I understand the Sohn Adaptor is just that, "an adaptor", that allows you to hook up a separate tank to draw (preferrably 2 stroke) oil into the combustion chamber instead of regular engine oil. The OMP still regulates flow (through the EMS), increasing the oil flow at increasing RPM and/or driving condition needs.

However the Sohn Adjuster, I think I misunderstood in the past. I thought the Sohn Adjuster allowed you to increase the base level flow amount of oil (thus you could increase it for track days or premixing purposes) at the Adjuster instead of premixing in the tank. "And" the OMP/EMS still regulated flow for increased RPM and driving conditions. That sounds like it should be right!

But now I read on the www.rotaryaviation.com site and It sounds like the Sohn Adjuster is in place of the EMS/OMP system. Thus the base level you set on the Adjuster would be the set amount you are always injecting into the combustion chamber.
That means you would have to set the level at the highest level you would need under any RPM or condition you'll be driving at. Thus you'll have more oil injected than you need, mostly all of the time.

Can that be Right!?!

I'm still on the fence about doing the Adaptor (mostly due to resevoir placement options & a low level indicator would be nice). But if I understand the Adjuster correctly, it doesn't seem to be a very good application for the RX-8 at all.

Please help me to make an educated decision about this mod!

 

This is correct. It goes in between the oil metering pump and the front cover. It still functions as normal providing the same oil metering rates as stock. The only difference is that it is pulling oil from a reservoir rather than the engine oil system. That is it's only function. It allows a different oil source. The rest remains as always. This is how mine works on my RX-7. I'm not sure if they offer a different one that does more or not. If you need more oil flow, look into the Racing Beat oil metering pump mod.

 

Thanks RG.

But Racing Beat's OMP (MOP as they refer to it) mod is for FI. I have not yet gone that route as I am waiting for all the new FI products to "eventually" become available. It looks as Racing Beat just alters your stock OMP to flow more at high RPM's. I might ship my OMP off to them when I go FI. But without a Sohn Adaptor, Racing Beat's mod won't pull oil from a separate resevoir. That's where my question/confusion is. I understand the part about the Sohn Adaptor itself. The Sohn Adjuster benefits is where I'm kinda stumped?

 

If I understand the adjuster, it replaces the "counter" that fits on the OMP, for a fixed delivery rate when the stock ECU isn't present.

However, being an adjuster, it can be turned clockwise from the "min" setting, to deliver more oil PER REV.

The rate would still be a fixed ratio at all rpms, not dynamically variable like the stock system, but that is its prime intended use - for an aircraft operating at a fixed throttle position without an ECU.

If you still have the ECU and counter, you would have the best of both worlds, and would have no use for the adjuster.

S

 

Thanks Stealth for the clarification.

So why is there even an adjuster developed for the RX-8?

Why would anyone have a need (or want) to run a set flow rate or why would the ECU not be present?

 

What has been stated on the Adapter is correct.

On the Adjuster - in stock form there is a dial-type controller on the side of the OMP that the computer controls the rotation of to control the oil flow rate.

In order to use the adjuster, you must remove this controller and replace it with this adjuster that is screwed tight at a fixed rate position, thus the controller is no longer connected and cannot set and/or control the flow rate (like for increasing for RPMs/load).

As for the flow rate while using the adjuster - you set the adjuster to a particular position to set the flow rate at a "fixed" level. If you do this, there will be varying of the flow rate based on RPMs only, not load.

I feel this device has limited applicability and is not necessary for NA engines - you would be flowing too much oil under most normal driving conditions which could lead to excessive deposit buildup and premature cat failure. IMHO, FI engines are the only ones that may benefit from the adjuster as they can likely use the higher flow rate all the time with the additional stresses they generally see.

Hope this helps.

 

It was developed for Aviation use of Rotary engines (not for RX-8's) where the aviation-specific ECU may not have the ability to control the OMP flow or it is just "safer" to fix it at a flat higher rate (remember, no cats for aviation engines)

 

the Renesis is now the prized NA rotary engine in aviation, the 20B for FI

 

Even in an FI engine, I wouldn't think you'd want a constant and max set amount of oil flow all the time. Racing Beat's OMP mod seems much more functional.

So basically, the Adjuster is listed on the rotaryaviation web site for application with the RX-8, but it has no real practical use in the RX-8.

 

I'm still alittle confused on this entire thing, is it usefull on a N/A 8 with nitrous?

 

I'm now confused too!

Does the Adjuster determine oil flow to a set amount and bypass the 60 OMP settings or not?

 

Here is the exact language out of Richard Sohn's Brochure - what's your interpretation?



ADJUSTER FOR THE RENESIS OMP

The RENESIS engine is becoming increasingly popular for conversion for use in
experimental airplanes. Using the Oil Metering Pump for top lubrication is an open
question, because most after market EMSs do not provide an output for OMP control.
In the RX8 automobile the OMP oil flow is controlled by engine RPM and pump-rate.
The pump-rate control is activated by the engine computer. This pump-rate control is
used to increase oil flow when there is an increased power demand at low engine RPM.
This condition does generally not occur in an airplane.

When the engine is used with an EMS with no output for the OMP, the only option is to
mix some oil in the fuel for top lubrication. The preferred oil used for this method is two-
stroke oil for its ability to readily mix with gasoline and lower combustion residues than
regular motor oil.

To overcome this draw back in aircraft use, the OMP pump-rate control can be fixed to a
certain position, and the oil flow will only change with engine RPM.

Solution.
The RX8OMP is equipped with a position sensor, (pic 1.), which monitors the position of
the control shaft on the pump. This position sensor may be replaced with an adjuster
(pic.2.) to set the control shaft to a fixed position. In this way, the OMP is fully
functional, giving an oil amount comparable to oil mixed in the fuel.

 

I think my problem on this topic is that I'm comparing apples to oranges. (Aviation vs. RX-8 Renesis Engine application)

In an "Aviation" Renesis Engine conversion an Adjuster is an alternative to premixing. (still not sure how flow changes with RPM if there is no ECU input, but I guess it doesn't matter here)

In a "non-FI RX-8" Renesis Engine the ECU/PCM and OMP/MOP handle the correct flow rates. So an Adjuster really isn't a good application. You wouldn't want to set the Load & Low RPM flows to a fixed rate when the proper rates are already being achieved.

For FI though...

1) The Sohn Adjuster (in addition to giving the benefit of essentially premixing outside the tank by being able to increase base flow rates at the OMP) also gives you the option to increase Low Load & Low RPM flow rates (albeit to a fixed flow rate)

2) Racing Beat's mod increases just the high RPM flow rates. (Maybe that's all that is needed?)

3) Add also the option to premix in the tank and...

Well I'm confused again on what if any combo of the 3 is the best FI setup?!?

I'm gonna get the Sohn Adaptor because I like the mod...and it's easy non-FI applicable. I hope by the time I go FI there is lots of info on this topic as the FI applications get better in 2007.

If I had to do it today...from all I've read I'd have to go with Racing Beat's mod and Premix in the tank for insurance. The Sohn Adjustor seems to be just a Premix alternative with a down side of set flow at low RPM and Load.

 

the reflash did increase flow. That is part of what is killing our engines, too little oil flow

 

IMO you are mistaken, everything I've seen indicates the MOP runs at 100% under open loop heavy load, that would limit software mods to low rpm/low load conditions. Only modifying the MOP or doing pre-mix will overcome this limitation, well a sohn adaptor too I suppose

 

The previous explanation I gave fell a little short - from the wiring diagram I see that the "counter" on the front of the pump is actually a position sensor and feedback switch for the stepper motor behind.

The stepper motor positions the blade that controls the flow - the old RB mod just increased the stroke/flow at all settings.

When the ECU sees the need, the stepper motor can position the blade for more flow. Could sense high throttle pedal demand at low revs, or high coolant temp, or any other stress the ECU is set for. The adjuster is strictly rpm dependant, so would usually be set too rich.

S

 

from the RacingBeat site:

 

You mean Sohn "Adjuster".

The Adaptor just allows you to feed the oil from a separate container. The Adjuster is what can change flow rate.


I'll try and call the Sohn folks at PCV Tech. again today. If I get through I'll post any helpful information I can get.

 

Let me take one more stab at this in a step-by-step way to minimize confusion (confused myself at times with this discussion)

The circular "blade" (as Zoom calls it) in the center of the OMP and Adapter sets the "base" oil flow rate for the OMP. From this "base" flow rate, flow ALWAYS increases with RPM at a pre-defined rate via the computer.

(FYI - there are two connections to the OMP for the computer - one for the blade position mover/sensor, one for the OMP flow computer control itself. Only the blade position mover/sensor is removed to use the adjuster).

Normally the computer varies the base rate up or down (via the position mover/sensor), mostly due to load, and the flow stiil increases proportionately at the standard, pre-defined level, on top of this base rate with RPM.

When you use the "Adjuster", you are taking the computers ability away to set the "base" rate and are setting that yourself, with the OMP flow still increasing with RPMs based on a standard algorithm. The adjuster does NOT set a single rate for all the time.

With this in mind, you do not have run way to rich if you do not choose to, but can, with a little experimentation, increase the oil "base" (with the standard incremental RPM increases) to add more lubrication up to the OMP base flow rate maximum.


The problem as I see it with doing this is that it is very much an educated guess as to where to set it with no way (other than seat of the pants) for the average person to tell if you are running too much or not enough "base" rate.

This is one of several reasons why I have chosen to stay with the computer controlled setup (other being better oil from Adapter should add better lubrication anyways and I also run FP60 which adds more lube via the gas).

Hope this helps some.

 

Didn't you mean adjuster here?

 

Corrected in response - thanks!

 

Am I the only one who notices that 100:1 is nowhere NEAR the actual rate?

At that rate you would have to top up a whole quart every two tanks of fuel. There is NO WAY we inject that much, even driving hard.

....and that is why engines are dying, Mazda backed off the injection rate to please the "average" dont-give-a-damn owner, and went too lean.

Does anyone use that much oil, even with the new flash?

S

 

exit, stage right even ...