ok im new to posting this forum but have spent a few hours reading some posts. i once had an 82 rx-7 which i beat up pretty good and gave lots of tlc to at the same time and it was a great car. had an 86 rx-7 which i did the same to and it to was a great car. now i have an 89 vert (i also now have a computer and more resources than in 1994 when i had my last rx-7). to top it all off i have a few jet skis ( which i tow with my 1990 300zx). anyways with these jst skis each has its own oil pump which adds an oil to the gas, in a 2 stroke motor this is only source of lubrication. for safety and all i have disconnected the oil pumps and gone to pre mix. in jet skis this the safest thing to do (if oil pump goes so does engine). well, with the posts i have read i have seen a few people talking about their rotaries and pre mixing!!?? like i said b-4, i just got my 89 vert a month ago, and am back into researching the dos and donts of rotary engines, and now with the computer the resources are much grander in scale but cmon? do we really premix an rx-7 rotary?


im only looking for the plus side and the minus side of doing this, and actually, until a few hours ago, never heard of such a thing.

i used my jet skis as an example. i understand that the rx-7 has an oil pump which is vital to the survival of the engine, much as the oil pump in a two stroke. but the oil in the 2 stroke is much more flammable (from what i understand) whereas........ you dont put a flammable oil in the pre mix do you???


i dont know im just confused by the notion of it. please respond if you know anything about this.

thx bauer

 

bauer;
Since you are familiar with two stroke engines you are aware that this type of oil is designed to burn cleanly and leave behind a minimal deposit of ash or abrasives. Such is not the case with regular lube oil. Over time the carbon deposits build up to the point where the seals on the rotors lock up solid in their grooves. This is where the use of two stroke oil gets its beginning.

I recently rebuilt my '86 NA. For a time I had an adapter that allowed the use of two stroke oil in lieu of crankcase oil for the oil metering pump. After a while I decided the drawbacks to using this system outweighed the benefits and went back to the factory stock oil injection system.

The original engine lasted for over 14 years and 124,000 miles of driving. At 12,000 miles of driving per year it would take me 10 years to reach that point again, and I will be very unlikely to keep this car that long (among other things I would be very near 60 years old then).

The probability of a failure in the OMP is greater than the risk of carbon build up in an older car. It would therefore make more sense to run pre-mix for this reason than for preventing carbon build-up, at least in my humble opinion.

 

Where can you get the premix adapter?

Does mazdatrix or RB sell it?

 

running premix in the gas wont ruin the injectors will it?

ive pondered adding premix to my gas in ADDITION to the stock OMP on my 88, just for extra insurance. and i know the Rotax oil for Sea-doo's is pretty good stuff, its supposed to be one of the lowest ash-content oils on the market, but not a bargain at $38 per gallon. its ok, you only use one OZ per gallon of gas anyhow.

the only reason i have not tried premix yet, is that i dont want my injectors getting clogged up w/ oil residue or getting gummed up. if someone can tell me that this WONT be a problem, then PREmix, here i come.

btw, Ser. 4 rotaries have mechanical OMP's which are more reliable. in that sense, if they fail, it will be over a period of time and you have better luck in catching it before it does fail.

in a Ser 5, its an electrical OMP, so if it fails, it fails as fast as a fuse can blow (so im told). so you wont really be able to catch it before it goes bad. the only prob is, if you eliminate the OMP on this car, it throws a CEL. not so in the Ser.4.

if you DO eliminate the Oil injectrion on your RX7, then you can run Full Synthetic w/o any adverse effects.

chris

 

http://www.rotaryaviation.com/

Description.

Wankel engines such as the one used in the MAZDA RX7 sports car need oil in the combustion area for lubricating the metal seals.

Most stock engines use a metering pump pumping a small amount of engine oil from the oil pan into the intake manifold and/or directly into the combustion chamber. Engine oil is designed to lubricate sleeve bearings and carry heat from the engine interior to some cooling areas. In the RX7 the heat is removed from the oil in an oil cooler. When engine oil is getting into the combustion chamber, it only is burning partially, leaving some unburned deposits behind. These deposits can build up and reduce engine performance.

One obvious method of preventing this is to disconnect the metering pump altogether and mix two-stroke oil to the gasoline like some older two-stroke engines require. With this method it has been demonstrated that two-stroke oil is an effective lubricant and there is no build up of combustion residues.

The Metering Pump Adapter, as offered by PCV Technologies takes the solution one step further in allowing to still using the stock metering pump but supply it with two-stroke oil.

With the Adapter installed, all that is needed is a small oil tank with two-stroke oil, connected to the Metering Pump Adapter. The oil level in the tank should never be less then 6” above metering pump.

Oil consumption is approximately 1/100 of fuel used

 

so are there any places that a person go to see or get feedback on the true effectiveness of this pre mixing?

i know the rotary is a finniky little engine, ive had a few, but for an ex. when slick 50 first came out it made sense to me for the rotary( i was 17 ) then later on it was understood or rumored that the teflon crap in it either stripped the engine or the seals ( rubber) or some ****. so are there any experts like fc3 website that have been doing this for a prolonged amount of time?

sometimes things look great on paper but when applied to science they just dont work. to me if this is a good alternative why wouldnt mazda have applied it to the 93 rx or others?


just a few thoughts.

ps i gotta respect the guy in the poll who checked " go screw yourself for asking" i love it.

bauer

 

Race cars - premix

Street cars - mechanical OMP

Dave
89 GTU
89 GTUs - ex-Escort now ITS
87 Sport - ITS

 

I have a mildly modded '87 FC turbo...
I pre-mix cause I see too much carbon build-up on engine tear-downs.
After running pre-mix, the engine comes out pretty damn clean; that's a good enough reason for me.



-Ted

 

Ted, i understand how the engines running premix end up cleaner on the inside. but, over time, will it clog/gum up the injectors?

to whoever asked: Mazda didnt use premix on the production rx7s cuz that would be too much of a hassle for your everyday joe to remember. hell, my friends w/ 2 stroke quads and dirt bikes complain about having to mix gas, or adding oil to the premix tank, and bitch about it being a pain int he ***. go figure.

however, from what i understand, in the 70s and 80s, the mazda GTU race team did run premix in their NA cars, along w/ 79 octane "race" fuel. that was somehwere on Scudiarcirani.net (sp?)

 

that post brings me to another question i ran into in these posts. somewhere along the line i saw a post that basically said that 87 octane gas was better for the rx-7 than premium 93.

my question is . is this true?


a few weeks ago i bought my vert. its an 89 with a 1 yr old new pettit racing street port 13 b (about 15,000 miles on it) and i used 87 octane for a few tankfuls and was not impressed with the power of my engine. last time i filled up i put 93 in there and it was a huge difference.

is there a drawback using 93 vs longevity of engine life using 87?



bauer?

 

Octane is a reference to the speed at which gasoline burns. The higher the number the slower the burn is. Running an octane higher than needed (87 is fine for an NA) is a waste of money, and the fuel is also still burning when it enters the exhaust system. That will shorten the life of the exhaust components.

Higher compression engines (turbos included) can benefit from higher octane fuel because it is more resistant to detonation.

 

RETed let me ask you somethin? your one of the most knowledgable person on this forum.

do you think that by disconnecting the omp rod that will stop the flow of oil (via the omp) into the engine? or is there still very minimal oil injected?

thanks!

 

Those of you that DO run premix, Do you use the same oil type that is in your engine oil pan? or do you run a thinner type? Or should you run 2stroke oil as premix?

Also someone was asking above about the injectors getting gummed up or clogged, does this happen freqently? I would also like to know this. And if you use any injector cleaner solutions, do you have any sugggestions of brands?

Thank you!

 

My $0.02...

I used to have an 89 GTU pictures in my sig. I met up with a local friend who had been into rex's for years and talked to many, many enthusiasts before I even knew what a rotary was. HE had had several of them, including a couple of other series 5(89-91). HE tells me about the electronic oil metering pumps, vbersus the older rod actuated ones(he had a s4 then so we compared). Apparently he lost 3 engines to bad seris 5 OMP's, and didnt even know it until it was too late. Apparently sometimes the OMP can go bad but not set off a code, or limp mode, so you continue running w/o knowing the engine seals are running dry.

Based upon this information I decided to run premix in said 89 GTU, and never had so much as a problem out of it in over 2 years, the most reliable car Ive ever owned. IT ran mint, adn would outrun a stock s4 turbo if driven right. I never had a problem fouling plugs bad injectors or anything. I used regular old 2 cycle oil in the gastank, 1/2qt. per complete fillup(I never did partial fillups). This was in ADDITION to the stock system which probably worked, but it was good insurance for me. I probably should have went in and disabled the stock injection, but thte car ran so well I never wanted to take anything apart on it and possibly cause problems, so stock it stayed.

THere have been long and hard debates on this subject ever since I can remember being int he rotary community. One guy had a s5 car with 365k on the original engine and called anyone who mentioned premix blasphemers. Others say s4 OMP injection is bulletproof, but s5 is questionable, so run it in an s5. I say, if you have a low mileage, good condition car, or ever rebvuild the engine, run premix from day one, regardless of what year.

THe reason being, a) it cant hurt anything, b) it costs very little, c) its very easy to do. Ive been tearing down a LOT of core motors recently as Ive started rebuilding engines. Most every one I find had poor rotor housings. Ive noticed on every one though, there is a line around the center of the housing, directly in line with the oil injector's hole up top. WHen I inspect teh apex seals of that rotor, I find that in the center, there is a bit of a high spot as compared to the rest of the apex. This tells me that the oil injected into the engine doesnt spread out and lubricate the entire width of the housing and seal, only the center for about 2mm. A close look at any old rotor housing should reveal this.

My though tis if the 2 cycle is premixed in witht eh gas, which gets atomized pretty evenly, then its bound to cover the entire combustion surface evenly, preventing uneven wear.

Id be willing to bet that if someone had a new engine with new housings and seals, and run premix ONLY the entire life of the engine, a) there would be very little carbon buildup like what Ted and myself see, which decreases performance and engine life, and b) there would be little wear on apex seals and housings leading to longer engine life and better compression throughout that life, maintaining a better idle and power characteristics. I bet such an engine, driven normally and cared for, in near stock form, would last 200k+ miles.

Any other thoughts?

 

The reason we pre-mix in our race cars is because the OMP doesn't inject the amounts of oil we need for sustained periods of high RPMs.

Amsoil and Redline both make great 2 cycle racing oils, but they're pretty pricey for everyday use.

On my daily driver, I just use the stock OMP for two reasons:

1) Pre-mixing requires more effort than I want put into a fill-up.
2) The mechanical OMPs are very reliable.

If you're not the orginal owner of the car and suspect that the previous owner was not diligent in their oil changes, you may want to replace the lines because they can clog with sludge.

 

thats right about the fuel. NA rx7s run better w/ lower octane since its more volatile. this means that is has a faster moving flame front which leads to more power pushing against the rotor faces thus turning the engine. again, the high octane in an NA is kind of a waste of money, and since its a more controlled burn, yes it will burn more slowly. maybe this is a good way to get flames out of your straight exhausted rx7.

so i had no doubt in my mind that burning 2stroke oil compared to 4stroke oil (Crankcase oil) is better for the longevity of the engine. but that still doesnt answer the question; will it cause the fuel injectors to clog/gum up faster than it would if straight gasoline was being ran???

that in itself is the ONLY thingi have against running premix, since i dont know what would happen to the injectors.

chris

 

Ive always done BOTH... I got 224k on my last engine. So I guess it works...

 

This is pretty interesting. We have a 91 NA with 1000 miles on a new engine.

 

Wow, I didn't know this will generate this much interest!

Make sure the pre-mix you are using SPECIFICALLY states it is for use with fuel injected engines.&nbsp The newest "TCW-3" rating also okays it for use in fuel injection engines.



-Ted

 

There is slight amounts injected due to vacuum (and boost for a turbo FC)...

If you're running strict pre-mix, we recommend removing ALL OMP components, which includes all four oil injection lines, oil injectors, and the OMP itself.



-Ted

 

well, i voted to not run premix but i would like to change my vote today to "run premix" because a few hrs ago my 67K motor blew and im suspecting it was the OMP. Weeeeeeeeee!

 

cmon Ted, you should know that when ever YOU praise a certain company, product, or Mod for an RX7, people will be interested. we all know that You know what the hell your talkin about.

besides, anything that can help us AVOID a rebuild is going to spark interest. i hear people talk about how my car is going to blow up soon since "rotaries never last longer than 100K miles". so this is good info to hear.

my only qualm was whether or not the fuel injectors would be affected, but apparantly they will be safe provided you run the proper grade of Pre-mix.

life would be better if we ALL ran premix!! just...a little more bothersome at fill-ups.

if i keep my car over summer; in go the 550 secondaries, and OUT goes the OMP system!!

chris

 

I voted premix, I am happy with it (just don't forget to add it!).
I was tempted to vote for "Go screw yourself" because I like to ********** as much as I like premix.
You need a "go screw yourself with premix" option.
Sean

 

and an even better twist to the info cycle is this.
if anyone has owned a sea doo xp like me they know that the only pre-mix you can use is the sea-doo oil. it is synthetic and better supposedly for the rave valves in the engine because it supposedly burns cleaner. whereas 4 cycle synthetic doesnt burn as clean?


the sea doo oil is expensive but is the only you can use for this jet ski ( use regular and you are stranded with a ski that dont run after a few tanks) but it works fine in my other skis. once again apparently it burns cleaner than any other 2 cycle oil, and my question is this.......its synthetic but burns cleaner than all other 2 cycle oils, but the synthetic 4 cycle burns less cleanly?

i dont know if anyone in this forum has dealt with this prob in the rave valves of a sea doo but if anyone had it does make you wonder how much better( if any) the sea doo oil might be in the rotary pre-mix than regular 2 cycle stuff( after all sea-doo uses it because it burns cleaner and it is true)


just a thought

also thx for interest and feedback in this topicand im looking forward to more info as far as pros and cons of premixing

bauer

 

Hope you have a bridgeport or something...