Courtesy of our member Daim.

 

 

Mine always makes tons of vapor even during summer nights, just tons of space in there for water to condense.

The H pipe muffler is also pretty isolating for each side, it's an almost straight shot through for both pipes with only a slightly shared area. There's pictures here of a couple cut open, post 16 https://www.jaguarforums.com/forum/x...5/#post1629539

 

 

Indeed exhaust vapor is plentiful w/ these under certain conditions.

 

Even with very little left in the exhaust system, my de-muffled and X-piped exhaust will still steam. No, no head gasket death or so. It just steams. My X300 did the same and my older XJ-S does (or will do it again) as well. Just below ~15°C is what I have noticed. I can have a totally warmed up hot and pinging exhaust, and it will still steam... All other XJ8s I have seen of the same age and model do it too.

Absolutely normal as it seems. At least here. I also run on E10 so that means more water in the system. Though on LPG there is nearly no water in the fuel so that doesn't explain it either...

 

+1 on what've been said above.

My XJR daily driver produces quite a noticeable amount of vapor when started cold - in particular when idling. Stepping on the accelerator does it away, but it comes back when sitting at the next traffic-light stop.
Even when warmed up it vapors still a bit when idling. As long as there's no steam on accelerating, I'm not concerned with this.
Besides a lot of huge limousines from this era with spacious and generously sized exhaust systems and engines show this behavior - e.g. Mercedes S-Class, BMW 7-series or Audi A8.

 

The LPG makes its own water . LPG, like gasoline, is a hydrocarbon. When a hydrocarbon gets burned with oxygen, the two major end products are CO2 and H2O. Assuming perfect combustion, carbon dioxide and water should be the only two substances coming out of the tailpipe.

 

Thanka for that, but what I actually meant was it contains no water E10 has a small content of water... A very low figure but it is there. LPG has loads of other comtents, but no water as water. Sure, due to an oxidation of hydrogen in the combustion cycle, but otherwise there is no liquid water in the liquified gas...

 

Noted. But the amount of water, even in heavily tainted fuel, would have to be massive in order to be seen as a plume coming out of the tailpipe. Every gallon of gasoline burned in the combustion chamber naturally produces 1.5 gallons of water. It's this produced water that's seen coming out of the tailpipe on cold days (the same amount is coming out on warmer days, it's just not visible).

 

Which woukd go in line with my ~15°C observation

 

They do tend to use an impressive amount of fuel while idling

 

You'd be amazed how little these engines actually use... At least the 3.2l... As I run bi-fuel, I habe E10 and LPG. To get the car to run on LPG, the car has to start on E10 (or any petrol). No matter if a warm or cold start. It will run then for about 1-3 mins on E10 and then switch over. 15 starts, with instant driving (no idle warm up here) from mostly cool or cold engines and it used a total of 0.26l of E10. That is like nothing... Not even a coke can size!

 

Maybe it's just the s/c engines - mine will nearly double fuel economy when on the highway vs the start/stop when putting about to work. Maybe the suspension work will help with that a bit though...

 

I got a 4L N/A, drive mostly non-highway, and the consumption is horrible too.
Only the now-and-then highway trip re-confirms my faith in the health of the engine .

And yes, you will be shocked how much water comes out of the installed cut-outs (which is now the lowest point, I guess before it collected in the rear silencers).