It is recommended to disconnect the cat. However, the noise is deafening.

The first time my car had water injection was done using this method as the shop manual recommends suggests it could cause damage to the cat.

 

i'm sure it's a possibility but i haven't noticed any catalyst failures after doing a decarb, in fact many times the cars go right to smog afterwards and seem to have less issue passing(non OBDII testing).

 

A month or so after my last test (this was a year ago), I got a buyer for my RX-8, life stuff forced me to sell it.

I admit that one of the reasons I want an RX-8 again is to keep going with this as a long term project.

I don't recommend having a this type of vacuum ingestion set up with the engine under load, since the delivery of the water is largely uncontrolled, and in some extreme boundry cases, could cause damage. If you are ingesting water/meth, it would be even more likely since it would be changing the AFRs with the added fuel from one face to the next, and the trims off the O2 sensor could lead to a single face lean spike, which would be deadly to the engine. Any setup for driving under load really needs to be a controlled injection of a specificed volume to ensure that all rotor faces will get the same amount, and you won't end up with a run-away injection amount.

Note that my compression test results were several years before this testing, and the difference was with Mazda's decarb process. I also believe that my engine was already damaged at the time (from a cat failure a couple months prior, the engine never felt right again), even though it took around 40,000 miles before it finally showed symptoms of compression loss and failed when i took it in for testing. This testing was 11,000 miles into a reman engine that replaced it.

I do believe that keeping carbon buildup down is beneficial to long term compression health, however it is just a belief without any actual evidence to back it up.

The testing in this thread was to simple figure out what is actually going on inside the engine when people decarb through various means. There are still unknowns when it comes to drawing conclusions about long term engine health, so don't be too hasty.

About the only thing I showed so far is that water can indeed remove the carbon, seafoam soaking does nothing, and un-atomized water/meth does nothing.

 

Out of curiosity, I went looking for my pre-sale compression scores, which was

So this test was done about a month after the testing in this thread:

@ 110,180 miles
1: 7.3, 7.5, 7.8
2: 7.6, 7.4, 7.7
@ 230rpm

Normalizes to:
1: 7.9, 8.2, 8.5
2: 8.3, 8.1, 8.4

 

technically vacuum would be reduced and at full load the water likely wouldn't even flow through the LIM ports since the resonant pulses actually begin to create pressure after a point.

this is partly why water injection kits must have their own pressure source, the other reason is for better atomization.

 

The vacuum only really supplies the pressure needed to move the liquid through the feeder lines. The volume of airflow significant increases, which increases the rate of ingestion. Even sitting still, the rate of ingestion went up dramatically bringing the RPMs up past 4k, to the point that it was starting to put out the spark.

 

I understand what you are saying about the decarbing under load, I also worry about the CAT getting blocked from carb breaking loss. I understand that they will burn off but I would hate to see too much clog it.

Looks like I miss understood you original post. If this was Mazda's decarbing then it looked like it worked by the increase of your compression. Am I correct here.

 

All the pics are from my own decarb testing, testing various methods that people like to use on the forum. The compression test results from Mazda's decarb was posted due to another member insisting that I couldn't prove that a compression improvement was possible.

 

Understanding this now makes me think that the Mazda decarbing does good. I also think you are onto something with the water decarbing. Many have know that this traetment cleans an engine well and there is no reason to believe it would be any different in the rotary.

 

So I did my decarb today. Managed to get both rotors at the same time using the the T line setup from the S2 (from the oil neck to T fitting to LIM service nipples). Got a whole gallon through. No smoking which is good (you shouldn't smoke if you are doing water i read). Going to do an oil change tomorrow.


https://fbcdn-sphotos-g-a.akamaihd.n...91903645_n.jpg

https://scontent-a-lga.xx.fbcdn.net/...26408698_n.jpg

https://scontent-a-lga.xx.fbcdn.net/...65304607_n.jpg

 

Looks like the ideal setup. Having the service nipples alrealy Y'ed is useful there.

Yeah, I just got some light steam from the tailpipes (no cat) when I did mine.

 

Lol it was funny hearing the noises. Car went from sounding like a MSP ... to a bridgeported 13b ... to a 2 stroke lawn mower.

 

So... why not just use steam, instead of liquid water...?

 

How exactly would you go about filling a container with a gallon of water converted to steam, then keeping it hot enough to retain it's gaseous state for the duration of the ingestion?


Vs it's rather simple to ingest water in the liquid state (mixed with air to keep the volume from causing problems), and letting it flash to steam when it hits the hot internals and/or the combustion ignites.

 

I don't know. You the pro.

Seems like just using a small steamer fed into the intake would be better than sucking water into it...

 

In theory, yes. It's just not really viable to actually make that happen for most owners.

The alternate option for a similar effect is not steam, but atomized water, such as with water injection, which would have the added benefit of injecting under various engine loads in a controlled and testable manner.

 

So I shouldn't feel stupid for trying? (Yeah I did it already)

 

Not at all

It's a good theory, just the practicality of trying to get it to work is not really something easily solved. If you tried sending it through the service ports, you likely had it cool and condense entirely on the walls of any tubing before it got to the air stream as well. Steam will disipate it's heat rather quickly.

 

Service ports? Yeah, I'm gonna excuse you on that, you have no clue how lazy I can be!

I tapped in on the accordion tube after the maf, where the little black box is. And fed it for about 20mins, didn't monitor how much water went in. car ran funny while doing it, obviously, and no smoke while doing it.

I'm calling it a success cause the engine is still going! Haha!

 

Well, that is probably the only viable introduction port, though how much condensed on the walls of the UIM/LIM vs making it into the engine I don't know. Of course the car would run funny though, because you were making a huge *** vacuum leak

 

Steam could be done, but it would have to be pressurized. Seems like a awful lot of trouble to to De-carb an engine though.

 

I like the set up in the video. Makes it very easy to control the flow and all done within minutes sitting in the car.

Thank you for the tip.

 

NP, just a heads up. The S2 has a filler neck to T fitting to Service nipple (i think some of the later S1's implemented this). Anyway, The part that slips into the filler neck is 3/8", but the side that fits into the T is, i think, 1/8". You can see from one of my pics i use 3/8" clear tubing, with a 3/8" brass barb to the end that connects to the filler neck

 

Anyone have trouble getting their fuel trims to calm the hell down after doing this? Obviously the car's trims would go bananas during this but after a few days I am still having trouble getting the car's trims to settle back down. I might need to give it a reset to see if it helps.

 

I don't remember a specific issue, though I wasn't driving it much at that time, and I know I disconnected the battery for a few days about a month later for the 3rd clutch replacement. Mileage driving out west after that was within what I normally expected.