That picture in the previous post is from the parts catalogue, that's the most detail you'll get apart from dropping the pipes off the car and taking measurements yourself.

 

Here's some pictures which might also help



Glad to see the stock exhaust has the X-pipe already fitted.

And some individual pictures of the cat pipes.

 

Oh yes, I agree. I was suggesting the mini-cat as a straight pipe "no cat" solution which would be more for racing. I haven't attempted changing the emissions spec. I'm not sure if the US based ecms have this similar ability. Thanks for pointing that out. I'll have to investigate as I did not know this was a possibility on these cars.


Do you know if anyone has plotted A/F with high flow cat options and operations? I can say with my 200 cell kit for the XKR, I have not noticed any impact from the rear 02 effecting trims negatively yet. I have not attempted this with a cat delete or 100 cell as I'm sure that would.
My current system for the 07-09 Setups has the factory orientation of 02. I'll have to monitor the mpg and fueling as we go along.
A big impact on efficiency and power on those that have used high-flow cats can be related to O2 positioning and the cross sensitivity related to positioning and/or quality of cat. I did replace the front 02's when installing the high-flow cat to make sure oil/fuel/age etc wasn't effecting the efficiency.

Thanks for the F-type pics Cambo. We can see in the F-type catalyst photo they incorporated a two substrate system with the front O2 being mounted between the catalyst. Water that is produced does not collide with the sensor with this method , rather collide with the substrate. In addition this allows for faster heating of the sensor as well as less hydrogen in the exhaust sampling which improves the a/f quality control.

Seems Capristo mounted theirs behind the catalyst which is another approach. With the front and rear 02 in the same stream with no catalyst in between, I suppose there wouldn't be as much if any cross sensitivity since they are sampling the same amount of hydrocarbons. I wonder if they noticed any fueling effects with this method of approach. This is the same approach I'm planning to take, or do a two substrate 200 cell with the sensor mounted factory style.

And as Cambo stated, the flange wouldn't be that hard for any machine shop to make.

Good thread.


Regards,
Derek Fricke

 

As far as I know there is only one way to do it, and only one guy who properly knows how (and it's not me). But for sure it's possible with ANY Jag vehicle regardless of it's original market specification.


Here is a dyno run with AFR plots from a 4.2L N/A XJ

Both runs are with 100 cell cats fitted. The red run is with minicats on the downstream sensors, the green run is with the minicats removed and Euro2 emissions settings.





You can see the lean patch on the red run, just after the transition to WOT. The minicats slow down the response time of the rear sensors, so the ECU can't get the fuelling right.


In addition to this, the owner of that car reported a major improvement to his highway economy, dropping from 9.8L/100km to 9.2L/100km, it was also evident on the tailpipes of the car, with the minicats the tailpipes would soot up quite quickly, with them gone the pipes were much cleaner.


Exactly the same as every other Jag model since the late 90's...

 

Hi Oracle,

Thank you very much for that video - its instrumental in the process golf deciding whether to de-cattify my friend's Big Cat!

Just wondering if you have any more video of the exhaust characteristics? I can only tell so much from this and am not sure how much is reverberation from the garage around it or where the microphone was placed (I presume a phone in the cabin with the roof down).

And I'm truly inspired by the detail and fervour displayed by everyone contributing to this thread - just brilliant guys!

This is what forums are for!!!

Aus V8S

 

It really depends upon the quality of the catalyst matrices and their ability to stand up to the exhaust temperatures. One of the reasons that a lot of factory tunes run 'fat' Air:Fuel ratios is because leaner=hotter, and by running richer AFR you can keep catalyst temperatures cooler. Challenging because emissions are higher with richer fuel mixtures.

We are currently working with Aston Martin Racing on developing a cat setup for their race cars. They had tested some from another supplier but found they were breaking down and melting within a couple of hours of track use. For some time, they have been using stock catalysts with the primaries removed.

Our catalysts increased power significantly, but also stood up to 55+ hours of track testing this year, including 14 hours of a 24 hour race in a very hot environment.

It is one of the reason that good sport catalysts are not cheap. Cheap ones can be fine if not used hard, but if you give them a lot of welly. In my experience, the pops, crackles etc. are not what wrecks them, but high Exhaust Gas Temperatures are.

FWIW, we have sport cats, and decat pipes in development and will be looking for product testers

 

Hi Guys,

I'm very sorry for being vague here and cannot provide details, but I had some warranty work done which could have been as a result of the cats I had on.

My advice after much time and cost is as follows;

1. MAKE SURE YOU USE EURO4/5 compliant race cats - Ive ordered and am fitting HJS HD Cats

2. Never use mini cats - the FTYPE is an intelligent car and the sensor readings impact engine timings

If you have fitted race cats in that are not EURO 4/5 compliant my advice is to take them out!

Will make a vid once I get the HJS HD's in.

Peace

 

Thanks for the update. And sorry to hear about your problems.

Reading between the lines I can pretty much guess what happened. I've trying to tell people for some time now that minicats are not a good idea on these cars.

Hope you're back on the road soon.

 

Certainly on the right page with eliminating the mini-cats. As Cambo has pointed out, these engines certainly prefer to leave the rear o2 signal unmolested.
HJS makes some great quality cats, good choice there.

If possible, what was the orientation and how the front 02 were mounted? Was this mounted in front of the Catalyst or did they mount the bung behind it? Contamination of the front sensor may have been a culprit if mounted on the front side.

Many variables to consider, Cats, 02, tune or the mini-cat.

 

Please see response below.

 

Vibrant GESI units seem to be a good Euro4/5 alternative to HJS Cats - for a much lower price.. Anyone looked at these?

http://vibrantperformance.com/catalo...1468_1469_1326
http://www.summitracing.com/parts/vpe-7525


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