ByzMax's exhaust sensor.

[Manky Monkey]

Brock has just sent me these photos of the exhaust sensor, specially built for him by Professor ByzMax for his drag car.
So Byz, here's the magic doohickey installed & ready to go.
 
Picture one, The Magic Thing as received from Dr. Byz at B'stoke

[Manky Monkey]

Picture 2 , Magic Thing in it's new home

[Manky Monkey]

Picture 3 , Magic thing installed

[Manky Monkey]

Picture 4 , universal sensor with built in heater and mounting plate fixed to exhaust

[Manky Monkey]

Picture 5, system rehung with sensor installed and wired, see it in the reflection ! We are off for a day of testing tomorrow so good or bad news to follow

[brock]

......and it was mostly bad news I'm afraid. The Magic Thing performs just exactly as it was designed to do, no surprise there being built as it was by the in house resident diodey genius, the problem lies in the fact that these little buggers don't start to read accurately until they are above 800 degrees and whilst I can't get a good reading on the gas temps, the inside of the pipes don't go much above 280 and even with the built in heater I can't see us making up the difference. I was quite surprised by the low exhaust temps, they always feel bloody hot when I lean on them, big bore and high gas speed I guess. So, we are back to glorified guess work, the plugs show that we are close, maybe slightly lean, with a strange colour break around the end of the threaded section, black and slightly oily on the top (as seen by the head) and bright and clean on the bore side. We are going to the track in a week or so and will take a huge selection of jets, a different set of spare tyres and the good timing light, given some decent weather we should be able to learn something as most other teams are headed to Santa Pod the same weekend so track time should be plentiful.   

[XL-erate]

May still work, if O2 sensor is relocated. As you probably know after each exhaust pulse exits the pipe as a positive wave form it's immediately followed by a negative reversion wave. This is a low pressure wave that enters right back into pipe and attempts to travel all the way to the exhaust valve face.

The high pressure wave exiting has low pressure behind it, so this reversion wave rushes in to fill the low pressure area. If pipe length is correct via ram tuning you can take advantage of that reversion wave which is also low pressure, so next exhaust wave doesn't have to fight against normal atmospheric pressure, but is instead extracted into the low pressure zone, pulled out of cylinder and then pipe.

In your case it could be the placement of O2 sensor so close to exhaust outlet allows the reversion waves to keep quenching it with relative cold external air. If O2 sensor is moved closer to heads in a single pipe it should give accurate readings. Also the readings are more accurate, with gases not diluted by atmospheric air coming back up from outlet. Probably have to use a 'bung' as a fitment tube so that only the tip of sensor is in exhaust flow, to not impede exhaust balance between cylinders.

[XL-erate]

Just thinking this morning of a quick test in the garage: attach a longer piece of pipe to the exhaust temporarily, about 2-3 feet, and see if you suddenly get your readouts. Any old flex or pipe would do, just to carry the exhaust heat farther past sensor and beat the cold reversion wave. Street machines take about 2+ minutes to warm up enough to get O2 sensor readings.

[Manky Monkey]

Good grief, I actually understood that & it made sense. Maybe I'm not as stoopid as I thought.
Maybe.

[texon]

Can`t the sensor be mounted closer to the head like on number 1 cylinder header pipe or has it got to be put in the collector box just a thought might be silly but I'm not up on all this electronic wizardry it just gets confusing to me, If it runs don't fix it   

[brock]

   Hi Guys, I think that you are pretty much bang on with the placement issue, I always knew that it would be imperfect but hoped to get some usable info anyway. The problem with siting it nearer to the head is that the bung has to be bolted in rather than welded and that means getting to the back of the mounting plate to secure it, so the fat end it had to be, also the sensor is nearly an inch long and needs to be fully in the pipe to function properly, the interuption of flow would far outweigh any benifit gained. I am sure that I could cobble together a temporary mount to hold the sensor where it needed to be but I am a bit loath to cut any more holes in the system, by the time I had bought in the sets of bends, had the plates cut, assembled them and had them glass coated inside and out ( hence the bung welding problem) there is probably near a grands worth of pipe there ! When we fitted them they made a huge difference to the way the motor pulled and really are so much better than the short open headers used by most others in the class (and us up to then) I hadn't fully considered the reversion thing and didn't think it's effects would be that great but talking it through tonight with a friend that knows these things better than I, I am quite happy to believe that it has a significant effect, every day a lesson learned.
   If we were going to run this car next year I think that I would make up a quick and dirty mild steel system with bungs close to the head and persevere, however with just a few meetings left it looks like it's back to the bad old fasioned way of test and tune. The Magic Thing will be carefully packed away for use on something else I have in mind, but not this year. Thanks for the input,

                                                  Steve   

[brock]

  Sort of PS,
    XL-erate, when we left Bakersfield in March I just drove the 99 and then I5 down to LA, what I would have liked to have done if we had more time was come out on the 58, and have a look at Tehachapi and Mojave and the museums at Edwards, is that your bit of country ?

[XL-erate]

Yes, that's pretty close! It sounds to some like I'm being evasive but this spot is really in the middle of nowhere, in a nice way though, quite hard to find or describe. That would have got you fairly close. Just in Bakersfield today, and glad to be home from the madhouse!

The whole Ram Tuning thing is pretty amazing for the power and/or fuel mileage potential, and virtually free horsepower at that. My buddy had the fastest car around back in the 60's and one day he explained it to me. Oh, so THAT'S it! Since then I've studied it. That's why all those Lotus, Coventry Climax, BRM's and all sounded so gorgeous screaming down the straightaways, perfectly tuned. Even changing from straight cut, 45 degree cut or resonator tip makes a difference, but total length/diameter is the big deal. I can give you an optimum length for a particular rpm if you need it, at least very close, then adjust a bit to dial in.

[ByzMax]

Only just noticed this thread!  Been too busy doing other stuff to keep up with whats happening. Shame it did not work but as you say it would need to be nearer to the engine. I think it's normally about 600mm from the engine.

Glad it worked as it was supposed to though