Exhaust

[manchild]

Just noticed something on photos Monstro posted a while ago...

What is that pipeline connected to exhaust manifold used for? If I recall right FIA reg. impose that fumes from engine block must be directed to airbox, so what can this be since afterburner is banned?
http://www.schlegelmilch.com/New/images ... 0019-1.jpg
http://www.schlegelmilch.com/New/images ... 0018-1.jpg

[Strax]

This is usually (at least in road cars) an exhaust temperatur sensor or a lamda (oxygen) sensor.

[Guest]

i would bet O2 Censor

[DaveKillens]

Interesting location. Different cars, yet what appear to be similar sensors are immediately downstream of where the five individual exhaust pipes form into one. And the sensor is located on the inside of the curve, where my experience tells me that is the place where you would expect the lowest velocity (maybe even stagnation), and probably the largest heat buildup. Maybe it's on the inside just because it's the most convenient location on that part of the exhaust. But the fact that it's just downstream of where the individual pipes collect, is relevant. I would expect that each cylinder and exhaust pipe would have it's own O2 and temperature sensor, that would allow the engine computers to optimize each cylinder on an individual basis.
But one sensor would indicate that whatever data it collects is collective, it measures the parameters of all five cylinders on each bank.
I didn't find any FIA regulations banning individual cylinder measurements, and in all honesty, I have always assumed that each cylinder was measured, so that each individual cylinder could have it's fuel and spark altered to meet each individual cylinder's needs. Maybe I'm wrong, for a race engine, they just collect data in general. Only on a dyno would each individual cylinder be under much closer scrutiny.
Anyone have more info? I have assumptions that appear incorrect. (as if that's not the first time lol)
By the way, I believe it's an O2 sensor.

[riff_raff]

It's an oxygen (lamda) sensor. Lamda is the Greek symbol designated for stoichiometric equivalency ratio in a spark-ignited engine. The exhaust oxygen sensor provides feedback for closed-loop engine control systems. Obviously, it must be downstream of the exhaust system collector in order to provide an average feedback value for all cylinders in its cylinder bank.

http://www.boschusa.com/AutoParts/Oxyge ... enSensors/

[Guest]

Could be.Or is it a one way valve ,where the oil mist from the crank zone is exhausted?
Because on the Cosworth engine it more looks like an oil line.
And we sometimes (mostly just after the race start) see engines blow
oil mist out of their exhaust.McLaren has it very often.

[manchild]

No, FIA regulations impose that oil fumes from engine block must be directed to airbox and any injection into exhaust is forbidden too.

[Guest]

I read this in the regulations. So the oil mist is taken into the intake , goes
into the cylinder and is burnt there? And the result is seen during the beginning of a race when some engines blow blue smoke out?
And this is common and of use for these high spec engines?
Just asking.

[manchild]

Well it is common thing for passenger cars and other vehicles since it helps a lot in reduction of pollution.

As you said it, oil mist is mixed with air and burned in cylinders. Tuned engines and high spec engines usually had opened engine block ventilation until FIA banned this in F1.

Previously it was also practiced on production cars with damaged/used piston rings, liners (bad compression) or damaged/used valve seals- you could see rubber pipe bent down on such cars.

It also helps in lubricating of cylinder because fuel mixture becomes a bit oily and covers the cylinder liner and intake valve’s rod (while it is opened/pushed down) but this is more important for long life engines rather than for racing engines.

Blue smoke is a sign of burned oil but I think that the blue smoke seen on starts usually comes from burned tyres.

[Guest]

I do not mean the blue smoke right at the start . Meant is the blue smoke a few kms into the race when TV moderators are fooled sometimes and/or are worried about an engine failure but nothing happens.
Could the F1 constructors bypass a regulation by sucking this oil mist out of the crank by a pump and then forward it into the exhaust.As it would be not a straight "sump breather" it would be ok.
I do not insist on this but it seems if the McLaren engine line goes straight
into one of the pumps.Also the oil line look at the Cosworth engine should not only prevent the sensor line as a thermal protection.Whereas I must
realize that mentioned line at the Ilmor engine seems to be thermal protected by a (copper?) wrap material.
Thoughts?

[manchild]

Blue smoke in first laps is probably just the result of engine being pushed hard without reaching full racing temperature.

Several years ago on one Mclaren in Monaco sensor malfunctioned and signaled that oil pump isn’t working properly so the computer turned on backup oil pump and messed things up (the blue smoke was coming out of the engine as it overflowed with oil since both of the pumps were working at the same time. Fortunately, back than remote engine management was allowed and crew from the pit managed to shout down the backup pump...

I don't know why Cosworth's pipe isn't isolated...

[riff_raff]

On top-fuel drag race engines, it is common practice to vent the crankcase to the header primary tube, with a check valve in between. The extreme negative pressure intervals occuring in the exhaust primaries can effectively scavenge the crankcase. A negative pressure in the crankcase area, below the piston, helps the piston rings to avoid flutter at the high piston accelerations encountered in a racing engine.

As for formula 1 engines, they typically employ high volume oil scavenge pumps. The scavenge pumps can flow as much as 6 or 7 times the volume of the oil pressure pump, thus creating a negative pressure in the crankcase. There are usually multiple pump sections (5 for a V10), and they are mounted low on the right side of the engine.

I haven't seen a modern F1 engine oil scavenge pump, but if you've ever seen an oil scavenge pump section from an old Cosworth DFV or DFX, it looks like a mini Rootes blower (supercharger). It's more designed to pump air than oil. Bill Dailey makes a good copy of it: http://www.daileyengineering.com/oilpumpmain.htm

As for what you see in those photos, it's just a fireproof sleeve (RTV/nextel) covering the wires of a Lamda (oxygen) sensor.

[manchild]

...As for what you see in those photos, it's just a fireproof sleeve (RTV/nextel) covering the wires of a Lamda (oxygen) sensor.

Ok, but why are wires on Cosworth engine without fireproof sleeve?
On Cosworth it looks more like a copper pipe than wires (just guessing here), but since the operating conditions are almost identical why is Cosworth’s version "naked"?

[DaveKillens]

I don't think anyone would engineer to have any form of oil excess vented overboard, even into the exhaust, getting caught with such a violation would bring dire enalties. If you are going to engineer any form of fluid vent, the solution is ot have it vent inside the air box.
Usually, when you observe a small puff of smoke, it's because a fluid tank was overfilled, and it's finding it's way out, usually through the oil overflow, which vents inside the airbox.

[manchild]

There are at least two clearly visible pipelines/sensors on this photo of Renault RS25 exhaust. One is on the engine side quite similar to those on Mercedes and Cosworth engines but there is also another one on the single cylinder exhaust pipe at the bottom