411 - Rear End view!

[Richardmulcaster]

Hello everyone -

I am renovating a 411 S2 and I'd love any pics you'd like to send me of your 411 if you have any cool ideas I might be able to see.
I am currently very interested in looking at every 411 rear end(!), as am working my way between a new exhaust; what style, shape, angle, number of. I know that the number of pipes doubled from the S3 onward, but thats then. I'm trying to get the best possible look for my 411 now and would really appreciate your input.

Best wishes to you all.
Richard

[jalli]

Just finishing renovating my series 3

This is it without back boxes and bumper

Rather like the look without bumper
Reminds me of Alfa gta

[jalli]

here are the pics of the series 3

it will have the standard down firing quad pipes which should arrive tomorrow

[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??

[Stefan]

Dear Richard

If photos of the 411 coachbuilders' Bucks rear ends are of any help to you I can send you ours - the bucks are currently stashed in the mighty Brabazon hangar near their birthplace. We managed to salvage the whole lot from the Bristol Cars Ltd bankruptcy auction at Windlesham, (regardless of cost!) and are finding suitable museum homes for them where they can be accessed - even, if at all possible, used as working exhibits.
We do have the (very heavy) resin templates for panelbeating the rear light details too, by the way.

Stefan Cembrowicz
Chair ,Bristol Owners Heritage Trust

[jalli]

Richard. There are others that know more than me out there. I was originally told that the down facing pipes were to stop marking the garage wall, which i think is nonsense.

I believe that there was an issue with exhaust gas being circulated into the cabin which was solved with the down facing pipe exhaust

[jalli]

Richard. I had the detail in the rear wing vents chromed. Not original i know but i think they work quite well

[Richardmulcaster]

Originally Posted by jalli

Richard. There are others that know more than me out there. I was originally told that the down facing pipes were to stop marking the garage wall, which i think is nonsense.

I believe that there was an issue with exhaust gas being circulated into the cabin which was solved with the down facing pipe exhaust

Yes, thanks for that- I did find a piece about this on the forum that seemed to get to the bottom of it, can’t find it now, but basically it seems accepted that there was a backdraft of exhaust emissions into the car if the vents were not present because exhaust smoke exited into the vortex behind the car, whereas it needs to vent into turbulent air below the car. Speaking with my mechanic last night he said that Jaguars and Aston Martins of the same era had the same problem- they solved it by making their pipes a bit longer. It seems Bristol had a more novel solution to the problem.

While the presence of downward facing slits is now a fact, what isn’t conclusive in my mind is the need to blank off the straight through route to the end of the pipes; I have read conflicting reports on whether they are needed or not if the slits are present.

[Richardmulcaster]

Originally Posted by Stefan

Dear Richard

If photos of the 411 coachbuilders' Bucks rear ends are of any help to you I can send you ours - the bucks are currently stashed in the mighty Brabazon hangar near their birthplace. We managed to salvage the whole lot from the Bristol Cars Ltd bankruptcy auction at Windlesham, (regardless of cost!) and are finding suitable museum homes for them where they can be accessed - even, if at all possible, used as working exhibits.
We do have the (very heavy) resin templates for panelbeating the rear light details too, by the way.

Stefan Cembrowicz
Chair ,Bristol Owners Heritage Trust

Yes please! And this all sounds very exciting! We will have to visit someday once the car is back on the road and we’re actually allowed to travel again.

[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.

[peter dowdle]

I believe this is a factory shot of the just released 411 series 1. Note the car is not registered. Some one please correct me if I am wrong.

[jalli]

i also changed the front indicators. also not original but i didnt like the blocky ones!!

[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.

[Richardmulcaster]

Originally Posted by 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.

This is Exactly the sort of think I need to learn about!! Thank you so much.
In the last 2 days I have gone from planning to put speakers hidden under the vents to recognising what the vents are for, to now thinking more about whether the vents are working properly! My father in law had a crash in an MG in the 70’s as a result of smoke ingress in the car- so we need to get this right!

All of this is very welcome content, thank you.

[Zorglub]

Not a 411, but for my 410 Series 6, we used round donwpipes to both address the downdraft issue and keep the period look. Round downpipes were used for the 410 and possibly for early 411.

The second photo is the recreation of Sir White’s personal 410 which is claimed to be 100% per factory specs.

[Richardmulcaster]

Originally Posted by Zorglub

Not a 411, but for my 410 Series 6, we used round donwpipes to both address the downdraft issue and keep the period look. Round downpipes were used for the 410 and possibly for early 411.

The second photo is the recreation of Sir White’s personal 410 which is claimed to be 100% per factory specs.

Wow! Don’t they look amazing! I’m seriously admiring the paintwork. Our brief is to get the mechanicals first class and the car driving perfectly , only then we will see how much is left in the pot for a paint job.

Re the exhausts- were the quad pipes original on the 410 or is that a later enhancement?
They certainly look good and the overall look is very in keeping with the 60’s era.
Thankyou for sharing.