Breathers....

[cobraracer46]

Alrighty then! I installed my breathers yesterday and my personal impression is quite negative. Oh the smell! Sitting at a red light you can definitely partake in the wonderful aroma - not to mention when I got home and the car is in the garage. Strong enough to make you gag and I am not joking. I'm second thinking this breather filter after this experience and am looking now into the oil separator mod instead. :xpl:

Put the PCV valve back on and forget about it. Am I the only one one at SVT performance who sees that running breathers is silly? :shrug:
If you look at racing vehicles that don't have PCV valves, they are either running the header collector evcuation system or a large vacume pump hooked up to the oiling system. No, I don't like the smell of oil, or the fact that the oil mist will go every where and I certinlly don't want to contaminate engine oil or sufficate the crankcase, so the PCV valve stays on my car.

 

[lemosley01]

The oil mist question has already been addressed a couple pages back.

For cars using forced-induction (no Nitrous), breathers appear to be a good idea, even necessary.

Some pretty good arguments against the PCV system have been made:
1) It sucks oil into the intake tract and deposits it in the lower intake
2) It becomes part of the A/F mixture thereby lowering the octane of the charge and increasing your chances for detonation. The question is, how much does it lower the octane rating. In reality, it can't be pulling in that much oil or our cars would eat the stuff quarts at a time (my car does not burn oil).
a) I would think that Ford would have accounted for this. If so, perhaps you can increase your timing slightly more by using breathers instead of the PCV?
3) It pulls hot air from the crankcase into the TB and raises the temperature of the air charge. This could be significant because the crankcase is going to be fairly hot. The air charge on an N/A engine should not be all that hot when it enters the intake - how much does the PCV system raise? Enough to be significant?

Arguments for keeping the PCV:
1) Oil misting on the engine (addressed already in that it doesn't happen and there are fixes for it if it does)
2) The engine was designed that way and therefore it must need them (the engine was also designed with water pump, crank, and alternator pulleys of a certain diameter and how many of us have replaced with different size pulleys).
3) You need it to evacuate the blowby gasses from the crankcase or risk sludging up your engine and contaminating the oil (thereby reducing the service life of the engine).
a) How much will NOT evacuating the gases reduce the engine life by? 10s of miles, 100's of miles, 1000s?
b) Do breathers allow this evacuation to occur in significant quantities compared to the PCV?

 

[lemosley01]

Put the PCV valve back on and forget about it. Am I the only one one at SVT performance who sees that running breathers is silly? :shrug:
If you look at racing vehicles that don't have PCV valves, they are either running the header collector evcuation system or a large vacume pump hooked up to the oiling system. No, I don't like the smell of oil, or the fact that the oil mist will go every where and I certinlly don't want to contaminate engine oil or sufficate the crankcase, so the PCV valve stays on my car.

Cobraracer46 - what kind of racing engines? Are we talking engines that are torn down and rebuilt after every race?

The question would be: Why do they run this way? It sure isn't because of emissions. So why else?
Perhaps to provide more power? These are high-revving and FI engines and probably flow way more exhaust than a bolt-on 4.6 Cobra can. Therefore the vacuum introduced by a header collection system or vacuum pump may actually be of value in providing additional power (or at least eliminating one barrier to power).

Could it be because they have significantly more blowby than an N/A Cobra and therefore they have to vacuum the crankcase or risk pressurizing it, and because of this blowby contamination is a very real issue for them.

Maybe it's all of the above?

 

[Snake Eyes]

For race engines that run for hours at a time at ridiculous RPMs the amount of oil they kick up could saturate a simple breather and the vacuum created by the venturi of the headers pulls clean air in to the valve covers and may provide additional cooling. In addition I would bet they would want to keep as much heat out of the engine compartment as possible and those engines run on the raged edge of performance. In racing they want every advantage they can get because that is the difference between winning and loosing.

 

[Mike_Hawk]

After thouroughly reading this thread, I think I'm going to try the double-breather setup. I'm probably going to put some type of sock or sweat band on it since I'm not too fond of oil mist getting all over my engine.

 

[REX-RACER]

op:

I think the last time this subject/argument came up the thread went on for 10 pages and by the end guys were threatening each other and calling each other all kinds of names ( :cuss: ).

I think at this point though it can be said that no one will be making an uninformed decision how they want to run their car. There seem to be three ways of doing it and there are pro's and con's for each way apparently.

So in the end, the real question seems to be, "How do you want it on your car?" Once you make that decision, as it is w/ any other mod or part or addition you may make to your ride, you set it up the way you want it and move on to the next thing.

Not trying to sound preachy, just making an observation.

As for myself, I'll probably try the breathers this spring after I pass my yearly emissions in March. ;-)

 

[WolfDogTom]

2) It becomes part of the A/F mixture thereby lowering the octane of the charge and increasing your chances for detonation. The question is, how much does it lower the octane rating. In reality, it can't be pulling in that much oil or our cars would eat the stuff quarts at a time (my car does not burn oil).

This is the only part that confuses me. I agree that we shouldn't allow the PCV system to suck oil into the intake.

...but you say getting oil into the A/F mixture lowers octane and increases chances for detonation. Your'e saying that getting oil into the A/F makes the gas ignite easier???
Lower Octane ignites easier than higher octane.

 

[TnPaulMan]

This is the only part that confuses me. I agree that we shouldn't allow the PCV system to suck oil into the intake.

...but you say getting oil into the A/F mixture lowers octane and increases chances for detonation. Your'e saying that getting oil into the A/F makes the gas ignite easier???
Lower Octane ignites easier than higher octane.

Yes, that is what he is saying. But that is not a good thing on our cars. We have such high compression we require fuel that burns slower so that detonation does not occur. You see, it is all about the timing of the flame, not how easy it burns.

Paul

 

[TnPaulMan]

Cobraracer46 - what kind of racing engines? Are we talking engines that are torn down and rebuilt after every race?

The question would be: Why do they run this way? It sure isn't because of emissions. So why else?
Perhaps to provide more power? These are high-revving and FI engines and probably flow way more exhaust than a bolt-on 4.6 Cobra can. Therefore the vacuum introduced by a header collection system or vacuum pump may actually be of value in providing additional power (or at least eliminating one barrier to power).

Could it be because they have significantly more blowby than an N/A Cobra and therefore they have to vacuum the crankcase or risk pressurizing it, and because of this blowby contamination is a very real issue for them.

Maybe it's all of the above?

cobraracer, I believe you just got owned.

 

[WolfDogTom]

Yes, that is what he is saying. But that is not a good thing on our cars. We have such high compression we require fuel that burns slower so that detonation does not occur. You see, it is all about the timing of the flame, not how easy it burns.

Paul

Oh, ok.
I just didn't realize that oil in the A/F make the gas burn easier. It does make sense, though, that it would change the way it burns, therefore the timing of the burn.
Thanks.

 

[Snake Eyes]

Octane (in the sense of a measurement rather than a chemical) isn't the measure of how easy you can ignite a fuel, but rather how much heat a fuel can handle before igniting spontaneously (and coincidently a linear relationship with how quickly it burns). The octane rating is dictated by (for the most part) by the compression ration of the engine and timing is dictated by the burn rate of the fuel. Now heat in the combustion chamber is a byproduct of many things like, compression ratio, air fuel mixture, and air temp.

Compression ratio generates heat because when you compress a gas (air) the molecules are packed closer together causing them to collide more often and this generates friction heat.

Air fuel mixture affects heat because when the fuel is injected in to the intake charge, it cools the incoming air because the warm air gives some of it's heat to the fuel. Fuel like alcohol always seems cold, this is because of its very low evaporation temperature (and a small amount will evaporate and become vapor before compression).

Air temp is obviously important which is why we buy CAIs. The colder the air is the denser it is, the more we can pull in to the cylinders.

The PCV adversely affects your engine in the following ways.
The hot air from the PCV heats up the intake charge (incoming air). The engine measured the air temp and now that measurement is off.

The oil mist collides with the misted fuel and causes some of it to burn slowly or to not ignite at all. This will cause the engine to run leaner.

And while oil is fairly stable it still burns under the extreme heat of combustion and I certainly don't know what it's octane is but I would assume it is very low and has a fast burn time.
This causes two problems, 1 if it ignites before the fuel is supposed to ignite it could cause the fuel to ignite prematurely (detonation). 2 if it burns fast it will cause the fuel to burn unevenly thus lowering the efficiency of the motor.

Note: Gas = Air, Fuel = Gasoline.

This may help. http://science.howstuffworks.com/gasoline1.htm

 

[01BlueCOBRA]

so when its real cold outside, like 30-40 deg or so. your car will run a lil leaner with a CAI ??

 

[Snake Eyes]

No, the MAF (mass air meter) and IAT (intake air temp) are located before the intake manifold. The car knows how much air is being drawn into the car, and what temperature it is. The problem is the PCV is behind these sensors, therefore any air that is exchanged (between the incoming air and the hotter valve cover air) using the PCV system is not the same temperature (density).

 

[REX-RACER]

Not to contradict SnakeEyes 'cause he seems to really know his $hit and he puts up a lot of good tech info for us hear ( and I'm sure he knows this ) but . . .

It is my understanding that a good CAI like the JLT will lean out the air/fuel ratio a tad bit. The reason this isn't such a big deal normally is because: 1). Our cars come from the the factory w/ an intentionally rich tune because that's safe and, 2). The ECU can handle air intake in a certain range and adjust the injector pulse to compensate for more incoming air.

If I remember correctly the stock A/F ratio is set at something like 11.5/1 at idle and then gets way rich at WOT, like 10/1 because it's a safe way to prevent detonation and control for real world factors that can't be accounted for at the factory like inferior octane, air temp, barrometric pressure, etc. This is why wide band O2 measurement is such a big deal when getting a dyno tune. One of the first things most dyno tuners do, especially on an N/A car is lean up the A/F ratio on the top end.

Like I said it's "safe" to do this w/ in a range and a CAI will usually add about a half a point, to a point to the A/F ratio so that it may come out to about 12/1 w/ out changing the factory tune. I've heard that some people have had problems w/ adding a CAI and a bigger MAF and running into a lean condition that caused detonation and driveability issues. Some folks have had these problems in using a larger MAF housing in conjuction w/ the factory electronics. It would appear that the way to go w/ this is to get a MAF w/ it's own dedicated electronics.

Any tinkering of the A/F ratio via the tunning should be left to someone who knows what they are doing as a too lean condition will cause detonation and that leads straight to broken parts!

 

[caseydp75]

I don't have any part numbers, but the PCV system on Volvos uses a small inline metal canister (about the size of a pinky finger) that is basically filled with a stainless steel mesh. The mid-70's Volvos were particularly bad about getting clogged, creating a positive crankcase pressure and seeping oil through the main seals. The mesh would allow pressure escape, but also capture oil mist.

 

[lemosley01]

cobraracer, I believe you just got owned.

Actually, there was no ownage intended. I just put that out there as both my thoughts on the subject and to open discussion to see what others who know more than me have to say on the subject.

Rex-racer, in theory, a CAI should not cause the car to run any more lean than when it had the stock airbox/filter on it. This is because the MAF knows the mass of the air that is being taken in, and therefore can calculate how much fuel to shoot into that air to make the proper a/f ratio. From the factory, I believe the cars are set to target something like 13.5(?) A/F at non-wot and at WOT it does seem to run into the 10s, although the WOT tables are derived from the input received during normal closed loop driving (when the oxygen sensors are being used).

I believe that CAIs that cause the A/F to run more lean are doing so because the turbulence in the intake charge causes the MAF to misread how much air it is seeing, and therefore not enough fuel gets injected.

One of the reasons our cars feel stronger when it's cold is that the PCM doesn't have to pull as much timing (if any) as when it's hot to prevent detonation. That 40+ degree difference (85 vs 45 degress) can make a lot of difference in how soon the fuel ignites. When it's hot, the fuel is more likely to pre-ignite, and therefore the computer will pull timing to prevent this (or when it senses detonation).

 

[REX-RACER]

Rex-racer, in theory, a CAI should not cause the car to run any more lean than when it had the stock airbox/filter on it. This is because the MAF knows the mass of the air that is being taken in, and therefore can calculate how much fuel to shoot into that air to make the proper a/f ratio. From the factory, I believe the cars are set to target something like 13.5(?) A/F at non-wot and at WOT it does seem to run into the 10s, although the WOT tables are derived from the input received during normal closed loop driving (when the oxygen sensors are being used).

I believe that CAIs that cause the A/F to run more lean are doing so because the turbulence in the intake charge causes the MAF to misread how much air it is seeing, and therefore not enough fuel gets injected.

One of the reasons our cars feel stronger when it's cold is that the PCM doesn't have to pull as much timing (if any) as when it's hot to prevent detonation. That 40+ degree difference (85 vs 45 degress) can make a lot of difference in how soon the fuel ignites. When it's hot, the fuel is more likely to pre-ignite, and therefore the computer will pull timing to prevent this (or when it senses detonation).

Good point! :beer:

I hadn't actually thought of that, I had just assumed that a good CAI would naturally lean out the A/F and the ECU just operated w/ in some sort of acceptebale range. Perhaps that "turbelance" is designed into the CAI in order to produce the slightly lean condition? That sounds like a good question for Mareck.

One of the other things to keep in mind that makes our cars ( or any car for that matter ) is high barrometric pressure which is kind of like natures own "forced induction". I love those early days of spring or late mid to late days of fall when the weather hits that sweet spot around 55*, low humidity and high barrometric pressure. The proverbial "good air"! I talked about it so much last year even my girlfriend can now identify "good air"! :-D

 

[01BlueCOBRA]

Good point! :beer:

I hadn't actually thought of that, I had just assumed that a good CAI would naturally lean out the A/F and the ECU just operated w/ in some sort of acceptebale range. Perhaps that "turbelance" is designed into the CAI in order to produce the slightly lean condition? That sounds like a good question for Mareck.

One of the other things to keep in mind that makes our cars ( or any car for that matter ) is high barrometric pressure which is kind of like natures own "forced induction". I love those early days of spring or late mid to late days of fall when the weather hits that sweet spot around 55*, low humidity and high barrometric pressure. The proverbial "good air"! I talked about it so much last year even my girlfriend can now identify "good air"! :-D

i feel you on that one. i cant tell when its really humid outside, cause the car doest respone 100%. if i had a bad (MAF) wouldt the 'Service Engine Light' come on ?? awhile back i cleanted the MAF and dunno if i F* anything up. cause a messed up MAF=messed up readings for the ECU. :bash:

 

[01BlueCOBRA]

Also. i think it wouldt hurt to get a Custom Tune for the JLT CAI. cause of how much air is being taken in. unlike the STOCK AIRBOX. it had to sucking in the air unlike the JLT were its getting forced air. is that were HP comes in ?

 

[REX-RACER]

i feel you on that one. i cant tell when its really humid outside, cause the car doest respone 100%. if i had a bad (MAF) wouldt the 'Service Engine Light' come on ?? awhile back i cleanted the MAF and dunno if i F* anything up. cause a messed up MAF=messed up readings for the ECU. :bash:

Yeah, I think if you get oil on the wires in the MAF it can read incorrectly and throw the SEL light. Perhaps you should got to an AutoZone or some place like that and have them read the code for you.

I think the way you clean the wires in the MAF is w/ a cotton swab and a little alcohol. I know I've seen the direction for that on here so you can do search on it and get the info you need!