My situation may be different than yours as I have no cats and went nutty with coatings. But it would help to determine what changes. To do that I would start with hooking up an OBDII logger and capture oil temp, coolant temp, air charge temp, cat converter temp, A/F ratio, oil pressure and speed (will explain). It can be done cheaply using a Bluetooth dongle and Torque on a phone or using better tools.

Rather than an all out cooling hack, determining the cause is very important. Removing the engine cover is the easy fix to a bit of it, on AWD removing the black rubber cover under the vents also increases airflow. The grille style vents on RWD cars offers far greater airflow than the ones with that appear flat with an overlap. Opening up both the front bumper side vents cools down the cat converters at speeds over 40MPH (tested on SVR and R).
Add water wetter to the coolant, cut to shape the styrofoam behind the grille center bar (overmolded at the factory), add a lip diverter on the topside of the intercooler radiator 1.5" attached to the OEM stock back plastic one at an upwards angle of 30 degrees to take advantage of the entire opening below the grille.

These are just some of the changes I made.

The reason you want to monitor all of those sensors is to help you determine the sequence leading to the power drop (air charge temp increase) or if you cat converters are just getting too hot causing the ECU to enrich the mixture. The speed will correlate to understanding if this is due to a lack of cooling airflow and how higher speed alleviate this (or not). As a result you may want to simply add evac vents under the car with a small scoop. Be careful not to interfere with the air intake in the belly an for the alternator, that needs to work perfectly and match the ducting behind it.

Ceramic coating your exhaust manifolds also provides a very noticeable temperature drop under the hood. I use Jet-Hot for that from manifold to the beginning of the midpipe.

 

Aren't the cat temperatures calculated by the ECU? So an output of all the temperate sensors you mentioned earlier? Or are the temps calculated using the values recorded by the O2 sensors?

 

O2 sensors

 

This is pure gold, thank you!

On ceramic coating, I know it exists but never bothered researching into it. Usually there is cheap stuff that not worth it, and good stuff that works well. What is the good stuff so I can ask for it explicitly?

 

I use https://www.jet-hot.com/ real pros, no BS. Ultra 2500 will do.

Going with Cell 100 cats helps also if one wants to keep cats (mandatory in many states for emission visual inspection). ECU Tuning is required to maximize the benefits and keep the CEL off.

Water/meth injection helps also with cooling, not only to aid in pre-ignition detonation. As a side benefit you also get clean intake valves. I use the Snom MAF/MAP controller unit from Snow Performance. All you will need is two small holes in the upper intake manifold cover and tap the holes.

---- SIDE NOTE for V6 owners ---
I have been reading of people swapping out mid-pipes with ones having an X pipe or with the one from the V8. DON'T! Not only it brings no benefit in terms of power to a V6 but it actually increases the exhaust temps. On V6 engines, the single best way to evacuate hot exhaust is to swap out the muffler with straight pipes (and they sound nice), not raspy as claimed.

 

Exactly right. And it will kill your fuel pumps much faster (including the direct injection one!!!)

 

Mostly not accurate, carefully check, we have 3 sensors per bank, one in the Cat Converter body. The goal is to tweak the mixture in order to keep the Cat Converter at optimal temperature. Too cold and it will not reduce emissions enough, too hot and you melt it. If it was a two sensor system, you would be correct (upstream and post cat)

 

WOW



Never noticed these vents were non-functional!

I already removed the engine covers...LOVE the way the heat from the vents shimmers my view over the bonnet when stopped in traffic.

 

 

LOL... OK.. Check the Flux Capacitor

 

Do you have a thread on your Snow Meth injection install?
They have a very good rep with the American muscle car crowd but like others I did not see a kit for Jaguar?
Have you had the car to the track at all?
Looks like a very nice set of mods too.
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If you search back, I posted a picture of where the injectors go and need to be drilled. You will need a 2 injector system, they can configure it for you. Essentially they start with the Mustang 4.6SC kit, go with braided lines and not Nylon

 

@FType17
One more avenue for better cooling that wasn't discussing. Supercharger work. I think SC rotors are coated, but can you confirm this is the case? Any point in coating anything other than rotors? Also, would port and polish have any effect on temps? (all assuming OEM tune).

Last but not least, if you willing to elaborate on your " head optimization and thermal coating " mod, I would be very curious to read about it.

 

Typically, that indicates that you were doing some track hooning and you overheated the e-diff which is disabled until it cools down. If the issue persists, the e-diff is fried and it's time to take to the dealer.

 

I swapped for a larger supercharger and did not touch it, I can't see any benefits from coating other than wear reduction (and they are coated from Eaton). Polishing, porting etc is mostly to keep the airflow faster and reduce unwanted turbulence. The ports in the original heads were restrictive and not polished so they were reshaped and polished after the point where the intake manifold meets the head, the exhaust side was thermally coated as well to reduce the heat transferred from the exhaust gasses to the head itself. The pistons (they were swapped because of larger bore) have a thermal coating on the dome as well as the dome (combustion chamber) in the heads and the lower part of all 4 valves (but again exhaust ports ONLY). The pistons have a lubricity coating on the sides/skirts from the manufacturer. I swapped the connecting rods (in spite of being forged) with Titanium ones made from billet 6AL4V, this saved around 34% in weight and most importantly it's rotating/reciprocating weight. I opted to up the rev limiter to 7200RPM, but it can go a tad more. This results in increased power (power is a function of torque and RPM)

 

I failed to mention, if one was to thermally coat the inner parts of the supercharger, it would actually hurt you (other than lubricity coatings). Thermal coatings would retain heat INSIDE the supercharger, something that increases the air charge temperature.