I'm considering running a water/meth system. I'm not thrilled on the idea of added complexity, potential risk, and having to deal with/remember to refill the tank, but boy is the potential enticing...

I have three questions that I can't find good answers to:

1. I'm wondering how long a tank is going to last under different conditions: general transport/cruising, "spirited" street/mountain driving, and track days. I don't expect to spray more than 500cc/min max (with BNR stage 2's). So with the SBG 2.1 gallon tank (7950cc) spraying a full 500cc/min, that 's about 16 minutes at full blast. That doesn't seem like a terribly long time, especially at the track. What should my expectations be here?

2. Does anybody know if the AEM "failsafe device" can be used without the gauge connected? I don't care about the gauge -- I only care about the alarm wire.

3. Somewhat related to #2 -- I have a PowerFC and Datalogit, and I'd like to keep them. Unfortunately as far as I know the only real aux input it accepts is in the form of a boost switch. Ideally you could setup an input to retard timing, or to switch maps altogether (I don't think this is possible?). So my plan would be to setup the low fluid sensor + failsafe alarms to trigger the boost switch to bring the boost down as low as possible, and probably stick a warning light somewhere (empty cluster spot?) Has anybody done something similar? Does that seem like a reasonable risk-reduction strategy?

 

It doesn’t have to be complex and remembering to refill has never been a big issue for me. But i don’t really track the car.
FWIW I run a M3 nozzle that comes on at ~ 1 psi with mostly water and don’t tune with it. My reservoir is the washer bottle which, iirc, holds just a bit over 3 liters. I installed a simple float switch that lights up a small red LED next to my temp gauge, but it’s not often needed. For even ‘spirited’ driving the water tank lasts about 3/4 of a tank of gas. So when I fill up...I fill up.

 

There's 2 approaches to using water/meth.

The first is to build the system for it. Large injectors, high amounts of meth, and you tune for it. If you are going for big power this is a possibility. But this is a LOT of complication and extra things to break.

Second option, and this is what most people do, is use a small amount of meth to cool down the intake air. You don't have to tune for it or adjust anything on the ECU for it. You hit a certain boost threshold, it sprays, intake air temps drop, everything is happy. As a friend of mine put it once, it's like making the car run like it's a cold day out.

The AEM kit is a great way to go. Simple install, quality parts, and easy to set up. I've run their controller for years now and have been nothing but happy with it.

To address some of your questions -

The AEM kit has an output to a status LED. I put an LED in my 2-gauge center speaker gauge pod that's green. Light comes on when it's squirting water/meth. If there's a fault with something it will blink a code. I also installed a float that is wired to the AEM controller, when I run out of water/meth the light blinks to let me know it's out.

The AEM also has an output for when you are out of water/meth. I tapped mine into my AVC-R boost controller. The AVC-R has a "scramble boost" button that, when held down, gives more or less boost. I set it up to basically turn the boost all the way down if I run out. You could also use that circuit to wire a relay to disable the factory waste gate control or other aftermarket EBC. But, it's not totally necessary - since you're not tuning for it, it will just run like it always has, not like it's a cold day.

On capacity, I use my stock windshield washer tank for my supply. I installed a level sensor and have a tube running from the top that the pump draws the fluid from. That tank isn't huge and I've gone a whole long weekend at Deals' Gap with LOTS of full throttle without needing to top off. It really goes a long time. I'm using kind of a medium sized nozzle. You can also use AEM's own tank or the Sakebomb rear tank.

Also, I just spray plain blue windshield washer fluid. Works great and I've had zero problems. Yeah, Boost Juice or some funky blend might be better, but I can get a jug of blue washer fluid for a buck or two and I'm good to go. I try to get the coldest weather stuff I can find, like the -20 deg rated, that has more meth in it.

If you look at my old build thread, I have some pictures of my setup.

Hands down the hardest part is finding where to put the pump and where to put the tank. The wiring is all pretty basic. Take your time with it, use quality connections and you'll have zero problems.

It's one of the better mods you can do I think. The only real downside is install is a decent amount of work. It's not terribly expensive and it really does make a difference. Watching the air temps drop like a ROCK on boost is satisfying.

Dale

 

If you track your car and use AI, you absolutely need the SBG tank or an alternative with a similar size. I was using the w/w tank and it would go dry. Only downside to the SBG tank is it's in the interior which means 30% or less of meth. Or take your chances (if you don't build a bulkhead)

 

—-> https://www.rx7club.com/auxiliary-in...ion-fd-959565/ (pics re-added at the end)

1st thing to do IMO is to decide what you want it for. If it’s mainly to lower IATs then you’ll want an alcohol mix and nozzle placement is more important. If it’s just for engine cooling (reducing load on the cooling system) knock suppression and carbon then water is enough. The latter doesn’t need tuning and usually not as much management.

 

why 30%? racing rule? Less than and up to 50% is not flammable, boost juice brand specifically markets 49% meth concentration for this reason.

 

One thing that has held me back from installing my setup is a fear that the fuel pressure regulator spring will become damaged from the water or water/meth. Awhile back there was a post of some aftermarket PR spring that seemed to dissolve with rust and corrosion. Would really like to know how folks with the OEM PR are faring longer-term once water/meth injection has been added.

 

the fuel pressure regulator is never going to see water/methanol as a result of running AI/WMI. If you think about it, the FPR is really ONLY exposed to fuel. If I had to guess, I'd think that the thread you read may have been a case of e85 ******* with fuel components that were designed for non-ethanol, or e10, fuel.

 

Could be, I seem to recall a consensus that moisture had traveled via the vacuum/boost hose connection to the FPR.

 

See here

https://www.rx7club.com/3rd-generati...nside-1122016/

Matt

 

Interesting... I definitely missed that thread!

I honestly have a hard time buying that it was caused by the WMI alone. Unless there was a leak somewhere close to his FPR then there really shouldn't be a way for the water/meth to make its way there while running. Hook a baloon to the end of a hose and blow into it, you'll cause the baloon to expand, but your breath won't be entering the baloon, at all, unless that hose is super short...

I can totally see that being caused by inferior materials and years of heat and condensation cycles though.

 

Just so everyone knows. I have written communication from the Chief Technology Director of NASA, that it is OKAY for us to install the SBG meth tank behind the rear plastics and be legal for their events.

 

Found this chart claiming to show the methanol content of different types of washer fluid (no idea where it came from or if it's accurate). I wonder how common it is to find the -20/-25 stuff in warmer parts of the country. Looks like I have a goal for tomorrow.



Methanol Injection 101 - thelsxdr.com

 

I don't know if, say, having 10% meth versus 30% meth is going to be enough to make any noticeable difference. Also I think many parts stores may be able to order colder weather fluid for you. Where I am (Florida) we maybe get 2 days a year where it gets just below freezing, yet I can still typically find the lower temp washer fluid.

IMHO it's just a good idea to have the stuff thats' at least below freezing so it doesn't freeze up in the tank and lines.

On the FPR, I think that is a valid concern, but I have a feeling that may be with lower quality aftermarket FPR's. Under boost the spring in the FPR can see some water/meth and an FPR with a cheaper spring that's not stainless or coated somehow could corrode. I could also see this as a problem with cars running E85, there will be some fuel vapors that could get pulled into the FPR and E85 is crazy corrosive.

Again, you want water/meth. It works so well. Also say goodbye to carbon inside fo the motor, I've been through engines that were running water/meth and the rotors barely needed cleaning.

Dale

 

It might depend on nozzle placement. If lowering IATs is the goal and you don’t have much time of contact (w/intake air) I think more alcohol makes a noticeable difference. No data but the few times I’ve switched from just water to boost juice the car did seem to like it in terms of power. Wasn’t huge, but I did notice it.

A side note reminder ...the OP lives in California so it’s probable not a factor for him. But where I live I always store the car with nothing but washer fluid and run it enough to fill the lines and pump. The garage is heated but you never know.

 

"I'm considering running a water/meth system. I'm not thrilled on the idea"

you should be thrilled with the idea.

the stock FD makes 217 rwhp

your BNR stage 2 makes... IDK, but probably close to 350?

check out the following Supercars as to power displacement:Rear Wheel Power Per Cubic Inch Displacement

2018 Corvette ZR1

1.71 cubic inch

2018 Corvette ZO6

1.47

2018 Porsche Turbo S

2.23

2018 McLaren 570S

2.06

2018 Merc Benz AMG GT C

1.91

2018 Accura NSX

2.0

Nissan GTR NISMO

2.2

Aston Martin Superleggara

1.91

Ferrari Superfast

1.69

the average is 1.91 rwhp per cubic inch

your motor at 350 rwhp (considered conservative- ho ho) makes 2.19 rwhp per cubic inch.

all of the above motors have extremely sophisticated automatic ignition retard when they encounter knock. they also have very sophisticated combustion chambers. ours are.... not sophisticated.... think bath tub.

they also are four cycle motors so they benefit from a cooling cycle. uh, we do not.

and at 350 rwhp we are making more power per displacement than many.

the turbo'd rotary easily generates very high combustion chamber pressure and heat.

along with proper fixturing and tuning AI is the fix. and it doesn't have to be complex.

or scary!

350 rw rotary hp requires 2763 CC of gasoline into the motor. that's .73 gallons per minute or 84,745 BTUs.

if you inject 500 CC/Min of 50/50 water meth...

.066 GPM of water 534 negative BTUs

.066 GPM of meth 3778 BTUs

so if your right foot is firmly on the floor and the doomsday scenario says hello...

you are using 84,745 BTUs from base fuel

you also are adding 3778 BTUs from meth and subtracting 534 from water so net loss is 3244

3244/84,745 = 3.8%

your AFR goes from 11.3 to 11.7
not exactly kiss your motor goodby. our motors are very high strung due to the power to displacement and they do need special care and feeding. lots of premix, modest timing and 10 or colder plugs along w AI.

water is fine from stock to 400, water meth from 400-500 as the meth component lowers IATs. i recommend, and have run since 2003, 100% meth for 500 +. these are not rules and are not proven but you will find they will work for you.

i had the pleasure of working with Robert Oberbuchner, the "O" in FJO. FJO developed a number of cutting edge items about 10 years ago including an AI system i ran for a few years and a stand alone ECU. Holley thought so much of FJO they bought the company and the Holley ECU and AI currently marketed is of FJO lineage. the company "car" was a Camaro that was making over 1500 rwhp on pumpgas and of course the FJO AI system.

what injectant did they run?

Fred called it "bugjuice" more commonly referred to as windshield washer fluid. Being in Canada they had the good stuff. i believe they were running minus 20.

Thanks Dale and MKD for the chart. BTW, Fred, among other things was a Chemical Engineer and mentioned that the fluid had, besides water and meth, coloring and soap in it and neither was a problem since it was such a small amount..

 

Imo the best combination is currently the SBG tank, Jp3motorsports pump bracket and AEM V2 kit, and boost juice. Or you can mix your own with M1 and distilled water.

 

What is it you like about the JP3Motorsports pump bracket? (Assuming you're referring to the rear subframe one.)

 

Its the best location for the pump imo, and the bracket is very well made.