Fastback's cars.

[Fastback]

I've gone to the time, trouble and effort to source an original precisely because I believe I don't want a straight through system. Last time I did that with a Powerflow (on the 825 SLi) it was flippin' awful. The constant intrusive drone and the loud boom under load was intolerable. It just didn't suit the engine at all and ruined the car. It was also missing what is possibly a key element, the little resonance chamber at the flange.



Like all OEM exhausts, I'm sure that layout did not happen by accident, so ideally I want to recreate it as close as I can. I may be asking too much...

I have the Sterling booked in on the 20 of this month, so in a couple of weeks we'll find out.

[scoobyh123]

Ah, that's what happens on the 827 if too large a bore is used! Also kills the performance and economy!

I totally agree you're going down the right road (no pun intended) to get an exhaust that doesn't give those problems. I doubt the square part of the perforated pipe actually does anything but it would also be too late to change it if you didn't recreate it.

Looking forward to the update/report on the 21st now!

[Alucard7002]

I've gone to the time, trouble and effort to source an original precisely because I believe I don't want a straight through system. Last time I did that with a Powerflow (on the 825 SLi) it was flippin' awful. The constant intrusive drone and the loud boom under load was intolerable. It just didn't suit the engine at all and ruined the car. It was also missing what is possibly a key element, the little resonance chamber at the flange.



Like all OEM exhausts, I'm sure that layout did not happen by accident, so ideally I want to recreate it as close as I can. I may be asking too much...

I have the Sterling booked in on the 20 of this month, so in a couple of weeks we'll find out.

Exhausts and performance over noise is such a bugger in the aftermarket.

Personally I'd have fitted a full 2" stainless catback system with a HJS sports cat, single 16"X6" round centre silencer and a 12” centre-twin baffled back box.

That'll keep the velocity up and the noise down. Still be fruiter than original as stainless does stainless things but certainly not loud.

Would however cost thick end of £1500

Same again if you needed downpipes making in 1” 5/8

So it's swings and roundabouts, magic triangle and all that

[Fastback]

Well as promised here is the exhaust update:

There is no update .

The chap looked at the pictures and suddenly it's all got 'very complicated'. I just hope he doesn't give up on it. Surely there must somebody, somewhere who can make an exhaust?

[scoobyh123]

Well as promised here is the exhaust update:

There is no update .

The chap looked at the pictures and suddenly it's all got 'very complicated'. I just hope he doesn't give up on it. Surely there must somebody, somewhere who can make an exhaust?

What's your welding like Mark? I'm thinking maybe you should make it yourself if nobody else can?

[Fastback]

I've not done any since day release to tech college over 40 years ago .

Well, after I've finished my current plastering course, I shall have book myself in on a welding course.

Trouble is the MOT is due on the first of November...

[scoobyh123]

For the MoT, i'd fit anything to get it through. I know on the 75 with the 2.5 KV6, it has the cat at the front (integral with the front pipe/downpipes) and then only the back box. If the back box goes on a factory system, a service joint has to be bought and the original back box cut off and the new one fitted with the service joint.

With this in mind, you may be able to find a 75 back box and cobble it together with your system to get a pass and for it to be quiet - if i come across a rotten 75 back box i'll perform surgery on it and get you some pics - doubt it'll be anytime soon though.

[Fastback]

Exhaust update:

The original chap I went to see has failed three times to contact me, so obviously not that interested. Shame.

Still, one door closes another opens. Today I have travelled the 75 miles to JP Exhausts in Congleton. They are happy to make a system up similar to the original with regard baffles etc, promising it will still be quiet. Also they will pattern make from the one I cut open, so the car does not need to be present, which is a relief.

Full stainless of course with stainless welds, lifetime guarantee etc. And best of all, endorsed by Tim Shaw! (Car SOS)

[scoobyh123]

Normally for me Mark, when one door shuts another one slams in my face!

Glad to hear you've found an alternative supplier and one amenable to working with your and the original design.

Fingers crossed it all comes good!

[Lodein]

Good new

Lodein

[Fastback]

At last, I can draw a (dotted) line under the exhaust saga. It's only taken most of this year.

Collected the new back box from JP Exhausts in Congleton in the Vitesse.





And given the couple of pleasant days we've had, managed to fit it. This is what I took off,



Patched and blown again. And for interest, I cut that one open as well,





All three systems together and some detail shots,









The last photo clearly shows the different size of the KV6 box, both longer and deeper than the 2L.

No major dramas taking the old system off and fitting the NOS GT Exhaust mid section and new SS rear, other than working on your own, in a confined space under a jacked up car (with an owl! )*.





Nice polished tail pipe detail and a good distance from the bumper.

Driven it a bit and so far so good. No intrusive booom at the 2000-2300 range even under load. The whole car is so much better than I have ever had it.

So why a 'dotted line'? As I was replacing the rear section, the heat shield decided to disintegrate. Thought I'd make a new one from aluminium or stainless steel sheet or if any body has got any ideas I'd be interested to hear.

* - Owl reference is from a sketch in 'The Fast Show'.

[scoobyh123]

Excellent news Mark, your perseverance paid off! Easy to see the differences between the 2.0 and 2.5 exhausts when they're side by side.

[820Vitesse]

Good job. Thanks for posting all the pictures, especially the Vitesse reflected in the bumper shot, tailpipes look just right.

Which heat shield broke? I recently used 1.5mm aluminium sheet to make some exhaust heat shields, it is easy to work with.

[Fastback]

Thank you. Yes, pleased with the overall outcome and worth the 300+ miles to get it done.

The heat shield that is disintegrating is the middle 'S' shaped one, labelled as '5' here,



The right hand end of that sits just above the join/bullet muffler. There are sheets of embossed aluminium and stainless on eBay but was wondering about 1.5mm aluminium (checker plate) but thought it might be hard to work the shape and perhaps a bit of overkill. But if you've done, then it would be on the cards.

I might have access to a shield on a donor but I was going to use it as a template rather than actually fit. So how hard do you think it may be to make that part, please? If heat helps, I could get one of those canister things.

[scoobyh123]

Aluminium work hardens very quickly so if you are going to do repeated operations, you'll need to anneal it in between them and i'd advise annealing it before you start.

https://makeitfrommetal.com/how-to-anne ... ers-guide/

That tells you a fairly easy/foolproof method, the big thing is to heat it evenly. You can either let it cool naturally or quench it in water, i prefer natural cooling but each to their own.

To minimise the amount you actually work it, i'd suggest making the bends in 3 parts so you can shape the "tunnel" parts then use brackets pop riveted (with aluminium rivets) to hold it all in place. If you don't have a pop-rivet gun, worth investing in a drill powered one, saves a lot of time and squeezing!

https://www.ebay.co.uk/itm/386083700254

Well worth a tenner to save the grief both during and after using a hand riveter!