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View Full Version : Shurflo based system teething problem?


Steve VXR
25-05-2005, 07:08 AM
I must apologise if this has been discussed before, or if it is a common trait of the Shurflo pump setup, but I have had a look around the forum and can't find anything relating to this setup.

My car has a Coolingmist system, based around a Shurflo pump, mounted in the boot (trunk) of the car. I took some advice from Coolingmist and have the pump setup to operate independently of demand at the solenoid, so that it is pressurises the feed to the front of the car and then shuts the pump off on its integral pressure switch.

In the engine bay the solenoid for water injection is controlled by a boost pressure switch, so the idea is that the engine comes onto boost, the solenoid opens and allows a pressure drop in the line, which then brings the pump in the boot back on and the WI operates.

Although when bench tested this worked fine, since fitting to the car I have noticed that the pump doesn't run constantly when the system is 'on'. Instead, it appears to be pumping intermittently (I have wired in an extra feed to a dash LED, which tells me that the pump pressure switch is electrically closed and this is flickering, rather than constant).

My question is this, is that a normal phenomena with a Shurflo pump when running such a setup, or do I need to increase the pressure at the pump pressure switch to overcome this? I did try adjusting this, but the screw does seem to be quite tight already and I was concerned about damage.

Also, my kit was supplied with rubber hose of approximately 4mm ID, but in order for a neater installation I used 6mm OD polyurethane tubing. Could this be a factor in the problem, as this is more rigid than the rubber tube? I have read about using pressure accumulators in line, but not really found any product information relating to this.

Thanks for any advice, I know I have gone on a fair bit!

Roverdose
25-05-2005, 07:31 AM
is your engine turbo/supercharged?

Drew

hotrod
25-05-2005, 09:12 AM
I have a very similar setup, although I have a shurflo accumulator in line between the pump and the solenoid.

The shurflo pump has a fairly wide spread between the turn on and the turn off pressure on its internal pressure switch. I can't give you a firm number but I think it is about 20 psi or so. The pump also generates a peak pressure of about 150 psi during each pump stroke, so it is capable of making up pressure quite quickly.

I suspect what you are seeing is normal. On my system, I only hear the pump stroke a few strokes each time the system activates.

I have an indicator light that comes on when my boost switch closes and it is typically only on for a second or two at a time in each gear. With a 2 - 4 gallon per hour nozzle you flow very little water in the time it takes to go to over 100 mph. If the nozzle is a 4 gal/hr nozzle, and the WI is on for 6 seconds it would only move 1/600 of the nozzle hourly flow or about 1.5 cubic inches or about 25 cc.

Larry

Slump
25-05-2005, 07:11 PM
I have an aquamist system 2s, but with a shurflo pump instead of the aquamist pump. My setup is similar, in that I let the internal switch of the shruflo control it's on-off cycle, and let the MF2 control the solenoid.

The pump runs intermittantly - remember it's a pretty high flow pump, so each "cycle" of the pump is capable of moving much more water then you're flowing. I think I probably have a 1 to 2 Hz (1 or 2 "cycles" per second" duty cycle on the shurflo at full tilt.

I don't have an accumulator yet, though. I think I see a pressure range of around 80psi to 120+ (my water pressure gauge only goes to 120 psi..)

Steve VXR
26-05-2005, 06:52 AM
Thanks for that information. I should have explained a bit about the car really, it is a Vauxhall (Opel) Astra Mk4 Turbo, which is a 2.0 litre 16v (4 cyl). Currently it is setup to run with 1.1bar boost and 1.5-1.6 bar overboost. The water injection comes into play around 0.35bar, as this is where we noted that the temperature would begin to climb when running on the dyno.

I will try the spare injector out of the car and confirm that the actual output from the injector is smooth, as this was my real concern, that the water wasn't being injected properly.

I did try to test the pressure that the pump was producing, but the gauge I had only read to 10 bar and I am guessing that these pumps can produce 'spikes' in excess of that because the bourdon tube in the gauge ruptured :roll:

As I had a basic Shurflo setup I was concerned about leaks from the feed to the front of the car, this is what brought about the original question, as I fitted an LED at the dash end of the system, which tells me when the pressure switch is on at the pump. There is also a secondary LED that tells me when the solenoid is being called for by the pressure switch. If I see the pump LED on and the solenoid LED off, therefore I know I have sprung a leak somewhere and can shut the power off to the pump before something in the car gets covered in water/alky mix :wink:

hotrod
26-05-2005, 08:20 AM
am guessing that these pumps can produce 'spikes' in excess of that because the bourdon tube in the gauge ruptur

Yes they can, I installed a 100 psi pressure gauge in line with mine into a 24 oz accumulator, and each time the pump stroked, it would pin the gauge hard, I'm guessing well in excess of 150 psi. It broke the gauge after only about 5 minutes of use. If you use a line pressure gauge you will need a substantial restrictor to control the pressure spikes.

One techinique I've seen used is to screw a fine thread allen set screw into the hose leading to the gauge. There will be enough leakage past the threads to give a pressure reading but the pressure spikes will not get past the high restriction.

I will be trying such a set up soon on mine, but need to go buy a new pressure gauge first.

Larry

AndrewC
27-05-2005, 02:27 PM
The pressure switch in the Shurflo pump is IMHO quite poor, much more accurate and reliable switches are available quite cheaply (around ?15 from RS Components in the UK), pressure range and hence pressure pulsing is substantially reduced and the stability of the mean pressure delivered increased.

Some other benefits:
1. Placing the pressure switch remotely from the pump, ie, pump in boot (trunk) pressure switch in engine bay means that pressure losses in pipework are allowed for.
2. Allows use of a wider range of (potentially cheaper) pumps.

The downside is of course increased complexity, having the pump/pressure regulation in 1 unit makes for easier installation.

Andrew...

DuMaurier 7
07-08-2005, 12:49 AM
Richard , as you may know , I am using a high pressure (150 psi) shur Flo pump , I also have two 200 psi solenoids located upstream each HSV that remain closed until injection is required , what is the highest pressure you think I can run between the pump and the solenoids without causing problems for the HSV's , right now its at 160 psi . :?:

Richard L
10-08-2005, 02:14 AM
Richard , as you may know , I am using a high pressure (150 psi) shur Flo pump , I also have two 200 psi solenoids located upstream each HSV that remain closed until injection is required , what is the highest pressure you think I can run between the pump and the solenoids without causing problems for the HSV's , right now its at 160 psi . :?:

I have tested the HSV at 160psi and it stayed shut. I havn;e tried beying this figure since we don't have a shurflo based system as standard.

We only supply shurflo system for tractor and drag racer when it only need to operate for a few second. An accumulator will help withe fluctuating pressure but not a long term solution.

Have you try using a by-pass valve to return to tank method?