AFR Sample Chambers
Turbo Mini Forums

Knocked this out as a first attempt.



Any thoughts before I make the other one?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Is the stainless take off for EGT?

No, stainless take-off for wideband sensor pre-turbo, so that you don't pressurise the sensor and damage it.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

My only thought would be make the "chamber" a little bit bigger relative to the downstream pipe. It just "looks" as if downsteam flow conditions may distort the flow from the small stainless pipe.

Also, perhaps, drill a bung and stick a thermocouple in first to see what temperature that chamber is experiencing in practice.

Without seeing the lengths of the two pipes to the manifold/exhaust, it's hard to visualise the potential temperature gradient.

But the principle is exactly what I was expecting from your earlier posts.

EDIT - it may be deceptive from the photo, what is the internal diameter of the chamber and the downstream pipe ???

Edited by Rod S on 19th Jun, 2009.

Schrödinger's cat - so which one am I ???

The actual sensor ports are in line with the incoming pipe that is 4mm bore.

The sensor is 15mm diameter. The bore of the chamber is 21mm and the downstream pipe bore is about 13mm.

There is approx 12mm of chamber before going to the smaller diameter.

It will get hot enough as the outlet pipe is going to be welded to the bend on the turbo outlet.

I've made the other one now.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Ah I understand now, nice work.

I don't know if you intend to put it on the same exhaust as the one you were using before but if it's the case and you still have the sensor bungs on it, you could put one sensor in the original bung and one on this new chamber and compare readings.

Other than that it looks good.

Jean

http://www.jbperf.com/

No, its for the turbo manifold, so all new.

I will compare readings with the existing setup, though.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Now tacked on the downpipe:



Need to add a couple of bosses to the manifold near the flanges and make up the pipes.

I think I'll make up the actuator bracket first just to ensure nothing clashes.

Off to watch the Big Pricks now though.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I thought this was for the sidemount turbo engine?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Nearly finished, just didn't buy enough of the 6mm tube.



Also need some rod to extend the actuator.

Avon looks like a possibility at this point.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

very nice Paul :)

The only potential issue I see is length of the small bore tubes, or are you going to run the second one in such a way it is the same length as the first ???

Schrödinger's cat - so which one am I ???

No, I plan on taking the shortest route.

I suppose that the inners are going to be a few revs behind the outers. The logs will show up if there is an issue.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Might have been better dumping them further down the exhaust, so there is less chance of the ex-tubine gasses shooting up the tube, contaminating your sample.

Or better still, vent the post sensor to atmos

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

You guys are so far ahead of me I dont really follow these threads, but can you tell me why you want to move the oxygen sensor away from the manifold instead of just putting it in a boss close to the turbo outlet ?.Is it because you want to sample for each exhaust port ?.

Yes, with port injection, the inner and outer cylinders run at different AFRs unless the timing of the injection is precise, so we need to measure inner and outer AFRs separately.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

http://www.summitracing.com/parts/DTC-85-100950/?image=large

http://www.summitracing.com/search/Part-Ty...yword=crankcase

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Ideally the two pipes would join the downpipe after the join but that would be a fabrication and installation nightmare.

Let's see if this works. If this doesn't show variation in AFR between the inner and outer cylinders, then I shall have to reconfigure it.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

i think both paul and steve are right ,at low rpm i can see steves scenario playing out ,particularly between pulses ,and once the turbo creats some back pressure then it changes around to reading as it should..

fitting a tap in the big return that could be adjusted ,would ,perhaps make it a bit adjustable .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

At low RPM. it will also depend on where the exhaust gas speed is higher. Due to venturi effect it will have a tendency to go where the speed is higher.

Jean

http://www.jbperf.com/

i just looked at the first pic, and thought you had welded your wb sensor to its boss

i had written a long post raising several issues with you doing this, then realised i had imagined it all

its been a long weekend, and i think its time for bed


p.s not that my opinion is worth an awful lot in this area, but i agree with stevie and the others about the pipe angle etc

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"