Lambda Mounting?

[John Sims]

Ok chaps so the story continues.

Having failed to get the original Porsche lambda bung out of my turbo up pipe I have been pondering other mounting methods.

Option 1. Weld a ferrule into the existing exhaust. The problems with this is I haven't got a welder so I would have to have the job done and I'm not sure that welding is a good thing for the electrics. I would also be worried if the hole was put through up stream of the turbo that an errant bit of swarf could get pushed through the blades.

Option 2. Replace the section of exhaust with one that the bung comes out of or have an alternative section replaced with a ferrule welded in before fitting. This seems and expensive option. I have been discussing this with Simon at Essential Styling with a view to having a ferrule mounted on a new de-cat section of exhaust. This would work but would put the sensor in the turbulant air on the exhaust of the Turbo, which can't be ideal, or would be a long way down the pipe.

Option 3 Have a saddle made up and jubilee clip it to the exhaust with plenty of exhaust paste behind it. The exhaust would be drilled prior to mounting the saddle to give access for the lambda (obviously). This should be a less costly option but still needs to be mounted "down stream" of the turbo because of the swarf danger as noted. Once the saddle has been fabricated it is a D.I.Y. job but I wonder how good a seal can be achieved or maintained.

What do you think chaps?

 

[Fen]

I think 3 would be a disaster.

 

[Diver944]

Aha it looks like Mr Sims is thinking about the impending group buy for a wideband AFR sensor []

I don't understand the point of #3, surely it is the same end result of just drilling and welding in a bung downstream of the Turbo.

I think the best and safest thing to do is the most awkward (typical []), and that's to remove the crossover pipe and have it drilled and mounted there. When it's off the car you have the chance to clean out any swarf from the drilling.

I have no knowledge but to my mind it would be fine to mount it after the Turbo. Would any turbo turbulence affect the AFR reading?

 

[John Sims]

Aha it looks like Mr Sims is thinking about the impending group buy for a wideband AFR sensor

Well in part but I currently have a realy nice narrow band AFR guage in the dash all wired up to the Porsche plug and ready to go. I also have a standard lambda probe. The only problem is the lambda probe is sitting on my desk with no way of getting it to sniff the exhaust.

I don't understand the point of #3, surely it is the same end result of just drilling and welding in a bung downstream of the Turbo.

The drilling is an issue and I would anticipate putting a hole through downstream of the turbo. As I can't weld, it means I can have the saddle fabricated and then fit it myself. I think Fen's view is a little over stated and if ultimately it did leak the saddle could be welded in place (by A N Other) so nothing lost.

I have no knowledge but to my mind it would be fine to mount it after the Turbo. Would any turbo turbulence affect the AFR reading?

Mr Cannell could perhaps shed more light on this but I believe there was some considerable debate on Rennlist as to where the best place for you Lambda might be. Aparently the location Porsche use isn't ideal as heat can effect the sensor. As the probe is "sniffing" the air I would have thought an nice even stream of molecules is far better than a disturbed vortex, hence not ideal on the Turbo down pipe.

Further down the exhaust might give the best reading but this would then demonstrate a delay between combustion and the display of the results.

Not easy is it?

 

[Fen]

I think Fen's view is a little over stated and if ultimately it did leak the saddle could be welded in place (by A N Other) so nothing lost.

Sorry, I wasn't in a particualrly garrulous mood when I wrote that. I still think you'd end up with a hole in your exhaust that will cause a leak and you'll have to take the exhaust paste off before you can get a good weld. All things considered maybe getting a collar welded there in the first place would be easier.

Also even if it did work, what would you think if you went to look at a car with a view to buying and saw that on the exhaust?

Fen (very much thinking of what a potential purchaser would make of things these days [])

 

[John Sims]

Mk II version

Length of pipe of internal diameter to match external diameter of existing exhaust. Weld ferrule in middle of piece of pipe.

Slice out approx 2" section of existing exhaust, sleeve joint with new ferruled pipe, secure with U bolts, screw lambda into ferrule and go and have a cup of tea.

 

[Guest]

Mmmm wide band group buy, sound good. I was thinking about this after the track day. I don't see there being too much of a problem sticking the bung in the middle section of the ESS exhaust I have, the bit that replaces the CAT. Considering that the probes that the Dyno guys use are stuck into the end of your exhaust, then anything close is bound to be a bonus. I always feel that too close to the exit and the sensors might cool too much as I believe they have to be at a certain temp to operate properly.

So what's the Group buy all about then?

 

[Guest]

As for fixing I would get a proper bung welded onto the the pipe. Any decent mechanic will be able to do it, or a fabricator for £20 and about £10 for the bung.

 

[eastendr]

ORIGINAL: slim_boy_fat

I always feel that too close to the exit and the sensors might cool too much as I believe they have to be at a certain temp to operate properly.

Wideband sensors (and most narrow band - 3wire) have heaters in them.