411 - Rear End view!

[Richardmulcaster]

That’s beautiful! Well done.
Would love to see the exhaust when it arrives, I’m looking to place an order for one, but haven’t done so yet.

[Kevin H]

Here's my S5 (the photo outside a house). In case you are not aware, these twin tail pipes are actually blanked off and exit through downward facing apertures.

I've also included a photo of an S4 which was listed for sale in the past.

One thing to be aware of when changing where and how exhausts pipes exit is that you could inadvertently change how the exhaust gases flow around the car at different speeds.

It would be interesting to know whether the vents in the rear wings have the weighted rubber flap in place behind them in the S2-4 411s (I assume they do). Also whether they also have the round ventilation grills in the rear parcel shelf.

[Richardmulcaster]

Thanks Kevin,
Both cars look absolutely beautiful.
Anyone got any S1 or S2’s they’d car to share???

Re the exhaust comments- thanks to this forum, I read about that very issue last night l, but wasn’t aware of it today. So conversation with our restoration mechanic today went quite well- yes he was aware of this potential issue but it meant I could discuss from a position of at least some knowledge.

He wasn’t aware specifically about the Bristols having downward facing holes in the tail pipe ends.

Thanks everyone.

[Kevin H]

Hi Richard,
I took some shots of the tailpipes - see attached - so you can see the blanking and bottom exit apertures.
Glad I did because I discovered several of my exhaust hangers had perished and need replacing!

[Richardmulcaster]

Thanks Kevin, that is so useful.
I just wondered, does the awkward change of direct for the exhaust emission cause a loss of power? I was reading how exhaust systems can deliver more or less power depending on design and using these principles I am guessing that such a sudden change in direction would cause at least some power loss?

Anyone??

[Kevin H]

Originally Posted by Richardmulcaster

I just wondered, does the awkward change of direct for the exhaust emission cause a loss of power? I was reading how exhaust systems can deliver more or less power depending on design and using these principles I am guessing that such a sudden change in direction would cause at least some power loss?

Richard, your guess is as good as mine :-)

Exhaust systems are inextricably linked to the intake systems, including valve timing and other variables. I suggest reading "Scientific Design of Exhaust and Intake Systems" by Philip H. Smith. It's an old book, first published in 1962, but still relevant, particularly to normally aspirated engines such as that in the V8 Bristols. It won't necessarily give you answers, but it will at last show how complex these matters are.

Bear in mind the engines in the S1-3 411s are different to the engines in the S4 & S5. The latter having greater swept volume but lower compression ratio. So the exhaust system on say an S4 may not be optimal for an S2.

[Kevin H]

While not strictly on-topic, I happen to have the rear parcel shelf and seat out on my car at the moment, so I thought I would take some photos of the vents on the inside of the rear wings on my S5.

There is a weighted rubber flap which appears to be designed to prevent air coming into the cabin while allowing it out.

I have attached photos of the vent from the inside of the rear wing on both sides of the car. The flap is present on one side but not on the other. You can see a horizontal slit of daylight in the photo where the flap is not present. Also included a pic of the flap itself, which had fallen off on the passenger side of my 411.


These vents and the operation (and existence) of the flaps will make a difference regarding exhaust gases entering the cabin.