Exhaust mods to Jagv12

Jag

Full member
Points
38
Location
Australia Biddaddaba
Car
1985 XJ 12 Jaguar
I have been playing around with the exhaust on my Series III Jagv12. One of the problems has been a very restrictive system (trying to keep the noise down) and an enormous amount of heat soak from the manifolding in the engine bay. I finally removed the engine pipes and remade the complete system.

The engine pipes now run almost all the way down to the transmission before the 2 pipes on each bank join into one (on each bank). I have increased the size of the pipes to 2 1/2 inches and then run the rest of the system following the original path to the rear, all pipe work is mandrel bent and the tail pipes are in stainless and look the same as original. The heat soak has been greatly reduced by coating the manifolds and engine pipes in extreme black ceramic coating by Competition Coatings in Brisbane.

The difference has been very significant. I found air intake temps before could reach 95deg C in city traffic and on average around 75deg C open road when the ambient temp was around 28deg C. The temps now have dropped just on 25deg C as a minimum to as much as 45deg C. Tests were carried out on the days when ambient was at 28deg C to get a fair comparison. Performance has improved noticeably I didn't have any dyno tests but the seat of the pants dyno backs up the improvement.

Acceleration has been the biggest gain and the economy has improved considerably. The tone on the exhaust is sweet under power and not noisy which is one thing I was determined to avoid. While cruising at highway speeds the note is very quiet and no drone at all. The next step is the air intake system. It has a cold air set up at present but will get an overhaul to improve it. I am hoping after Christmas to have my dyno here to put into my home workshop. Looking forward to that.
 
Last edited by a moderator:
That's an amazing testimonial for an exhaust coating. What are your next mods going to involve then?
 
That's an amazing testimonial for an exhaust coating. What are your next mods going to involve then?
The exhaust coatings are not just for looks even though they can look very good. One area I have used it for looks was a month ago on my wife's BMW R1100R motor bike.

The engine pipes were blue and looking a little tired so I sent them in to be coated in a silver finish and looks very similar to chrome.

The coating also reduced the heat she could feel on her legs at low speed in traffic. The next mod for the Jaguar however is to increase the size and change the shape of the cold air intake tubes to the air filters I set up as a test some time back which did make some improvement but limited. I will be relocating where the air intake starts to pick up a better flow of cool air and improve the shape of the intake tubes.

The intakes and air filter housings will also be ceramic coated to help keep the incoming air cool. These type of tasks are now becoming very technical to archive the desired result. I was lucky enough to be head mechanic where I spent a good number of years working for a company that designed and built many different classes of race cars.

I also have a son that has his Masters in Mechanical Engineering and is a petrol head like his old man. So many of these projects end up becoming a major piece of work with many hours of research for what appears to be a minor job. I will then be working on the ignition system. I am trying to archive 30 miles per gallon with a little over 300hp out of a vehicle weighing almost 2 ton. So I have some work to do yet. By the way I can get 27 miles per gallon out of it at present this is at highway cruising 100kph with a/c on.
 
Last edited by a moderator:

Similar threads


Please watch this on my YouTube channel & Subscribe.


Back
Top