Crushing the rear oil regulator increases the oil pressure. The shims just allow the valve in the front of the e-shaft to be held in the closed position.

 

There were a couple misconceptions I saw in the above quote and I addressed the first directly while answering the second by explaining the oil flow route to show how the loop line fits in.

To clarify my statements-

First, Pineapple Racing does sell a couple of washers to shim the front pressure regulator for $2.95. I explained why raising "front oil pressure " will not raise oil pressure at the front stat gear bearing.

Second, a FD rear oil pressure regulator or an adjustable MFR rear regulator or a modification to another rear regulator will raise overall oil pressure. Without a loop line you still have pressure drop reducing oil pressure at the front stat gear bearing as compared to the rear. Race engines use a MFR rear regulator and a loop line.

There is pressure drop in the oil supply to the front stat gear bearing that feeds the front rotor bearing as it travels from the filter stand through ~19 inches of passages of varying volume and smoothness with three intersections of 90 deg where the passages are simply bored at right angles to each other.

The rear stat gear bearing enjoys a ~6 inch straight shot of smooth constant volume from the same oil filter stand.

That pressure drop is what a loop line addresses.

Hope I was clear this time

 

when you say a 6" straight shot ... I'm trying to picture what exactly you're refering too. would you be able to provice a picture? I'm trying to absorb as much of this as possible but lack of engine rebuilds isn't helping.

Also about the copper nano particles, do you have a few sites to back up the statements ontop of your head (the increase in thermal conductivity that is)? I might be trying this out in the Formula SAE car that I help out on.

 

Now I understand TII, you and Adam were referring to the thermal bypass in the eccentric shaft.

As a side question, I wonder how many main bearing failures have been front vs. rear. I have had only one, a rear.

Barry

 

Okay, okay now it's clear to me now. And I actually spoke with Rob at Pineapple racing today about the line loop feature. He said yes that the line loop will help and he has done it on his race motors in the past. He also said it's more of a long term durability mod.

I will give this some thought, may incorporate it into my motor. Thanks TII for your contribution to this thread.

 

Glad to help! Sorry if I come off sounding like a know it all sometimes; the fact is that I am just very enthusiastic about the rotary engine and excited to share what little knowledge of it I do have.


As far as I know in main bearings it is usually the rear one that fails due to e-shaft flex and the loading of the flywheel/clutch mass. This is precisely why the RX-8 has a tapered rear e-shaft journal.

The loop line mod is to gain more oil pressure at the front stationary gear bearing, but only as a round about way of getting more oil pressure at the front ROTOR bearing as it is fed through the front stat gear.

I have had only one rotor bearing failure after I lost oil pressure (blown turbo oil feed line) and it was the front rotor bearing that seized- both main bearings were still perfect.

The race oil jet modification to the e-shaft also is to gain more oil pressure at the rotor bearings by using a SMALLER orifice than the stock check valved jet. This smaller orifice means higher pressure at the rotor bearing since it is a smaller oil leak.

The race oil jet just happens to be a larger leak at idle than the stock one as it doesn't have a check ball closing it off for faster warm up.

 

TII, getting back to the cooling of the housing in the sparkplug area.

I think Adam is doing a great job in addressing this, the number one problem with our rotary engines.

Do you have any additional thoughts on shrinking the growth of the sparkplug bosses besides using an alternate cooling fluid?

Barry

 

I have nothing more to add as I have never had a problem with this area.

I just machined the grooves in the rotor housing as Racing Beat suggests and used NPG+ coolant.

 

They're not important. The critical thing is to cool off the combustion area. First and foremost. Heat is not generated in the intake port area.

The air isn't in the intake port long enough to get enough heat to justify the additional heat exactly where you need it least.

Something to ponder - the coolant goes down the bottom of the engine, flows up, and then comes up through the top. Maybe the coolant coming through the top is HEATING the top of the engine and not cooling it. So, if you wanted to keep the intake ports cool, perhaps you'd want to avoid getting coolant in that area.

 

Yes you have....You just didn't relize that this was the cause.


-J

 

What were some of the symptoms?

 

Have you ever broken an apex seal?

Do you have stains on both sides of the sparkplug?

Do you have cracks emanating from the sparkplug bore?

Have you ever been linked to the Communist party.... sorry, I got carried away.
Barry

 

Also Adam's housing.

This is what breaks the apex seals. We can use stronger seals but this is the root cause of our #1 problem with our rotary engines.
Barry

 

No, I don't get the stain of blow by on my rotor housings.

I have used old rotor housings with cracked spark leading spark plug bosses, but haven't had one crack or spread in my motor.

I have certainly broken apex seals, though not the 3mm and 2mm Rotary Aviation seals I have used on the last several builds

It has been sideseals breaking with the rotary aviation seals.

I do tune for very low EGT under load with rich AFR.

 

It's not really "blow by" by definition, blow by is oil getting into the combustion chamber (usually in excess). The stain we see is the apex seal "jumping" as it passes over the spark plug hole. Which is due to excessive heat in the plug boss area, causing it to "swell".

-J

 

So, has there ever been any actually before/after testing of the coolant passage mods as illustrated here and on Racing Beat and other web sites? Is this all theoretical?

It seems like it would help but I'm curious if there is data on it.

How does one come to decide that they should do this mod? Do you decide to do it based on the coolant temps you see or on some other basis?

Thanks for the education.

 

Gracer7

Mazda embedded many temp probes within millimeters of the surface in their testing of housing temps. We don’t have that level of investigation. The best we can do is to observe teardown clues of what is happening. My next disassembly will be in about 5000 miles.

My/our problem might be solely related to high EGT’s. My engine peaks at 1000şC at 8000 RPM.

I added an idler to increase traction on the waterpump pulley. This may help.

I'm getting ready to compare water, 50/50 water/meth, and 100% meth for EGT readings.

Barry

 

Now that you mention it, I could see Mazda doing that kind of R&D.

I do have some further questions on the topic of water jacket mods. I hope you guys don't mind me revisiting that even though it came up early in this thread.

Referring to Racing Beat photos of the water jacket mod here:
http://racingbeat.com/resultset.asp?partnumber=11488


Rotorsports has a similar image on their site.

In the photo above, they etched grooves into the housings where the water flows through. I have heard people referring to this as adding "surface area" that would aid in cooling. Racing Beat's content says:
"This modification involves cutting grooves in the water jacket in the vicinity of the leading and trailing spark plugs to increase heat transfer out of the housing inner surface."

Now we know that area gets very hot and that this heat can potentially cause "localized boiling" of the coolant. However, thinking about it from a flow perspective, I wonder if this type of modification could itself cause "localized boiling". With the striations/grooves perpendicular to the flow of the coolant, I would think the grooves disturb the smooth flow of the coolant in a similar way as the water pump spinning beyond its effective range and causing cavitation.

When you run water perpendicularly over a ridged surface such as that, it starts to foam and splash. Wouldn't the same thing happen in your coolant passages and wouldn't that worsen the potential for hot spots and localized boiling?

Thanks.

 

If you cut the grooves with the flow (as opposed to the pic above) you'll weaken the rotor housing. If this weakens it to the point of more movement/expansion or even failure I don't know.

 

Maybe so. But the other side of the coin could be the 'boundary layer' effect? Possibly the grooves 'smoothen' the water flow, and coupled with the added surface area, lead to better cooling?

Worth considering I suppose. Personally I'm a fan of 'relieving' that side of the housing by hacksawing between the through bolt area and the water seal groove, just as the MFR housings are. Not only does this increase surface area, it lets the housing deform under high load situations without being permanent. In my experience it reduces the high spot around the spark plug holes, as does running the coldest plug you can get away with.

 

PDF, do you cut the bolt areas on boosted engines? How much boost have you run on these "weakened" housings?
Very interested. I am ready to try this next.

Gracer7, I only add the grooves in the area around the sparkplug at the housing side. The grooves add area and as PFD said , act like vortex generators disrupting boundary layer/smooth flow for better cooling.

Barry

 

Adam, I found this picture of a 4 rotor using your cooling idea on the rear # 3 & 4 housings.
Barry

 

interesting ... whats ontop of the engine though? All those bango bolts.

 

oiling

 

Is that something for a dry sump system?