OMP vs premix
03-29-11, 06:02 PM
#1
OMP vs premix
I normally wouldn't post such a noob thread unless I had a good reason to.
I'd like you to check out this RE-Amemiya video of a race p-port 20B teardown and notice specifically at 1:58 and again at 3:36 you clearly see what looks like an S4 MOP on a dry sump cover.
You can even see it right here in the preview picture \/
http://www.youtube.com/watch?v=QMRszpqmKRg
Why don't they premix over there? Is it because they have to use race gas and refueling would take too long having to mix in some 2 stroke oil?
Did RE-Amemiya hog out the OMP to deliver more oil? Did they rig up a rod to lift the lever as the throttle is opened? I don't know. Does it even work very well on a p-port application? If you keep watching the vid you'll see that there is some step wear once he starts separating plates. Not sure if it was caused by a lapping/resurfacing job removing to much nitrided layer, or maybe just sustained high RPM use?
Well I'm posting this because I'm running a streetported NA 20B and I have an option of either going premix or using a GSL-SE front cover which allows me to use an S4 MOP, same as in the vid. He just blocks off one of the ports with a bolt. So can I.
If I had my druthers, I'd prefer the OMP/MOP option for the convenience. And I figure if it's good enough for RE-Amemiya.
One problem I can think of is the S4 MOP was designed to provide enough oil for a 2 rotor with four lines feeding it at two per rotor. I'll be asking it to provide enough oil for a 3 rotor where one line feeds one rotor and the last one blocked off. What do you guys think? If I jack it open will it provide enough cc per minute at 7k?
I'd like you to check out this RE-Amemiya video of a race p-port 20B teardown and notice specifically at 1:58 and again at 3:36 you clearly see what looks like an S4 MOP on a dry sump cover.
You can even see it right here in the preview picture \/
http://www.youtube.com/watch?v=QMRszpqmKRg
Why don't they premix over there? Is it because they have to use race gas and refueling would take too long having to mix in some 2 stroke oil?
Did RE-Amemiya hog out the OMP to deliver more oil? Did they rig up a rod to lift the lever as the throttle is opened? I don't know. Does it even work very well on a p-port application? If you keep watching the vid you'll see that there is some step wear once he starts separating plates. Not sure if it was caused by a lapping/resurfacing job removing to much nitrided layer, or maybe just sustained high RPM use?
Well I'm posting this because I'm running a streetported NA 20B and I have an option of either going premix or using a GSL-SE front cover which allows me to use an S4 MOP, same as in the vid. He just blocks off one of the ports with a bolt. So can I.
If I had my druthers, I'd prefer the OMP/MOP option for the convenience. And I figure if it's good enough for RE-Amemiya.
One problem I can think of is the S4 MOP was designed to provide enough oil for a 2 rotor with four lines feeding it at two per rotor. I'll be asking it to provide enough oil for a 3 rotor where one line feeds one rotor and the last one blocked off. What do you guys think? If I jack it open will it provide enough cc per minute at 7k?
03-29-11, 09:53 PM
#2
I actually aquired an S4 OMP years ago before I started my 20b conversion. I figured a way to modify it to mount to the FD front cover. My plans to use the S4 OMP went away once I found out that my Haltech would control the 20b OMP. The internal oil feed orfice of the S4 pump is very very tinny. I'm sure they modified it to some extent. Since I'm not currently using it, I'm gonna save it for a future 4 rotor project. 
The OMP will always provide the superior lubing to the rotor housing but does nothing for the side plates, however pre-mixing will give you an oil film all over the combustion chamber (side plates, rotor faces, ect). I wouldn't be suprised that they are also premixing. Personally I'm getting ready to install my 20b OMP because I know it does the job. I will still premix mainly to help control carbon build-up. Also premixing can be done in the fuel drum itself. So there's no need to measure every time you add race fuel.
The OMP will always provide the superior lubing to the rotor housing but does nothing for the side plates, however pre-mixing will give you an oil film all over the combustion chamber (side plates, rotor faces, ect). I wouldn't be suprised that they are also premixing. Personally I'm getting ready to install my 20b OMP because I know it does the job. I will still premix mainly to help control carbon build-up. Also premixing can be done in the fuel drum itself. So there's no need to measure every time you add race fuel.
03-30-11, 05:03 AM
#5
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they run both omp and premix,
the good thing about omp is that it lubricates the hottest part of the engine around the spark plugs..
however ive been running premix for years in all my cars even my street driven FD..
these people tear their engines apart often so they dont care about carbon build up.
the good thing about omp is that it lubricates the hottest part of the engine around the spark plugs..
however ive been running premix for years in all my cars even my street driven FD..
these people tear their engines apart often so they dont care about carbon build up.
03-30-11, 12:02 PM
#6
Ah, they run both. Good to know. I'll do both too. 
I looked for my S4 NA OMP. Couldn't find it. But my GSL-SE OMP is in great shape. I'll just have to get a set of NF01 oil lines. I'll ask j9fd3s for the microfische part number when I'm ready to order, or maybe I can fab something up from a set of S4 lines I have here.
Another subject: Anyone notice the really light flywheel on that engine? I've got an RB aluminum and RB light steel flywheel here. Now I'm wondering which to throw on the 20B.
I looked for my S4 NA OMP. Couldn't find it. But my GSL-SE OMP is in great shape.
I'll just have to get a set of NF01 oil lines. I'll ask j9fd3s for the microfische part number when I'm ready to order, or maybe I can fab something up from a set of S4 lines I have here.Another subject: Anyone notice the really light flywheel on that engine? I've got an RB aluminum and RB light steel flywheel here. Now I'm wondering which to throw on the 20B.
04-01-11, 12:21 PM
#7
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the S4 TURBO pump is bigger than the S4 NA pump.
and yeah there is no carbon build up in a race engine, it runs hot enough to burn everything off. its only a "problem" on street cars
and yeah there is no carbon build up in a race engine, it runs hot enough to burn everything off. its only a "problem" on street cars
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04-01-11, 03:23 PM
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the GSL-SE is N236 (should be the same as a 12A turbo)
the S4 NA is N326 (you can't keep N326 and N236 parts even close to each other)
the TURBO is N318. off the top there's a mark or an N318 on it somewhere.
04-17-11, 06:42 PM
#12
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is there ever a concern with just premixing (no omp) Im guessing that the premix oil and fuel will seperate and since seperated you could be getting too much or too little premix especially in my case since im using e85
04-18-11, 05:38 PM
#13
2cy oil does not separate when mixed with gas with regular fuel. They become one mixture. With no OMP .5 oz per gallon is normal. 1oz per gallon if your racing. Too much premix will lower the octane, make the engine smoke, and weaken the fuel.
Now with E85??? I have no idea!
04-19-11, 09:21 AM
#14
Sir Braps A lot
premix is the way to go, i have a leaky OMP on my 13B but ive been premixing for 3 years. when i took the turbo manifold off to inspect the rotors and apex seals all have great spring left in them and little to no carbon on the rotor faces. that's why ive decided to pull the OMP go with a Banzi block off kit and just run premix. also when i did a compression check all faces show over 100PSI and the motor is 7 years old.
07-03-11, 01:15 PM
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Bump to a semi-old thread....
I've been running both on my street car since shortly after a rebuild about 15k ago. The OMP for the reason stated above and the fact that inj. duty goes to zero or near zero on long periods of decel. Premix for added lubrication in hopes of extending the life of brand new housings.
The theory is my AI will keep carbon down so it's not a problem....even for the street. We'll see.
I've been running both on my street car since shortly after a rebuild about 15k ago. The OMP for the reason stated above and the fact that inj. duty goes to zero or near zero on long periods of decel. Premix for added lubrication in hopes of extending the life of brand new housings.
The theory is my AI will keep carbon down so it's not a problem....even for the street. We'll see.
