just wondering if anyone knows of a premix chart i can look at. going to have my car at the track a lot and dont want to starve the apex seals of any oil. i know for normal driving its in the 1oz per gallon range, but i hear for racing conditions it can go up to 5oz per gallon, just wondering if anyone has any definitive numbers i can look at.

thanks

 

I still only use 1oz per gallon weather I am driving daily or autoX

in all actuallity the temp of the engine should not increase if u have a good cooling system and you wont use alot more gas then u would if u were just driving it hard daily..

if u overkill you may not run so good but that I cant be for sure on

 

NORMAL driving uses much less than one oz a gallon. One oz a gallon is for maximum throttle use. That is my personal opinion and nothing more, nothing less. Just personal experience.

Want to find out for yourself? Rig a seperate oil tank to feed the omp. In other words blockoff the oil feed to the omp from the engine and use a seperate oil tank to gravity feed the omp. Then measure how much oil is used during NORMAL driving. Ain't a oz per gallon.

I am NOT in any way knocking using one oz per gallon. Can't hurt having a bit too much. Having too little would worry me.

 

The reason why I always pour 1oz per gallon of gas

Dave

 

The Spencer Racing Team uses 1 oz./gal. for their cars. I use 25 ml./gal in mine at all times, based on the advice I got from Peter Farrell. I believe 1 oz. = 28 ml., so it's a small difference.

I was recently talking with Ray Wilson at PFS. He said that he had seen cars where the owners were using too little pre-mix. It resulted in uneven wear of the apex seals which, in turn, caused a loss of compression.

IMHO, using more than 1 oz. would probably lead to carbon build-up and/or fouling the plugs.

 

I run half oz per gallon without issues.

 

I've only been pre mixing for the past lets say 3k miles and I've been going with 1oz/1gal and haven't had any issues. I fully agree with too much can cause carbon build up but at the same time if you use an ash free 2 cycle it should help slow down the process of carbon build up. I think it goes without saying that too little is not worth the risk. More is always better because at the end of each season you could do an ATF wash to clear out the over load of carbon thus starting back to square one with nice clean seals at the start of the new season.

Personally I just feel better having that piece of mind knowing that the seals are well oiled because the little maintenance at the end of the year to clear out the carbon (if any) is worth not running the seals dry.

 

before every event I use a can of seafoam through a vac hose... it helps keep the carbon away

 

ATF + Rotary = bad time for the oil seals.

Do some math and think about how much sump oil your OMP is injecting and you'll see that 5oz/gal is ridiculous. That's DOUBLE what weedwhackers take.

I highly doubt we're smarter than Mazda regarding the OMP (not saying its the best solution, but I have a personaly fight against pre-mixing so I'm doing what Hailers is and injecting 2-stroke) but I think they got the lube thing down pretty well. Think about how much gas you burn in 3000 miles, than do the math and figure out the oil consumed. It's around 600:1, and people are suggesting to use a better oil @ 64:1??? & have heard 25:1!!

Math = 3000 miles and 1 qt low = pretty common. Good mileage = 20mpg = 150 gal which is 19,200 OZ of fuel and you burned 1 qt of oil or 32 oz. Your ratio is 600:1. If you manage about 12 MPG becuase you drive like a punk, then you'll be way more than a qt down. Now then, I've read somewhere that buring 1 qt in 500 miles isn't unheard of either..... track type stuff averaging say 7 mpg.... 71 gal or 9088 oz / 32 oz = 284:1... still less than half the oil some people are putting in.

I am not to be heald responsible if your motor blows up though

 

I race an E Production 2nd gen and use 1 oz per gallon as per my engine builder. FWIW, my engine is putting out around 250 hp n/a.

 

E Production? Specs on your build Don please. Thanks.

 

depends on what kind of pre-mix you use. they make a great synthetic pre-mix for motercycles you can get at specialty shops. that requires less per gal. instructions are on the bottle apparently.

 

For street cars, I use 100:1.
For high rpm race cars, I use 50:1. No visible smoking, and reduces the apex seal wear you otherwise find during teardown at the end of the season. Racing beat also recommends 50:1 for use on racing engines.
Carbon build-up on a racing engine? Do you seriously think an engine that spends the entirety of its life putting down as much power as possible is going to have a problem with carbon build-up?

 

1 gallon is equal to 128 ounces... so if you used 1 ounce of pre mix oil to one gallon of gas you would have a ratio of 128:1

 

The thing you are forgetting is that the OMP delivers undiluted oil driectly into the combustion chamber. I would think that you need alot more pre-mix to get the same effect as plain injected oil.

FWIW, I too agree with the 128:1 ratio and use pre-mix at every fill up.

 

I am assuming that the OMP is going to inject the same volume of oil whether it be sump or 2stroke from a resevior. In practice I think the viscosity of the 2-stroke will allow a greater volume of oil to be injected. Others agree. (Get my back HAILERS!!!!) Not to mention in the combustion chamber I would think that the 2-stroke by volume would do a better job of lubricating than the sump oil. My plan is to use the electric OMP and build a MAP that ties in with the duty cycle of the injectors, load, and TPS to come up with a ratio. There will be some heavy math involved and a few test of the output of the OMP at idle vs 3900 rpm (1/2 redline) becuase it is shaft driven so the output should increase linearly, etc etc, but you get the idea. I'll be shooting for a mix of 500:1 to 100:1 based on certain variables.

ScathCart - what about street vehicles that aren't constantly @ 7000+ RPM???

 

On low rpm street engines, or sub-500hp engines premixing more than 100:1 is pretty pointless. I haven't found any accelerated wear in using this ratio. Premixing an engine at 400:1, I have seen accelerated apex seal wear on an N/A street engine. Yet to get any engines apart when the guy is running 200:1, so we'll see.
At 100:1, carbon buildup is pretty minimal. I can't see any reason why this would present a problem for any street engine.
Even injecting 2 stroke using the metering oil pump I don't like. You still wind up with that stripe of polished chrome, surrounded by greater wear, immediately following the rotor housing oil injector. You never find that stripe on a premixed engine built with new rotor housings.

(I choose 100:1 over 128:1 simply b/c I live in a metric world. 500 mL full bottle of 2-stroke to a 50L fill-up works very easily for me.)

 

thanks for all the info, i've been doing about 17oz per full tank on S4 (16.6 gallon tank) so just very slightly over 1oz per gallon. sounds like thats a good mix from what everyone is saying, i'll stick with that for now and may do slightly more for track use, probably try for 100:1 on the track and just the ~128:1 on street.

i'll be switching to either Idemitsu, Royal Purple, or Redline synthetic premix soon, what do you that have experience recommend from the 3? it seems idemitsu might be the best choice since they do things specifically for rotaries, but im not too sure.

 

just to be picky but if you have 1/4 tank and you put 17 ounces in and only 12 gallons of gas you mixing 90:1 This is one reason I hate pre-mixing becuase it's never constant. You should put the oil in before the gas but you can't do that accutately becuase you never know how much gas you can get in the tank, you know roughly, but never accurately if your goal is to top the tank off. Read below than below below

FWIW - my theory. O/B's run @ 50:1 full load, ~200:1 idle and it's rather linear the ratio as throttle is applied. That premix is being used to lube main bearings, rod pins, rings etc etc. In the rotary we need to lube the apex seals. Take it as you will.... my $.02 that is often disagreed with on the subject

I'd say idemitsu becuase of the comments above and the loads and such on the apex seals are very different that the loads and such on bearings.

 

is it better to put the premix in before the gas? i have been adding premix after filling up so i know how much to put in.

 

I would imagine it would be best to put the premix in first so the fuel mixes it up thoroughly... However, to aid measurement and guessing, you can just dump a good amount of it in, then fill up, then dump the rest in.. But, by reading your gas needle, you should know about how many gallons you have to put in.... math shouldn't be that hard. Never hurts to err on the side of too much.

 

if you have a working fuel guage lol, mine is off by over 1/4 tank, i need a new cluster.

 

same here

 

Probably prior to putting the gas in, BUT the fuel pump is a constantly running pump that returns unused fuel back to the tank over and over and over again. So there's lots of mixing going on anyway.

 

Most likely the senser in the tank is bad, rather than the guage. There's checks you can make in the FSM. Either Engine Electrical or Body Electrical sections, I forget which.