The Number One Reliability Mod for the Rotary Engine.

[Barry Bordes]

Originally Posted by f1lthy

Barry, any more insight on this? Reading through a few things, I noticed using a bit of exhaust gas (through I assume reversion), a preheating of the rotor housing takes place, distributing thermal load and subsequently lowering housing surface temps. Their findings are interesting in that it drops temps about 20* c in the exact area in question... So is there a balance there that could be found to maybe increase the effects of this design?

Also, should rotor face temps be considered? Could higher rotor face temps (which wouldn't be obviously apparent, being Iron, takes longer to reach higher temps, as well as resisting the destructive properties of heat. On top of being near impossible to measure accurately.) play a role in this? Sustained high rotor face temps (which are, as found by mazda, higher at the leading face) at this point in timing could play a distinct role in the housing temps, just by radiation?

Being that, by design, the rotors are cooled by oil AND intake air charge causes me to consider RICE RACING's opinion on the water injection to be evidence to support this.

Thoughts?

-Matt

Matt,
I believe that the function of the water (or MW) is to stabilize the burn rate.
We really want as much heat as the engine can handle!!!
We should address only the parts that are temperature limited.
Heat is horsepower!
Barry

[RICE RACING]

EGR as you state does NOT produce power or heat, it is the inverse to that as you are limiting the amount of oxygen and therefore fuel in each chamber so "ultimate heat" and power go down not up.... it's a temp control thing and emissions thing not a power thing.

Same applies to water temperature.

Running a rotary at 90 deg C+ reduces HC, it also reduces power (proven fact).

It does not matter if its a Aixro go cart rotary or a Mazda R26B 4 rotor these engines all and in between make MAXIMUM power from 65 deg C to 75 deg C.

The key is density increase in aspirated volume, and the correlation to reduced knock events is directly proportional to the lowering of HEAT (in the air, the block etc) not increasing it........ though through the effect of combusting more stuff we do get higher end heat in the chamber..... there is no lack of heat in any rotary engine as I listed above. What there is a lack of is control of the end heat and where it is put into and this is why water injection is the #1 rotary engine modification when looking boosted applications.

Every year goes by and I run more and more water injection, and so do my customers, there is good reason for it, unless you are actively testing this and from every angle and verifying it with performance figures and long term durability tests then you really are doing nothing more than hypothesis based off very limited information be it first hand or recycled.

[Libor]

Originally Posted by RICE RACING

EGR as you state does NOT produce power or heat, it is the inverse to that as you are limiting the amount of oxygen and therefore fuel in each chamber so "ultimate heat" and power go down not up.... it's a temp control thing and emissions thing not a power thing.

We should note, that cooled EGR actualy can work as water injection I.e. controling of end-gas temperature - autoignition chemistry.

Originally Posted by RICE RACING

Same applies to water temperature.

Running a rotary at 90 deg C+ reduces HC, it also reduces power (proven fact).

It does not matter if its a Aixro go cart rotary or a Mazda R26B 4 rotor these engines all and in between make MAXIMUM power from 65 deg C to 75 deg C.

The key is density increase in aspirated volume, and the correlation to reduced knock events is directly proportional to the lowering of HEAT (in the air, the block etc) not increasing it........ though through the effect of combusting more stuff we do get higher end heat in the chamber..... there is no lack of heat in any rotary engine as I listed above. What there is a lack of is control of the end heat and where it is put into and this is why water injection is the #1 rotary engine modification when looking boosted applications.

Very true. Its balance between higher volumetric efficiency at lower temperatures of block and intake system and slightly lower frictional losses at higher temperatures and vica versa.

It seems that most people consider <100°C as success, during cruising
Many people are forgetting that water isn't only knock suppressant, but also total loss internal coolant, and honestly, how many RX-7's can run at full power for any significant length of time? Why bother with expensive engine modifications when all what is needed is a bit of water?

As far as end-gas behaviour goes, it would be interesting what direct injection of water to the trailing side of rotor face during final phase of compression could do with knock, but I must partially agree with lowering of overall EGR rate as partially burned hydrocarbons are unstable combustion species prone to autoignition and consequent detonation.

[RICE RACING]

http://www.importtuner.com/tech/impp...r/viewall.html

Nice little real world ghetto test of engine temps to back up what I was saying happens in real world rotary race engines.

Remember this is not F1 where you are running 125Deg C water temps to reduce cooler sizes etc. Fact is you will make more power on a colder engine and its more reliable. Out in real world 65 Deg C to 75 Deg C target will always win, and its compounded in a boost engine when talking knock sensitivity.

p.s. same for my daily Toyota FJ Cruiser its a real common mod to put in a lower temp thermostat, more power more reliability, less knock on normal fuel and thats NA too. Emissions ? well who give s a fuck about that. > http://www.aprpower.com/timing_gears.html

[Barry Bordes]

Originally Posted by f1lthy

Barry, any more insight on this? Reading through a few things, I noticed using a bit of exhaust gas (through I assume reversion), a preheating of the rotor housing takes place, distributing thermal load and subsequently lowering housing surface temps. Their findings are interesting in that it drops temps about 20* c in the exact area in question... So is there a balance there that could be found to maybe increase the effects of this design?

f1lthy, I believe this is the Mazda research you were referring to.
The intake section is heated by exhaust gases but it is not EGR being reintroduced into the intake itself.
It also helps vaporize the fuel for a faster burn rate.







Also, should rotor face temps be considered? Could higher rotor face temps (which wouldn't be obviously apparent, being Iron, takes longer to reach higher temps, as well as resisting the destructive properties of heat. On top of being near impossible to measure accurately.) play a role in this? Sustained high rotor face temps (which are, as found by mazda, higher at the leading face) at this point in timing could play a distinct role in the housing temps, just by radiation?

Being that, by design, the rotors are cooled by oil AND intake air charge causes me to consider RICE RACING's opinion on the water injection to be evidence to support this.

Thoughts?
-Matt

Mazda also did research on the rotor face temps. They used slip-rings for the multiple sensors embedded in the rotor. (Yamamoto '71 and '81)

We have natural EGR from exhaust port overlap. This is very detrimental to efficient burn-rate.

I need one more good housing to build a special anti-reversion experiment this winter.
Barry

[RICE RACING]

It is incorrect on a racing engine (run on the street) to assume it has EGR at full load and power, at light load yes, but at full revs/power no is more the answer, unless its choked up.

The overlap does indeed help to get rid of exhaust gases, this is how Volumetric efficiencies of around 117% are achieved........ even back in the 60's and 70's.

[Barry Bordes]

Slow burn-rate or retarded ignition makes the shallow peaks to the right of the actual trace in this depiction.

The closer the peak is to 45 degrees the better.

The area under the curve can also be increase by adding boost

The Rotary is notoriously for its slow burn-rate.
We must find methods to maximize it.

[f1lthy]

Well, isn't the obvious answer to that question the same thing Mazda did on the r26? Add a third spark source spaced properly....coupled with the added homogeny of the water injection, this would result in a more stable, faster burn rate.

Forgive the question if its a stupid one, but is raising AFR's a bit to increase burn rate out of the question? Again, with the water injection stabilizing the burn rate, do we have enough control to lean out the AFR's enough to speed up the burn rate safely? Wouldn't bringing up the flame speed this way help combat knock?

[Barry Bordes]

The third plug gave a couple of % fuel efficiency, great for endurance racing.


When we adjust our timing some of the considerations are:
An AFR of about 12.5 will burn the fastest but will not be as cool as richer AFR's.
Boost increases flame speed, as does higher CR and turbulence.
Water slows the burn rate.
Reversion gases slow the rate.

[Barry Bordes]

Originally Posted by RICE RACING

It is incorrect on a racing engine (run on the street) to assume it has EGR at full load and power, at light load yes, but at full revs/power no is more the answer, unless its choked up.

The overlap does indeed help to get rid of exhaust gases, this is how Volumetric efficiencies of around 117% are achieved........ even back in the 60's and 70's.

Does anyone have any clear graphs of the pressure traces at the exhaust and intake ports?
Mazda has one shown in Yamamoto's book but it is very blurry.
Averages from gauges don't show as much as we would like.
Barry

[Barry Bordes]

As an update.... Here is a picture of both housings as removed.

50k miles since installed, 100k miles since new.

The water passage mod seems to work great!

Barry

[My5ABaby]

Tiny pic.

[Barry Bordes]

Originally Posted by My5ABaby

Tiny pic.

Try it again.
Barry

[speedjunkie]

That's great!

[RICE RACING]

Originally Posted by Barry Bordes

Try it again.
Barry

Did you ever get around to the answer from your supplier on the BMEP + Friction to derive real BHP in the 1 bar power thread mate?