Sports cats - 100 or 200 cel?

[v-rex]

Wow 120k miles. It will be years before I reach that. I'm at about 85k now and do maybe 5K miles max a year.

If any CAT can do that on the RX8 it will be the OEM one, that's a beast. My ECP cat had a warranty of two years, not sure what warranty a new OEM one would come with.

I remember speaking to TPS when i was there and they said a Japspeed hi-flo CAT might be able to pass the MOT for the first couple of years before needing replacing, and maybe if you spend more on say a racing beat one as it's bigger, you might get another year out of it, but if that's the case the OEM doesn't seem that expensive over the full life.

Of course it will all vary with usage and strictly the CAT isn't completely dead when it doesn't pass the MOT, but if legislation for these things is 120K and that means passing the MOT in all that time, then that's tough imo.

[350matt]

I think you guys are judging catalyst tech against the rather difficult case of an RX8 which is not a clean engine by any means

the load on the cat with a 'normal' engine is far less as emissions regs have typically gotten 10 times more stringent in the last 10 years
there's a lot of talk of lambda 1 being mandatory for all the engine operation ranges

[350matt]

120k miles

They expect a cat to last up to 15~ years plus for some people? Thats actually mad.. Is that even achieveable at all?

I think its worded 10 years or 120K miles

[WildMan10]

Alas, rotaries are hard on catalytic converters. It doesn’t help that the Mazda cats are worth so much leading to scroats nicking them, although I doubt that engineers took that into account in their design; it’s a good reason to have an aftermarket cat, mark it and have warning stickers in the window (more in the hope that they’ll go for an easier target than it’ll stop them).

Has anyone seen any articles covering the prevalence (ie how often? rather than the what?) of the various failure modes of Wankel/rotary engines?

I did a lot of work on fatigue and reliability, primarily on aircraft and missile systems but also including theory on car/vehicle systems. This gives me a chance to reminisce and pontificate . . . .

The prime causes of failures are the stresses of first working and, to a lesser degree, on normal stopping working. This is particularly true of electrics, electronics and, importantly for us, for car engines. For example, on Jet Provost radios practically all failures occurred on start up, which the manufacturer defended on the grounds that the design operating life requirement was based only on a continually-operating unit. I had a hard time explaining to aircrew that introducing a ground crew check before every flight would therefore make no difference and be a waste of time.

I always wanted to scream when people extolled long-life light bulbs because the life claims were highly misleading, based as they were on a continually-operating bulb at steady temperature without any cycling reflecting real world use, and the mercury in them highly polluting. The same is true today of their successors, albeit without the pollution problems.

[v-rex]

I always wanted to scream when people extolled long-life light bulbs because the life claims were highly misleading, based as they were on a continually-operating bulb at steady temperature without any cycling reflecting real world use, and the mercury in them highly polluting. The same is true today of their successors, albeit without the pollution problems.

Never switching rotaries off would definitely solve the cold and hot starting issues many start to face when their engine is going to go kaput !!

It would be interesting to see what the failure modes are. It would also be interesting to see how many are caused by people not doing the right maintenance as well. I know italian tune ups now and again are a must to clear carbon build up, and I know at least one RX8 owner (ex now) who used to wait till the oil light came on before he filled up...

[WildMan10]

I’ve always wondered why Mazda never put in a large oil tank for the oil injectors. There’s plenty of room for one of sufficient size for thousands of miles. Put in a warning lamp, preferably 2, so non-oldies* can forget about regular dipstick checks. There are plenty of AdBlue cars around with similarly-managed tanks. .

And, whilst I’m at it, a system to limit cold shut-downs causing flooding. A simple temperature-generated voice warning would do.

*Because we grew up checking oil levels regularly and old habits die hard.

[v-rex]

The Mazda powertrain engineers wanted a factory "Sohn" solution, as they were perfectly aware of the product developed to run rotary engines in aircraft, and recognised the advantages of a separate oil supply and a stable sump oil level.
to the OMP.
It was Marketing that blocked it, saying that it would be unacceptable to owners and wasn't compatible with the halo brand.

They revisited it when developing the R3 Renesis, and nearly got agreement, at least within Japan, but Mazda NA Marketing threw a spanner in the works.

[v-rex]

*Because we grew up checking oil levels regularly and old habits die hard.

I remember the conversation with my friend. You need to check the oil probably every fill up or two.

Why ?

Because the oil might be low

If it's too low the oil light will come on.

I said by the time the oil light comes on it will be too low.

Mazda wouldn't have designed the oil light to come on when it's too low.....

Tbh I didn't really have a comeback.

[Goobie]

120k miles

They expect a cat to last up to 15~ years plus for some people? Thats actually mad.. Is that even achieveable at all?

I think its worded 10 years or 120K miles

My factory cat on my Honda was still going strong after sixteen years and 188,000 miles!

still looked really good when I took it off too.

[WildMan10]

Before those scroats stole it, the cat on my 19 yr-old Accord was still fine, albeit at fewer miles than you.

I said by the time the oil light comes on it will be too low. Mazda wouldn't have designed the oil light to come on when it's too low..... Tbh I didn't really have a comeback.

Well, he has a point as the handbook says nothing more than:
@ although the car has low level and pressure warning lights, it's best to check the engine oil regularly. Note the use of 'best', which is rather underwhelming.
@ if the low level light comes on, pull over, check the oil and add oil as necessary.

I also couldn't find anything on switching off cold, only on what to do if the engine is flooded.

[v-rex]

I also couldn't find anything on switching off cold, only on what to do if the engine is flooded.

Isn't there a section on revving to 4k for 10 seconds before switching off? It's so long ago now I don't know where I read that. Am sure it was in the manual...

[v-rex]

I also couldn't find anything on switching off cold, only on what to do if the engine is flooded.

Isn't there a section on revving to 4k for 10 seconds before switching off? It's so long ago now I don't know where I read that. Am sure it was in the manual...

I thought I remembered reading that, looked at the digital manual I have and all I can see is this:

Screenshot_20210224-171329.png

On shutting it down after one adaptive redline has gone off (2009 manual I have)

I'll have a dig in my paper manual when I get home

[Ollie]

It was in a small booklet which came with the car if memory serves. I have it with my owners manual somewhere.

[WildMan10]

The money-saving section is hardly the place for that warning. In any case, that's in a series 2 (ie R3 for us) booklet and I can't find it in my copies of the series 1 (everything else) manual.

Quick Tips leaflet. Well, blow me down, that surprises me. I've neither seen nor heard of one in over 10 years of ownership and owning numerous RX8s, but googling it came up with a US version and a trader saying that every UK car came with one. The attached US version does indeed cover both aspects:

QuickTips_OilAndShutDown.png

[HarSc]

Ok, no, not in my paper manual at least...

PXL_20210224_182037272.jpg

(sorry for rotation, on mobile)

Got a short trip driving section but no rev advice on cold shutdown no idea

[v-rex]

When I next get to my car I'll check the manual and see if it's in there.

Sounds like it won't be, but I'm stumped as to where I read it then if it's not there.

[v-rex]

Yeah... When you mentioned it I was almost sure that I read it in the manual when I first got mine (I think I'm one of the few that went through the manual when I bought it even learned about the boot release lockout switch in the glovebox on day one!)

[Nanotrox]

Just had a flip through my manual and the leaflets that came with it and can't find anything hmmm could swear I read it in the manual

[Ryan Rotary Performance]

Probably the most beautiful CAT made for the Rx8.

received_444344656716233.jpeg

[ChrisHolmes]

The Rotary equivalent of Carlsberg

[Goobie]

advice from anyone who has experience of comparing the 100 cell and 200 cell sports cats.

Did anything come of this in the end Dan? I have no idea how anyone can go without one on a rotary, it even stinks my clothes out hours after....

I'm going to need some thing, but only for a few months, dunno if to get a 100 or 200. If I did recycle it on my turbo set up then I guess the 100 cel makes sense, but I doubt Il be using a cat on the swap with the power it will be pushing with the boost.

So I guess what will be easier to sell on? 100 or 200 cell?

[warpc0il]

A 100 cell is unlikely (impossible?) to get through an MOT, so there's got to be more value in a 200.

[MadTaz]

I run a 100 cel on my own car, have no issues with smell, currently have the 4inch (3 inch inlet/outlet) version of the 100cel good for operating temps of 1200 Celsius, I will be swapping over to the 5inch (3 inch inlet/outlet) which is good for 1600 Celsius when I put the turbo on in aid to reduce back pressure as much as possible whilst keeping the nasty smells away.

I wouldn't go back to decat now

[Goobie]

I run a 100 cel on my own car, have no issues with smell, currently have the 4inch (3 inch inlet/outlet) version of the 100cel good for operating temps of 1200 Celsius, I will be swapping over to the 5inch (3 inch inlet/outlet) which is good for 1600 Celsius when I put the turbo on in aid to reduce back pressure as much as possible whilst keeping the nasty smells away.

I wouldn't go back to decat now

I did have a peak at what's on offer, I'm looking at standard fitment, say's both 100 and 200 in stock, but I don't know how real time the site is. Fair few bobs for some thing I don't really need hence thinking of re-sell after I'm done with it, the £30 post is a bit of a sting for some thing that max 10kg box weight.

Are you hinting that your current fitted 100 cell will be going spare shortly Carl? I like my good's new, but I guess for some thing like this that doesn't really matter.

[Dr. FrankenRex]

I messaged the guys at Kraken on eBay and they recommended the 100cel to remove the smell with minimal restrictions. I just haven't gotten around to it yet!