I happen to live in a very hot place and also one where the higher octane gasoline grades aren't readily available, but I rather enjoy the performance of the XKR and also tinkering with ways to enhance it.

So, looking ahead to more serious performance upgrades, I liked the idea of the water injection cooling the intake charge and also the detonation prevention aspect. The idea of de-carboning the engine is also appealing, especially in light of the discussions of Terraclean and the positive results some members have had.

The boost gauge is nice indication to have for future supercharger upgrades and adds just a little bit of cool factor.

I did a write up of the trials and tribulations of making it all work in the hopes the someone might find it useful. It's not all inclusive but I tried to document some of the pitfalls so that maybe the next guy can learn from the dumb things I tried.

The system is a Snow Performance MAF based one, that uses the gigantic washer reservoir as a source and runs off of the MAF voltage. It's nice in that you can set a start voltage and a full spray voltage and it varies linearly between them so that you can tune the amount of water based on engine load.

The injection nozzle is plumbed into the stock intake tube just downstream of the last resonator. In the picture you can also see the injection controller module mounted in the ECU bay.


I added a gauge pod to the A-pillar with a "system active" LED and an on/off switch to disable the injection system from inside the car. When it was all together and working I had the pillar re-covered to match the existing headliner.


With all the talk of Terraclean lately and just for fun, I took a shot down the throttle body to where the EGR comes in. Yuck! I'll check again after using the injection system for a while and see if any of that crud has been removed.


First impressions are very good... the boost gauge indicates maybe 2psi more when the system is on (90 degree day), I presume because of the charge cooling and maybe the fluid sealing the tolerances of the S/C rotors a little better.

The car is definitely more consistent across multiple full throttle pulls, with no discernible fall off in power.

The kit came with 3 injection nozzle sizes so there is some butt dyno tuning coming up.

Another interesting side effect is that where I used to get that vaguely rotten egg smell after a hard run that some of you are familiar with, the water injection seems to have cured it.

The work was spread across maybe 4 or 5 days, but that includes pondering, a number of trips to the store and several mulligans. If I did it over again, it could reasonably be a weekend job.

The write up is split into 2 parts to meet the forum file size requirements.

 

Thanks for all the hard work in writing this up.

 

Superb write-up Charlie! Keep us posted as to how it is to live with over time.

 

Very nice work. The way you have mounted the boost gauge is especially cool. Too bad mine is normally aspirated.

 

Cool!

 

My pleasure, glad to give something back to the forum that has helped me so much.

Jeff, your raving about your system is what got me thinking about it. Now I just need a twin screw!

 

Thanks so much for the timely (for me) write up!

By the way, in a recent intake system tear-down I completed, the hardest part to clean up was the throttle body manifold (where you too, are seeing lots of gunk in your photo) the EGR heat entering at that point just below the T/B causes the oil blow-by mist brought into the manifold by vacuum from the valve cover area to "coke-up." That hardened goo was super sticky and two over night soaks in in the parts cleaner only softened it a little bit! I had to use small wire brushes, carb cleaner and an hour of elbow grease to get it looking nice and clean "down in thaar!"

Any Hoo, Water/methanol injection is the project I am currently beginning work on myself on my '03 XKR. I have chosen to go with a system made up out of several manufacturer's products. Using recommendations from some local JAP import and Buick turbo tuners I have recently become friends with. These guys are in their upper 30s and early 40s years old and have been playing with high boost applications that need injection for cooling and knock resistance for years.

At this point I have obtained a Coolingmist 200psi pump, CM-GS progressive controller, flow meter, checkvalve/filter and a really cool Aquamist manifold and injectors.

My plan is to use a trunk-mount tank and I'm designing a multipoint injection system running two super-fine mist injectors before the throttle body and either two or four injectors mid-system (post supercharger at the "hat" and before the charge coolers.

I just picked up (on eBay) a salvaged "hat" or air outlet elbow and plan to begin drilling it for mounting the injectors.

Thanks again - I'm reading everything I can to learn about these systems!

 

Thats a pretty serious set up you've got planned, there must be some major boost or nitrous in your future.

In my research I didn't come across a clear winner for whether to inject before or after a positive displacement S/C so went with the less complicated route of putting it before the throttle body so that I didn't need the check valves and all that.

Ultimately I'm thinking of doing an aluminum intake tube and would have more flexibility on where to put the injectors, so when you get it running, I'd be interested I your experience of whether multi point injection before the S/C is worth the trouble.

If you don't mind, I'm curious your reasoning for doing both before and after the S/C as opposed to one or the other?

 

ccfulton, I too, have had difficulty in imagining which would be better for our Jags - injecting water before or after the supercharger. I'm not aware of anyone actually putting the idea of before and after injection into practice - but it's not that novel of an idea, so probably it's been tried before.

My combo: is a 2003 XKR with a stock engine except for a smaller drive pulley on the supercharger. I'm noticing two things since changing the pulley. First, on days where the ambient temperature is above about 75F degrees I hear a bit of "pinging" or a slight high freq tapping when I dip into the loud peddle at about 2500-3000 rpm and start to feel the boost come up. Second, on 50 to 60F ambient temp days, I don't hear the tapping and WOW! The car has MONSTER power compared to the warmer days. So... I'm figuring I need to stop that pinging and the intake air temp is making quite a difference on the performance of my car. Quite likely, the computer is pulling the timing back when the knock sensor is detecting the evil stuff.

My understanding, like you mentioned, presenting water BEFORE the compressor may help to a small extent on rotor sealing - thus slightly more efficiency. Also, a small amount of cooling the M112 (particularly when they are running smaller pulleys) cant hurt. But I have heard that too much H2O can strip the rotors of their factory coating. So why not inject some (but not all) the water you intend to add at the front end.

I'm only theorizing here, but introducing water or water/meth after the supercharger could only help lower the mixture temp just a bit more than adding all of the water up front. Am I wrong here?

The tuner tribe tends to go for direct port injection. And while I'd like to do that too, plumbing all eight cylinders at those little short manifold runners (under the charge air coolers) or the runners coming out of the bottom of the charge coolers themselves would present a real challenge - particularly because access problems would create a huuuuuuge hassle for water jet tuning and add to that the problem of massive heat soak problems in that area. Probably would have to plumb it with stainless tubing.... no good options there huh?

So no, I'm not planning on major boost and no N2O (Hmmmmm, I do have an old NOS "powershot" wet system I'm not using.... Just kidding)

I'd just like to try something a bit different - even though it may take a bit more engineering. I like the challenge and satisfaction.

By the way, I love the look of your finished gauge pod. I'm thinking of locating my controller/gauge down by my right knee, up against the corner of the dash and the console. I'll have an easy line-of-sight through the steering wheel.

Peace!