Which pump for Water Injection

[Chris611]

I am looking at building a water mist injection system for my truck. I have been looking at Shurflo pumps and can't decide between the "on demand" and the "bypass" model. It appears that most companies that sell systems are using the "on demand" pump, but it seem to me, I would want to use the "bypass" pump. The on-demand pump pumps until the pressure is say 100psi and then turns off until the pressure hits the lower limit, say 85psi, then back to 100 etc... What I don't know is if this constant cycling will hurt the pump. If I understand the bypass model right, it will run continuously and hold the 100 psi +/- and just circulates the water around until its needed. What style have you guys used that have made your own systems? Also what size nozzles?

Thanks
Chris

[ 03-23-2005, 09:12 AM: Message edited by: Chris611 ]

[More Power]

I have only a limited experience with water injection, but I would contact Bill Heath www.heathdiesel.com (http://www.heathdiesel.com) to ask his advice. He's been doing water injection since the mid 90's, and continues to experiment with systems and products while attempting to achieve the best results.


MP

[dieseldummy]

I would probably recomend the on demand style of pump for the simple fact that it isn't running when it's not needed. The people who design these pumps do it for a living so I'm sure they take into consideration the load stops and starts put on the motors and such. Just my .02.
Justin

[Chris611]

Thanks guys. I was planning on using a pressure switch and relay to power the pump. In other words, once the pressure switch triggers the relay to supply +12V to the pump it will run. Otherwise it will be off. I was also planning on using a solenoid just before the nozzle and triggering off the pressure switch as well and using the power from the pump relay to power the solenoid. This way if the pump relay fails, the solenoid will keep the intake/engine from filing with water...unless the pressure switch also fails closed...then it will be bad news!
You guys may be right that I can get away with an on demand pump. I noticed on one website that they used essentially a holding pressure tank to keep the pump from cycling. This was for a gasser though.

Thanks
Chris

[Billman]

Chris

I use a Diaphragm Type Demand Pump. Originally rated for 45-60psi @ ~4.9gpm.

I don't recommend doing it, but, I bypassed the regulator. I wired it direct. I'm not concerned about longevity. I'm still testing.

This pump, with my configuration, produces over 200psi with a 3gph nozzle.

I run a small nozzle because the Intercooler does the majority of the work.

The tank you read about was probably an accumulator. Helps the longevity of the pump.

[Marty Lau]

Chris;

Why don't you check out Heath Diesel I think his whole kit is like $249 and the includes everything but the water tank. Bill has also made 2 & 3 stage ones that add a little water at lower boost and more at higher. I've seen the pumps most people use in the local farm supply stores and they run about $80 alone.

[Chris611]

I have looked at some pre-done kits and you are right, Bill Heath's kit does appears to be the least expensive. I've decided to try and see if I can put together a system myself. Mostly because I think its fun to find all the parts, putting it together and getting it to work. I also don't want to spend too much time learning what other have already! I'm trying to keep the two in balance.

Thanks
Chris