mattmaclennan

Sorry, I thought you had coated your rotor housings. Fantastic to have someone on the busniess end of a plasma sprayer sharing information. what other materials have you tried?

Cheesy

most of the testing ive done has been looking at seals and coatings, most of the actual work ive done has been trying to get free samples of stuff!!. There is a stainless steel that has very similar wear characteristics (slightly better) to the mazda apex seals and is alot tougher, the coatings may also be useful on the apex seals and oil control rings DLC, TiN, CrN, WCC, TiAlN, TiCN and then there are multilayer coatings which are better again. Then there are the ceramic seals which people make now anyway, silicon nitride, boron nitride and alumina etc


actually if I could gind the housings back to spec I would have a go with a couple of coatings

timrxmotors

Grinding is no problem,send over your housings.My housings have gone off to be coated with a Nickel-Ceramic coating, which is well proven in high performance engines.

timrxmotors

And the people I spoke to were not at all surprised by what happened to the cermet coating I had.

Cheesy

I think that the ceremet coatings need to be thicker but not quite as thick as it would be by removing the steel insert, which is there because the chromium flakes off due to the lack of support from the aluminium. The plasma sprayed coatings that I have been using are around 0.2mm to 0.5mm thick, is the nickel silicon you are trying an electro plating process, one of the Poeten ones?

timrxmotors

Yes it is.It will be a while because they need to set everything up to do the job.The thickness required is no problem with this coating.The housings will have to be ground after the coating of them.

Cheesy

I had a look at that material but couldnt really test it since its not particuarly easy (cost affective) to get it evenly onto a flat surface, the coating thickness and structure is propbably more comparable to the original chromium than the plasma sprayed coatings though, are you going to try any of there piston ring coatings on the apex seals?

timrxmotors

I am looking at apex seals too,yes they can coat them,but they would prefer to make a new apex seal and coat that.I asked about a 1-piece seal,they said that is possible if made from a certain grade of stainless steel.Sounds very promising.

karism

What a wealth of knowledge here.Makes the work i did with a friend on titanium seals look like babytoys!

I will definately be comming back here very day.
karis

Cheesy

Titanium apex seals?. Ive also had a look into this and it is possible and would give some substatial benifits, if the titanium is nitride to a depth of maybe 70 microns the seal would be very wear resistant, almost as good as a ceramic and only a little bit heavier, the problem would come when the nitriding wears off and the seal would then destroy the housing. the titanium seal would also be significantly tougher than a cast iron or ceramic seal. I know that there are companys in the US that can nitride taianium, this said I havent actually tested this material because non of the local heat treatment companys could perform the nitriding

karism

Yip Titanium Apex seals.We dcided to try it,and see what happened.The engine started up quicklly,and had very good compression.

We ran it at various low RPM`s ,to bed the seals in a bit.Let it cool down for a few min.Started it up again,and did the same.Let it cool doen for a second time.

The last time it didnt want to start up.Odd,we thought.Tried again,and after allot of effort it fired up.It ran irratically ,and had no ability to rev up at all.

Engine was stripped down.What an interesting sight we saw.The Chrome was worn of the Rotorhousings.The compression area,and between the plugs the Chrome was completely worn of,the alluminium was visible!So in a matter of 40 min of running,the housings were worn out,and couldnt be re-used.

The gauling properties of the titanium agaisnt the chrome was way to high.Another problem was allso to get the Apex seal the right size,as the heat expansion rate differs greatly from mild steel. So we notched one up for the community,of what material does NOT work for Apex seals

Karis

wpgrexx

are they not surprised because you ground them down past what they were supposed to be. JHB parts are tried and tested and the results are good. The only one to have any sort of problem at all is you, and you modified them.

There are quite a few guys racing with cermet motors who have never been happier, motors are much stronger than chrome counterparts.

timrxmotors

So were they suppose to be out of spec.? 5-6 thou is a long way out.

yodaddy

I realize this is slightly off topic but I just blew my motor and was looking at the coatings JHB has to offer and I noticed they have apex seals available, which of corse they HIGHLY recomend. Has anyone had any experiencce with these seals or know anything about their hrdness, flexibility and such? thanks for any info.

wpgrexx

no they werent at all, but you should have sent them back for them to rectify the situation instead of trying to grind down a surface that you dont know the properties of and than publicly dismissing the product before they had a chance to fix the situation. 5-6 thou is way out, send it back man!!


As for JHB apex seals, I dont know anything about their properties. I have been using Mazda seals with great results on the cermet stuff.

yodaddy

thanks for the opinion. i guess i'm just worried about the seal being worn down more quickly, which really doesn't makes sence if you think about the cermet being a smoother finish providing less friction. right now it's basically a tossup for me between the ra seals(i am running now) and the stockers, guess i will just have to wait to decide until i crack the motor open and find out what failed and why.

yelwoci

Bit late on this thread but here goes:

I have raced an12A RX-& here in UK for a number of years...relatively rare occurance in UK and habe known Tim for most of those years.
I'm an engineer by training, though unfortunately no longer by profession.
I have been involved in moroting racing engieering on a number of cars in clubman racing for over 20 years.

In 1998 I started to investigate ways of recovering well engineered but worn/scored 12 housings.
I was also interested in trying to reduce the heat loss to the water and oil systems; and to reduce the frictional losses on the side seals.

I have use Ceramic coatings in Industry and know they are used extensively in F! and in the current mororbike industry.
I spent considerable time discussing the options with Aptec/Poeton, who along with Perfect Bore here in UK manufacture/coat/finish liners for Illmor, Offshore powerboat engines and nutters who overbore Fireblade, Hyabusa and R1 engines.

While Aptec's products appeared to meet the requirements there were 2 problems:
1. Their coating process was designed for tubular bores. There are minor engineering, but relatively costly procustion issues in ensuring a consistant cover with the wankel housing. Grinding back to remove inconsistances doesn't help if the deposition quality varies because of distance.
Thus we felt it was not suitable at that time or at the volume levels.

Tim then found out about JHB.

In the meantime I built a fully Cryogenic and ceramic treated Triumph Dolomite Sprint engine using Aptec coatings. In the thread above there is comment about the ring coatings that migt be applicable to apex seals. The rings are coated with Titanium Nitride. If your using Carbon or ceramic seals this would be of no value. This engine had ring gap problems (inexperience on our part), but otherwise was stunning. Perfect bore wanted tolerance figures unheard of when the engines was designed, so we have to make them up using averages.

2. There were no known engineering shops that at that time could at reasonable cost fine grind the ceramic coating on the housing. Tim has now identified such a shop.


Having identified JHB product, Tim sent new components; intending to use old recoverable housings later. The engine was to be built using these.
I saw the housings as Tim built up the engine. The errors in dimensioning were visible without measurement tools.
Given the difficulties and time lost using resources across the Pond local resources were used to restore the dimensions.

In the thread there is some comment on the effects of grinding.
Please note that all ceramic coatings that require sliding contact need grinding.
In comparison to a normal bore this is more akin to honing and is a slow process using a very fine tool. Too fast or too deep cause immediate surface problems.
The housing that came back had a polished surface indicating correct procedure.

Tim the ran the car on the road for over 500 miles before subjecting it to serious work. Exactly the same sort of procedure I used on the Dolly engine.

While Tim's facilities are not up to a top flight motorsport team he has followed good procedures in testing a new component on his race engine. This is not a road application and Tim is prepared to pull an engine if it doesn't feel right.
On a road engine a little more throttle covers a weakness.

Is there anyone out there who has also pulled and stripped a JHB coated engine?



IanC

IAN

iTrader: (3)

I only know of two people that have JHB housings. They appear to function correctly. But time will tell. I was thinking about using it on my car with a semi bridge port motor or just an extended street port. Problem with this I would never know how it will hold up until something went wrong. I would not rip apart a running motor just to see if it's holding up But I'm sure the motor will be subjected to 15psi runs and various track days

I truly hope that this IS the magic cure! Since we will have to result in machining the rx8 housings soon enough which will only add to the cost of these motors.

I've mentioned before I was worried about the tolerance and clearance issues but when I called JHB they said they are to factory spec. Not sure if that means "new" factory spec or rebuild spec etc. Also found out that another company NRS that develope ceramic seals also played around with similiar coatings.

A local rotary shop here that has been in business for ever said he does not trust coatings. He mentioned all the best but at this time he does not know the value of these coatings if any. BUt at $1400cdn for a set of housings maybe eventually he might use them?

So far I only know of two occurences of improper tolerance's. But I gather most people probable do not even measure it to begin with..................

Ian

yelwoci

Titanium Apex Seals - Why

Titanium and its alloys are an interesting aerospace material but I would have thought completely unsuited to the role of seals.
It expense and galling properties alone should be enough to avaoid it, let alone a armful of mechnaical properties in this application that are inferior to the Mazda standard, Iannetti, Carbon or Ceramic coated alloy versions.

Again why?

wpgrexx

the housings are spec to new housing spec, and when measuring a new Mazda chrome housing, they are actually sloppier than JHB's housings.

Cheesy

I wasnt looking at Ti for apex seals. But Ti seals with a TiN layer for use as compresion seals in a funny two stroke engine, in this case thermal expansion can easily be designed in. TiN is very wear resistant and will not readily gall or micro weld. For the application I was looking at it wasnt bad cost wise (much cheaper than ceramics) and has the benifit of being much lighter. It is also alot tougher then any of the materials used for apex seals even at the elevated temperatures.

yelwoci

Ah ha

I use TiN coatings on the oil and compression rings when they are to be used with Nikasil bore coatings. Reciptocators of course.

dufourmike

iTrader: (1)

Anyone know if there is a company experimenting with silcon nitride coatings, as this is the next logical step, as cermet has been used in tooling for god knows how long.

MrDirt

The stancion tubes on my mountain bike's fork are coated with titanium nitride. I can vouch that it does make a noticeable difference in performance. There is no stiction with the seals, so all you are getting for resistance is purely what you set up with the coil springs and dampening.

Cheesy

They tend not to be as tough as the TiN, CrN or DLC coatings and cant be applied very thickly, also all of these coatings work better when they are applied to a relativly hard surface so they dont crack and flake off when the surface is deformed ie a soft surface can deform more than a hard surface