Plasma, cement, ceramic coatings. First Impressions Part 2
 

OK its been a while, the waiting is over!
A package made it to the house today and I even found a little time to look at
the rotor housings.
This is a very quick check and at first glance they are perfect,
the width is within spec and the bore is very close, but I have yet to check the bore with a bore gauge.

Here is what I did measure.
You can see in these pictures what I found you can make your own conclusions.
I am posting what I see with out prejudice.

The time it took to get to this point doesn’t matter and I am sure no one getting housings done in the
future would have a delay like this.

I will say that I will be using these housings with nrs ceramic seals so they are close enough for
me to feel comfortable using them. After all the apex seals are over 1000 and I wouldn’t chance using
them in a housings I didn’t feel good about.

would I recommend getting housings done at jhb?
YES
would I get more housings done in the future?
YES

matt

What results do you expect, now that you have them back.

Why do choose to put the ceramics in though?
It would seem that you would prove them with stock seals then throw those ceramic seals in once t has proven to work well only changing 1 parameter, and knowing that a investment like that would be safe and sound?

Other than the time involved with tearing it down, it would seem practical to do so, and you strike me as a person that doesn’t mind taking a little extra time to be sure of something.

Good luck regardless!
How many miles do you typically see in a year?

They look great Matt...

why ceramics?
JHB suggests the use of ceramics with their housings.
also this motor is being built for a guy who wants it pinned and clearanced as well
as thermal barrier coatings on the rotors. (something I am doing myself now)
it will be run at 12 to 15 psi boost.
the last engine was run at the same boost numbers and needed to be rebuilt due to a side seal failure.
this time almost everything is now and should be reliable to 15 psi or more.
matt

they are not perfect but are much better than before:)
I really would have like to see "0" on the dial gauge all the way across the
surface but 2 thou shouldn't be enough to worry about.
matt

Silly question.. (not being critical, just seeking clarification.) I can't see the rest of your measuring jig. What reference point is the other end of your dial resting on? At first glance it looks like you have both the housing and dial base resting on a table. Is the base located by the dowel or something?

Edit--- Nevermind. After looking at the pics again I see what you were measuring. For some reason I thought you were trying to compare two different housings. Still, with this measuting technique, you're relying on the fact that the bottom of the housing is perfectly flat and exactly 90° to the housing. Since this is a surface made to be sealed with glue, I wonder if this is acceptible.

the housing is on the carriage of my lathe and the dial gauge is on the bed.
i checked the carriage with the gauge before and it is a solid "0" all the way across.
matt

You need to clamp the rotor housing to a precision ground angle plate, sitting on a surface plate, and taking the measurement with an indicator attached to a surface gage. This will tell you whats up.

for a quick measurement of flat what i have done is within .5 thou
a stock mazda housing in new condition i can get a "0" all the way across which is
what i would call perfectly flat.
the jhb housings with a slight drop off at the edges of a couple thou is close enough
it would have been nice to see perfect but i guess this is as good as it gets.
matt

more pics dude and you better show us some pics of the assembly with those

very very cool Now 2 thou out is not horrbily bad but it can be better, what would be your recomendations for Apex seals for a daily driver but a friday night racer Rx-7?

another qeustion for ya, where in Alberta do ya live?


Prôdigy

I thought these housings were ground via a machine so as to have no variance? What are mazda's tolerance on this?

Thanks for the update as I have a few housings eventually that will need this treatment:)

Are you going to check to see how much material has been added. (for Rotor clearance?)

From what I can see the look good. Alot better then used ones:)

I would use the mazda 2 piece seals they seem to be the next best thing.
I am in wetaskiwin (just south of edmonton)
later
matt

A new mazda housing is almost perfectly flat, they are all a little different
but are all very close to spec.
this falling off at the edges is due to deflection IMO .
I have yet to check the bore to see what the clearance will be like but will for sure
check rotor clearance.
matt

Hi Matt, have you made any more measurements of the housings? Interested to see how "thick" the coating is

well there is no real way to measure how thick the coating is other than to drill a hole through it in a number of places, i dont think i realy want to do that:)
as for more measurements i have not really had time been to busy working on the garage.
matt

If you make the back half of the engine you should be able to measure the gap between the apex of the rotor and the housing. This should be exactly the same all the way round. This is what went wrong with the ones Tim got.

or stack a new mazda housing on top of the resurfaced one with the dowel pins in them
and they should be the same.
they appear to be really close, maybe a thou or two out which is close enough.
but will look closer and will be clearancing the rotors before it goes together.
later
matt

For anyone who is wondering, Ceremet is a hybrid material. It's a cross between ceramic and carbide; being harder than carbide but more impact resistant than ceramic. It's an amazing coating, and the Ceremet A coating is identical to the coating used in the 1991 LeMans winner 787b.

Ceremet is most commonly used in the tooling industry as a material to make thousands of cuts for manufacturing steel parts.

What's the difference between Cermet A & Cermet B?
The JHB website doesn't go into detail other than that Cermet A is twice the price.

Kyle

Bump.
Anyone else use them or have any findings?

I'm using them in my halfbridge FD engine, and also a few customer FC engines at this point. All used with atkins or mazda seals. THey build a strong motor just like new mazda rotorhousings, with great initial compression (100-105psi after 30 minutes runtime) and great compression later (I am currently seeing 115+psi with 600 hard breakin miles on my engine with 3mm seals and solid corners). I can't comment on the power increase due to lower friction, but personally comparing them to stock housings they are certainly harder and slicker. The coating is so hard that it is in fact very hard to port compared to a stock housing.

My second big batch of housings is on it's way from JHB now. I plan to keep this as an option offering for my rebuilds for a long time.

hurry up and get that motor together so we can get more feedback. although, i love what i'm hearing so far.

porting should be done before housings are sent off to be coated.
the stuff chips off if you are not careful.
matt

if this was directed at me the motor was built makes great compression
on first start up and seems to run well.
matt

That's not realistic for my operation. Remember I am offering these in customer rebuilds. JHB's turnaround time does not allow for me to send a customer's cores off pre-ported and wait for them to come back...I cannot have an engine here for 2-3 months waiting on them. I have been doing core exchange with JHB thus far, it's the only way to get a reasonable turnaround...even so I have been waiting 2-4 weeks turnaround.

I am trying to buy up enough housings to keep on the shelf and last for a couple of months at a time, in other words keep some in circulation at all times. I am financing this out of pocket of course, to try and speed things along. Since every one of my builds is done on a per order basis, it makes no sense for me to port every housing, since not all of my builds are streetported engines, nor do all of the ported ones require the same style of port.

Porting after the fact is really my only reasonable alternative. The ones I have ported so far have not flaked whatsoever, they just took a LONG time to get through the coating.

Anyone have a website for JHB?

jhbperformance.com

I'm with Kevin...JHB will definatly be my first choice for housings over new Mazda ones anyday!
https://www.rx7club.com/canadian-forum-42/jhb-housings-rotors-524762/

Thanks to someone, I was refer to this thread.

I do have a question.. I have a giantic poster of a rotor housing from Mazda dealership.

If you look close, you see that the housing has been etched and the coating is placed on top. I'm wondering if Cermet is coated in the same manner. If not, I would think it will come off over time. If you look at the pic I post, you'll see that the etching is angled.

Can someone take a magnified pic of the ceramic coated housing? If you don't have a way to do so, send the housing to me as I have an access to dissecting scope at work (40x) with a digital cam.

Here is the close up pic of the poster I have of the rotorhousing.

https://www.rx7club.com/attachment.p...d=166203&stc=1

those are the fingers of the steel insert. that is left alone only the coating on the steel is removed then a new coating applied.
matt

Dude , more light :P

Considering that both are propriatary materials 'A ' coating is not the same as the Lemans coatings..

Also I've had 5 aircraft engine customers walk away from getting this treatment done via this comapny, (and go with std. housings), based on thier and the Ontario resellers complete lack of willingness/inability? to answer even the most basic questions.. That and thier god awful turn around time.. one of the most basic questions they refuse to answer is; wear rates with different apex seals? they either have none or are unwilling to share long term trials data.. in fact they are unwilling to be forthcoming with any basic information.

I won't be using this company ever, they give engineers a bad name..

Heres the best pics my fuji 3.1 digicam could take. Note that I am not a photographer, but this probably gets the point across. It *looks* like they grind down to the point just above where the stock steel liner is inserted. Then they build back up. This is consistent with what they tell me about the process. The depth looks to be around 0.5-1mm but I havent bothered to check.

TO those questioning the exact specs and procedures of the material and resurfacing process, JHB would be pretty stupid to GIVE away years of R&D results to the first person who asked. Bottom line, their offering seems to be working quite well and lives up to the billing, the price is right, the performance is *AT LEAST* as good as stock (which costs more, might I add), and until I find some evidence IN PRACTICE that tells me these are not what they are cracked up to be, I won't be questioning the processes or specs they use to make these.

http://www.rotaryresurrection.com/kl...b/DSCF0802.JPG

http://www.rotaryresurrection.com/kl...b/DSCF0810.JPG

http://www.rotaryresurrection.com/kl...b/DSCF0812.JPG

http://www.rotaryresurrection.com/kl...b/DSCF0813.JPG

COMPARISON OF JHB VERSUS A NEARLY NEW STOCKER with maybe 10k miles.



http://www.rotaryresurrection.com/kl...b/DSCF0814.JPG

http://www.rotaryresurrection.com/kl...b/DSCF0816.JPG

Here's my .02 for what it's worth. I work in the tooling industry and have not heard the term ceremet in many years. That does not mean there aren't other useful applications. The coatings we use are TiAlN, AlTiN, PCD(poly-crystalin diamond), to a much lesser degree chrome, and quite often nitriding(not exactly a coating).

a while a go I contacted JHB with regard to testing this coating (wear and friction) although I never to the chance to test these materials, from the materials that i did test I found that different lubricants had as much difference on wear rates as the different materials (ceremets, plasma spprayed coatings, pvd coatings etc)

So, does anyone have any information on Cermet in terms of reliability, flaking, compression, etc?

Definitely looking at a rebuild in the near future and I want to make a damn good motor. This material sounds promising, but is slightly new to me. Any info would be great.

Absolute crap.

It's too thin to have any strength.
It's not actually a suitable material to be used in a hostile environment
it's applied very badly
it takes forever to get your housings back
it peels off in the intake stroke (neat fuel)
it doesn't have any data, because it's used mainly in race applications where there are no tangable comparisons.
Not enough people have taken apart their "cermet" coated engine to find the horror story that awaits them.

but who am I to say?

A local rotary shop will have some test data in the future I hope.

I have some used housings that could use that treatment.

Thanks for the update. But do you have pictures by chance of these bad housings to back it up?

Ian

This is silly.. they've put these on the market, raised price, are reccomending what seals to use with them and are making wild ass claims..

yet they have done no physical testing and any testing they are trying to reference is still on going and in low mileage cars.. they have no data except a guess at to which seals ' might' be the best to use and they have the horrid customer service ( eg: ignored/lied to/side stepped ) when it comes to answering ANY questions regarding anything technical..

I'm not and my customers are not about to pay through the nose for the privilege of testing their product for them.. " oh you say the coatings wore off with the RA SS seals.. well thanks for telling us that. Oh and we can re-coat those for you if you want for another $500+ oh you run a p-port.. gosh we'll hurry up your order for you, it should only take 2months or so to et them to you again " * based on actual information I've received..

What a joke. I'm embarrassed they are Canadian..

That nicely sums up the truth,and my experience with JHB and cermet coating.
Totally unsuitable for the application.

I emailed them several questions a while back, I'm no engineer, so I didn't ask for wear rate data or anything too technical. Here is the guts of the questions with there awnsers spliced in. This is dirrect from them.


doridori-rx7 , do you have any actual experience with there products, or is what your posting based on assumption?



Also all I see in the above posts regarding there products are conjecture. There is nothing solid whatsoever.

What is your experience? Why do you think its unsutable?

Here are my questons to them with there awnsers:

Does the thermal barrier coating on the rotors require the rotating assembly to be re-balanced, after its been coated, because of the added weight of the ceramic?

No rebalancing required



Can you give any figures or a specific example for how much the oil temperature is lowered as a result of the rotor coating?

The cooling requirements are reduced by about 20%, temperature drops depend on the cooling system modifications and such but will be in the ballpark of 15% or more.



Do side housings need to be lapped before they get to you, or do you lap them?

We grind them, coat them, grind again and then lap and polish.



Why are the different 13b housings different in price for the cermet coatings?

The coating thickness is different; the steel liner material is different the housing preparation is different and also core costs and marketing… this would a also be a good question for Mazda!



I am planning to use NRS 3mm one piece ceramic apex seals, have these been used with your coated rotor housings yet with good results?

Yes, we also sell these seals and have 2 sets of 3mm currently on sale.



I am also curious about the break in time when using ceramic seals with ceramic coated rotor housings. It seems like, during the initial break in the harder ceramic seals might damage the coating, instead of wearing down like the stock seals would. Or that the 2 surfaces would be so hard as to never really break in?

Break in time is average, in this case its just for the seals and the cermet to burnish in. Both surfaces are very hard (silicon carbide vs silicon nitride) and they don’t break in per say nor do they need to; both are flat and true and form a good seal. Break in is more for bearings and for ferrous apex seals that distort and wear down great amounts.



Is there any length of time estimate on how long the coated rotor and side housings will last?

Our parts will far outlast stock or other aftermarket parts, we have yet to wear out a housing so I cannot give you an “expected wear out date”. Our lab data predicts in excess of 100,000 hours

Yup. I think it's safe to say that nobody really knows. It's all hearsay.

I have yet to actually see any success or failure pictures etc.

I still think I may try it.

I agree absolutly. Conjecture and hearsay. And I think I am also going to try it.

If anyone has an actual experience please post.

I will be trying a set of the A housings in a few months with my 20B. A local guy had three housings and a bunch of other stuff for sale for a crackhead price. I bought them up just because. They've been sitting on a shelf for a long time. So why not? Looks like I'll be using NRS seals with them. I'll keep everyone posted.

Ok since everyone is looking for input i will add a couple things.
this motor that was built and run with nrs seals.
started great the first crank, ran great with no real time needed to
seat seals. started cold and hot no problems at all.
due to tuning issues and a corner seal problem the motor
lived a very short time, only a couple tanks of gas.

the apex seals on the front rotor ended up broken in a very bad way.
my first thought was that the coating started to peel and took the
apex seals with them. after opening the motor this was not the case.
the coating on the housings was not the problem and the coating
stayed on very will despite being very very damaged by the apex
seals turning into smashed glass.

anyone who says that you can detonate a ceramic seal have it brake
and not damage the housing is dreaming or very very lucky.
not only did the fragments destroy the housing that came from
they managed to get back into the good housing and do a little
damage there as well.

nothing against the nrs seals i run them in my supercharged 13b
and they have taken some really hard running without problems.:)


my 2 cents
matt

No seals can take repeated detonation. Which NRS seals did you have?

I am posting my experience with the jhb housings and how that stood up to the worst thing that
could happen to them and from what i seen the coating stayed on better than i expected.

what apex seals were used doesn't matter because it was not the fault of the apex seal
that caused the failure, it was a clearance issue with the solid corner seals.
so if you are using ceramics i suggest using mazda corner seals because some of
the solid corner seals that are out there are not made very well.

matt

Don't forget to mention the inadequate seal to groove clearance of less than 0.001".

Remember when I came to check it out and I had to try and jam the 0.001" feeler next to the seal and could only get it in about 1 or 2mm.

There were 3 problems going on in that engine.

my 3 cents, Sven