Tuning H2O Injection Basics

DCsleeper · Jul 30, 2007, 10:02 AM

I should have my HFS-5 aquamist kit installed shortly and would like to know if anyone has established some basics for tuning water injection.

Currently, I am tuned on 93 pump and target the following values:

AFR - During ramp up goes from 12.8 to 11.5 and then holds to redline
Timing - 6deg peak torque to 18deg 7250
Boost - 22psi tapering to 21psi at 7250
EGT - 1525 F at top of fourth

With this setup I am getting about 320 hp 280 ft-lb torque, I think that I maybe able to get more out of this setup and I am going to try and bump up the timing some.

With Water Injecting at 14% water to fuel what should I do first? Here are my thoughts please comment:

1) lean fuel to target - ramp up goes from 12.8 to 12.5 holds to redline
2) Increase timing throughout till limited by knock, this should bring down EGT
3) Back off timing from new limit 2 degrees
4) Increase boost till EGT exceeds 1550 F
5) Back off boost 1 psi

Edit: This is for 100% H2O

Richard L · Jul 30, 2007, 11:47 AM

Are you going to run pure water or methanol mix? if so , at what percentage?

DCsleeper · Jul 30, 2007, 01:42 PM

I will be running pure H2O initially.

Additionally, it maybe helpful to discuss the differences with tuning H2O vs. 50/50 water methanol mix, vs. 100% methanol.

ryan0 · Jul 30, 2007, 01:57 PM

i found that running about 26psi, keeping afr around 11.8-12and adding more timing makes the car very happy compared to leaning it out even more.

dudical26 · Jul 30, 2007, 01:59 PM

I have recently started to play around with my HFS-5 kit. I have an Evo 9 so my timing can not be as aggressive but other than that I have a similar tune to you.

running 100% water and using 2x .7mm nozzles I initially increased my boost from 21-22 to 24-25. I have left my fuel and timing the same for now as I plan on running meth and I am just using water to test. I notice occasional 1 or 2 counts of knock at an equal or lesser occurrence than before the water.

Your philosophy sounds pretty good. Personally I would target an AFR of about 12.0 rather than 12.5 on only water but to each his own.

Keep us updated on how it goes.

DCsleeper · Jul 30, 2007, 02:17 PM

What is your reasoning for increasing boost first? Here is my reasoning behind the strategy I posted;

lean afr to 12.5:

From what I have read 12.5 is the best afr for making the most power, it is on the lean side for the Evo's best operating window. Using pure water should allow this lean afr due to its higher latent heat capacity than say methanol.

increase timing:

By increasing timing you create a faster (more complete) burn in the cylinder and will reduce the EGT values. This can be achieved to some extent with using water, but would be greater if using pure methanol due to its octane boost characteristics. By reducing the EGT values now it provides head room to increase boost in the next step.

increase boost:

This is where the real increase in power and torque should be seen. The use of water injection negates to some extent the fact that we are pushing the turbo outside of this efficiency window. Additionally, the in cylinder cooling effect of the water keeps hot spots from developing. Basically, in theory you should now be only knock limited by the octane of the fuel/water mixture.

I am trying to work through the reasoning behind my tuning strategy. Please if I am stating anything incorrect or if it is debatable comment. I have never tuned for water injection before and would like to educate myself and others about to attempt this.

shivaswrath · Jul 30, 2007, 02:25 PM

this may sound like a noob question since I'm new and keenly interested in water injection, but how do you guys deal with the water freezing in the winter? do you progressively add more alcohol or HEET to the water as temp's cool off?

I would run 100% water at first as well since it's cheaper than methanol, and easier to obtain. . .

SlowCar · Jul 30, 2007, 02:37 PM

Quote:

Originally Posted by shivaswrath

this may sound like a noob question since I'm new and keenly interested in water injection, but how do you guys deal with the water freezing in the winter? do you progressively add more alcohol or HEET to the water as temp's cool off?

I would run 100% water at first as well since it's cheaper than methanol, and easier to obtain. . .

water-methanol mixture - freezing point

http://www.ashland.com/pdfs/technica...sh%20Point.pdf

DCsleeper · Jul 31, 2007, 05:04 AM

Slowcar,

You have been doing this for awhile. Can you share what works for you when tuning?

dudical26 · Jul 31, 2007, 06:16 AM

I like to tune boost first since a change in boost can have a dramatic effect on AFR and the timing you can run. If you tune AFR and timing first you will have to go back and adjust them for each change in boost.

I like to get a safe AFR and timing setup, then dial in boost.

For the most part it seems with water or meth injection you will reach almost the same HP at 25psi as you will with 30psi on the stock turbo.

I would suggest you start at 25psi with your safe timing and AFR. Once you get a nice boost curve, then adjust your AFR to hit your target. Lastly tune timing.

You can always tune for 12.5 AFR and then tune for 12.0 AFR and see which makes better power for you.

SlowCar · Jul 31, 2007, 06:38 AM

water-methanol mix:
http://www.srtforums.com/forums/showthread.php?t=308693

DCsleeper · Jul 31, 2007, 10:35 AM

Slowcar,

Thanks for the read. Actually read this allready but it was a good refresher. If you really dumb this down to a simple procedure it states:

keep adding boost till the EGT rises above 1600 F to produce power (or you hit knock).

So based on input so far I have my steps in the wrong order. They should really be:

1) Start with a map optimized for non-water injection
2) Raise boost till EGT exceeds 1650 F or limited by knock
3) Lean afr down to 12-12.5 stop when power stops increasing or knock
4) Tweak timing to gain the last bit of power back off when knock starts
5) increase water flow and repeat till no gains are made

On a side note: What MAF values are you guys seeing at ~ 25psi? I would like to have an estimate so that I can scale my load range correctly.

EVO8LTW · Aug 21, 2007, 10:02 AM

I'm finally getting to installing my HFS-5 and wanted to start with straight water.

What nozzle size should I use? My car on pump is in the 350 whp range (at 22 psi) and I have 660 cc injectors.

Thanks!

milo · Aug 21, 2007, 10:48 AM

This is some good info

DCsleeper · Aug 21, 2007, 11:26 AM

I just got the hardware completely installed last weekend and now in the process of figuring out how to adjust all the settings.

Currently, I am using a .8mm nozzle and injecting pure water. Based on my calculations I should be injecting between 315 and 360 cc/min at the top of each gear. This puts me at ~ 17% water to fuel given that I am using 650cc injectors.

Whether or not this is the best combination only tuning will tell. I will definetly post more as I learn more about how the tuning side works.