how often should I redline for carbon removal?
 

I have an '87 TII. Its all stock with an open exhaust and a FCD. I don't want to blow the motor (105K) but I don't want to be too easy on it and build up excess carbon. The engine runs excellent, but has low compression. I am currently saving up for a J-spec and fuel mods. So how often should it be redlined? Once a week? Twice? What do you guys think?

I like to do it each time before I shift.:devil:

Yeah, well, its just that I don't want to pop this sucker just yet. My wastegate isn't ported, and its all stock besides gutted cats. The poor thing had a shitload of carbon in the ports of the intake manifold. The throttle body wasn't too bad. So I know there is a lot of carbon built up on the rotors and in the seal grooves. I plan to ATF it soon. More replies!!!

If you have low compression don't redline it. It's a bit of a myth that redlining the motor burns all the carbon and is good for the motor. A spirited long drive is adequate.

aqua mister cleans the motor out realy well. and keeps the air cooler and increases HP. it good stuff give it a try.

What is, and where do you get, aqua mister. Is it through an injection system, or just a one time treatment?

thanks,
Kris

Yeah I want to know were you get aqua mist to

I never understood how redlining a car could be good for it since when your redlining the engine is turning at 7k or more i mean this is stress on the engine any way you look at it, but hey they are FC's i guess right? I redline everyonce in a while not too often. The maintence is what will save your car do very frequent oil changes, maybe change to premix. IS there any way to prove that redlining is good for our cars??

redline once a day keeps the mechanic away...thats my belief anyways

To get the carbon out, I took off my air filter, and with the car running, gave it a few 5 second shots of carb cleaner. You have to hold the RPMs at around 3k or the car will stall. I was amazed at how much smoother the car ran after word.

Try at your own risk, it worked worked great for me.

Damm I feel like I abuse my car compared to what some of you dudes are talking, mine cops about 10 redlines a day. However, im not doing it to get the carbon out though :)

I take my car to redline at least once every time I drive it. Why do you think the redline is there? So you can look at the pretty red color? And as for the carb cleaner thing, straight water is the best thing to clean carbon out of any engine. A mist spray in the TB while holding the RPMS up works very well. Try it at your own risk, but I have seen the results in a piston engine so I know it works there............

Find the Aquamist system by searching the internet. They are an australian company.

James

spraying directly into the TB is kinda hard without a MAP sensor. The engine won't run if you disconnect the MAF.

It's njot a bad idea to redline once in a while since there are so many features that actuate above certain rpm's such as vdi, aux ports, secondary fuel injectors and such. It helps to keep things from getting gummed up or stuck. I redline about every start, but I have never been known to be nice on cars - but I keep maintenence up at least :D

all of that strain is part of why the carbon is freed. If there's that much strain on the internals, then there is equivalent strain on the carbon.
I rarely redline, like once every two weeks, if even that. Mostly I drive easy, and occasionally take it to 5.5k.

What Redline????
 

In the old days, I had an RX4 that shook its rear stationary gear loose. I had a friend that was a Mazda service manager and he got the engine replaced for me under warranty. This guy knew everything. He told me that the red line on the tach was pretty much put there for the flywheel and trans. He took my engine clear off of the scale just to show me. Best rotary I ever had. He also told me that frequent oil changes were the ultimate answer to longevity.
He also showed me a neat trick for reviving a dead rotor. He had a customer's car that had a dead rear rotor. To say the least, the car had not been well maintained. Before pulling the motor, he started the engine and poured pure ethylene glycol down the secondaries (slowly with the engine running about 3500 RPM). It, of course, started putting out clouds of white smoke, but after three tries the rear rotor started firing and the engine idled well. He said that the ethylene glycol was the best way to remove carbon from the seal springs. I saw it work and couldn't believe it!
Just as a reminder......The old Rotaries used straight ethylene glycol injection so that the damned engines would turn over in cold climates. There was a tank and everything from the factory.
I use ethylene glycol every once in a while to clear out my engine. It has some lubricating value (unlike pure water) and does a good job of keeping the combustion chambers clean. The wife's '91 NA (stick) idles smoothly at 650 and it's got 94,000 miles on it. I've never read anything about this, but it works well for me. The wife always shifts at about 4K and I rarely drive the car.

will redlining really help and how long should i redline.

if you fell the need to ask this is the wrong car for you :D j/k there is no NEED to go past 5500 rpm to keep stuff working, but the way i see it. why bother doing extra to keep stuff working if you don't drive in a way that needs it? if your want to get rid of carbon put some Marvel oil in your tank.

Re: What Redline????
 

Just a thought... does ethylene glycol work like Automatic transmission fluid treatment? If not what are the differences and where can ethylene glycol be purchased? Interesting topic BTW

Uh, wait a minute. Are we talking ethylene glycol as in the main ingredient in anti-freeze?

If so, that stuff dissolves rubber. :eek: Want an example of how fast? Next time you do a coolant change/flush, pour a little blurp of it on the ground and step in it (assuming you're wearing running shoes.) Now put that foot on dry pavement or cement and push it away from you. It slid like you put it on ice, didn't it? That's how quickly it attacks the rubber.

I'm not challenging that it works for you. I've taken enough crap myself over supporting other 'controversial' maintenance techniques. I want to point out that IF we're talking about the same thing (ethylene glycol/antifreeze) then those who do this are pouring a potentially damaging liquid into their motors. The apex seals and rotors aren't rubber, but the oil side seals are. I don't know enough about how things work in there to speculate on whether or not the ethylene glycol would reach them. I'd guess not from reading about the longevity of your motors, but the whole thing still makes me wonder...

coolant disolves rubber????? what about all the rubber hoses seals and o rings that are in every coolant system since the begining of time. coolant does not disolve rubber any more than oil. the whole slipery shoe thing would be the same with oil also, but because of the lubracating properties not because your shoe is melting.

Yea do you guys seriously only take your cars to redline once or twice a week? Because whast the fun in that? We have these extremely high reving cars that well atleast for me dont get real power till I hit about 5k and the engines well there not gonna last long and the longer you make them last by not driving them spirited the less fun you have and to me its not worth that just so I can keep the same engine for a few years more. Dont get me wrong I change the oil every 1500 miles and I constantly check over the car but I also except the fact that even tho I just dropped a new streetported engine in it I will have to replace it within a few years. Well just my thoughts on the matter.

Another story about coolant. :)

The company that I work for has a shop to maintain their heavy equipment in. It's a family-run business and they try to service everything themselves.
Short version - one day the son was topping up the windshield washer fluid in all of the dump trucks. Well, sometime earlier he had used an empty WWF container to store coolant. He used this same container to top-up all the WWF reservoirs.
The next day it rains. Everyone drives out to the job site and then spends the next hour trying to scrape the remains of the wipers off of their windshields because the coolant ate the wiper blades, leaving one hell of a mess.

Also, last fall scathcart was looking for recommendations for goo to put on his tires to get the most smoke out them. Guess who recommended coolant? He later reported back that it was the coolant that produced the best results. :)

https://www.rx7club.com/forum/showth...hreadid=121008

Coolant is a lubricant? That's new (to me.)

As for corroding the innards of the cooling sys, the components are designed to carry coolant. Just like you wouldn't use ordinary rubber hose to carry gasoline, so too would you use a particular hose type, etc to carry coolant.
I don't know whether or not the oil rings would tolerate exposure to coolant (if they even would come into contact with coolant doing the suggested cleaning...?)

Coolant is not acid, it will not eat through your shoe that quickly. If you got some bleach on the other hand it might do something of that sort. Coolant does have chemicals that probably will break down rubber but not in that short period of time. The rubber on your shoes is not that much softer than the hoses used in your car.

I think ill just stick to the ATF trick.... proven effective

very interesting..someone should try it....just not me. Although the nxt time someone's motor blows this may be a last ditch effort. eh?

I'm betting it would be doing the same thing, or close to the same, as injecting straight water into it.

the difference, i thought, was that the ethyl whatever stuff was poured in while the car was running. usually the ATF trick is done when the car is off, so the ATF has time to hit the oil seals.

coolant has a lube in it for the water pump. the crap in coolant "can" make it an acid that is one of the reasons to flush and fill the system. it would take days to make your shoe gummy, and if it eats your shoe it would be grippy not slipperier.

Coolant is the only substance in your cooling system that lubricates the water pump. It is not harmful to rubber and the lubricating properties of it (have you never felt the stuff? it's pretty damn slippery) is what prevented the tires from gripping and thus making the most smoke for sean. Bleach has been used for the same effect in the past. (it's also pretty slippery stuff)

Amur, You need to come up with something someone else has published to back up your little analogies. What if the day before using the WWF container for coolant the guy used it for sulfuric acid? Maybe he also used that thing for circle jerks? Anyone who doesn't properly clean containers of contaminants isn't my idea of a smart person or a good mechanic.

Coolant hoses are not specially treated or formulated for use with ethlene glycol. The idea is rediculous!

Personally Im a fan of redlining any car I drive (that isnt being broken in from a rebuild or just had a used engine installed that week) once per driving session, be that once per day, once per week, or 5 times a day.

Now, about this maintenance debate. I am personally a fan of water injection. Not the type turbo guys run to keep intake temps down, but the type you do in your driveway as a maintenance procedure. Find a vacuum line or lines (teed together) that feed both the front and rear rotors, grab the throttle and rev the engine up to 4k or so, and dip the hose in a jug of water and let it drink. The water gets pulled in, hits the rotors and turns to steam, and takes carbon (slowly) with it.

If you're starting with an original/old used engine, Id do this 3-4 times weekly for about a month to clean as much as you can out. I'd also do 2-3 gallons per treatment. From then on, once per month. IF Im maintaining a rebuilt engine, I do this once per month or once per thousand miles to keep everything clean inside.

I have torn down engines where I had previously done this treatment, and they are always very clean, if not carbon-less altogether. The water treatment, along with straight premix, would result most likely in a rotary engine that lasted over 200k miles as the rule, rather than the exception.

As for antifreeze, I have not heard of using that as a maintenance item. I suppose it would have similar effects as the water treatment. I do concur that mazda used to use it for cold climate startups, since I remove the damned bottle on half the engine swaps I do (it aint that cold in the south). For that reason alone, I will theorize that antifreeze would not be harmful to engine internals when used for a short period of time, after all mazda did many years and several million dollars worth of R & D on this engine, I cant imagine they'd make it a policy to inject a harmful ingredient to their engine.

Ethylene Glycol
 

First: Yes it is antifreeze. I specifically said ethylene glycol because there are other coolants out there these days.

Second: Go soak some seals in it. It does NOT dissolve rubber. It IS VERY slippery. That is why Mazda injected into their engines as a cold start assist. In Illinois (where I originally came from - just south of Chicago), the temperatures would drop so low that the rotary engines wouldn't crank fast enough to start. One hit on the anti-freeze injector button would let it spin right up.

Third: The best way to get it off of a windshield is straight gasoline. There was nothing wrong with the wipers. I think everyone from the colder regions has seen someone make the mistake of putting anti-freeze in the washer bottle. Only alcohol-based solutions work on glass. Here again, it is the fact the the ethylene glycol adheres so well to the surface and is so slippery that it causes a problem.

Fourth: If you don't think it's right for you--DON'T DO IT!
I still won't overheat my rotary to flush the cooling system like someone else suggested. I even read the link from the Mazda "expert" that was quoted and didn't feel comfortable doing it. Regular flushes are keeping my rotary just below mid-range on the gauge with the A/C on at 115 degrees in Phoenix!!

Re: Ethylene Glycol
 

Okay, I gotcha. :) I had some observations about coolant plus that story about the wipers, and I came to a conclusion that was wrong. I've no problem acknowledging that. I'm glad that you posted this because I want to share the most accurate 411 possible with people when these questions come up. And the next time this comes, in the Forum or elsewhere, I'll be ready (and way more helpful.) :)



hypntyz7 - that's the first time I've read a complete description of what the water injection method is meant to do, and what the results are (I'll take your advice anyday.) :bigthumb:
So I did it this afternoon. I don't know which of the vac lines go to both rotors, so I chose the one that was easiest to get at - the uppermost one on the front of the UIM.
The motor did NOT like it. :) I did the t-junction and dipped the hose into the water and the motor would bog. I finally found a nice balancing point where I would let the hose just barely sip at the water. The engine still bogged, but not as badly as before.

What vac hose do you use, and does the motor respond this way when you do it?

Amur:

You chose (for an s4 NA) the proper hose. This one feeds the 4 oil injectors, which siphon straight into the engine evenly. For an s4 t2, I use the ? shaped hose above the BAC, which tees evenly into both primary intake runners. For an s5 NA I use 2 capped off/unused nipples on the middle intake, by the acv...I use 2 vacuum lines of my own, teed into one, and dip that into the water. For an s5 t2, well, you have to get creative :D

BTW, bogging of the engine is normal. Water doesnt combust. In fact it cools the internals to the point that it's hard to maintain combustion (the direct opposite of detonation/preignition, which is where the internals maintain enough heat to ignite the mixture before it should be; this is why water mist injection is effective on high power engines). The key is to grab the throttle before you dip the hose in the water, rev it up to say 3-4krpm, and hold it, dip the hose, then give it a bit more to maintain that speed. After it is done drinking, the engine will slowly smooth out, at which point you can gradually release the throttle.

Oh, I know that water doesn't combust. :D I was just concerned about how the motor reacted. I was revving her to around 4k (going by my ears) when I dipped the hose, and I still snuffed her twice. :) That compromise that I settled on was still at high revs. While I didn't rev the hell out of her, she was definitely getting a workout.


edit: I'll try it again tomorrow and report back. This time I'll be more generous with the throttle. :)

I have a n s5 turbo. I'm interested in tryin this as well. Any ideas on where to let it suck.:D

Yeah, thats all it is, balancing throttle with water. Sometimes I find myself giving an engine near WOT and holding it there, which isnt so bad in this case because it still doesnt rev over 4-5krpm.

On the s5 turbo, you need to find the large vacuum hose for the oil injectors on the back of the dynamic chamber/throttlebody. Take it off, put either a) a smaller hose inside it, b) a larger hose around it, or c) a metal or plastic tube to allow you to join another hose onto that one.

Okay, did the water injection today. Had a fellow 7 owner on the gas and things went very smoothly this time. He had it around 4k and she took the water without bogging. Thanks, Kev. :bigthumb:

did you know that the sub zero starting fluid in all mazda rx7s is antifreeze. call the dealer

did you know there was a service bulletin to REMOVE the sub-zero start systems?

that's just because it did nothing and was just adding dead weight

ok i live in ontario, north of the border, it gets real cold here, am i going to have a hard time starting my 7?

I used to "steam clean" my old piston engines by slowly pouring water through the carb. It always worked for me, but shouldn't you warn amour that water does not compress and that if he "injects" too much, he may break some internals?

http://www.physlink.com/Education/AskExperts/ae15.cfm

No, since we're talking about rotaries, not pissed on engines.

LMAO

Anyway, interesting topic...I'd try that steam clean trick...just need some time and someone who knows what the hell is what in the engine bay, lol, I'm stupid when it comes to stuff like this...for some reason, looking at pictures or trying to find something by description never works for me, lol

Why? Too much water is still too much water?

I'd like to see you hydro-lock a rotary.
The only thing that happens if he injects too much water will be that the car will stall...

I'm not very experienced when it comes to RX-7 "tricks" like most of you seem to be, but my engine is running strong at 180,000 miles and idles evenly. I redline once every day or two and change my oil often. Filters get cleaned every two months (K&N). I usually shift at 3,500RPM, ocassionaly at 5,500RPM if I'm in a hurry. If gasoline itself is very good at breaking down gunk and all sorts of buildups, why would putting water or other things into you engines clean it any better?