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exhaust porn

craigdiver - 26/2/18 at 10:15 PM

Want this look on my straight-6 BMW haynes roadster but need to accomodate 2x O2 sensors (one on each bank of 3 cylinders), any ideas?

Nickp - 27/2/18 at 07:10 AM

Seems ambitious, who are you paying to make that for you?

I'm pretty sure the O2 sensors wouldn't work right. Each one takes a reading of the mixture for those 3 cylinders and adjusts the fueling accordingly. You could line one up just after cyl3 and that may work OK but the other will be reading all 6cyls so I don't see it working right and may not even pass emissions.

I'm happy with my 6-2-1. Works correctly, sounds amazing and cost peanuts to make

[Edited on 27/2/18 by Nickp]

theduck - 27/2/18 at 07:37 AM

Why do you need 2 o2 sensors? I assume you are on aftermarket management? You should be fine running one o2 sensor that reads all 6 cylinders.

Not sure why there would be an issue with emissions...

Nickp - 27/2/18 at 07:39 AM

quote:
Originally posted by theduck
Why do you need 2 o2 sensors? I assume you are on aftermarket management? You should be fine running one o2 sensor that reads all 6 cylinders.

Not sure why there would be an issue with emissions...

I use the BMW management (remapped) which uses 2 sensors (for 1-3 and 4-6). I think he's planning to do similar.

theduck - 27/2/18 at 07:45 AM

oh i see, i assume the OEM ecu has some kind of trim table then to adjust for the banks running differently. In which case you could probably get away with running them both reading all 6 cylinders. In fact, you could possibly even get away with running 1 and splicing the signal to both inputs on the ecu. Or switch to aftermarket management and just run 1 wideband

nick205 - 27/2/18 at 09:05 AM

That is certainly a rather tidy looking fabrication!

Do you know what car it's on?

I'm guessing something where the exhaust system is fairly visible and it enhances the overall look of the vehicle.

craigdiver - 27/2/18 at 11:38 AM

It does look good but I agree probably not sensible due to the likely cost and issue with the O2 sensors. This exhaust system was on a V12 with this exhaust mirrored on each side.

The OEM ECU had 4 O2 sensors - 2 before and after the cat on each bank of 3 cylinders. The ECU has been altered to delete various things including the post cat sensors to make the engine usable without ABS etc.

These engines with dual-vanos (variable valve timing on both inlet & exhaust) are tricky setting up with aftermarket engine management.

[Edited on 27/2/18 by craigdiver]

coyoteboy - 28/2/18 at 03:12 PM

It's also a dodgy header design - it's basically just a log with long runners.

Mr Whippy - 1/3/18 at 07:03 AM

oh lovely....if your are a fan of chitty chitty bang bang

craigdiver - 1/3/18 at 07:58 AM

Original post is how I imagine it would look fabricating it myself, how it would actually turn out..... ;-0 :-)

Mr Whippy - 1/3/18 at 08:33 AM

WTF take that for an SVA....

AntonUK - 1/3/18 at 04:17 PM

reminds meof this work of art

craigdiver - 1/3/18 at 05:23 PM

quote:
Originally posted by AntonUK
reminds meof this work of art

That is truly awesome

coyoteboy - 1/3/18 at 11:50 PM

quote:
Originally posted by AntonUK
reminds meof this work of art

Oh my eyes! That hurts my eyes and my sensibilities!

slingshot2000 - 2/3/18 at 12:05 AM

Is that the beast that was being built on an old London black cab chassis, with two Jag straight sixes in it ?

(I lost the link to it, was on Garage Journal)

Angel Acevedo - 2/3/18 at 12:39 AM

quote:
Originally posted by craigdiver
Want this look on my straight-6 BMW haynes roadster but need to accomodate 2x O2 sensors (one on each bank of 3 cylinders), any ideas?

Sorry to chime in late...
Could you not put the first three into a center pipe concentric with the other three on the annular space?
Put the first O2 sensor after the third cylinder merges with this.
put the second just before both exhaust streams merge together.
May be a b1tch to fabricate, but I think its doable.
HTH.
AA

AntonUK - 5/3/18 at 01:22 PM

quote:
Originally posted by slingshot2000
Is that the beast that was being built on an old London black cab chassis, with two Jag straight sixes in it ?

(I lost the link to it, was on Garage Journal)

That’s the one

CTLeeds - 4/4/18 at 11:21 AM

Hi Craig, here's what my M52 exhaust ended up like... I wanted it to look like your original post but there are so many reasons why it couldn't exit straight out of the block...

Regards,

Chris

craigdiver - 4/4/18 at 11:42 AM

quote:
Originally posted by CTLeeds
Hi Craig, here's what my M52 exhaust ended up like... I wanted it to look like your original post but there are so many reasons why it couldn't exit straight out of the block...

Regards,

Chris

That looks great - massive help, thank you. how have you managed without lambda sensors (my ECU had 4 before it was reprogrammed to delete 2 after cat). Was your emissions ok to pass IVA without cat?

cheers

Craig

CTLeeds - 4/4/18 at 12:04 PM

Hi Craig, I do have the 2 x pre cat sensors fitted...

I haven't been through IVA yet, and at the moment it's running a bit rough. I'm hoping it's just a sticky ICV or similar though.

Chris

craigdiver - 4/4/18 at 04:50 PM

quote:
Originally posted by CTLeeds
Hi Craig, I do have the 2 x pre cat sensors

I haven't been through IVA yet, and at the moment it's running a bit rough. I'm hoping it's just a sticky ICV or similar though.

Chris

Ah - see them now. Your exhaust looks great, did you TIG it yourself? Do you have a cat in there somewhere?

[Edited on 4/4/18 by craigdiver]

CTLeeds - 4/4/18 at 04:57 PM

I wish! No, I had to hand a large sum of money over to a professional.

Chris

craigdiver - 4/4/18 at 06:08 PM

Do you have a cat in there somewhere?

CTLeeds - 4/4/18 at 06:11 PM

Yep. There's a 300 cell sports cat in the silencer.

Chris

craigdiver - 5/4/18 at 03:08 PM

quote:
Originally posted by CTLeeds
Yep. There's a 300 cell sports cat in the silencer.

Chris

Do you mind me asking how much it cost to have the exhaust fabricated including cat?

CTLeeds - 5/4/18 at 04:11 PM

Not at all. It was an eye watering 1500+VAT!!!

craigdiver - 5/4/18 at 05:39 PM

quote:
Originally posted by CTLeeds
Not at all. It was an eye watering 1500+VAT!!!

you seem to have put the point in the wrong place :-)

seriously though I had a fear it was going to cost that much for a decent exhaust.

CTLeeds - 5/4/18 at 06:05 PM

It's all in the labour really Craig. The parts altogether probably came to less than Ł500 but he did have the car for 9 days. Being such a fiddly design it took him a while. It was though in my opinion a fair price for a good job. I just wish I could weld stainless.

Regards,

Chris

craigdiver - 5/4/18 at 07:26 PM

quote:
Originally posted by CTLeeds
It's all in the labour really Craig. The parts altogether probably came to less than Ł500 but he did have the car for 9 days. Being such a fiddly design it took him a while. It was though in my opinion a fair price for a good job. I just wish I could weld stainless.

Regards,

Chris

it looks fantastic definitely an artform creating these exhausts. Kind of knew it was going to cost a bit for the exhaust. My good friend has a Mondeo ST220 which you cannot buy an off the shelf exhaust for. He ended getting one made in stainless and that cost around the same as yours but didn’t include the cat.