Hi,

A friend is considering swapping out the OEM catalytic converters on his V8S F-Type and I'm wondering if there is any experience on the effects of this out there on this forum.

Apparently the OEM cats are in-line units with two cats on each side arranged in series - the first (closest to the headers) is a 600-cell unit separated by the O2 sensor from a 400-cell unit located rearward in the same physical 'can'.

My friend is considering changing to custom-made 100-cell cats on each side - with a switch to Euro-2 compliant engine management to maintain the fuelling function of the O2 sensor but deactivating it's monitoring of the function of the 600-cell catalytic converter's function as an actual catalytic converter.

I'm interested to know if anyone has done it or heard of what it does to the car?

- does it affect the pops 'n crackles?
- does it affect the exhaust volume with exhaust flaps open/closed?
- does it drone?
- does it improve throttle response and/or perceived performance of the car?

I'm not sure what the effects would be but I know for a fact that when I CLOSE the exhaust flaps (i.e. make the car QUIETER) on my V8S there seems to be a definite IMPROVEMENT in throttle response - probably due to the increase in back-pressure - leading me to wonder if the more open 100-cell cats might drop the back-pressure of the OEM units a bit too far - this actually lowering the engine's performance.

Over to you guys...

Cheers,

JD
Aus V8S

 

I think we wait with bated breath?

As to what happens, it probably depends on what is he hoping to achieve with this modification...

 

I'm still concerned with the longevity of ANY cats. Since the pops and crackles are caused by dumping some raw fuel, this has to have a negative effect on the life of the cats. I have the active exhaust on ALL the time, and I hope Jaguar planned on the reduced life expectancy of factory cats with all that extra raw fuel being dumping into them over time.

(Sorry didn't mean to hijack)

 

The pops and crackles are there all the time, even on cars without active exhaust. However, your point is an interesting one. Only time will tell.

 

Cats are generally destroyed by metallic contaminants, not by unburned or partially combusted fuels.

 

The cats on my R53 Works survived 9 years of pops and crackles on overrun, as fuel was injected to cool the exhaust valves. HTH

 

I think he might mean used up and much as destroyed, at which point yes, the cats would be used up more quickly. But i dont think anyone should worry about the factory cats as thats why there are 8 and 10 year emissions based warranties.

 

13 years on my R53 Works.

 

It doesn't look like its a very common mod judging by the lack of responses here!

Cheers,

JD

 

There are lots of posts on this in the XK section. The modification suggested appears to be similar to what people are doing with their xk models. Or maybe it's the XF. All I know is I've read it somewhere on here. Seems like I also recall they had to put the O2 sensor in some special part of the exhaust flow to get it to read right and let the injection system function correctly.

 

Changing the cats is a reasonably common modification on earlier model Jags. I think since the F-Type is still quite a new model not many people have gotten into these sort of mods yet. The XF and XK has been modified a lot more, but they've been around longer too so more have ended up in the hands of people who like to modify their cars.

 

See below

 

Per this discussion striking up, I decided to jump on the wagon and buy a set of cats to investigate. I've build some for my test mule XKR and have been planning on jumping into the F-types as well.

One thing to keep in mind, you mentioned better throttle response with the exhaust flaps closed. Sometimes due to so much discussion on the net and car talk, this is misinterpreted as "back-pressure". This is in fact, more related to "flow velocity". With the low end engine flow, the additional cross sectional area of the open valve, can slow the velocity profile. On the high-end, this additional cross section is needed for the higher volume of air flowing through the engine. By having the valves open on the lower end, this in fact can slow the velocity profile by having too much cross sectional area.
This is all related to Bernoulli's Equation (Euler's Eq) :
Pressure + 1/2 (Density)(Veloctiy)^2 + Density(gravity acc)(height)= Constant

From this equation we can deduce the equation for a pipe:
A1*V1=A2*V2

 

Decreasing area = increasing velocity profile
increasing area = decreasing pressure


Thus explaining the throttle response on the low end. *Hope this helps understand the physics side*


To answer your questions :
- does it affect the pops 'n crackles? Probably make them more prominent due to the increased flow. The pops are still controlled by the ECM tune. Ignites later, and delays when the fuel is cut. This is typically controlled by Throttle position sensor.
- does it affect the exhaust volume with exhaust flaps open/closed? You are still restricted by the pipe diameter, so the flow through the cat is faster.
- does it drone? I've not witnessed any drone in past car projects from Cat upgrades, only more roar. The unpleasant frequencies are still baffled by the resonators.
- does it improve throttle response and/or perceived performance of the car? Only the setups I've built, I've noticed a low end torque increase and peak hp increase typically. Every car is different so numbers are relative. But the greater flow velocity will certainly enhance the performance of the car. The noise I imagine on these cars should be amazing by doing so. I've not heard anyone with a setup yet.

As lhoboy, Cambo, Stohlen all mentioned; not much concern with cats failing.

Nookieman's point about locating the 02 is correct. The rear o2 signals the efficiency code. The 200 cell and under cats can alert the P0420 code which is prevented by spacing the 02 properly and letting the Cats heat up before you drive out the drive way.
I've ran a 200 Cell on the test mule for 8 months now and only had the light triggered twice. Both times it was because I hopped in and drove immediately. No need to be concerned with that, keeping a OBDII scan in the car or using the 02 spacer eliminates this.


I'm going to build a fixture and reverse engineer the factory setup. Completing this in SS-304 , possibly coating in ceramic chrome. I'll have a couple cats I'll be testing, the final package I'll produce will more than likely use v-band flanges at the cat for removal and installation of a straight pipe (for track purposes )

I'll start another thread once I get the stock parts in and post fixture progress etc. I'll be in need of a few people to test the prototypes as well. These will fit K16260 to K22184 models

See other threads for the other projects I'm working on:
Carbon engine panels , GT-Class Race headers, Carbon Inductions (XKR/F-types. Cat fixture for the XKR is being laser cut now, I'll be working on the fixture for the F-type as soon as they come in.

Hope this is helpful,

Derek Fricke

 

Well I can't that you enough Derek!

I'll let my buddy know straight away - and I'm quite excited to work out what the cats have to offer!

As far as your designs are concerned - let me know about anything that could enhance performance of an F-Type V8 - seems to be the GT headers and possibly the induction bits. Both my friend's and my F-Types are earlier than what you require for prototype use.

Let's stay in touch!

Cheers,

Aus V8S

 

No problem. I'll certainly have good updates on these parts shortly.
The heads and the induction parts are going to be well noticed performance increases. The stock manifolds are very restrictive in the 4.2 and 5.0 engines. I'm wrapping up the design on the 4.2 engine now and have another thread for that in the XKR section. I'm going to start on the 5.0L setup as soon as that setup is complete.
The stock cat setup should have very similar dimensions for the F-types, I'm trying to investigate what was changed in the models. I'll make a setup for each unit. I'm going to work on a long tube header for the six liter too. Starting on the Cat scanning and reverse engineering for the fixture when they come in next week.
Once I order some of the induction tubing, I'm going to work on the Carbon intake as well. I'm working on the carbon design for 4.2 setup now. I'm finishing the carbon molds for the panels and then jumping back on the intakes. I finishing one project at a time while things are being cut, fabbed etc.
I'm having Kenny Thompson (Creator of the bundle of snakes) for the GT40 welding up the header designs. With no doubt, these will be the best quality set of headers I could imagine.

More updates soon.

Best Regards,
Derek Fricke

 

Awesome stuff!!

Cheers,

JD

 

Could be different in Oz, but here, it's "bated breath". "Baited breath" would be after you ate some worms, fish eggs, chum, or other bait.

 

Hi Guys,

I have put 200cell race cats on my Jaguar F Type V8s, my experience is that the car can breathe slightly better and does offer minor performance improvement, however I notice the engine sound is not as nice as stock and only sounds good when fully opening her up. You should also note there are 6 lambda sensors so you are at risk of having unnecessary lights come on as per what I have read from others experiences.

 

Hi Guys,

I have put 200cell race cats on my Jaguar F Type V8s, my experience is that the car can breathe slightly better and does offer performance improvement although a few bhp, however I notice the engine sound is not as nice as stock for regular driving and can sound a little ricer at low to med revs, when idle and blipping the revs it sounds great also when fully opening her up. You should also note there are 6 lambda sensors and from what I hear most installs have the amber come on after some time. I'm considering reverting back as I'm not getting the note I desired also if your active exhaust is off expect drone at 3K revs only. The pops do sound louder here is a vid! .