Misthael

I typed up a little guide since I can't figure it out in my head at the gas station. Hopefully this will help some people figure their premix.



How to figure the oil/gas mixture when premixing:
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G / 150 = Og
Og x 128 = Oo

G = Gallons of gas purchased
Og = Amount of oil to add to the mixture in gallons
Oo = Amount of oil to add to the mixture in ounces

simplified:

(G/150)128 = Oo
(x/150)128 = y
_________________________________________________

Quick Reference Chart:
________________
| gallons | ounces _|
|____1__|__0.85__|
|____2__|__1.71__|
|____3__|__2.56__|
|____4__|__3.41__|
|____5__|__4.26__|
|____6__|__5.12__|
|____7__|__5.97__|
|____8__|__6.83__|
|____9__|__7.68__|
|___10__|__8.53__|
|___11__|__9.39__|
|___12__|_10.24__|
|___13__|_11.09__|
|___14__|_11.95__|
|___15__|_12.80__|
|___16__|_13.65__|

Glazedham42

iTrader: (4)

I just do 1 oz per gallon. A little rich, but it is easy to remember...

Blake

Why make it harder than necessary? One ounce of premix to one gallon of gas is 1:128 ratio. That's a good starting point for a non-oil-injected engine.

Misthael

The proper mix is 150:1. I'd rather get as close as I can.

Blake

According to whom and for what application? You state that like it's a scientifically proven optimal mixture, which is bullshit. If that's what you want to target, that's fine by me, but don't say it's anything other than an arbitrary ratio.

The stock OMP puts out about 250:1 on the lean end and 150:1 on the rich end, but that lubrication is targeted at the seals. Premix is suspended in fuel and the dilution may not be consistent. Therefore, we always err on the rich side. 128:1 is by far the most common ratio and if we notice a lot of sludge on the bumper, we play with the ratio until we don't have so much residue. What ratio that works out to be mathematically is totally irrelevant; what matters is consistency. Synthetic and non-synthetic behave differently, as well. In racing, we typically target anywhere from 160:1 ot 100:1, but we are also considering the effect on octane rating to the gas. In the end, precision is not nearly important as accuracy (accuracy and precision are two very different things). You are tying to be very precise but you may not be shooting at the right target and don't seem to understand that the target may move based on application.

Misthael

Do you just like to be a jerk to random forum members and make yourelf sound like an ***? I get my info from other people on the board. Like rx7carl, DAVID GRIMES, cdrad51, and rx7doctor. If I ask what the proper ratio is and I consistently get the same answer I'm going to use it. You're the one that acts like he knows everything 100% definite. Don't ever answer any of my threads again unless you're going to be helpful rather than disrespectful. I wouldn't mind being corrected if you weren't such an *** about it.

Blake

I wouldn't correct you if you weren't parroting information as if it were gospel. I have first-hand knowledge and you are simply repeating what you've heard (parroting). There is a huge difference. You specifically claimed 150:1 is the "right" mixture. That is wrong because there is no "right" mixture and 128:1 (one ounce per gallon) is FAR more common both on the street and in racing, not to mention a safer place to start. You might want to go a bit leaner but the exact ratio is not important. That's all I was saying.

On that other thread, you similarly made claims you obviously can't back up with facts...more parroting and the result is potentially misleading. Parroting is responsible for a great deal of misinformation that gets absorbed as "conventional wisdom". It is a plague and those who do it need to be corrected in no uncertain terms. Sorry if that ruffles your feathers.

What are my qualifications? I crew on a professional race team (Grand Am Cup), I am part owner of Pineapple Racing (one of the more respected engine builders) and I've owned and raced many, many rotary-powered cars (from stock 12A to PP13Bs). Take my advice for what you think it's worth, but at least respect that I've been there and done that before I start telling people what is "right".

DeRFmAn

now fellas lets not fight we are not a bunch of little kids here. lets not act like a bunch of 16 year old 2nd gen wanna be drifters.

Blake

If I came off as childish, I appologise. What I meant to sound like was authoritative, knowlegeable and unambiguous. Sometimes people get offended when corrected in no uncertain terms but that's not my problem when they stick their nose out like that. Again, I'm not saying 150:1 is a "bad" ratio; it's just not the only ratio or even the most likely ratio.

DeRFmAn

I wasn't calling anyone childish I just like the 1st gen area better because we seem to be in general a lot nicer and more helpful then the other areas. I wasn't speaking to any one person. I just want to keep this place laid back. You did come off a little harsh but sometimes that happens since we cant hear the tone of each other.

Misthael

That's a much nicer way of puting it. Thank you. So would you recommend 128:1 for a stock port 12A with header,exhaust, and a mikuni sidedraft carb? I noticed there's a bit of "smoke" out my exhaust like it's burning oil and it didn't do that before I started premixing. It may have been teh light or temperature outside that made it more visible also.

John64

Blake grow up. If you did not like the info he was giving, then don't take it. I personaly enjoyed the read and take everything with a gain of sault as you should.

Rogue_Wulff

Since it's a fairly fresh rebuild, start there. If the exhaust has a strong odor from excess oil, or shows signs of too much oil, lean it out a bit.
It really boils down to how hard you drive it. The harder you drive it, the greater the need for oil.

Misthael

The exhaust has a fairly strong odor of fuel, but not unburnt fuel, and it's not spitting like it used to with the larger pilot jets. I'd really like to switch to a rotaryshack throttlebody setup. Carbs are getting annoying.

Blake

Yeah, just use it as a starting point and work your way leaner. You will always get some unburned residue, simply because premix ratios must be richer that the OMP ratio due to the method of delivery. But, it's not rocket science and the worst cases are either too lean (a bit higher wear) or too rich (too much smoke/residue). Hardly any combo will result in engine damage, as long as there's some lubrication getting in there. I've never lost sleep over it. At one point, on an 8,000 mile round trip from Oregon to Florida and back, I ran low on premix and just ran 1/4 oz per gallon on my PP13B for about 500 miles...no problems. On turbo cars you want to be careful about the effect on the octane rating of the fuel and on any car, the fuel mixture may need to be tweeked richer due to the displacement by the oil. Just more variables. Even the type of apex seal (e.g. carbon-aluminum and ceramic need less lubrication and cast iron needs more) makes a difference in what may be "ideal", but it will still be a fairly wide range of ratios.

blown 83

I run Racing Beat's suggested 3.5oz per 5 gallons. A friend of mine that used to work there stated that's what RB has always ran in there bridge-ported cars. Again, I'm running a 13B bridge and the ratio RB suggested seems a little heavy but it works. I would rather have a heavy mix when turning 10K rpm than too little. I have a strong scent due to the type premix I use, Maxima Gold Castor 927, a esther-based premix. I've always ran this stuff in my 2-stroke race dirtbikes and never had any problems. I tosses a puff of smoke on a cold start-up, but it's clean after she warms up. My problem is the discoloration on the bumper from the flames .

EDIT: I also meant to include that my mixture ration may not work well for you. Just tossing it out so that you can see a variance. BTW, Blake may have came across harsh, but he knows what he's talking about.

rxtory

ahhh is it necessary to even premix

trochoid

iTrader: (6)

A little off subject here. What size pilot jets did you decide to go with and what size was in there before. My pilot circuit is running too rich on the 1/2 bp.

If you PM me with your e-mail addy, I can send you a very interesting article on pre-mixing. You might be suprised at some of the #'s.

trochoid

iTrader: (6)

If the omp is disabled, yes. It also gives you a choice of running a lubricant that is more appropriate, with less carbon build up.

Hyper4mance2k

iTrader: (40)

100% correct. Also because when you premix the whole gas tank is not getting the same exact mixture. Since the premix oil is heavier than gas it will sink to the bottom. You're going to be leaner than you think. Put an o2 sensor in your car. fill up. premix. than drive the tank to empty. remember to make carefull note of your air/fuel ratio through out the tank. It's clear that at the begining of the tank it was running richer than at the end of it. Better safe than sorry. If mazda was running a mechanicaly controled system that injected directly onto the apex seals at 150:1 then it's better to run richer than mazda with a premix system that is mixed through hope. And for a tip. Right after i fill up i drive along the dots in the road for a block to help mix everything up. lol It works. For those of you who have ever premixed a 2 stroke you can clearly see that the gas can needs to be shaken up before you put the fuel in the chainsaw...

Blake

In re-reading my earlier posts, I do realize I may have come off a bit harsher than I intended. Sorry. My big pet peave is parroting. It's the only reason people still believe "synthetic oil doesn't burn" and that "peripheral ports are unstreetable" and "carbon-aluminum seals only last 10K miles" and... You get the picture. All I expect is that people use some restraint before preaching as gospel something they read or heard (even from a good source) and may not quite grasp the nuances that get lost in the repeating. Almost every misleading psudo-fact has a *grain* of truth somewhere that, along the way, snowballed into a pile of misunderstanding. And, even experts don't always agree or, even if they agree on the outcome, they do not agree on the *reason* they got the outcome. I once got lectured by Feter Ferrel (owner of PFS, and one hell of a great driver) about the evils of 3mm apex seals. The man is passionate...but wrong. At least, that's my belief. Live and learn. If you try enough things, you can at least say "This worked for me. Your mileage may vary."

Kentetsu

That was pretty big of you Blake. I kind of have to stand up for Misthael on one point though; we all come to this forum to learn and to help each other out. We take our lessons from the more experienced members and pass it on to those who are seeking knowledge. If we cannot take our cues from members like RX7Carl and RX7Doctor, who can we get them from? Even though I hate to see people stating opinions as though they were facts, Misthael's information does come from (one of many, I admit) a good source. Peace to all...

blown 83

That's not necessarily so, either. It depends on the entire fuel system you are running. I am running a full return system (Aeromotive A1000 pump, -10 feed line, -8 return line into a 16 gallon fuel cell). With my setup on a full cell, my fuel is clearly and constantly swirling like it was some river rapids. If the car sits for days, I always let the system cycle for a minute or two prior to start-up. For the most part, though, your statement is very true running the stock fuel system.

Pele

iTrader: (28)

Questions:

1.) Would it be okay to run 1qt/tank MMO premix in addition to the stock OMP as a safety measure? MMO IMHO doesn't appear to be a suitable premix alone, as it's too thin. But it's a good fuel system cleaner and will do something in the event of an OMP failure.

2.) Is the 250:1 ~ 150:1 range applicable to S4 and S5 OMP's? I know some of us are running non stock engines.

3.) Is it better to run the OMP as a function of RPM or throttle if you have the option? On fuel injected vehicles, you have ZERO apex oil injection when engine braking. This scares me. On OMP equipped vehicles, you get minimal on engine braking. This is better, but still makes me wary. (Assume one has electronics necessary to do so. Actually, all you'd need is a small microcontroller.)

85gsl2ndtimearound

Just putting in my 2 cents/sharing my experences. MMO has done me right for 60,000 miles, used in a 16oz. to 16 gallon fill up fashon. O ya i ahve also had the "KISS OF DEATH" the whole time and beat the **** out of it on a daily basis. once again just my .02.