Hey guys,

First time posting in this section, didn't know anything about AI until after i got my FD, I've been cruising this area for info + the links that howard coleman's been linking, great stuff! After looking into it, I'm convinced that WI is the way to go for me in my build, but I still had some questions I haven't been able to figure out. Sorry if the following questions are pretty nooby!

I mainly drive the car on weekends for fun, but I'm planning on using it for road racing maybe 3-4 times a year. My main goal is reliability overall, and during the events, not additional hp.

Oh, some background on my car, reliability mods done (radiator, AST), all the bolt ons, m2 large IC not installed, and still need to pick up a high flow cat + PFC.


1. After installing a WI system and running it, my AFR should be richer right? If this is the case, why have people been saying that the car should be tuned without WI running, and that there won't be a difference in hp after they put it on? If it's the case that my AFR isn't any richer than before, would i be able to safely lean it out? the sticky here: https://www.rx7club.com/auxiliary-injection-173/ai-tuning-afr-important-582856/says I shouldn't.

2. I was looking into the AEM progressive pump speed system: http://www.aempower.com/ViewProduct.aspx?ProductID=1359 I think it would be fine for driving around on the street, but how would it hold up under road race conditions, if i'm not "tuning up" my car, just using it as a safety against overboosting + the following detonation? Will this system be able to keep up with rapid throttle changes? or will i start getting weird throttle response from too much water at the wrong time?

3. Can somebody confirm that the AEM system comes with a check valve? If it doesn't, would water be sucked in under vacuum even if i mount the pump and tank in the trunk, lower than the nozzle?

4. On the evo forums, there was an explanation about how the change in flow on a PPS is only a fraction of what the nozzle can actually handle: http://forums.evolutionm.net/water-a...n-systems.html. What sized nozzle should i be looking into for my build? How much water should i be injecting under boost numbers a bit higher than stock?

5. How long would a 1 gal tank last under road race conditions? What size should I need?

6. I looked into the PPS as the best bang for your buck, especially since i'm not looking for major hp gains. Are there any other non HD systems, as howard calls them, that would be adequate for road race conditions?

Thanks in advance!

 

Rice Racing was referring to Air/Fuel Ratio should be tuned for the same AFR even if your running methanol injection.

If your running only water, your AFR's won't change. To be honest I never heard of anyone tuning a car without the AI system on whether it is water or methanol. It doesn't make sense really :P.

If you read Howard Coleman's thread, you will realize non-HD AI systems are not suitable for road course racing.

thewird

 

i think what confused me was the 2nd post here: https://www.rx7club.com/auxiliary-injection-173/need-help-questions-aem-50-50-w-m-water-methanol-injection-system-807000/, Did he mean tune the AFR while the AI isn't on, then the timing when it is?

My primary goal for WI is to keep my motor happy and clean, and from what i understand, correct me if i'm wrong, but I'd keep the same power after installing a WI system without making any ECU changes. Basically all things equal except for reduced risk of detonation, cooler chamber temps, and less carbon deposits. On the other hand, tuning with the WI system on would be for raising boost and increasing power, which isn't really what i'm going for.

I read howard coleman's thread about the PPS systems concerning road racing, but on another thread in this section, a guy running his car for HPDEs was referred to both HD and non HD by Howard Coleman, and and PPS system by the coolingmist vendor. https://www.rx7club.com/auxiliary-injection-173/wi-stock-ecu-807333/

Would not "tuning up" on 100% water have anything to do with what systems I'd be able to use?

Thanks!

 

Im in the same boat as you. More info would be great.

 

I'm following this as well, and have just begun to research this. ie what is the correct amount of water in cc/min, to add vs boost, just to avoid knock, in my engine (turbo 13brew)?

Let's say an engine is tuned for 11/1 a/f at max power, 400 hp, 14 psi boost and 7000 rpm without water injection. It's possible to calculate the exhaust flow, fuel flow, and airflow.

I believe this is how the ai system mfrs size their system for each application. Knowing the air , fuel and exhaust flow rates for your engine (from the above), they have a target water flow rate cc/min to produce 106 equivalent knock protection.

I'd like to know that water target flow rate vs exhaust flow rate, if anyone finds it in the literature or on the forum. The ai mfrs also ask for measured intake air temp for the engine. I believe they have a target amount of additional water just to cool the engine, if this is too high.

So would this affect the tune? Yes imo. It may make the engine rich if too much is injected/required (the water displaces some of the air ingested ignoring any cooling effect on air density). A more expensive system may be better if it can control the cc/min based on some target cc/min vs boost level/or fuel inj duty cycle (ie water flow is proportional to exhaust flow). So the hd ai for sure is better, and makes tuning easier..





If the a/f desired is 11/1 (ie 11 lbs to 1 lb fuel), without water injection

 

http://www.rbracing-rsr.com/waterinjection.html

nice, got part of the answer

 

^^cool link it was a good read, although you might want to warn people that there's a NSFW picture in there!

thewird I disagree. I think that a simple non-HD AI system could work just fine for what the OP is looking for. A HD system would be better, but that doesn't make it the only option.

I use my car as a weekend/DE track car. I wanted to setup a water injection system last year but didn't have the funds. I plan on doing a simple boost activated system this year as a safety precaution....meaning I will not tune up for it. I'm still trying to decide on systems and features but I'd like to keep it as simple as possible since I've got enough things to worry about on track.

I'm interested to hear people's thoughts on how much water to run. Using the calculator in the link posted it seems that one 300cc nozzle would be fine for me, but I was wondering if anyone else has experiences with that. I'm running stock twins at 13-14psi, on stock ports, it made 328rwhp when tuned.

 

Injected water amount "displacing air & costing power" is a fallacy

You can run so much water to the point of using 150% the amount of fuel you use and still the power will be high so long as you can fire the mixture.

The only thing you need to remember is to get the MAXIMUM amount of octane increase you are balancing the water amount to the increase in octane rating as a function of excess fuel ratio, more water less fuel, less fuel more water.... its pretty simple ALL explained here in great detail. http://www.riceracing.com.au/resourc...rinjection.pdf ratio's (water to fuel) of 20%, 40% to 60% are normal for automotive applications, and for maximum octane increase AFR's of 10:1 are recommended as in the above report.

You will see a summary of percentage increase of BMEP (power basically) at various ratios of water.

Water injected pre compressor is PROVEN to increase power with making NO changes to the fueling of the car! so that totally debunks the crap most people go on with about it costing power due to taking up air space etc etc You just need to talk to people who are experts in water injection and making them work, most do not understand the theory or application of it..... and virtually none of the suppliers are engine tuners with matching results to back up their systems & guidance.

http://www.riceracing.com.au/water-injection.htm < This **** knows what he is doing!

 

I am in the same boat as you. Interested what others have to say. I was looking at AIS setup that can run from my Windshield fluid tank even allowing for a little more power out put, (methanol in the fluid... but is it safe?) but I am confused about rates, when and how much, etc. My car has been tuned @ 11:1 AFR @ 14 psi on the stock twins. so going straight water should give me the engine protection, but is it safe adding in Methanol via the -20degree washer fluid idea AIS has. Any experience on this out there?

 

RXHEAVEN WA... The information you provided is very useful in understanding this concept.

The positive and negative aspects of a small amount of water (300-500cc) virtually cancel each other out, so what you are left with are solely benefits to engine. The only major downside, as far as I can tell, is the fact that you are ultimately limited in the sheer volume of water that can be applied.

 

I basically have the same setup as stu2211, but I think I'll be going HD AI, with the FJO system.

I was thinking about using the rear washer tank and placing the pump there as well as done in these pics.

What do you think ?

Also, I am planning to spray about 8-inches AFTER the intercooler.

My goal is also reliable 300-325 RWHP for road-course usage.

:-) neil