OMP Oil Metering pump output and modification
#226
77 cylinders, 4 rotors...
Sohn OMP causing failures on racetrack?
I had an A-HA moment when thinking about Brett's racing buddy attributing engine failures on the racetrack to the use of a Sohn. There could be a correlation, maybe just not for the reasons stated.
Maybe both ideas are correct. The Sohn can oil starve, but most of the time doesn't. Especially on the street, since G loading like this is very seldom, but in racing it can be a couple of times a lap.
Maybe this has been covered somewhere before, if so, I haven't seen it.
Brett's racer friend had said the stock system provided positive pressure at the OMP feed hole, which we have found it does not.
BUT, the gravity feed on most Sohn installations may be subject to temporary interruption of flow, not due to gravity, but to negative G loading in the tube going to the Sohn under low speed (high G) acceleration, which, in 1st gear, can approach 1g.
Since there is a larger offset longitudinally than in height from the OMP to the Sohn tank, hard accel may cause the flow to the pump to slow or cease as normal gravity is overcome by G loading from acceleration. The pump has no ability to "suck" oil into itself. It has to be bathed internally in oil to pump that oil.
Also, changes in track slope can also affect the flow into the Sohn, when combined with lower gear acceleration. I don't believe there is enough of a difference for R/L turns to pose problems.
The stock system gets its oil from drainage from what appears to be an oil/air separator in the front cover. It is immediately above the OMP feed.
The way to "fix" this is to possibly mount the tank so there is no "slope" in the line to the pump, and the mass of oil in the tube is always subject only to normal gravity, not potential interference from G loading for the car's motion.
This is kind of an undeveloped idea so far, so its definitely subject to change!
What do you guys think of this?
Maybe both ideas are correct. The Sohn can oil starve, but most of the time doesn't. Especially on the street, since G loading like this is very seldom, but in racing it can be a couple of times a lap.
Maybe this has been covered somewhere before, if so, I haven't seen it.
Brett's racer friend had said the stock system provided positive pressure at the OMP feed hole, which we have found it does not.
BUT, the gravity feed on most Sohn installations may be subject to temporary interruption of flow, not due to gravity, but to negative G loading in the tube going to the Sohn under low speed (high G) acceleration, which, in 1st gear, can approach 1g.
Since there is a larger offset longitudinally than in height from the OMP to the Sohn tank, hard accel may cause the flow to the pump to slow or cease as normal gravity is overcome by G loading from acceleration. The pump has no ability to "suck" oil into itself. It has to be bathed internally in oil to pump that oil.
Also, changes in track slope can also affect the flow into the Sohn, when combined with lower gear acceleration. I don't believe there is enough of a difference for R/L turns to pose problems.
The stock system gets its oil from drainage from what appears to be an oil/air separator in the front cover. It is immediately above the OMP feed.
The way to "fix" this is to possibly mount the tank so there is no "slope" in the line to the pump, and the mass of oil in the tube is always subject only to normal gravity, not potential interference from G loading for the car's motion.
This is kind of an undeveloped idea so far, so its definitely subject to change!
What do you guys think of this?
Last edited by kevink0000; 06-28-2022 at 02:34 PM.
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SiNfidelity (07-24-2022)
#227
That guy wasn't someone I knew personally , but was well known in the racing scene.
You may have a point .... although we don't know how the reservoir was set up in that car that had all the engine failures . Plus , that is the only instance I've heard of so the info isn't exactly compelling.
You may have a point .... although we don't know how the reservoir was set up in that car that had all the engine failures . Plus , that is the only instance I've heard of so the info isn't exactly compelling.
#228
77 cylinders, 4 rotors...
That guy wasn't someone I knew personally , but was well known in the racing scene.
You may have a point .... although we don't know how the reservoir was set up in that car that had all the engine failures . Plus , that is the only instance I've heard of so the info isn't exactly compelling.
You may have a point .... although we don't know how the reservoir was set up in that car that had all the engine failures . Plus , that is the only instance I've heard of so the info isn't exactly compelling.
Oh I see. I thought there were multiple track failures and he pointed out every car that failed had a Sohn. I misremembered the account I guess.
#229
Quoted from my post ...sounds like just one car .
Gary that is why I only ever talk about the results on the track of the Sohn vs standard cars. The Sohn car ate engines (on my competitors car he destroyed an engine every weekend, and at Mid-Ohio he killed an engine every single session he was on track) while the standard car never had an issue. Also the amount of oil used was extremely telling. The sohn used half as much oil at best as did the standard car. You cannot and will not ever convince me the Sohn provides anything but a failure point when it is using 1/8th to a 1/4qt of oil vs a 1/2 or more qt of oil in the same session on the same track in nearly identical cars. And that is the real key. Now yes, we were running the cars hard, shifting at 9400 and the engines rarely dropped below 3k on track, but at a track like St Pete, which is a street course you are going all the way down to 2nd and back up to 5th several times per lap, 10 or 12 laps in a session, so believe this is as close as mere mortals can get to a proper stress test.
#231
I had an A-HA moment when thinking about Brett's racing buddy attributing engine failures on the racetrack to the use of a Sohn. There could be a correlation, maybe just not for the reasons stated.
Maybe both ideas are correct. The Sohn can oil starve, but most of the time doesn't. Especially on the street, since G loading like this is very seldom, but in racing it can be a couple of times a lap.
Maybe this has been covered somewhere before, if so, I haven't seen it.
Brett's racer friend had said the stock system provided positive pressure at the OMP feed hole, which we have found it does not.
BUT, the gravity feed on most Sohn installations may be subject to temporary interruption of flow, not due to gravity, but to negative G loading in the tube going to the Sohn under low speed (high G) acceleration, which, in 1st gear, can approach 1g.
Since there is a larger offset longitudinally than in height from the OMP to the Sohn tank, hard accel may cause the flow to the pump to slow or cease as normal gravity is overcome by G loading from acceleration. The pump has no ability to "suck" oil into itself. It has to be bathed internally in oil to pump that oil.
Also, changes in track slope can also affect the flow into the Sohn, when combined with lower gear acceleration. I don't believe there is enough of a difference for R/L turns to pose problems.
The stock system gets its oil from drainage from what appears to be an oil/air separator in the front cover. It is immediately above the OMP feed.
The way to "fix" this is to possibly mount the tank so there is no "slope" in the line to the pump, and the mass of oil in the tube is always subject only to normal gravity, not potential interference from G loading for the car's motion.
This is kind of an undeveloped idea so far, so its definitely subject to change!
What do you guys think of this?
Maybe both ideas are correct. The Sohn can oil starve, but most of the time doesn't. Especially on the street, since G loading like this is very seldom, but in racing it can be a couple of times a lap.
Maybe this has been covered somewhere before, if so, I haven't seen it.
Brett's racer friend had said the stock system provided positive pressure at the OMP feed hole, which we have found it does not.
BUT, the gravity feed on most Sohn installations may be subject to temporary interruption of flow, not due to gravity, but to negative G loading in the tube going to the Sohn under low speed (high G) acceleration, which, in 1st gear, can approach 1g.
Since there is a larger offset longitudinally than in height from the OMP to the Sohn tank, hard accel may cause the flow to the pump to slow or cease as normal gravity is overcome by G loading from acceleration. The pump has no ability to "suck" oil into itself. It has to be bathed internally in oil to pump that oil.
Also, changes in track slope can also affect the flow into the Sohn, when combined with lower gear acceleration. I don't believe there is enough of a difference for R/L turns to pose problems.
The stock system gets its oil from drainage from what appears to be an oil/air separator in the front cover. It is immediately above the OMP feed.
The way to "fix" this is to possibly mount the tank so there is no "slope" in the line to the pump, and the mass of oil in the tube is always subject only to normal gravity, not potential interference from G loading for the car's motion.
This is kind of an undeveloped idea so far, so its definitely subject to change!
What do you guys think of this?
solution = small surge reservoir in between the main reservoir and omp.
I have a question, is there room
and an ideal location for an inlet to be tapped into the factory omp for a fitting ?
I love the SOHN concept as I used one with my Lpg /propane 20b t rx8. Worked a treat. I was surprised/shocked at how much 2 stroke the omp actually flowed. Got a bit expensive actually 😛🤣
obviously I’d have to block the engine oil flow to pump also for the omp Mod.
thoughts?? Can it be done? Is there room ?
#234
#235
Oil flow?
now that I’m looking at it, maybe the front cover oil channel is gonna be the best option. Omp not a lot of room there.
need a front cover disassembled grrr
Last edited by SiNfidelity; 07-27-2022 at 02:19 AM. Reason: Add picture
#236
Registered
#237
Registered
iTrader: (2)
I recently talked about pressure differential with the sohn compared to the engine oil sump, and I believe others in the past have done a deep dive of how the omp truly operates with the physics of fluid dynamics in mind.
#238
Registered
Ya engine oil must be pushed to the Omp. So how can gravity fed oil supply possibly give enough to the Omp. Add In the g force factors of driving and I don't trust it.
#239
Registered
iTrader: (2)
My question was always, what exactly does the fuel atomization and combustion look like inside a renesis engine?
I tried finding a see through renesis engine example on youtube to no avail, but I did find a couple videos of test bench rotary engines with a see through style side plate so we can watch in slow motion.
The first link is about as basic as a rotary engine can get. It looks like he is likely to be premixing this gas a little, and the AFR is unknown, but looking at the likely very rich mixture, it is pretty evident how much that air fuel mixture covers essentially all of the apex seal. Given the side seal side seal and exhaust port design of the renesis, I would think premixing the fuel would allow it to have better coverage in that area as well. Some food for thought, not very scientific, but I was always curious what this truly looked liked.
The second link looks like an updated version of the rotary engine, too bad this design never made it to Mazda. The company currently has some projects with DARPA for I am assuming aircraft engines, and recently did a generator project for something in the military. @TeamRX8 You get your hands on one of these yet?
I tried finding a see through renesis engine example on youtube to no avail, but I did find a couple videos of test bench rotary engines with a see through style side plate so we can watch in slow motion.
The first link is about as basic as a rotary engine can get. It looks like he is likely to be premixing this gas a little, and the AFR is unknown, but looking at the likely very rich mixture, it is pretty evident how much that air fuel mixture covers essentially all of the apex seal. Given the side seal side seal and exhaust port design of the renesis, I would think premixing the fuel would allow it to have better coverage in that area as well. Some food for thought, not very scientific, but I was always curious what this truly looked liked.
The second link looks like an updated version of the rotary engine, too bad this design never made it to Mazda. The company currently has some projects with DARPA for I am assuming aircraft engines, and recently did a generator project for something in the military. @TeamRX8 You get your hands on one of these yet?
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SiNfidelity (07-27-2022)
#240
depends on how good I set up the reservoir and line I guess. It worked fine in my 20b. Worked too good actually. Was using shittonnes of 2stroke. The the official measurement.
#241
77 cylinders, 4 rotors...
AGREE 100%. BASED on what we already know about the omp flow chart, the SOHN mod could really only be blamed if there were starvation issues due to race conditions.
solution = small surge reservoir in between the main reservoir and omp.
I have a question, is there room
and an ideal location for an inlet to be tapped into the factory omp for a fitting ?
I love the SOHN concept as I used one with my Lpg /propane 20b t rx8. Worked a treat. I was surprised/shocked at how much 2 stroke the omp actually flowed. Got a bit expensive actually 😛🤣
obviously I’d have to block the engine oil flow to pump also for the omp Mod.
thoughts?? Can it be done? Is there room ?
solution = small surge reservoir in between the main reservoir and omp.
I have a question, is there room
and an ideal location for an inlet to be tapped into the factory omp for a fitting ?
I love the SOHN concept as I used one with my Lpg /propane 20b t rx8. Worked a treat. I was surprised/shocked at how much 2 stroke the omp actually flowed. Got a bit expensive actually 😛🤣
obviously I’d have to block the engine oil flow to pump also for the omp Mod.
thoughts?? Can it be done? Is there room ?
I would just buy the Sohn. Its a lot of work to adapt a different source and as you know its rather important to have it working properly. Its something I wouldn't mess with and I mess with a lot of other things. Its just good to know you have one less garage mod you have to double check all the time. Which, in my garage is a good thing.
Last edited by kevink0000; 07-27-2022 at 04:43 PM.
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SiNfidelity (07-28-2022)
#242
77 cylinders, 4 rotors...
Engine oil is not pushed to the OMP, it is a gravity drain from one of the small bearings, in the front cover, I can't remember which one.
Last edited by kevink0000; 07-27-2022 at 04:44 PM.
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SiNfidelity (07-28-2022)
#243
77 cylinders, 4 rotors...
#244
77 cylinders, 4 rotors...
1/2 oz gallon is not enough even for super-awesome oil. Ok for low throttle, not OK for anything close to full throttle.
Last edited by kevink0000; 07-27-2022 at 04:47 PM.
#245
No respecter of malarkey
iTrader: (25)
apology if it wasn’t clear; assuming gasoline fuel with the MOP still in place and functioning properly it is. Again, don’t waste your money on an unnecessary Sohn kit.
If you don’t have a MOP then premixing 1 oz/gal is the NA racing standard.
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If you don’t have a MOP then premixing 1 oz/gal is the NA racing standard.
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Last edited by TeamRX8; 07-27-2022 at 08:03 PM.
#246
Registered
iTrader: (1)
While I'm not trying to sell anyone Sohn adapters, the arguments against it are strange or not different from the stock setup. But at least with the Sohn I can choose different oils for injection and for engine lubrication/cooling.
Premixing solves different a different problem from the Sohn: getting oil into places where the stock injection system can't - side seals. Premixing and running a Sohn are not mutually exclusive.
Last edited by Loki; 07-27-2022 at 11:53 PM.
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SiNfidelity (07-28-2022)
#247
Have you looked at a Sohn setup closely? There is no slosh volume, it's filled with oil all the way up to whatever reservoir you set up. g forces make no difference, unless the car is upside down. Nothing in the injection setup requires oil pressure, it only requires oil to be available at the OMP entry, which the Sohn provides.
While I'm not trying to sell anyone Sohn adapters, the arguments against it are strange or not different from the stock setup. But at least with the Sohn I can choose different oils for injection and for engine lubrication/cooling.
Premixing solves different a different problem from the Sohn: getting oil into places where the stock injection system can't - side seals. Premixing and running a Sohn are not mutually exclusive.
While I'm not trying to sell anyone Sohn adapters, the arguments against it are strange or not different from the stock setup. But at least with the Sohn I can choose different oils for injection and for engine lubrication/cooling.
Premixing solves different a different problem from the Sohn: getting oil into places where the stock injection system can't - side seals. Premixing and running a Sohn are not mutually exclusive.
the oil line itself from the reservoir is not gonna empty under g”s the arguments against it are quite baffling to me.
I guess if one was set up extremely poorly, then u Cld be in trouble. But u wld have to be a complete moron to mess it up
Last edited by SiNfidelity; 07-28-2022 at 11:31 AM.
#248
I would just buy the Sohn. Its a lot of work to adapt a different source and as you know its rather important to have it working properly. Its something I wouldn't mess with and I mess with a lot of other things. Its just good to know you have one less garage mod you have to double check all the time. Which, in my garage is a good thing.
I think the blue circle Cld be the sweet spot. Not a lot of room between manifold and Omp. But maybe enough. And thread a grommet to block off the oil out from front cover
#249
77 cylinders, 4 rotors...
That is indeed what the racing standard is in most places I have seen. I still have questions about that.
I also know from my previous experience that any 2 stroke piston engine would seize when run at high or full power with that ratio, 128:1. The bearings might tolerate that ratio for a period of time, but the piston and cylinder wall would become good friends, even with modern cylinder and piston coatings superior to what Mazda uses and has used in the past in their rotaries
Since we are talking about the OMP here, it should be noted that the stock OMP at the stock settings delivers 3x-4x that ratio at full throttle. And, it can be modified to deliver more than that.
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SiNfidelity (07-28-2022)
#250
77 cylinders, 4 rotors...
Have you looked at a Sohn setup closely? There is no slosh volume, it's filled with oil all the way up to whatever reservoir you set up. g forces make no difference, unless the car is upside down. Nothing in the injection setup requires oil pressure, it only requires oil to be available at the OMP entry, which the Sohn provides.
While I'm not trying to sell anyone Sohn adapters, the arguments against it are strange or not different from the stock setup. But at least with the Sohn I can choose different oils for injection and for engine lubrication/cooling.
Premixing solves different a different problem from the Sohn: getting oil into places where the stock injection system can't - side seals. Premixing and running a Sohn are not mutually exclusive.
While I'm not trying to sell anyone Sohn adapters, the arguments against it are strange or not different from the stock setup. But at least with the Sohn I can choose different oils for injection and for engine lubrication/cooling.
Premixing solves different a different problem from the Sohn: getting oil into places where the stock injection system can't - side seals. Premixing and running a Sohn are not mutually exclusive.
I have the opposite view of the OMP vs premix. I believe the OMP does a better job on the side seals/irons than the apex seals or aluminum housings. Based on one of my engines that had a verified history, the OMP did a great job in 185000 miles of keeping the side seals and irons lubricated. The apex seals and chrome were severely worn. I reused the front iron in another build that is running currently. If that engine was premixed also, it may have gone well over 200k miles.
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SiNfidelity (07-28-2022)