madcows

I've been thinking about carbon buildup lately.. Redlining may help, but that's not always an option for me when putzing around town on short trips.

Anyone have any thoughts on water injection systems like those used on old SAABs, and WW2-era plane engines?

9krpmrx8

iTrader: (46)

Hopefully my Lucas UCL will help with Carbon. I use it as premix.

GeorgeH

iTrader: (2)

Or FP+, which is what I use.

9krpmrx8

iTrader: (46)

Yeah I need to read up on FP+.

ASH8

Umm...Rotaries do not like short distance driving....this is and always has been an issue. Of course a lot depends on the "driver"...I personally would not own or use an RX-8 or ANY rotary if I only traveled 5-10 min a day, your oil and everything else (gearbox and diff) would not even get to normal temps.

But for the rotary engine they like to keep moving, look at how successful and reliable they have been over the years in long distance events..they love it.

And yes, as the Oil Scientist said it is the diluted oil and oil that does not reach Op temps is not good.

You have to remember the majority of "owners" are not like members here who change their oil more frequently.

Until we see a Hydro rotary, or "another alternative gas" Carbon will continue to be an issue with rotaries.

I would like to install a Oil Pressure guage, but, I really don't like what I see on the market..perhaps 9K's find is the best I have seen.

ASH8

A well know and respected member suggested the "Steam Clean" method, I suggested this to my now Mazda Service Manager guy here, they tried it on two RX-8's that were borderline and were happy with the results, the only issue after using a litre of water was the CAT, started to Glow and "other" surrounding parts were melting!...

9krpmrx8

iTrader: (46)

I just don't like the idea of chunks of carbon breaking free in the combustion chamber.

GeorgeH

iTrader: (2)

I get all that. But, if I am careful about how I drive & change the oil, I should be able to avoid the "avoidable" damage (that caused by careless high-rpm usage on cold oil, and usage of contaiminated oil).

Of course, an engine with many short trips probably will not be able to accumulate as many miles as one that does longer trips. That's just a fact of life. But, I have an '04 with 45k miles on, still on it's first engine, and it pulled 210 rwhp on a Mustang dyno over the summer. So clearly, a short-trip car can be managed - even an RX-8. That's my point.

madcows

I was thinking of a more modest amount than 1 liter, but done with some frequency. Actually, I was thinking along the lines of an automated system that does it every so many miles (don't know how many miles, and how much water).

It sounded like some of the people on here who have done the steam clean using a lot of water ended up having their oil diluted. This is really bad unless you can get a very through oil flush afterwards. I'm thinking that a much smaller volume of water ingestion might avoid the, though.

olddragger

iTrader: (3)

i run a water meth system already
OD

madcows

I'm really starting to think that a water injection system is an almost mandatory mod to prevent carbon buildup and eventual carbon lock, even on N/A motors.

Looking at your most recent UOA, olddragger, it's nice to see that there is no sign of water in your oil. With a continuous injection of small volumes of water, it looks like it prevent dilution, as well as hopefully eliminating the chance for carbon to build up. I'm hoping that the low volume of water also avoids stripping the oil from the apex seals. Any thoughts?

olddragger

iTrader: (3)

w/m makes too much sense NOT to do it. Guarantees octane, cools intake charge temps, which helps with egt's, + the cleaning affect. You should see my sparkplugs now--no carbon on them--some ash but no carbon.
I have not heard of any lubrication washing occuring, in the rotary or in recips. Too small of an amount perhaps?
OD

9krpmrx8

iTrader: (46)

OD, what do you think about W/M in a NA setting?

olddragger

iTrader: (3)

remember --we dont tune for the w/m injection. so as for as power benefits that will be limited.
As far as insurance against detonation--imho there is non better.
As far as a decarbonizer---there is non better.
Whether or not it helps the longitivity of the engine-- no long term data available on this.
Lodgically one would think so?
If I had a na engine and tracked in the heat I would get one.

9krpmrx8

iTrader: (46)

Bump, added Rotella T6.

GeorgeH

iTrader: (2)

I thought this might be of relevance to this thread:

http://www.bobistheoilguy.com/forums...127#Post478127

9krpmrx8

iTrader: (46)

Thanks, that AGMA 7 oil has a viscosity of 30cst??!?!!!?!?

rotarygod

I am the person that Ash is referring to that steam cleans the engine. I do this on an RX-7. There are pros and cons to it.

Pros:
It's easy.
The engine runs very smooth afterwards.

Cons:
It will scare the living crap out of you the first time you do it!
Your car may or may not like it.

That last one may be a bit scary. How do I know if my car will respond good to it. The answer is simple. Do you own an RX-8? If so then it probably won't like it. At least not one equipped with a cat.

The problem is that the RX-8 ecu is so controlling that when it detects such an off reading on the O2 sensor when water is runnign through it, it dumps more fuel in, in an effort to compensate. This fuel isn't getting burned. Instead it is passing through the engine and pooling in the cat which is where it is then getting burned. This is why the cat will glow orange and get very hot.

If you don't have a cat but rather just a straight pipe and the ecu sends more fuel through, it can't puddle in the cat but it's going to somewhere else if possible. It probably isn't the best thing to do with the RX-8 ecu but in small amounts could be fine. The amount I do probably isn't recommended though.

My car is a '90 FC RX-7. It's got a royally dumb ecu. It has no idea if I am emitting oxygen, CO2 or puppies. It won't try to add fuel as a result. I still have a cat. Mine doesn't glow as fuel isn't puddling in it though and nothing gets real hot. The opposite is true actually as the water is pulling the heat out of everything. There is a ton of steam from the exhaust pipes and from the amount you'd swear the engine was actually running on it.

Now for the downside in my car. It keeps steaming for several minutes after the water is gone. Why? Remember what I said about excess fuel puddling somewhere? That applies to water too. It settles at the bottom of the low points in the exhaust system whether that be the low point of a pipe or a muffler. The steam continues until all of that moisture evaporates. This isn't an issue if you keep running it until the steam ends. If you drive it, this is only a few minutes and shouldn't really add to any corrosion. If you shut it off though that's different.

I typically do the steam cleaning during oil changes although lately I've been at about every third. I steam clean it first, drive it, then park it and let it cool. Then I change the oil. New oil and a nice clean engine make for very smooth running.

I pick a vacuum nipple that favors each rotor and do one side at a time. While some water will go to the other rotor, most favors one. This helps keep the engine running.

In case you are curious, I run a gallon of water through each rotor. All 2 gallons takes me about 5 minutes. Now work out what my water to fuel ratio is for that 5 minutes! This is at a steady 2000 rpm.

9krpmrx8

iTrader: (46)

That sounds scary

GeorgeH

iTrader: (2)

RG, thanks for posting that. I have a local FD guru who wanted to do the steam cleaning thing on my car, and it's good to know the potential pitfalls of this on an RX-8.

Perhaps I'll try it with my cat removed using smaller amounts.

9krpmrx8

iTrader: (46)

Any new oils anyone is trying? I am now using Rotella T6 5W-40.