Mixing the gas??
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Junior Member
Joined: Jan 2005
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From: Twin Cities
Mixing the gas??
I just bought a 79 rx7 and the guy told me that you have to pour oil in the gas tank. Is this true? And if so how much should you put in if you fill the tank from empty? What kind of oil ect.
Thanks this is my first rx7
Thanks this is my first rx7
My wife bought me 2 RX-7s
Joined: Aug 2001
Posts: 2,328
Likes: 3
From: Saskatoon, Saskatchewan, Canada
If the car is stock, you don't have to mix oil with the gas. However if the car's OMP (Oil Metering Pump) is not working, or has been removed, you will have to mix.
Open your hood and look at the carburator. There should be two plastic lines running to the drivers side of the carb. These lines are routed just over the thermostat and then curve around the front of the engine and go down to a small pump that injects oil from the pan into the carburator. If the lines are broken or removed, or if the pump isn't working (unlikely) the engine won't get the lubrication it needs.
If you need to mix, use 2 stroke mixing oil, the kind you'd use in a snowmobile or chainsaw. Use no more than 1 oz per gallon.
Open your hood and look at the carburator. There should be two plastic lines running to the drivers side of the carb. These lines are routed just over the thermostat and then curve around the front of the engine and go down to a small pump that injects oil from the pan into the carburator. If the lines are broken or removed, or if the pump isn't working (unlikely) the engine won't get the lubrication it needs.
If you need to mix, use 2 stroke mixing oil, the kind you'd use in a snowmobile or chainsaw. Use no more than 1 oz per gallon.
Do a search on premixing, and you'll find all the info you need.
This way is much easier
http://rotaryaviation.com/oil_inject...p_adaptors.htm
This way is much easier
http://rotaryaviation.com/oil_inject...p_adaptors.htm
Originally Posted by quiklilrex
Cool I'll take a look and see whats goin on. The guy was putting 10w30 into the tank. I didn't think that was right.
thanks
thanks
~T.J.
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Thread Starter
Junior Member
Joined: Jan 2005
Posts: 43
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From: Twin Cities
93 octane? The guy told me that 87 was better. Now I'm all confused. I know how to check for the omp now and the lines to the carb, but if it is working correctly what pump gas should I use. And how about if I'm premixing. I guess I'll check everything out when I tear the carb apart. I have to change the acc. pump anyway.
Thanks for everyones advice- keep it coming
Thanks for everyones advice- keep it coming
Originally Posted by Snapshot
If yours is stock just use 93 octane & check your oil level frequently.
^^^ well its just a matter of if your OMP doesnt work you need to do it. It just lubricates the moving parts of the engine, if you don't have it im sure your engine wouldnt last to long...
^^^ well its just a matter of if your OMP doesnt work you need to do it. It just lubricates the moving parts of the engine, if you don't have it im sure your engine wouldnt last to as long...
Rockn' The Galant
Joined: Jan 2005
Posts: 1,901
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From: Shreveport, LA
Pre-mixing makes it to where when you use 2-stroke everything burns off better which is ESENTIAL in a rotary engine from what I've been told.
Personally, I use Royal Purples Racing Two-Stroke...does it do any better? Probably not but that's ok because I can order it online and not have to worry about the store. I was scared to premix and truth be told I don’t know if I’m doing it right even now, I just do the following, 7 dollars worth of gas then I pour about 3 seconds worth of oil in BEFORE I poor the gas in…seems to be working!
- Tech
Personally, I use Royal Purples Racing Two-Stroke...does it do any better? Probably not but that's ok because I can order it online and not have to worry about the store. I was scared to premix and truth be told I don’t know if I’m doing it right even now, I just do the following, 7 dollars worth of gas then I pour about 3 seconds worth of oil in BEFORE I poor the gas in…seems to be working!
- Tech
Joined: May 2002
Posts: 5,972
Likes: 37
From: Ottawa, Soviet Canuckistan
Okay, let's try and cover all the bases.
1. The OMP is a pump that Mazda installed on our cars to take small amounts of oil from the oil pan and inject them into the intake to mix with the air and gas. The reason for this is because this is the only way that the Apex Seals can properly be lubricated. The result is that our cars burn small amounts of oil on a regular basis, and are supposed to do so.
2. The OMP itself can't fail, but the rubber seals inside it can degrade over time, causing the pump to not be able to pump very efficiently or at all. These seals can be replaced, and it's actually really simple and cheap to do. I rebuilt my OMP with the kit that Lowe's Performance sells (search for Lowe Performance here on the forum and give them a call). This is cheap and easy insurance to make sure your car is getting it's oil.
3. Many people decided that they would rather pre-mix oil with their gas instead of using the OMP. There are a few reasons for this. First, the oil that gets taken from your oil pan was designed to lubricate under conditions of intense heat and pressure, but to resist burning (which would be a good thing in piston engines). This means that since it wasn't an oil specifically designed to burn away cleanly, that perhaps it won't cleanly burn away and will leave residue (carbon deposits) in the engine. Also, the oil in your oil pan can get "dirty" if you don't change your oil frequently enough, and a lot of people aren't comfortable pumping this "dirty" oil into their engine to be burned. So people premix with two stroke. Two stroke oil is designed to burn off when mixed with gasoline, and leave a lubricant behind. This sounds like exactly what we need. For Mazda to have our cars burn two stroke from the factory though, they would have had to add a two stroke resivoir, and try to get people to fill it. People will change their oil more frequently than they would think to refill their two stroke resivoirs, so Mazda thought it would be better to do it the way they did.
4. You can buy an adapter from rotaryaviation.com to have your OMP take two stroke from a resivoir instead of 10w30 from the pan. Which brings me to another thing, the 10w30 vs 20w50 thing. I dont' know about you guys but the Mazda manual that came from my '84 specifically says that I should be using 10w30 unless I'm in a region which never sees temps under 30 degrees (Celcius). I know I don't live in one of those regions.
5. Now for the fuel octane. This has been discussed over and over and over again on the forum. All that octane does is resist detonation due to pressure. Gasoline will explode (combust) under two conditions. When there's enough heat, and/or when there's enough pressure. What you want is for the gas to explode only when your spark plugs give the spark. If you're driving a piston powered car, or a rotary with forced induction, then you run the risk of the gasoline exploding earlier than you want it to because of the high pressure in the combustion chamber. If it explodes at the wrong time, it will try to force the rotor (or piston) back the opposite way, or at least put undue stress on the rotor, seals and whatnot because the blast's energy isn't focused in the right place/direction. Higher octane = less ability to combust from pressure. For a regular old naturally aspirated (carb or FI), the pressure is nowhere near high enough to cause detonation, and so you'll get just as much power and drivability out of 87 octane as you will out of 94 octane. In fact, I've heard that race car drivers used to bring low-octane gas to races when driving rotaries, because it ran better than race fuel. You're throwing away good money if you buy higher octane than you need because it doesn't give any power, like the common misconception.
6. Little side note: The main reason why people think octane = power is because with higher octane you can force a more pressurized air/fuel mix into the chamber. More pressurized air/fuel means more air/fuel to combust. More air/fuel to combust means more power. The only thing is that you have to have some kind of forced induction (ie: turbo or supercharger) or a high-compression engine to take advantage of this. My teacher's Saab 95 Aero Wagon with the High-Output turbo has a computer that can sense the octane rating of gas based on a multitude of sensors (O2, A/F, knock) and adjust the turbo's pressure to take advantage of the higher octane.
Premix Advantages:
- Cheap insurance if OMP Fails
- Arguably better lubrication after burning
- Cleaner burn-off than 10w30
Premix Disadvantages:
- 1oz/gallon is something like 100times more oil than your OMP puts out, so you're actually adding a large amount. This costs money, and could be argued that "too much of a good thing" could be a bad thing, because it might not burn as cleanly when there's that high of a concentration
- It's a Pain In The ***, and if you forget, your engine goes unlubricated
The way I see it, the OMP works, don't screw with it. Rebuild your OMP so that it won't fail, check your lines for cracks, and if you wanna run 2-stroke, then get the adapter.
Jon
1. The OMP is a pump that Mazda installed on our cars to take small amounts of oil from the oil pan and inject them into the intake to mix with the air and gas. The reason for this is because this is the only way that the Apex Seals can properly be lubricated. The result is that our cars burn small amounts of oil on a regular basis, and are supposed to do so.
2. The OMP itself can't fail, but the rubber seals inside it can degrade over time, causing the pump to not be able to pump very efficiently or at all. These seals can be replaced, and it's actually really simple and cheap to do. I rebuilt my OMP with the kit that Lowe's Performance sells (search for Lowe Performance here on the forum and give them a call). This is cheap and easy insurance to make sure your car is getting it's oil.
3. Many people decided that they would rather pre-mix oil with their gas instead of using the OMP. There are a few reasons for this. First, the oil that gets taken from your oil pan was designed to lubricate under conditions of intense heat and pressure, but to resist burning (which would be a good thing in piston engines). This means that since it wasn't an oil specifically designed to burn away cleanly, that perhaps it won't cleanly burn away and will leave residue (carbon deposits) in the engine. Also, the oil in your oil pan can get "dirty" if you don't change your oil frequently enough, and a lot of people aren't comfortable pumping this "dirty" oil into their engine to be burned. So people premix with two stroke. Two stroke oil is designed to burn off when mixed with gasoline, and leave a lubricant behind. This sounds like exactly what we need. For Mazda to have our cars burn two stroke from the factory though, they would have had to add a two stroke resivoir, and try to get people to fill it. People will change their oil more frequently than they would think to refill their two stroke resivoirs, so Mazda thought it would be better to do it the way they did.
4. You can buy an adapter from rotaryaviation.com to have your OMP take two stroke from a resivoir instead of 10w30 from the pan. Which brings me to another thing, the 10w30 vs 20w50 thing. I dont' know about you guys but the Mazda manual that came from my '84 specifically says that I should be using 10w30 unless I'm in a region which never sees temps under 30 degrees (Celcius). I know I don't live in one of those regions.
5. Now for the fuel octane. This has been discussed over and over and over again on the forum. All that octane does is resist detonation due to pressure. Gasoline will explode (combust) under two conditions. When there's enough heat, and/or when there's enough pressure. What you want is for the gas to explode only when your spark plugs give the spark. If you're driving a piston powered car, or a rotary with forced induction, then you run the risk of the gasoline exploding earlier than you want it to because of the high pressure in the combustion chamber. If it explodes at the wrong time, it will try to force the rotor (or piston) back the opposite way, or at least put undue stress on the rotor, seals and whatnot because the blast's energy isn't focused in the right place/direction. Higher octane = less ability to combust from pressure. For a regular old naturally aspirated (carb or FI), the pressure is nowhere near high enough to cause detonation, and so you'll get just as much power and drivability out of 87 octane as you will out of 94 octane. In fact, I've heard that race car drivers used to bring low-octane gas to races when driving rotaries, because it ran better than race fuel. You're throwing away good money if you buy higher octane than you need because it doesn't give any power, like the common misconception.
6. Little side note: The main reason why people think octane = power is because with higher octane you can force a more pressurized air/fuel mix into the chamber. More pressurized air/fuel means more air/fuel to combust. More air/fuel to combust means more power. The only thing is that you have to have some kind of forced induction (ie: turbo or supercharger) or a high-compression engine to take advantage of this. My teacher's Saab 95 Aero Wagon with the High-Output turbo has a computer that can sense the octane rating of gas based on a multitude of sensors (O2, A/F, knock) and adjust the turbo's pressure to take advantage of the higher octane.
Premix Advantages:
- Cheap insurance if OMP Fails
- Arguably better lubrication after burning
- Cleaner burn-off than 10w30
Premix Disadvantages:
- 1oz/gallon is something like 100times more oil than your OMP puts out, so you're actually adding a large amount. This costs money, and could be argued that "too much of a good thing" could be a bad thing, because it might not burn as cleanly when there's that high of a concentration
- It's a Pain In The ***, and if you forget, your engine goes unlubricated
The way I see it, the OMP works, don't screw with it. Rebuild your OMP so that it won't fail, check your lines for cracks, and if you wanna run 2-stroke, then get the adapter.
Jon
Rotary Freak
Joined: Mar 2003
Posts: 1,711
Likes: 0
From: Calgary, Alberta, Canada
For those contemplating using this adapter, I've been running one in my 12A-powered '85 GSL for almost two years, and I have no regrets whatsoever. If you're considering this option I've just finished replying to a post by David Grimes on the subject, detailing the installation process, ordering info, costs and experiences. Here's the link:
https://www.rx7club.com/1st-generation-specific-1979-1985-18/does-anyone-have-rotary-aviation-omp-replacement-399043/
https://www.rx7club.com/1st-generation-specific-1979-1985-18/does-anyone-have-rotary-aviation-omp-replacement-399043/
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