I dont see the big deal. The shadow from the picture is making it look worse than it is IMO. It being only 0.5mm in depth, I see that causing no problems. To me this is nothing more than a cosmetic issue, which you wont see when its built. Im no seasoned rotary engine builder, but I have worked on piston engines and cars in general long enough (close to 10 years) to use some common sense and figure out that this wont cause much of a problem if any. Only thing I can see being an issue is next rebuild you do, wether it be 100k or more miles, the groove might have deepened to the point that its garbage. Then again maybe not, It might wear down to meet the bottom of the groove and smooth itself out. I dont see it being a big deal though at all. The most you might see is a 1-2psi of compression loss, if that much.

 

0.5mm is massive in terms of quality control for mechanical parts...

It's not like this was a 50-dollar used iron. He paid 400 dollars for it to be re-surfaced to what they claimed would be better than new.

Even aesthetic defects matter in manufacturing.

 

Maybe 0.5mm in moving mechanical parts, but for a housing, I dont see it causing issues. yes I agree the manufacture should have probably redone this housing, but it got out for whatever reason. Probably like cause has already been said, its not a major enough flaw to redo

 

You know...I got a weird question to ask...

Was this groove there before it was sent in?
Or was it created after you sent the housing?


-Ted

 

This is an example where 400$ would have been better spent towards a new housing.

Unless this has changed, JHB used to return to you different housings then you sent in (unless you specifically request your own back, causing major delays). Was the housing that came out of your engine salvageable? If the one you sent in did not have this groove, why should you be stuck with this now?

I think the cermet coating is a good process, but I don't see why JHB should even waste their "expensive material" on a housing like this.

 

I think it will probably be fine, considering theres a gaping hole right next to it (peripheral exhaust port) that doesnt seem to **** the apex seal off too much... and the oil injection hole and spark plug holes are peripheral voids just the same...

The only problem I have with this groove is its length, thats quite a duration for the gas seal to be compromised, but since it's so close to the exhaust port there shouldnt be much impact. It does extend a bit before the exhaust port into the tail of the power phase so maybe it would dillute the intake charge a bit more than usual and make a little less torque?

As for the overall quality of the JHM cermet coatings? No personal experience here.

I do recall around when they first started offering these there was at least one customer who posted photos of rotor housings which the coating had come off almost completely in their turbo motor after very little run-in... was that on teamfc3s.org? anyone? anyone? bueller?

 

ill look into it...i can only expect the worst from this thread to be honest with everyone...i cant help but shake the feeling that im going to get the title of PDQ. but is it just me? i dont know. i think there might some others on this forum who think similarly

 

several good points


i honestly dont know if it was done before or during shipping, all i know is that this is what it looked like when i pulled out. but based on the great powers of deduction,

"Since this is a JHB resurfaced housing that was ground down and built back up, clearly this is not

the case...it's just a small gap with missing material, which will affect nothing." this would indicate to me that there was knowlege of the gouge before hand...either case


VERY good point why diddnt someone else mention this? it completely passed my mind. if the EXHAUST port doesnt seems to mind the apex seal why would this? However, if this groove may infact rob the engine of tourqe, has there been any cases of the integrity of an engine being comprimized due to one housing having less tourqe? or is it a case of "your only as fast as your slowest man"

 

People almost never have exactly the same compression numbers on both rotors, and with no ill effect. my rotors are different by around 12-15psi. And the ammount of torque lost would be minimal. i wouldnt see it being over just a few lbs/ft

 

<-Not an expert, but would such deformities in the housing cause weak spots in the ceramic coating to the point where it will flake? Just a thought. I have exactly zero experience with engine rebuilds or ceramic coating. So this point may be moot. But I still would like to know.

 

As an engine builder, I can't see that there would be any damage caused to the apex seals from this groove as someone else had mentioned. The apex seals will have spent most of their time sweeping against smooth surfaces on the rest of the rotor housing and very little time going across the groove. As I mentioned earlier, there might be some exhaust gas leakage into the intake charge through the groove, but the more I think about it, the dilution would probably be a negligable amount. I'm not a ceramic coating expert, but it would seem to me that as the coating wears down from use that the groove would diminish somewhat also. I hope everything works out if you decide to use the housing. Best of luck, keep us posted.

 

I spoke with JHB today and they confirmed what I've said above. I know you're looking for unbiased opinions from people not involved, but honestly, JHB and myself are the 2 that probably matter the most here, because they are the manufacturer of the coated housings and I am an experienced builder, so there's not many otherwise who are qualified to speak on the matter.

Let's just entertain the idea that gases could pass through this miniscule scratch near the exhaust port. Before the port is open, a little gas may seep through to the next face of the rotor, where the port is already open. This next face of the rotor is still in the process of compressing it's gases and pushing them out the massive, open exhaust port. So the minute amount of gas that may have passed through from the previous face, goes where? OUT THE EXHAUST PORT.

Okay, so the previously mentioned rotor face now moves over the exhaust port, and expels it's gases. The exhaust port closes. Now you are worried about gases from the previous face pushing through to pollute the intake charge? Not a valid concern...gases will take the route of least resistance, and since the previous face is now above the open exhaust port, the gas would much rather go out that gaping hole than through this small groove.

To address Ted's last comments:

This is not a high spot, let's be clear on that. IF an apex seal breaks in an existing chrome housing, it digs out a groove like a bulldozer, pushing excess material to the side and upward like a snowplow does on the sidewalk, meaning there's extra material sticking up to wear into the apex seal. This is not the case here, as it's a perfectly flat surface with no extra material sticking up, so there's nothing to wear into the seal. There is steel under the layers of ceramic, but its 1mm below the surface, and has no affect on how the top coat performs. Since the ceramic creates less friction and rejects heat, it's also safe to assume it expands less, so expansion of the gap is not a valid concern in my eyes.

IF you got 2 nice housings for $100 then you got a great deal, not the norm. I sell very good condition stock housings with no flaking for $300-400 each. New housings are $475 from mazdatrix for FC, and $590 for FD (the FD has a stronger coating). However, these are supposed to allow more power by creating less friction than stock chrome, the surface is supposed to resist flaking and grooving like the stock chrome, and they're supposed to reject heat from combustion more than the stockers, so it's basically like saying you're getting a better product for less money.

 

Jesus. Would you return a tire you ordered online if you found that it has a slight flaw in the tread from the molding... probably not. I dont see how this is any different. Once its installed you will never ******* know it is there. I dont see it having any long term effects, any performance effects that you will be able to tell, and no problems leading to any kind of failure. Let it ride and quit stirring the pot. Im gonna go send back my boost gauge becuase one end of the supplied hose was crushed close, out of the box.

 

Kevin has had bad experience with jhb anyway.

From what i've read i would never buy a cermet coated housing produced by jhb.

I say take it up with the producer of the product. Has anyone told the bbb about their business yet?

 

I would agree if we were simply discussing tire-tread or $.10 worth of hose... Kind of a bad comparison IMO.

 

I think you're all missing a really important point, performance IS going to be effected. The tears in his eyes from something he won't even see, that both the seller (a very experienced engine builder) and the manufacturer of the product say are perfectly fine, will make it so he can't drive well and wreck his car or blow his engine, which ever comes first.

Furthermore, with my dealings with RotaryResurrection, he'll gladly answer any question that a person might have on whatever he's selling, and with his experience and the fact that he's already given a detailed answer explaining that the little deformity won't bother anything, should prove to you that he isn't trying to con you out of $400 bucks. It's a non moving remanufactured part that's over twenty years old. By your logic I should drive back to Tennessee and demand my money back because the probably twenty year old diff mount on the car he sold me broke. Fortunately, I have some common sense.

 

not really. seeing as this flaw is just as minor and will cause just as little problems. i can sort of understand where the buyer is coming from, but damn, who has to tell him its ok, jesus christ? Obviously, its not exactly what he wanted, and its not 100% flawless, but the manufacture and the seller wouldnt have let it out unless they felt it was completely fine to install with no ill effects. how is that not enough of an answer

 

I honestly don't think Kevin is trying to rip you off, but he really thinks this housing is fine. I think it's perfectly useable. I personally have used much worse, but if you're makeing 499whp that gouge and the exhaust delution of the intake charge might keep you from getting that next 1 whp. But if that's not your goal then I wouldn't worry about it. I'd worry about your cermet flaking off turning into paste and ruining everything. Like I've heard they like to do.

 

kevin, im thinking your name is that cus people are calling you that...

anyways, give him his money back, keep your "shop" or business rather in good word and honor him a full refund. if you still say its good, you shouldnt have a problem selling it right?



orig post: how pissed would you be putting together your engine, drive it for 2 months, and your apex seal becomes weak due to a gouge in your rotor housing. even tho kevin knows a lot and says it wont make a difference. are you willing to take that chance that it MIGHT work, it MIGHT not.

not bad mouthing anyone. im sure kevin is a great builder and trust worthy person. and i know he is knowledgable.

my $2....cus my opinion is more important than 2 cents. j/k

 

even if nothing bad would come having that tiny scratch. he is rebuilding his engine.... not bad mouthing your shop or saying that you provide bad business, but he is obviously not trying to just deal with defects. although i would be rebuilding my engines diffrently. with the newest parts i can get my hands on. I think all you can do is tell him your opinion over weather or not the housing will last. the next step is for him to decide if he wants it.... simple as that. if he wants to be maticulate about his parts no one should try to talk him into keeping them. its his car, so if he wants perfect parts, he shouldnt settle for less than perfect...

 

you would spend the close to $1k on new housings? When much cheaper, useable but not perfect housings exist?

 

well se i thought by getting like new housings with the coating, they were going to simply have some wear on the surface...not what i found....i realize that im stirring some **** here and making a mountain over a mole hill, i was simply concerned about what i bought. but i think im go ahead with it becuase of the cases and opnions shown....but really, the main reason why i dont really have a problem with using it is.....well, jesus! look at the big *** gape right next to it????????????doesnt really **** the apex seal off to much does it. :shrugs:

 

JHB has asked that skatingsamurai call them so that they can personally explain things and reassure him.

 

Id use it.

 

There are many vendors that would never let a part with such a defect(even if it really won't have any noticeable effect on performance) leave their shops and get into a customers hands specifically because of threads like these. If they do sell slightly defective items most often the vendor will make it very clear that the item for sale is defective or a first run prototype etc.

If JHB really cared about the way the rotary community perceives them they would never let a housing like this out their door. With the way JHBs customer service is it probably would have been a huge hassle for Kevin to try to send one housing back to get fixed or replaced. Especially since it shouldn't make a difference in this case.

I don't know about you guys but if I were buying a new housing I wouldn't expect to see any gouges in it. Granted these are not new housings but they are re coated and should have a "like new" surface. Thats the whole point of getting them recoated, along with the supposed benefits of Cermet, right?



I say if Kevin & JHB are both 100% confident that this will not have any significant performance drawbacks or cause premature engine failure that Kevin should offer a free rebuild if the engine fails down the line and it is determined to have been caused by the gouge. I know that kind of unfairly falls on Kevin's head there but he was the seller of the product to the customer, maybe Kevin could get JHB to pay for half the rebuild. What do they have to lose if the gouge won't be an issue?