Lotus Esprit V8 "In-Dash" Water Injector Duty Cycle Meter
Now that additional performance modifications have been completed and installed, in particular the Water Injection System. It would be nice to know when, and how much water is being injected into your inlet manifolds. If not enough water is being injected, inlet temperatures could reach extremely high levels during high boost and/or load. If to much water is being injected a significant amount of of power could be wasted.
Now, you can go and buy the monitor from your favorite after market parts store, and install it somewhere in the car where it is guaranteed to look like an "afterthought", or you can do a proper job. We chose to integrate our Water Injection Meter into the Dash so it looked if it was there from the factory. This takes a lot of planning and measuring, in the long run it will look perfectly acceptable to the most discriminating connoisseur.
The first thing you need to do is acquire an electronic Water Injection Monitor, or make one using our plans as described in this article. If you purchase one, you will need to take it apart and remove the LED indicators from the module and install them in your dash. You will need to be reasonably proficient with a soldering iron and lead solder, as you will be using them a lot. (Or you could get someone else to do it)
This article is for the real "Do It Yourselfer", we designed and built our own Water Injector Duty Cycle Monitor, and that is what this article covers. If you buy one ready built, and want to install it in your dash, as we have, then simply skip the Layout Diagram part and go directly to the in-dash installation.
Main Water Injector Duty Cycle Meter Layout Diagrams
As you can see by the schematic, there are a few components. In this setup it is configured as a 2.5 volt monitor. The signal comes into the unit from the driver side of the Water Injector Solenoid or the Brown Wire on your MF2 Controller, and is cleaned up by TR1. We chose the MF2 Brown wire source. Remember to DISCONNECT the BATTERY BEFORE beginning any work of an electrical nature on the vehicle. If you installed the Water injector using our methodology as described in a previous article, the MF2 is under the center console of the car. Simply splice a signal wire into the Brown wire entering the MF2 connector and you are done. There is no wire fishing or hole cutting that needs to be done. (Please refer to the details on installing the Water Injection System for more information)
If you wish to construct a Printed Circuit Board as we did, here is some more diagrams that you may find useful.
Main Component, Layout, Component Side, Actual Size
Main PCB, Trace Layout & Components
The power for this device is derived from +12 volts from the positive terminal of your car battery via a 1 amp fuse. (or some other fused source, we used the dash/fascia board light +12 volt supply line) It also need a good ground. (Again the dash/fascia lighting ground was used)
As you can see the circuit fits quite nicely onto a small Printed Circuit Board (PCB).
Installing The Water Injector Duty Cycle Monitor in the Lotus Esprit Dash
This is the part we were quite concerned about doing, but a quick call to our friendly Lotus dealer, reassured us that the parts we were about to potentially destroy were available as replacement parts. The cost surprisingly enough was not as expensive as we initially anticipated. Armed with this "insurance" we proceeded very cautiously. The following steps involve drilling and cutting the dash assembly. Unless you are pretty good mechanically, we recommend you simply read this for interests sake, and put a commercially available duty cycle monitor somewhere in your car. If you do choose to remove the dash assembly for any reason, do not forget to DISCONNECT THE BATTERY.
Step 1 - Remove The Dash Complete With Gauges and Wiring
This is a very easy procedure. You can refer to the Lotus Esprit V8 1998 onwards, workshop manual for details. We proceeded as follows:
Now that you have removed the dash assembly, the fun can begin.
Step 2 - Measure and Mark up The Dash and Prepare for Drilling
This is the very tricky bit. It can be done a number of ways, this step describes how we went about doing it. We chose to locate our 10 Water Injector Duty Cycle LED's (5mm T1 3/4) above, and slightly to the right of the Speedometer. We located the 10 Fuel Injector Duty Cycle LED's (5mm T1 3/4) above, and slightly to the left of the tachometer to provide a symmetrical "Eyebrow" effect. (Please refer to the alternate article on the Fuel Injector Monitor for additional details) The measurement was not that easy, and partially done by sight, for ascetic reasons.
You will now notice there is a very narrow gap between the edge of the Tach, Speedo and Binnacle. This is where we placed the LED's. As you will see in the photos that follow later in this article, it was a tight squeeze. At this point, depending on how many monitors you are going to install, you will need to use a mathematical compass, and a flexible curve to mark up a curve that somewhat resembles the Binnacle outline you made earlier, and blends in with the circles of the Tack and Speedo. We marked up about 4 or five combinations, and chose the one we liked the best. Once we marked it all up and were happy with the dimensions and ascetic qualities of the work, we moved on to the next step.
Step 3 - Drilling The Dash!
As we only had one chance to get this right, we checked and double checked our measurements, and then we checked them again. The drill we chose was a 15/64 ths. of an inch. (1/64th. smaller than recommended) It was the pilot type that made a very small pilot hole prior to the actual drill size. We used a drill press at 2000 rpm. We chose the plastic type LED mounting assemblies found at Radio Shack, there is only one type for 5mm LEDs.
We then placed the LED holders in the holes we drilled, and installed the LEDs. We used a dummy/spare Tachometer and Speedometer so as not to damage the stock parts during our fabrication.
Lotus Esprit 1998 Dash, Removed from Car, Drilled with LED's Installed
The above photo shows all three monitor's LED configurations. As you can see it is a very tight fit. This photo also shows two optional switches that we installed. One to turn the Air Fuel Monitor off, (It can be annoying for general driving) and one to turn off both the Fuel and Water Injector Monitors off. (for symmetry)
Step 4 - Wiring up The Monitor(s)
This part is pretty straight forward, if you are electrically inclined that is. The LEDs were wired to the Printed Circuit Boards (PCBs) using 2.5" wire leads. Then the PCB's were mounted directly above their respective bank of LEDs. This was done by drilling 2 small holes in the edge of the dash assembly for each board (6 total). Then they were countersunk for the 2/56 screws that were used to attach the PCBs to the dash. (Small aluminum brackets were fabricated to finish off the installation) The following photos show the PCB's mounted and wired into the dash, with a dummy/spare Tachometer and Speedometer installed.
Lotus Esprit 1998 Dash, PCBs Installed and Wiring Complete
If you look closely you can see an extra connector in the middle rear of the above photo. This is used to take the signal wires down to their respective sensor points. This was done so we would remove the dash easily at a later date if needed.
Step 5 - Adding White Lettering, and The Finished Product
The following photos show various close ups of the dash before re-installation into the car. The white lettering is dry lettering available at any hobby shop. We added the lettering just as a finishing touch, it really is not needed.
Water Injector Duty Cycle Monitor PCB and Wiring Close Up
Water Injector Duty Cycle Monitor, LED Layout
Water/Fuel Injector Duty Cycle Monitor On/Off Switch
Dash Mounted in the Car, with Binnacle Installed
We hope you find this article interesting. If you would like to receive your own kit, please go to our Gauges For Sale pages.