Premixed fuel: good idea?
09-20-15, 07:38 PM
#26
Eats, Sleeps, Dreams Rotary
You're welcome to keep thinking that. Name one reputable rotary builder/shop who's torn down a premixed engine and not noticed a difference.
There's very little need to premix with a working OMP at stock to moderate power levels. However, those of us tracking our cars, redlining every day, spinning high rpm, and put down 350, 400, 450whp have a very serious need for more protection.
There's very little need to premix with a working OMP at stock to moderate power levels. However, those of us tracking our cars, redlining every day, spinning high rpm, and put down 350, 400, 450whp have a very serious need for more protection.
So yea, we can listen to this or that builder but the proof of 12 yrs of hard running and then some is adequate and all the proof that i need.
09-20-15, 09:23 PM
#27
RX-7 FD3S R-1
The octane number is the volume percentage of n-Octane in the fuel and it don't indicates the rate of burn. It indicates how much the fuel mixture tends to knocking. that means how big the possibility of self-inflaming of the fuel is, because of pressure.
If you want to reduce that knocking, you have to use high octane fuel. I don't know which types of fuel is buyable in the USA but in germany there is 95, 98, 100 and 102.
102 is a kind of tricky extrapolated number that indicates that the fuel has characteristics of an hypothetical fuel with 102 volume percentage of n-octane.
Because oil won't inflame itself at a pressure under the one in a wankel engine, it should cause the mixture of fuel and oil to seams like having an higher octan number.
[This is just my gues: in reality I think it realy does not matter, because I think the oil and the fuel will mix in an heterogeneous way and the kind of how the fuel in that mixture acts under pressure is not affected. ]
So:
In my opinion you don't need to worry about the change of octane number when mix fuel with 2 stroke premix oil.
I think 2 stroke premix oil is designed to burn with very less carbone arrears in 2 stroke engines. The wankel rotary engine burns at very high temperatures, so the arrears sould be even less than in 2 stroke engines.
If you want to reduce that knocking, you have to use high octane fuel. I don't know which types of fuel is buyable in the USA but in germany there is 95, 98, 100 and 102.
102 is a kind of tricky extrapolated number that indicates that the fuel has characteristics of an hypothetical fuel with 102 volume percentage of n-octane.
Because oil won't inflame itself at a pressure under the one in a wankel engine, it should cause the mixture of fuel and oil to seams like having an higher octan number.
[This is just my gues: in reality I think it realy does not matter, because I think the oil and the fuel will mix in an heterogeneous way and the kind of how the fuel in that mixture acts under pressure is not affected. ]
So:
In my opinion you don't need to worry about the change of octane number when mix fuel with 2 stroke premix oil.
I think 2 stroke premix oil is designed to burn with very less carbone arrears in 2 stroke engines. The wankel rotary engine burns at very high temperatures, so the arrears sould be even less than in 2 stroke engines.
As you said, it does not relate to the rate at which it burns but to the comparison in a test of the fuel and a sample of iso-octane.
09-21-15, 06:41 AM
#29
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On an N/A engine the fuel is usually Regular..like 87 octane.
The car is happy with 85 actually but that low of octane is not readily available.
So really all this talk of octane rating for an N/A is kind of irrelevant.
Now,sure you can Premix your fuel as a safeguard against damage,at a ratio of 1/2 ounce to one gallon,but honestly If you have a running OMP and just daily drive the thing,again.the premixing is just unnecessary.
I now see that your Post count is UP and you can post in the Main sections for further inquiries,so I will ask that in the future you do so.The info is readily available and you can search the Main Technical sections and the Archives of your series of car for further info.
Thanks...and good luck to ya..(btw,you'll really "love the smell" if you premix..haha..like 'lawnmower cologne'...lol!)
The car is happy with 85 actually but that low of octane is not readily available.
So really all this talk of octane rating for an N/A is kind of irrelevant.
Now,sure you can Premix your fuel as a safeguard against damage,at a ratio of 1/2 ounce to one gallon,but honestly If you have a running OMP and just daily drive the thing,again.the premixing is just unnecessary.
I now see that your Post count is UP and you can post in the Main sections for further inquiries,so I will ask that in the future you do so.The info is readily available and you can search the Main Technical sections and the Archives of your series of car for further info.
Thanks...and good luck to ya..(btw,you'll really "love the smell" if you premix..haha..like 'lawnmower cologne'...lol!)
09-21-15, 01:10 PM
#30
An opinion is just that, an opinion. Personally, I'd rather leverage truth and experience. With that said, I made 365 rwhp running stock motor and stock twins for 12 yrs running 15 psi on the street and 12psi at the track. Car trapped 118-120mph so the hp is right. The car pulled 20in vacuum on the day I installed a boost gauge which was year 1 and it pulled 20in on the day I sold it. I never had one single issue with the car. Zero in 12 years. I sold it to a forum member 5-6 yrs ago and my understanding is that the car continues to run flawlessly.
So yea, we can listen to this or that builder but the proof of 12 yrs of hard running and then some is adequate and all the proof that i need.
So yea, we can listen to this or that builder but the proof of 12 yrs of hard running and then some is adequate and all the proof that i need.
09-21-15, 01:26 PM
#31
your setup was sort of ideal for an MOP-only car/engine in that it was all stock. i think a lot of the "recommended" or "warranty-required" premix talk from some builders comes from the fact that many people opt to build modified engines (using seals other than OEM). that is an undeniable factor, and for those that are interested (and have been paying attention), it is just as valid because with the seal-to-sealing surface interfaces, the stock lubrication requirements sort of go out the window. it varies wildly from brand to brand.
out of curiosity, the engine you mentioned that you had build for you, is it all OEM?
09-21-15, 03:50 PM
#32
Valley's response is uncalled for IMO. You've been on the forum, and presumably owned your car for 1/10 of the time Matty has. So tone it down. He's not trying to sell anything and his experience has worth.
With that said...My personal believe based on experience (with the FD) is that neither the OMP or pre-mix is optimal BY THEMSELVES. I think the OMP was probably developed by MAZDA for owner convenience as much as anything. They didn't want to have to tell the prospective buyer of a weird and unique engine (particularly in the early years) that they had to add oil themselves. And if the owner forgot, bad terrible things happen which practically had to be warranteed. But the OMP has it's downsides which are well documented. On the otherhand those who believe in JUST premixing should watch what their injector-duty does during decel. It goes to zero. No fuel, no lubrication. And coming down a hill, aggressive driving or on the track, that can be for a prolonged period at high rpm.
If you can augment the OMP with pre-mix for a bit of additional lubrication of hard seals and there is NO downside other than a bit of hassle while at the gas pump...why not? Especially since 6 or 8 years ago you could buy both new housings for about half what they're going for now.
With that said...My personal believe based on experience (with the FD) is that neither the OMP or pre-mix is optimal BY THEMSELVES. I think the OMP was probably developed by MAZDA for owner convenience as much as anything. They didn't want to have to tell the prospective buyer of a weird and unique engine (particularly in the early years) that they had to add oil themselves. And if the owner forgot, bad terrible things happen which practically had to be warranteed. But the OMP has it's downsides which are well documented. On the otherhand those who believe in JUST premixing should watch what their injector-duty does during decel. It goes to zero. No fuel, no lubrication. And coming down a hill, aggressive driving or on the track, that can be for a prolonged period at high rpm.
If you can augment the OMP with pre-mix for a bit of additional lubrication of hard seals and there is NO downside other than a bit of hassle while at the gas pump...why not? Especially since 6 or 8 years ago you could buy both new housings for about half what they're going for now.
09-21-15, 04:49 PM
#33
Blue, I'm unaware of how you read my post but I'd appreciate it if you did not attach your personal feelings to my typed words and use that as justification to admonish me. My post clearly stated the situation within this thread and pointed out the fallacy of his post dismissing all others as opinions, even those based upon facts, and attached to such statements one of the several words which would fall under such. Speaking of fallacies, I recommend avoiding arguments of implied authority based upon assumed time. Especially when your own post contradicts, in part, what you're defending.
If you care to continue this, feel free to PM me as I don't desire to clog up this thread but did feel the need to point this out in public as you did.
If you care to continue this, feel free to PM me as I don't desire to clog up this thread but did feel the need to point this out in public as you did.
09-21-15, 06:39 PM
#34
Blue, I'm unaware of how you read my post but I'd appreciate it if you did not attach your personal feelings to my typed words and use that as justification to admonish me. My post clearly stated the situation within this thread and pointed out the fallacy of his post dismissing all others as opinions, even those based upon facts, and attached to such statements one of the several words which would fall under such. Speaking of fallacies, I recommend avoiding arguments of implied authority based upon assumed time. Especially when your own post contradicts, in part, what you're defending.
If you care to continue this, feel free to PM me as I don't desire to clog up this thread but did feel the need to point this out in public as you did.
If you care to continue this, feel free to PM me as I don't desire to clog up this thread but did feel the need to point this out in public as you did.
Last edited by Sgtblue; 09-21-15 at 06:43 PM.
09-23-15, 10:07 AM
#35
Junior Member
2stroke injection system set up
Triple-R: Engine Rebuild - Dedicated 2-stroke oil injection.
Seems legit in my opinion
Seems legit in my opinion
09-23-15, 04:29 PM
#36
^Yep. Very effective option. But of course you have to deal with packaging. What to use as a reservoir and where to install the reservoir. Not so easy on some cars. And you still have to remember to keep it filled.
...
*Some owners keep the factory system because it's relatively trouble free and requires little monitoring.
*Some people remove the factory injection system because it injects engine oil which they believe isn't as suitable, and substitute pre-mixing 2-cycle oil in with the fuel at a ratio of 1 oz. to 1 gal.
*Some owners keep the factory injection system and pre-mix at a reduced rate of ~ .5 oz. to 1 gal.
*Some owners opt for an adaptor on the factory pump which sources 2 cycle oil from an aftermarket tank.
...
*Some owners keep the factory system because it's relatively trouble free and requires little monitoring.
*Some people remove the factory injection system because it injects engine oil which they believe isn't as suitable, and substitute pre-mixing 2-cycle oil in with the fuel at a ratio of 1 oz. to 1 gal.
*Some owners keep the factory injection system and pre-mix at a reduced rate of ~ .5 oz. to 1 gal.
*Some owners opt for an adaptor on the factory pump which sources 2 cycle oil from an aftermarket tank.
...
09-24-15, 10:47 AM
#37
Junior Member
Yeah i just bought a 88 fc3s last week and it already had the connection from the crank disconnected. Im going to try to use the same tank, and set up for a yamaha blaster to set up the 2 stroke injection 
09-26-15, 08:05 AM
#38
^If you're contemplating the RA adaptor, there was also a recent review of sorts in the 3rd Gen. section on it.......
https://www.rx7club.com/3rd-generati...apter-1089280/
https://www.rx7club.com/3rd-generati...apter-1089280/
10-10-15, 02:58 AM
#40
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My take on premixing is simple. I was against it too, but after looking into it I ran into one fact that made me decide to remove the OMP and premix only. OMP's fail. There's no warning for it either. If it fails while the engine is running... it's game over. Premix will always be lubricating your engine as long as your car is running. It also is thinner, so it will reduce carbon build up. That and as a side note... it's been proven time and time again in 2 strokes... which rotaries pretty much are anyway.
10-10-15, 09:33 AM
#41
...I ran into one fact that made me decide to remove the OMP and premix only. OMP's fail. There's no warning for it either. If it fails while the engine is running... it's game over. That and as a side note... it's been proven time and time again in 2 strokes... which rotaries pretty much are anyway.
But on the FD there is not one but THREE CELs associated with the OMP. I don't think any other system is monitored as thoroughly. And all three would be shaded during a sensor check with a PFC.
And it's not "game over". As I recall, it's a 0 to 5v sensor dependent on load and rpm. When any problem appears it defaults to 5v, puts you into limp mode while providing max oil.
In my experience most owners, especially new owners on a budget, simply have a failure and use this logic to justify removing the OMP rather than fixing the issue properly.
And rotaries are nothing like two strokes.
Last edited by Sgtblue; 10-10-15 at 09:38 AM.
10-10-15, 12:10 PM
#42
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OMPs will fail occasionally, yes. I had one go.
But on the FD there is not one but THREE CELs associated with the OMP. I don't think any other system is monitored as thoroughly. And all three would be shaded during a sensor check with a PFC.
And it's not "game over". As I recall, it's a 0 to 5v sensor dependent on load and rpm. When any problem appears it defaults to 5v, puts you into limp mode while providing max oil.
In my experience most owners, especially new owners on a budget, simply have a failure and use this logic to justify removing the OMP rather than fixing the issue properly.
And rotaries are nothing like two strokes.
But on the FD there is not one but THREE CELs associated with the OMP. I don't think any other system is monitored as thoroughly. And all three would be shaded during a sensor check with a PFC.
And it's not "game over". As I recall, it's a 0 to 5v sensor dependent on load and rpm. When any problem appears it defaults to 5v, puts you into limp mode while providing max oil.
In my experience most owners, especially new owners on a budget, simply have a failure and use this logic to justify removing the OMP rather than fixing the issue properly.
And rotaries are nothing like two strokes.
Well Sgtblue, you're the expert. I'm just a new guy. And thank you for telling me how wrong I am. Though... you might want to look at this: The Two-stroke Cycle - How Two-stroke Engines Work. Looks almost EXACTLY how our engines (minus the piston vs. rotor thing) work.... only technically you may be right... it's more like a 3 stroke? But I say 2 so people understand it more easily, but hey, I don't know anything. I'm just a noob.
Also if an OMP fails (I'm pretty sure it's just an electric motor right?) and you're out driving your car... flashing a cell and it going into limp mode and trying to make it pump more oil (it failed, it's not pumping anything at all... that's why it's broke....) isn't doing any good. You're screwed. I would also say that I am a "new" owner, but I took mine off while it still worked... I actually have 3 working OMP's on a shelf... so that logic doesn't always apply. It was a preemptive decision to do things better and safer after a lot of research and discussion.
Thanks for giving your opinion, on my opinion, and pointing out again why I hate forums. It only took what? 11 posts for someone to make me not ever want to post again... cool. But again... you're the expert and what do I know. I will probably never know as much as you. You sir, are my hero.
10-10-15, 04:19 PM
#45
You are almost right about the octane number.... in reality the octane number in the Combustion Engines Fuels in the market is NOT the amount of n-octane in it, but a number taken from a test done by compressing the tested fuel and finding at what point it auto-ignites and referring this compression ratio to a sample of iso-octane under the same conditions of pressure and temperature.
As you said, it does not relate to the rate at which it burns but to the comparison in a test of the fuel and a sample of iso-octane.
As you said, it does not relate to the rate at which it burns but to the comparison in a test of the fuel and a sample of iso-octane.
10-10-15, 04:27 PM
#46
An opinion is just that, an opinion. Personally, I'd rather leverage truth and experience. With that said, I made 365 rwhp running stock motor and stock twins for 12 yrs running 15 psi on the street and 12psi at the track. Car trapped 118-120mph so the hp is right. The car pulled 20in vacuum on the day I installed a boost gauge which was year 1 and it pulled 20in on the day I sold it. I never had one single issue with the car. Zero in 12 years. I sold it to a forum member 5-6 yrs ago and my understanding is that the car continues to run flawlessly.
So yea, we can listen to this or that builder but the proof of 12 yrs of hard running and then some is adequate and all the proof that i need.
So yea, we can listen to this or that builder but the proof of 12 yrs of hard running and then some is adequate and all the proof that i need.
Rotaries designed by those who know the most about them had refined the designs over the years that many people are now finding out the mistakes of going with aftermarket seals.
The OEM seals are very hard, people call them brittle, but by design they have to be. They need to be very hard at the interface between the housing and seal. When boost pressures increase and temps rise, many have observed that some/most of the aftermarket seals are too soft and will damage the housings and live short lives. This occurs irrespective of how much lubrication is used.
OEM seals are the best for this interface.
I would only put OEM seals in my engines.
Most engine builders can definitely make observations, but they aren't running controlled DOE's. They also don't do a ton of R&D on seals. They also work in a world is poorly controlled builds. OEM engine builds are probably the best builds with all new parts, hence tightly controlled, not only on the assemblies but also the parts going into the build (all new). so its tough to say X seal is good or bad with a bunch of unknown parts. OEM you know is the most researched and tightly controlled manufacture wise, so I would go with those.
10-11-15, 02:12 AM
#47
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Sgt Blue, apparently your knowledge of rotaries is only surpassed by your grasp of sarcasm. You my keyboard cowboy friend, are my hero... God help you if they start taking warning labels off and let natural selection do it's work...
10-11-15, 09:03 AM
#49
If you check my post history in this section you'll find that my focus is and has been to be helpful. I disagreed with your post and gave specific reasons for that disagreement. If your sensitive backside is too sensitive for this forum, then get some ointment and go elsewhere. Because if you leave the new member section, it WILL get a lot worse.
As for warning labels and natural selection thing, I've been around along time...literally. And have a few real scars to prove it. With not a bit of sarcasm, I'm pretty sure I can survive some cupcake like you trying to insult me.
Last edited by Sgtblue; 10-11-15 at 09:06 AM.