Water-Injection for planned twin-turbo setup?
 

Hi all,

So while planning a twin-turbo setup for my 370z, I came across the topic of water-injection into the main intake. However, still being new to my car, I was wondering if anyone has any experience/recommendations for if/how I should go about injecting a water/methanol mixture into my engine to reduce knock. So does anyone have any experience with it? The reason why I am trying to use it is because the "premium" grade gasoline here in Washington is 91-93 and I'm afraid that with a twin-turbo setup it's going to cause engine knock.

Thanks,
Nuc370z

I recommend one injector per runner -- injecting before the turbos can pit the blades. Sizing will have to be calculated -- links below to help -- the better the atomization the better it will run.

You'll want a progressive controller that is linked either to boost, MAF voltage, or TPS, and will have to adjust the tune to account for the complex mixture of air, water, alcohol, and petrol.

You'll want good check valves and a failsafe to either pull timing or alert you if there's a clog or you run out.

You'll also want to experiment with a good mixture -- pure water is best for anti det; a mixture is best to avoid freezing (if you live in cold climate) and to compensate for the displacement of fuel and air. Water must be distilled. Also, methanol and other alcohols have a lower stochiometric value, and produce more torque than petrol. Still, the ideal mixture will take a bit of playing around with. Another benefit is that with any mixture, it will cool the charge -- but also displace air and fuel, so its a balance.

You can run 95% isopropyl alcohol in the mix (cheaper, easier to get, and less toxic than methanol), but methanol tends to be the preferred alcohol. Be careful with it -- very bad stuff to get on you.

It's WWII fighter plane tech... You can find lots more general and technical info here waterinjection.info - Powered by vBulletin

On my old SC'd Celica GT-S, I ran an IM port coolingmist kit and was very happy with it.
Water Injection, Methanol Injection, Alcohol Injection Systems | water injection Coolingmist

The aquamist kit has a more slick pump, but a standard pump works perfectly fine.

All that said -- you could just tune for 93 AKI and call it a day, but you should be able to make more power and torque with water-alky injection.

a lot of times it is best to compliment the port meth injection with a larger jet after the mafs in each intake pipe. you can run just the jets in the intake pipes but the distribution will not be as good as having a jet in each port. the best place for a simple setup is between the maf's and the throttles, this way you don't have to worry about the engine pulling meth under vacuum.

Edit: Read the bottom of this page it details location and sizing(this changes with different systems due to the differences in pump injection pressure)Aquamist Kit Info

If E85 is available in your area go that route over water/meth injection

You won't knock with a good tune on your pump gas.

You need to start :postwhore:ing. You're only a couple hundred from elite status

Not necessarily true, unfortunately. Not all gas is created equal and there is such thing as bad batches, especially when it sits for a while in the underground tanks and creates moisture. I try to use the same gas continually from where my car was tuned on. I still had an issue where there was water in the tank which drops the octane levels and can cause detonation, not the tune's fault in the least. I had to drain the bad gas, fill up somewhere else and did some data logs. After a few pulls, I made all the timing back and the air fuels were dead nuts as they were on the Dyno originally.

It's always a good idea to choose the gas stations that have the most amount of traffic and half a quart of Torco Accelerator has worked great for me on every fill up.

Thanks for all of the replies guys :) Sadly, there isn't any gasoline in Washington that's either E85 or >93 AKI. Will over-injection of water/methanol have a negative effect? eg. too much water sprayed and causing water to flood the chamber and cause chaos?

You want between 12% and 24% of the fuel flow. If you inject too much or too soon the motor will hesitate went it comes on. It isn't going to be a big deal since you are injecting a mist that will be vapor my the time its in the chamber. Ideally you want to ramp the rate via MAP or MAF but depending on how fast your boost builds it may not make much difference.

Hey man I have the stillen sc kit with aem meth kit. I have learned that it does not make any power. We had the car on the dyno at uprev we made a pull on the meth and lost 20whp. I don't know how it will work on a turbo setup but on mine it was not a good gain. But it does make some cool fire out the back of the pipes! Good luck man!

Pics or it didnt happen.

Do you still have CATS or are you running with tesp pipes?

You still use Torco even though you have methanol? Please explain, prior to using methanol I did look into using Torco for an anti-detonation solution.

I have the Stillen SC and Aquamist meth injection and my WHP didn't go down any. My tuner said we could add some timing and probably gain some WHP but I told him not to. I just wanted it spraying as much Boost Juice as it could take without costing me power. I'm guessing you are spraying to much because when we turned it up to high mine started dropping WHP.

In my experience water or water/meth will not by itself will not add any significant power. While you would expect some due to the cooler combustion the mixture displaces some air/fuel so its about a wash.
Why then use it?
1) Added to a correctly tuned engine with no tuning changes it is the best insurance against detonation.
2) It allows you to increase timing and reduce fuel both of which add power. The down side is that you are then relying on the system to protect the engine so it had better be bullet proof.

I have good video on you tube of it shooting fire out the back but I can't post it here cause we were doing some street runs against an Evo. I'm running the 3" AAM catback with test pipes too.