Jag
Full member
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.
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: