The Number One Reliability Mod for the Rotary Engine.
 

The Rotary’s biggest flaw is the hump at the spark plug opening in the housings.

http://i287.photobucket.com/albums/l...2523_IMG-2.jpg



This problem area can be minimized by using cold plugs and a good water pump. But this is the Root Cause of Apex Seal problems. Hard seals chip; softer seals warp, bow, or bend.


The actual problem was aggravated by a Mazda improvement.
Mazda found the combustion burn-rate could be improved by widening the distance between the leading and trailing plugs. In order to do this as economically as possible they kept the through-bolt locations in the same place so they could use the existing side plates. This in turn decreases the size of probably the most important water passage in the engine!
This Generational housing change is shown it the following image.


http://i287.photobucket.com/albums/l...sagesearly.png


Notice that the water passages in the top housing drawing gradually get larger which corresponds to the heat map of the housing.

http://i287.photobucket.com/albums/l...lugtemps22.jpg

The lower drawing is of the latest version with smaller water passages on the more critical higher temp section.



This is what the actual flow looks like on a 3rd housing.

http://i287.photobucket.com/albums/l.../mazda2005.jpg

We need to increase flow at passages #3 and #5.



This next shot shows the solution. The housing is ported to increase the flow at this critical area.

http://i287.photobucket.com/albums/l...IMG_8998_1.jpg


This is a critical area so as always a compromise must be had… cutting enough to increase flow while not weakening the housing surface which supports over a 1000 psi (although over a very short period of time).
Do not cut the area next the plug boss anymore than removing the casting slag. Concentrate on cutting the thru-bolt side and the floor next to the housing face. I join the 3rd gen’s end mill cuts from one side to the other. They are about 5mm deep. Try not to cut through boss for the thru-bolt but if you do it is not a big problem. I use a 6" long 1/4" burr.


I have presented most of this information before in different threads but I thought it would be best to consolidate it as Problem/Solution , especially for new guys and home engine builders.
Barry

I know you want to increase the flow to a extent, but if you remove too much material and speed up the flow by too much your end result would be worse than what you started with.

Making the passage bigger and smooth as it appears is probably worst thing to do. At least from what I gathered about cooling principles. You want turbulent flow, very turbulent, to carry heat away. Hence the grooving on "ported" housings. Large surface is rather side effect than purpose. Otherwise just play with flow rate, this is most omitted part of whole system...

Making the passage bigger would slow the fluid speed(mph) down if the flow rate(Gpm) remains the same. I have no idea if faster flow coolant is better or worse compared to slower coolant with more contact area.

exactly!!

Bigger passage is only a problem if you have no extra flow capacity. I seriously doubt Mazda designed the cooling system with zero extra flow capacity. Looks like Barry maybe onto something.

Or increase the turbulence and the surface area... *That will aid with cooling too, or make the passage zig zag, like a Koyo n flo does (I know for this application of the coolant passages it is irrelevant, but it still stands as a proven way to extract heat, allow the medium (this case water) to a longer passage do it can be heated, or cooled...

But if the flow was increased as per the OP stated it could aid with keeping it cooler, *if the flow or quantity of medium (water) passes by it, and the medium is kept cooler due too increased flow, then it could provide cooling benefits...

Although surface area is still in my opinion the greatest way to increase the cooling capacity of a system...*

But then again it's been quite a while since I've ever really had to think if anything relating to physics, so I might be off my rocker..


J.

Interesting discussion. My first thought was that increasing the surface area, say by cutting little grooves in the coolant passages, would improve heat transfer. But I'm not a mechanical engineer, nor did I ace thermodynamics some 30 years ago when I was in school for my BSEE, so I have no idea which of the techniques discussed above (individually or in combinations) would be most effective.

Barry - were those wall temp curves something you generated yourself through testing or were they found in a reference somewhere? Would be cool if someone with an ample supply of housings, appropiate test equipment and skills could rig up a test to do a comparitive evaluation of these techniques. What I'm thinking is the housing can be installed in a test jig that allows coolant to flow through at a controlled rate. A torch or similar localized heat source to heat the area of the plug holes on the housing, which would be instrumented to measure & map the temperature distribution of heat applied. Then simultaneously measure & map coolant temps as was apparently done to generate those curves. The curves would then answer which technique or combination nets the best result.

I've often wanted to place a coolant temp gauge in that exact location and datalog the results.

I think that is what Racing Beat does.

+1


-Ted

I think the reason for the material increase in that are was to use it as a heatsink to pull heat away from the sparkplug area.

Barry, you don't by chance have any of the sae papers for these changes do you? I'd love to read them.

Maybe it will work ,I hope it does . One way or another its still an innovative idea.

I've been building and tuning some of the worlds most powerful true street rotaries for 20+ years ......... I've never really had this "issue" personally nor seen on engines running in the upper stratosphere of power I am used to obtaining that have been tuned and set up correctly (eg, non BDC or HC tuned or built lol).

It must be more of a thing seen by people who have poor cooling systems? or *stupid* AFR settings the would over heat any engine (even at far less power).

Put in a decent radiator
Do proper exhaust shielding
Keep water temperature at 77~78deg C
Use AFR of 10.8:1 @ full load
Use water injection
Use Mazda Factory 2mm apex seals

You wont have any of these "problems"

However, I have seen these marks with brand new rotor housings using inferior after market apex seals and springs (to stock) on a few engines built by experts that I have had here after only completing run in of 600miles! (engines never been boosted or seen over 5000rpm) and power levels less than 150bhp....... much more from the apex seal not staying in contact with the rotor housing than anything to do with heat or distortion of the housing.

I 100% agree with Libor, get a handle on your coolant temp and you wont have these issues, in my experience, also use stock Mazda 2mm apex seals as they are most compatible with rotor housings and actually seal far better on the rotor housing in this area especially. ;)

Just trying to think outside the box...

How about we just drill through the rotor housing and just add an extra coolant line?
I've seen this done to oiling systems on 13B's but not for the coolant system...
Adding an extra coolant line into the area would:
1) add more coolant if the system can handle it, and
2) create more turbulent flow due to the "cross flow"


-Ted

I highly doubt temp is an issue at all, you only need to look at the body of the spark plug and the FACT that carbon so readily builds up there, any meaningful heat would mean no carbon would accumulate there, it is much more a sign of a mismatch of apex seal materials, after market "modifications" lol or springs used by some people where the apex seal starts to lift off the rotor housing well before the spark plug hole ;) you see it on some engines you don't see it on others.

That area on the leading plug is very cold (look at the amount of carbon accumulated on the spark plugs for verification of that fact) much more so than on the trailing plugs which are shielded :ugh2:

It's just the apex seal decides to jump off the housing and this is exaggerated by crap tunes especially ones relying on methadone injection (borderline detonation machines) that are causing apex seals to bounce all over the place :)

You see many "precision" self called "shops" wont even use new rotors let alone rotor housings in their builds and they wonder why they get odd wear patterns on the pieces of garbage they self assemble and post all over the internet and theorize as to why they get fucked up wear patterns in engines, let alone how they tune them, or what temperatures they run at.... it laughable at best, disturbing at the least.

After Market apex seal after a few hours
http://www.rotaryeng.net/Damaged-rotor-house.jpg

Stock apex seal after thousand hours
http://www.rotaryeng.net/Perry-rotor-house.jpg

Wow! Lots of replies.
Pete that wall temp diagram is from Yamamoto’s book, but it is very similar to those in the NSU and Mercedes papers.

What I would like you all to do is to go out into your garage and grab an old housing.
Now examine the water passages around the periphery. You can see how Mazda is trying to balance heat in the housing.
Their plan was disrupted by the plug move.

Now look back at that picture of the water flowing through the housing.
Do you really want to flow more water though section #6 which by its size is depriving flow through #5?
If you think higher velocity is the answer than restrict #6.

http://i287.photobucket.com/albums/l.../mazda2005.jpg


We are not going to run out of flow. It increases with RPM to the point of pump cavitation (for me around 7400rpm).

I realize this information is not for everyone. It will only be logical to some. It is really for those guys in the background who are quietly trying to build more dependability into their engines. You know who you are.

Barry

Thanks Barry, now does this information hold true to the S4 and older housings as i "thought" the S4 and older housings had a bigger "gap" between the plugs?

"the home engine builder"
Scott.

The first picture appears to have the 5/6th port actuators as on an S4 N/A.

People need to look up conduction, convection, & radiation. Do some basic experiments of you own "at home" you will see water flow is not your problem at all.

Apex seal materials, springs, and tuning + theology to certain rubbish set ups are the single biggest reliability issues in rotaries.

Use the right parts
Keep the "whole motor" cool
Keep the inside of it cool (correct tuning)

And you will not see these carbon wings lol, be it at 200bhp or 1200bhp on a 13B (all on stock std 13B-REW rotor housings)

I'll see if I can dig up a pair of CLR housings that had been modified for extra cooling tubes added for more cooling in this area for his road racing cars. He really has a lot of good experience and ideas for keeping motors alive! Most of his engine and race cars see no less than 7k rpm for hours on end.

There is many different things I could rate as #1 mods before fucking around with this on the internet advice of others.

That's just me though.

Calling this #1 reliability mod is so off base its not even funny, not to make a point Barry but it just is.

Put in a proper cooling system
Put in a proper thermostat
Put in proper drive pulleys
Tune your car right
Run the right parts on a rebuild
Find a legitimate rebuilder (#1 best bit of advice)
Find a rebuilder who has a running car to show what he preaches lol
Run a proper ignition system
Tune the car correctly
If its turbocharged make sure its water injected (absolute #1 reliability mod)
Don't use after market apex seals (#2 reliability mod)
Don't go to BDC for anything (#1 reliability mod)
Don't read anthying written by Howard Coleman (#1 reliability mod)
Use the internet mostly for porn (#1 reliability mod)

I've never had "carbon wings" LOL like I stated, some do, you have to question why???? probably cause they don't do any of the other basics properly???? Mis diagnosis and false conclusions abound........ welcome to forum hypothesis :) :001_005:

+1 on all the stuff Rice just stated.

Heres a pic of the RB solution. I know theres some engineering time behind
this as well.

http://www.racingbeat.com/images/ite...x280/11488.jpg

Not a fan of the REC Apex Seals?

http://www.rotaryengine.com/products/apexseals.htm

Wouldn’t it be more appropriate in a technical section ie. not the lounge, for responses to include a source supporting an opinion. For instance the effects of cooling… flow vs. velocity.

RX200013B- I am not sure when the widening of the plug spacing took place. I am more familar with 3rd Gens. Maybe someone can enlighten us.

rxspeed7- I would love to see some of Carlos’ cooling modifications. He is one of our Rotary Intellects.

How about the Factory Racing Engines. Here is a picture of the R26B racing housing. "The Money is No Object” project. What do their housings look like? It looks similar to the one being proposed. Well I'll be darned!
Barry

http://i287.photobucket.com/albums/l...bordes/26B.jpg

Rick Engman's place?


-Ted

BARRY,

Can you copy and post all the information(if you have time) that has been gone over on the "evil forum" forever ago. With all the real data, real tests, real results, real conclusions, real pictures, real sae papers ect ect.

That is probably more than I have time for. My typing is so slow and it seems to iritate some people when "the secrets" are revealed.

Chuck Westbrook and arghx have a great collection of papers to select from under Chuck's Notes.

I am not sure if it is proper for me to link the papers, but most can be found if titles are supplied.

What are you looking in particular?
The process for cutting perfect sideseals?
Making a cold air filter box?
Pre and post water/meth injection?
Combustion chamber pressure tests?
Two-stroke oil injection conversion with block-off plate?
Port scribing tools?
AFR Corrections Excel program?
Waterpump mods?
Oil pump and passage mods?
Oil pick-up mod?
Boost controller fail-safe off without AI operating wiring diagram?
.....Maybe PM would be best.
Barry

Huh?

I only ask because a trusted engine builder raves about them. Those and the Goopy.

Post away Barry.

I am just saying I have never ever had this problem unless its been a motor fitted with after market apex seals, a poor build from an otherwise self proclaimed expert, or a similar shoddy engine calibration to cover up some other thing they did have no experience in or just a flat out wrong opinion.

SAE papers are just that papers, if any of you have worked in a university say where papers are written and submitted 24/7 for funding and status reasons you will see some of them are only really respected by mutual love from other academics lol.

Best for you yourself to go out and prove one thing or another, DO IT YOURSELF as I have been doing for 20 years and you will see that there are many variables involved and let alone fixed variables used that have nothing much to do with reality in most of these "papers"

I'll give you a real world example, if papers are all they are cut out to be then NSU would have conquered the globe with Wankels just like most of their in house papers stated, most papers are put out to spin a positive light on a subject for various reasons (mostly to do with obtaining funding for extra research or to build an empire within an organization) let alone ones that are "sponsored" by certain commercial entities with affiliations with a said organization be it a company or an academic body.....

Moral: Don't believe everything you read, most things are proven in reality. My own reality is that carbon wings is not an issue, but then again I have a running car that makes 600bhp on petrol and water, and is faster than most pretenders lol .......... and its the same engine for 4 years. Others just post shit on the internet and have no running car ;)

What is the consensus of the effectiveness of this mod?

Adam Hayward

I would like to see the side seal notes......

Don't know who this guy is.
That website has a lot of missing links.
I'm suspicious.


-Ted

Godamn TTT, it's "Adam Heyman". :P
Google traces him back to another Calgary shop called RX-7 Specialist.
Link from the evil forum:
http://www.rx7club.com/showthread.php?t=537345

I think that says it all.
Canadians...


-Ted

Peter, Check page C-57, item 3 of the Mazda workshop manual. You know the inspection where the two apex seals are put face to face to check for wear. I don't have to tell you where this wear comes from... it comes from the hump. If you look closely at your excellent pictures of the plug openings you can see that both are polished from being raised.

If you don't like this mod please feel free to ignore completely. I am not in competition with you.

But if you want to compete... you can start by divulging your best secret mod which would help the whole Rotary Community too.
Barry

^ Best Secret?

Tune your car right!

You wont ever have these non existent problems

The apex seals wear on a taper and preferentially due to mis matched product, insufficient hardness, lack of lubrication, & poor tuning. Chopping up your rotor housing is 100% not necessary I have proved that. You just need to know what you are doing when you set up and run your engine.

200bhp or 1200bhp, some people can fuck up anything (BDC or HC) others have no issues. :cheers2:

If there is any secret then its water injection, but I already started a thread on that ;) when you have tested as many apex seals as I have and over the amount of km's at the power levels I have then I will listen to threads like this and opinions like yours, till then most of the advice is crap *honestly*

http://www.riceracing.com.au/apex-seals.htm

(no BS threads about why apex seals break lol) I have run them to a couple of mm wear in height on 600bhp motors (not fiction but fact lol) and never broke a seal or had it preferentially wear or have any carbon wings lol....... its in how much knowledge you have personally.... not what you have collected in toilet papers.

I will bet anyone who does these mods will still have preferential wear on an apex seal (any type) depending on the application.

You can see a carbon apex seal I pictured on a Peripheral Port engine (which I personally ran for a cumulative 150,000km over 5 years testing & 3 different sets of apex seals!) will wear the shoulders down, this is due to lubrication deposition and not carbon wings.

There are plenty of examples I can give across all the forms of rotary engines and seal types I have extensive experience with where the biggest root cause is apex seal lubrication and other factors and not this "hump" or the area around the plug. You only need to look at the wear on the rotor housing to see a biggest factor for apex seal wear where the gas pressure is the highest is in the center of the seal in the lower sector of the housing and this is more so when the apex seal temperature is out of control... especially in turbo engines.

This is why we water inject cars :) My #1 mod for rotaries ;)

Peter,

Tuning sounds like a good one for you to illustrate for us. A nice primmer on how to get the best out of ours engines would be great.


As for water injection. A little history. The first turbo kit that I made was in 1974... followed by making my first wastegate… then my first blow off valve ( I called it a “surge and lag pressure relief” because I didn’t know that they existed). Late 1974 I started using water injection because I had reached the fuel enrichment limit of my Spica 400 psi mechanical injection. This allowed performance exceeding a 911S, the fastest car at the time.


So I like to tune also. But a class would be great!

Right now my 5 yr old engine with about 20k miles (with housing water mods), a (10 lb spring) 12 psi boost. I think it is about normal.... 492 hp at clutch/ 418 rwhp on a 90 deg F day in New Orleans.
How should we tune it for more power at low boost?
Thanks,
Barry




http://i287.photobucket.com/albums/l...s/1k47atdc.jpg

I always thought that the exhaust port dynamics was what cause this kinda wear on the apex seal?


-Ted