There’s been some discussion about tanks and level switches lately, so I though I’d share some of the changes I recently made to me WI system.

My original WI install made use of the windshield washer bottle, and I mounted the pump behind the front bumper, just forward of the right front tire. Here's the skinny on the original setup: https://www.miataturbo.net/forum/showthread.php?t=6932

‘Twas a nice and simple setup that kept the lines short and didn’t kill any trunk space- two of my major design goals. Unfortunately, I soon found out that the washer bottle is entirely too small. I measured it out of the car at 1.65 liters, but due to the odd shape and placement of the fitting I’d say that only about 1 liter of this is actually useful capacity. (this is a US-spec NA without ABS) What this translates to is <50 miles of hard driving between refills.

So I basically resolved that I was going to have to deal with a tank in the trunk, though I wanted to keep the pump up front where it was. Short lines = less pressure drop. Of course, a long supply line (tank to pump) would create drop just like a long delivery line (pump to nozzle). Solution? Keep the existing system connected exactly as it is (the washer bottle still feeds the injection pump) and install a second tank, with a transfer pump, to replenish the washer bottle as needed. A bit complex on paper, but as I mulled it over I really started liking this solution.

I finally found the perfect tank from enginerunup.com. Apologies to Chase & WideOpen (you know I love you guys) but this tank was the one: http://www.enginerunup.com/shop.php/...uart/p_21.html Turns out it’s actually a 5 quart Kart fuel tank, but it’s perfect. It’s got a reinforced area at the bottom pre-cast for a 1/8” MPT fitting (just finish-drill and hand-tap it) and the best part- it fits! Namely, I have mounted the tank directly opposite the battery, on a wooden platform (5/8” plywood, cut to fit this rather irregular space) situated above where the jack normally goes. The jack has been relocated to the floor behind passenger seat. It’s perfect- I can still put my big toolbox into the trunk with room to spare.

So you can see the wooden platform covering the jack recess. Mounted to the underside of that is a generic windshield washer pump that I bought from Pep Boys. Trico part # 11-100. Twenty bucks. The tank sits atop this held in place with a pair of ¼-20 bolts into T-nuts on the underside of the wood.

Nylon hose runs across the front of the trunk, forward through the passenger’s tunnel, then down and forward through the factory plastic rail on the inboard side of the rocker.

This project finally forced me to remove the last vestige of the A/C system- the evaporator box. Surprisingly heavy sucker, and with that out access to the firewall has gone from an utter nightmare to a fairly pleasant experience. I mounted a bulkhead fitting in the smaller of the two A/C tube holes to pass the hose up to the front.

Now, the electronics:

Mounted in the washer bottle are two float switches: http://www.alcohol-injection.com/flu...itch-p-10.html
The description on the website is wrong- turns out these are actually ½”NPT (not 1/8”) but such is life… You can set these up to be either normally open or normally closed depending on how you rotate them. “Normal” in this case is when the water level is below the level of the switch. I mounted the two switches at different levels. One on the side of the tank defines the upper level, one on the back of the tank defines the lower level. Both are installed in the “N.C.” orientation and wired to a DPDT relay as indicated.

When the water level in the washer bottle drops below the level of the lower switch, the switch closes causing the relay to energize. This activates the pump and also places the upper switch (which is also closed) in-circuit. Thus, even after the water level rises above the lower switch, causing it to open, the upper switch continues to hold the relay on until the water rises to the upper limit. Then the upper switch opens, releasing the relay and taking itself back out of the circuit.

The result? Well, after finishing this up I went out on a run through the mountains with the local Miata club, and was pleasantly surprised that after 150 miles of nearly continuous on-boost running, the big tank was only about ½ empty. Under normal driving I fill it up about once a week whether it needs it or not, and it usually doesn’t.

If nothing else, maybe others will be interested in this tank for use in a “conventional” system. It’s really slick- fits in there like it was made for the Miata.

In fact, with the remote filler that Kung Fu Jesus discovered, the tank could be almost completely hidden- the only reason it’s currently protruding into the trunk at all is to make the filling hole accessible.

 

Details on the washer bottle itself...

 

joe that's brilliant. what pump do you use between the bottles?

 

The schematic shows a windshield washer pump.

 

Now that is a cool setup. That tank you have is exactly the one I was looking at when I was getting ready to buy one. Might still get that tank because I too like my trunk space.

 

Just a generic "Universal" windshield washer pump. Specifically, a Trico model 11-100. Link: http://www.tricoproducts.com/catalogs/washerpumps.pdf
Nothing special at all about this pump other than that it happened to be sitting on the shelf at Pep Boys at the exact moment that I was searching for a pump, and since it's a universal type it has hose barbs for inlet & outlet. Many of the OEM-replacement style have odd inlet fittings designed to mate directly to a tank.

This was the second pump that I tried, actually. The first was purchased from JC Whitney, and failed after about 10 seconds of operation. This is the one NOT to buy: http://www.jcwhitney.com/autoparts/P...003809/c-10101

I'll also add that I did have to use some flexible hose between the tank and the pump, and then from the pump to a hose-barb adaptor on the regular nylon tube that goes up to the front. Since I'm running methanol I decided to splurge on some fancy silicone vacuum hose, rather than using the rubber stuff that I normally keep on hand.

 

Thanks. I was really happy with how well it came together, especially since it was a race against the clock. The project took a few days, and was finally completed and working the night before a huge fun run.

I do know that you NB guys have a slightly different trunk layout than us barndoor folks, but I've not spent a lot of time in an NB trunk so I'm not sure what this space looks like in your car.

 

I'll measure my available space and see if it will work.

 

Pretty sure us NB guys have the same kind of space over there. There's a little plastic cubby under there that might be useful for *something*.

I wonder though. If I use the aquamist high speed valve and their race pump, will the length equate to pressure drop if it's a pressure demand driven pump? 12 feet of 2.7mm ID line is more of a surge suppressor I'd think. But the tank itself... nice.

 

I guess I'm lucky for once being Canadian....our washer bottles have over 1 gallon capacity.

 

Very clever, I love the tank, but can the washer pump move water fast enough to keep up with your water use on the track?

Seems to me that a slightly less ambitious person like myself could mount the water injection pump under the plywood that holds up the tank (well I have some sheet aluminum, so I would use that) in the well where the jack used to be.

 

Joe,

I think it's great that you keep working and finding different solutions to various problems.

But if you were worried about pressure drop why not just fit the pump in the trunk and one of these:
http://www.turbobits.co.uk/acatalog/...y_806_201.html

If you fit it directly before your water switching device/valve and up the pressure of the the pump to just slightly over the switching pressure you've got no pressure drop between your tank in the boot and your water valve under the bonnet, plus it also means you then have 2 pressure fail safes.


Cheers
Mark

 

Though I haven't tested it, it's my impression that the washer pump is more than fast enough to keep up with any rate of consumption you could throw at it. On the average, it seems to take maybe 20 seconds once triggered to fill the tank to the upper limit and shut off. I'm guessing that the volume between the two switches is maybe 750ml. So let's call it 37.5 ml/sec. That comes to roughly 35.7 GPH, and my nozzle is rated at 3 GPH. So assuming I am running at maximum boost continously, I have a margin of well over 10:1. Assuming the exhaust manifold doesn't melt first.

I think I'm going to add an LED somewhere in the cabin that indicates when the lower switch is closed. That little washer pump is bound to fail eventually and while I have a failsafe on the boost controller, I'd really prefer to know about a transfer failure before the washer bottle runs completely dry.

Should be a simple addition, I just have to find space to mount yet another indicator.

 

Joe, your posts are as ever well written and contain some ingenious ideas. Thanks for another great writeup



(which i will hopefully get to use one day on my own car)

 

Love that idea and you take the word innovating to the max. Good job.

 

An Update:

I finally got around to doing the warning light install. It’s pretty slick.

I wanted to put the light into the stock gauge cluster, and I recalled from the list time I had it out that there were some unused “idiot light” positions. So I removed the gauge cluster from the car and held it up to a light, which revealed that the position just to the right of the Seat Belt warning (viewed from the normal position) is a washer fluid warning! What luck. So I removed the bulb from the seat belt position and moved it over to the next hole.

What really surprised me however is that while this bulb position is supplied with +12 just like the rest of them, the other side goes to a trace that just terminates at a dead-end copper pad- it does not go all the way to the connector. According to the Yorba Linda / Madracki wiring diagrams it’s supposed to show up on position 1L at the gauge cluster connectors, but it’s not in the FSM diagrams for either the US or Canada. Also, you can see in the picture that pin 1L is in fact labeled “Washer” but it’s like there’s a missing jumper that wasn’t installed at the factory to complete the circuit, nor was there a wire for it in the mating harness. Do you UK folks have a washer fluid level sensor?

Oh well. I carefully soldered a wire to the pad where the trace ended (it’s *VERY* easy to melt that plastic) and then as you can see I used a ring terminal and tie-wrap to secure the wire. Otherwise I’m fairly certain it would have torn the plastic. The wire goes into the existing transfer circuit as you see in the updated schematic. The diode is there to prevent the transfer circuit from back-feeding the rest of the car through the Meter fuse, since my transfer system is powered in the ACCY position. Also, the +12 feed to the lamp is indicated in gray since it is already provided for you in the cars wiring.

So with this circuit, the lamp comes on when the lower switch closes, and stays on so long as the pump is running. If I wanted it to operate only when the lower switch was closed a second diode placed just above the point where this line connects to the rest of the circuit with the stripe (anode) facing downwards would prevent the lamp from going to ground through the upper switch when the relay is active. Unfortunately, that part of my circuit is encased in hardened epoxy right now, and therefore inaccessible.

 

Just keeps getting better and better.

 

Joe....

That's cool. My car with ABS has a functional "washer" warning light, since the bottle is up between the nose and the drivers front wheel. You don't know if it's out of fluid otherwise. It's a '95... BTW....

Maybe that trace is only active on ABS cars? I haven't had the cluster out in my car in a while.... (hum.... maybe I should pull it to check on those LEDs. <G>

Dave,

 

Good point, Dave. I hadn't thought about that funky ABS water bottle. I'll have to re-check the FSM diagram, maybe it's hidden somewhere with an ABS note.

I'll never understand why there are so many tiny little inconsistancies in the Miatas wiring harness, like the one wire for the VSS only being in the instrument harness if you have cruise or an A/T, despite the fact that the cruise computer harness is there on all cars. I'd think it'd be a lot easier to just have one single harness with all wires in it to accomodate every possible LHD car built, rather than have to juggle three or four different versions of the harness depending on option pakage.

Looks like maybe people with ABS can just tap the blue wire at position 1L of the instrument harness rather than having to solder on that flimsy plastic circuit board.

 

This is a ******* sweet setup...love it.