why does this have to turn into a pissing match? i already stated that the car should take breaks between each injection treatment of about half a quart of water at a time. i have seen people suggest a whole gallon of water for the treatment with no mention of letting the car cool off periodically which is wrong, that is far too much to do in a single treatment.

none of my statement is incorrect, i said the exhaust could likely have been severely overheating which could melt the plastic but i added the possibility that it could have been popping flames out the back as well, either or.

the treatments are also very hard on the cat, it needs to cool off before it melts down internally.

Don't mean to make it a pissing match. But you dismissed Gomez's post off-hand insinuating it was the engine , not the water ingestion. You absolutely claimed it was "other issues" "rich" and due to flames shooting out, despite evidence to the contrary. And now, where is the evidence that water treatment is particularly hard on the cat? By design they're made to handle heat. They tend to work best that way. And the treatment might even be beneficial.

FWIW, I think this facination with water ingestion is misplaced. A decent AI system should, IMO, make it unnecessary.

well, water injection isn't for everyone, some have stock cars which will have hiccups with the water injection even though it is a safety precaution but everything you add to a car can fail eventually.

cats can handle heat because they are made to, but excessive heat is another thing. the cats aren't supposed to glow red or yellow, ever. what makes cats fail? lean conditions which superheat the exhaust temps to act like a blowtorch on the cat and also overheating the case, as the case gets hotter it expands and unseals the core from the case and eventually allows the core to rattle around inside the cat and fracture as it cools down too rapidly. this is why precats fail so regularly, the main cats are much further downstream and have less heat expansion to deal with.

just did the steam cleaning. Wow, what a difference it made. Car runs and idles much smoother. I bought a bottle of seafoam but I think that I'll save that for next time.

No, it was caused by the water treatment (which makes the car run lean, not rich).

Yes, the car has a cat converter.

No, the owner didn't have an observer assisting him during the process. He didn't notice the flames from the bumper until after he had shutdown.

Yes, he was aware that the exhaust would get hot....just not this hot!

It's not well known amongst RX-7 owners that Mazda recalled the RX-8 for "thermal" issues.

One or two RX-8's went up in flames when owners revved their cars for extended periods whilst stationary. Others suffered melted fuel tanks (the RX-8 tanks are plastic).

During the recall, Mazda changed the ECU software to prevent owners from doing extended high rpm runs whilst stationary (ie, no wheel speed input) and added extra heat shielding to the fuel tank.

It's a known fact that rotary engines produce high temperature exhaust gases.....owners need to be on their toes when doing extended high rpm engine runs with the car stationary.

i admit i didn't go back through the whole thread so i missed that point. the engine shouldn't be run at high RPMs during the treatment anyways though as it tends to void any of the effects of treatment. the car should be at low RPMs and stumbling a bit to catch up, telling you the water is overpowering the fuel mixture and not just going straight through without even touching the rotor faces.

Even 3000rpm can be considered high rpm when the car is stationary.

is that the RPMs he was running it at? that still sounds strange for it to overheat the exhaust that much unless ambient temps were already sky high.

is it a good idea to drive around while doing this? I did this today but got scared because the exhaust was smoking hot, luckily I stop it before anything burn. my question is: can I run the vacuum line to inside the car where I may have the bottle of water hanging there, then drive the heck out of it.?

is it safe doing so?

Does not sound like a safe idea. Try to keep the revs low and it will drink the water faster. Helps to have a buddy watching your catst.

not safe because BOV disconnected?

No not safe because of the amount of water you are putting in and the load the car is taking. When you are just revving the car there is 0 load on the motor.

Not safe because you're driving and the engine would not be running well. Because the engine will be under load when your driving I think you would be likely to have less vacuum than just revving in neutral. Boost builds under load, and since boost is the opposite of vacuum I think that will be the issue. The higher you rev, the less vacuum you'll have and the longer it will take to suck the water. It won't be easy to drive around under 3k rpms anyways. I just think it will be difficult. Maybe you could do it driving around in a parking lot but I don't think you'll gain anything over doing it in your garage and it might be more difficult.

:icon_tup: ok got it. :)

Is there any reason why we couldnt put say 2 or 3 gallons through to clean it out to the max?
Obviously will need to let the exhaust cool down numerous times throughout this treatment, perhaps do it over a span of a whole day.
But my main question is, could attacking the carbon in a big way like this in a relatively short timeframe cause any problems, such as bigger chunks of carbon to fall off which could potentially get jammed in the engine or something?

I've been doing this directly before each oil change, since 2011. I've still got excellent compression on the factory (never rebuilt) 1992 JDM engine, at approx. 72,000 miles now.

My method is to do one rotor at a time via vacuum ports on the UIM with engine fully warmed up. 900ml of water per rotor is enough. Then stop engine, wait 15 minutes and do the oil change.

A friend of mine can't stand to see me do it as he believes it would hurt the engine. But my engine is quite happy and healthy and his REW has blown up... I'll continue to steam clean it every oil change because it honestly does feel smoother afterwards.

Intuitively there is some risk. That's why I personally would recommend a more gradual approach via an inexpensive WI system... which comes with the additional benefits of cooling and knock suppression.

I'd love to see some objective data.
Some borescope images through the spark plug holes, compression data before and after, and even an oil analysis would be great.

Would any of you do that for the board?

Not of ingestion but Howard Coleman has posted such pictures of his housings with and w/o AI. Can't find the thread now but it was pretty dramatic and convincing. I may look again tomorrow.
On a side note, BMW just started putting factory WI (rpm and load activated thru the ECU) on their boosted M4.

Ok so I steam cleaned my engine twice today with a 45 min interval, 4 litres per rotor so 8 litres in total. After I did a rotor id take the car for a spin to let the exhaust cool down.
Car is running good. Is it running better or not i dont know, maybe its psychological but its feeling nice.
For some reason both times after I steam cleaned the front rotor and then took it for a drive it would blow a lot of white smoke for about 5-10, then it went away. But it never happened with the rear one. Any idea why that would happen?

You and I think alike my friend.

I took some video last time I did an oil change, here are before and after videos I took with a boroscope style webcam.
https://youtu.be/YvanM1MdStA
https://youtu.be/_qRoxbtyEvg

My technique is as follows

1. Allow engine reach operating temp
2. Use a tee piece to connect the two upper intake vacuum nipples to a single long hose.
3. Prepare a 5L bucket of water
4. With the car running and the hose attached, lower the loose end of the hose into the water. Doing so will slowly suck up some water into the engine, and the engine will misfire and stumble. Increase the rpms to 3/4k to ensure that it doesn't stall. I allow the car to drink the water 15-20seconds at a time then give it a 30-40s to cool down.

I'm due for another oil change in the new few weeks, so I'll do another before and after video to see if the carbon build up is less/more than last time. This will help indicate how often this procedure is required. I also got myself a compression tester, so I can hopefully get some numbers. Last time it felt like I gained 5Kw!



Here are some screenshots showing the carbon reduction on specific parts of the rotor.


Before:
https://cimg2.ibsrv.net/gimg/www.rx7...ceec713297.png


After:
https://cimg3.ibsrv.net/gimg/www.rx7...f6b1712bf5.png








Before:
https://cimg4.ibsrv.net/gimg/www.rx7...0552d646e3.png




After:
https://cimg6.ibsrv.net/gimg/www.rx7...64cc633654.png