's already a 0-5V signal. If a boost controller was used, I could still tie the EGT to the flow valve for on/off control and start/stop of the pump.
Do you have any thoughts on the above? Am I just thinking too far outside the box for a simple IDI? My goal is to get the old 145HP (or 130HP...not sure which for a '91 and can't find any specs for the later 6.2's) engine up in the 160-175HP range and the 20-21mpg up into the 23mpg range. Part of doing this will involve a J Code intake swap which will allow additional air into the engine and I may put a scoop on the vehicle to cramp some extra air into the intake. A simple 2-3psi would be a big improvement on an NA IDI. Please let me know your thoughts because someone on here might have a lot of experience in trying this.
With the above stated, I have a 1991 Suburban with the old, reliable, economical 6.2 diesel (in addition to a 6.5 in a truck, a 6.2 in an '86 Suburban, and a 6.2 in a Military Police Blazier, a Duramax (LB7) that I have been building from the ground up, and that's not counting my hoards of VW diesels). There's not much to go wrong on the 6.2 diesel due to the simplicity of the design (just like many older idi vehicles). This vehicle is non-turbo. I intend to use the vehicle for family vacations and tend to travel all of the US on these excursions. Reliability is a must for this reason. Also, a '91 6.2 diesel uses a Throttle Position Sensor (TPS) for lockup control and gives a 0-5V signal.
I want to keep the EGT within check but be able to advance the timing (3-5 degrees) and Injection Quantity some (within reason) for a little additional power and mileage. However, that comes with the tradeoff of increased EGT's. In order to help keep EGT's within reason, I intend to put a thermocouple into each exhaust manifold to monitor EGT of each side of the engine. I'm going to hook each thermocouple up to it's own Process Temperature Controller that can be programmed for a Relay (or SSR) output. The relay wired to that can be used to start a pump for Injection as well as open a Flow Valve and the Temperature Controller can be programmed to start the water injection at say 700 degrees F. Now, this can be put into different stages (a 2nd Temperature Controller with another set of Nozzles, etc start flowing at say 900 degrees F) but I'm not looking into doing that at this time. Because I'm not doing anything radical, a 1GPH nozzle should be sufficient I would think.
Question I have for you....
Is it a good idea to consider using a boost controllers to vary the pump output or for a simple NA IDI is a simple on/off based on EGT good enough? I can tie it to the TPS which will be an indication of how hard the engine is being worked and it's already a 0-5V signal. If a boost controller was used, I could still tie the EGT to the flow valve for on/off control and start/stop of the pump.
Do you have any thoughts on the above? Am I just thinking too far outside the box for a simple IDI? My goal is to get the old 145HP (or 130HP...not sure which for a '91 and can't find any specs for the later 6.2's) engine up in the 160-175HP range and the 20-21mpg up into the 23mpg range. Part of doing this will involve a J Code intake swap which will allow additional air into the engine and I may put a scoop on the vehicle to cramp some extra air into the intake. A simple 2-3psi would be a big improvement on an NA IDI. Please let me know your thoughts because someone on here might have a lot of experience in trying this.
