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techtalk:ref:engmech04 [2019/07/12 21:20]
hippysmack [Oil Tank's Role vs Wetsumping]
techtalk:ref:engmech04 [2019/07/23 03:30] (current)
hippysmack [Venting the oil tank]
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 ===== Blowby ===== ===== Blowby =====
 Blowby pertains to the condition of ring seal at the cylinders / pistons. \\ Blowby pertains to the condition of ring seal at the cylinders / pistons. \\
 +It is fundamentally just exhaust that went past the rings instead of out the exhaust port. ((aswracing oftheXLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4)) \\
 +It's depleted of oxygen, it's hot, and it picks up moisture and oil in it's travels through the crankcase and into your intake tract. \\
 +So it's displacing oxygen in the intake charge (through the air cleaner) that would otherwise contribute to combustion. \\
 +It also heats the intake charge which contributes to detonation. \\
 +It's just a bad thing all the way around, robbing power, causing detonation, and contributing to carbon build-up. It's well worth it to remove it from the intake tract and vent it to the atmosphere or exhaust instead, in my opinion.
 +
 Combustion above the piston is pushed past the rings and into the crankcase. \\ Combustion above the piston is pushed past the rings and into the crankcase. \\
 What actually 'blows by' the rings and into the crankcase is a mix of unburnt fuel, water, soot, acids etc. ((bunny32 of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=67658&​page=2)) \\ What actually 'blows by' the rings and into the crankcase is a mix of unburnt fuel, water, soot, acids etc. ((bunny32 of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=67658&​page=2)) \\
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     * Bad ring seal helps evacuate the sump from oil. ((Jorgen of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=75740&​highlight=reed+valve&​page=7)) \\ But on the other hand it increases the flow rate through the crank vent system to such levels that a lot of oil droplets join in.     * Bad ring seal helps evacuate the sump from oil. ((Jorgen of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=75740&​highlight=reed+valve&​page=7)) \\ But on the other hand it increases the flow rate through the crank vent system to such levels that a lot of oil droplets join in.
  
-Reasons ​for oil puking out the engine breather:+Helpers ​for oil puking out the engine breather:
   - Wet Sumping:   - Wet Sumping:
     * During engine down time.     * During engine down time.
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     * Makes a clicking noise during operation.     * Makes a clicking noise during operation.
  
-|  Mercedes Benz P/N# 271-018-00-29 ((photo by electronbee of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=72099&​highlight=reed+valve&​page=10)) ​ |  Reed Valve ((photo by Bluto of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5761290#​post5761290)) ​ | +|  Mercedes Benz P/N# 271-018-00-29 ((photo by electronbee of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=72099&​highlight=reed+valve&​page=10)) ​ |  Reed Valve ((photo by Bluto of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5761290#​post5761290))  |  Doherty Power Vent ((Photo by goblin_dust of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=72099&​highlight=wet+sumping&​page=23))  | 
-|{{:​techtalk:​ref:​engmech:​mercedes_benz_pcv_valve_by_electronbee.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​reed_valve_by_bluto.jpg?​direct&​300|}}|+|{{:​techtalk:​ref:​engmech:​mercedes_benz_pcv_valve_by_electronbee.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​reed_valve_by_bluto.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​deimus_mod_2_by_goblin_dust.jpg?​direct&​300|}}|
  
 ==== Regarding horsepower gains from different breathers ==== ==== Regarding horsepower gains from different breathers ====
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-===== Breather System Air Volume Testing =====+===== Breather System ​Air Volume Testing ===== 
 + 
 +The following is to share some dyno testing by aswracing of using the timing plug location for an additional crankcase vent. ((aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4)) \\ 
 + 
 +First, a little background. \\ 
 +In the stock configuration,​ the crankcase vents through a pair of "​umbrella"​ valves, which are essentially check valves. \\ 
 +There is no air inlet into the motor. \\ 
 +The pistons come down the first time and the crankcase air is expelled, the air is forced out through the umbrella valves. \\ 
 + 
 +But when the pistons go back up, the umbrella valves block the inflow of air, causing a slight vacuum in the crankcase. \\ 
 +The next time the pistons come down, crankcase pressure will return to atmospheric at BDC before the upstroke. \\ 
 +If no air is allowed into the motor, the crankcase will cycle between a vacuum (pistons up) and atmospheric (pistons down). \\ 
 + 
 +However, some air is actually allowed to enter, primarily in the form of blow-by that escapes the combustion chamber past the rings. \\ 
 +Therefore, in the stock design, there is a small net outflow. \\ 
 +The amount will vary with the condition of the motor. 
 + 
 +Properly functioning umbrella valves therefore serve the purpose of significantly reducing the breather capacity requirement while also minimizing crankcase pressure. \\ 
 +Excessive airflow & oil discharge through the breathers can be caused by malfunctioning umbrella valves that are allowing air into the motor. \\ 
 + 
 +For this test, an additional vent was added at the timing plug hole. \\ 
 +No check valve was installed on this vent. \\ 
 +Therefore, the crankcase is being allowed to pull in air as the pistons go up. \\ 
 +**This fundamentally changes the engine'​s venting design**. \\ 
 + 
 +Some people feel that allowing the engine to both inhale and exhale in this manner reduces crankcase pressure. \\ 
 +Several people cite a "seat of the pants" improvement in performance. \\ 
 +The purpose of this test was to determine if there actually is a performance improvement from this change to the venting system. \\ 
 + 
 +The fitting arrangement used is in the pic below. \\ 
 +The threads on the flare match the timing plug hole threads. \\  
 +There are two fittings threaded together and app. two feet of 3/8" I.D. hose was attached to the hose barb. 
 + 
 +|3/8" flare to 1/4" FPT fitting \\ with a 1/4" MPT to 3/8" hose barb. ((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))|Fitting and hose as installed on the bike.((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))|Test bike (near stock 1999 M2). ((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))| 
 +|{{:​techtalk:​ref:​engmech:​timing_plug_adapter_by_aswracing.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​testing_cc_pressure_1_by_aswracing.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​testing_cc_pressure_2_by_aswracing.jpg?​direct&​300|}}| 
 + 
 +Lots and lots of dyno pulls were performed in each configuration and the configuration was switched back and forth a few times. \\ 
 +Dyno results are not 100% repeatable, and as such, below is a range of results for each configuration,​ as well as a comparison of best pulls. \\ 
 +Click on a chart to enlarge: \\ 
 + 
 +|10 best pulls from the stock configuration. ((chart by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))|10 best pulls from timing plug vent configuration. ((chart by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))|Best stock pull and the best timing plug vent pull. ((chart by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4))| 
 +|{{:​techtalk:​ref:​engmech:​dyno_and_breathing_1_by_aswracing.gif?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​dyno_and_breathing_2_by_aswracing.gif?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​dyno_and_breathing_3_by_aswracing.gif?​direct&​300|}}| 
 + 
 +As you can see, the difference is within the repeatability of the measurement. \\ 
 +If a person *had* to declare a winner, the results with the stock setup would seem to have a little edge. \\ 
 +(both in the "​best"​ results and just looking at the average of the 10 best results) \\ 
 +But I'd be careful doing that, you could be looking at normal variation. \\ 
 + 
 +**Observations**:​ \\ 
 +I was surprised at how little air movement there was at the end of the hose. \\ 
 +When a motor is started with nothing screwed into the timing plug, there'​s a massive inhalation and exhalation evident. \\ 
 +But apparently, necking it down to a 3/8" hole and connecting 2 feet of hose adds a pretty significant restriction. \\ 
 +Air flow was nowhere near what I expected. \\ 
 +Unfortunately,​ getting a 7/16" or 1/2" hose into that area would be problematic,​ space is tight. \\ 
 +Plus, a fitting with the correct thread and a 7/16" or 1/2" hole may not be available. \\ 
 + 
 +Another surprise was just how easy it was to plug the hose with my finger, and how it felt when I did. \\ 
 +The pressure was not great. \\
    
 ===== Engine Venting Mods ===== ===== Engine Venting Mods =====
-See also [[techtalk:​ref:​oil05|Engine and Primary Oil System Modifications]] for a listing of mods from the XLFORUM. \\+See also [[techtalk:​ref:​engmech05|Breather Venting / Relocation]] for a listing of breather ​mods from the XLFORUM. \\ 
 + 
 +In addition to the above, I also did a bunch of testing of the aftermarket breather check valves from Spyke and Hayden. ((aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1946516&​page=4)) \\ 
 +(and even did some experiments with vacuum pumps and the like) \\ 
 +Did some magazine articles here and there at the time. The motor was remarkably insensitive to anything I did with the breathers. \\ 
 +Like I said, the only thing I could get to show up on the Dyno sheet at all was the removing of the blow-by from the intake tract. \\
  
 Engine breathers control when CC pressure exits the engine. \\ Engine breathers control when CC pressure exits the engine. \\
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 This practice is not just restricted to rubbermounts although due to the CC pressure change in 04, it is a more accepted practice. \\ This practice is not just restricted to rubbermounts although due to the CC pressure change in 04, it is a more accepted practice. \\
 The tank acts as an oil / air separator like the breather valve but the air only expels the engine from the engine breather vent. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1971026&​page=28)) \\ The tank acts as an oil / air separator like the breather valve but the air only expels the engine from the engine breather vent. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1971026&​page=28)) \\
 +
 +==== Lowering the oil level in the tank ====
  
 ** *When you lower the oil level in the tank, you are just masking the real problem* ** . \\ ** *When you lower the oil level in the tank, you are just masking the real problem* ** . \\
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     * The oil level only matters if the tank has been overfilled past the top mark on the dipstick. ((Toejam503 of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5750657&​highlight=lower+oil+level#​post5750657))     * The oil level only matters if the tank has been overfilled past the top mark on the dipstick. ((Toejam503 of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5750657&​highlight=lower+oil+level#​post5750657))
     * This is easy to do if you check the oil level and fill the tank BEFORE heating up the engine to operating temperature. \\ See more about [[techtalk:​ref:​oil01#​overfilling_the_oil_tank|Over filling the oil tank]] in the REF section of the Sportsterpedia.     * This is easy to do if you check the oil level and fill the tank BEFORE heating up the engine to operating temperature. \\ See more about [[techtalk:​ref:​oil01#​overfilling_the_oil_tank|Over filling the oil tank]] in the REF section of the Sportsterpedia.
 +    * Overfilling the oil tank can bring the level up over the vent to the crankcase. \\ This would stop up the vent to the cam chest, over-pressurize the tank and hinder scavenging from the sump. \\ Increased sump oil (not able to be scavenged fast enough) aides in oil suspension or air /oil density increasing crankcase pressure. \\ Increased crankcase pressure aides in oil puking out the vents.
   - **Running the oil level on the bottom dipstick line helps curb blowby. \\ Running the oil level at the middle to high side of the dipstick causes more blowby.** \\   - **Running the oil level on the bottom dipstick line helps curb blowby. \\ Running the oil level at the middle to high side of the dipstick causes more blowby.** \\
     * Running the oil level on the low mark of the stick effectually lowers the amount of oil that would collect in the sump.     * Running the oil level on the low mark of the stick effectually lowers the amount of oil that would collect in the sump.
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     * Lowering the amount of oil in the sump also leaves less oil there to get pulled up into suspension which thins out air / oil mist.     * Lowering the amount of oil in the sump also leaves less oil there to get pulled up into suspension which thins out air / oil mist.
     * It's the more dense air / oil mist that is the problem, not the oil level in the tank. \\     * It's the more dense air / oil mist that is the problem, not the oil level in the tank. \\
 +    * Many people say that it is important to leave plenty of empty space in your oil tank. ((Deimus of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=72099&​highlight=wet+sumping&​page=21)) \\
 +      * If you don't have excess crankcase pressure, you don't have to do that. You can fill the oil tank to the full mark on the dipstick without any issue.
 +      * The oil tank is a sealed space with a seal / O-ring on the dipstick. \\ The oil tank space is connected to the crankcase space via the vent hose that runs from the oil tank to the cam cover. \\ By filling the oil tank only half full, you create a larger air volume in the crankcase space itself. \\ This increased air volume can help buffer the pressure in an engine with only a slight problem with blow-by gasses combined with the restricted head vents.
 +      * However, if you either;
 +        * Restore your engine to like new low levels of blow-by.
 +        * Or if you improve the engine'​s ability to vent the pressure. \\ Then you don't need the extra buffer space provided by half filling your oil tank. \\ You can go ahead and fill your tank with the proper amount of oil. \\ Which means you have more oil to circulate through the engine which is a good thing.
  
-**So the answer is to address the oil density, not the oil level.**+**So the answer is to address the air/oil density, not the oil level.**
  
 +==== Removing the oil cap - engine running ====
  
 +With the oil cap off the tank on a hot idling engine, the engine speed can drop app. 1,000 RPM at 1050 idle. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5763694#​post5763694)) \\
 +Another example with oil temp 210, raised idle to 1200 and lost 700 RPM. \\
 +So the exact power loss is variable but true. \\
 +Barely opening the cap or fully removing it had no affect on RPM. \\
  
 +This is the same as having a bad breather valve opening but not closing. \\
 +Oil doesn'​t puke out the tank since higher density suspension oil comes up the return line from the sump. \\
 +The suspension fluid and return oil together in the line helps to separate the oil back out of suspension by the time it reaches the tank. \\
 +The bulk of air / oil mist is generated in the crankcase, not the cam chest where the vent line to the tank is. \\
 +(leaving what comes out the top of the oil tank to be nothing but air). \\
 +The higher air/oil density drags the flywheels and more oil is picked up in suspension with the engine breathing both in and out. \\
 +The engine responds at idle from the higher load on the wheels. \\
 +Read more on [[techtalk:​ref:​engmech04#​fluid_drag|Fluid Drag]] above. \\
 +
 +==== Venting the oil tank ====
 +Neither the oil cap nor the oil tank should be vented without a one way check valve / pcv. \\
 +The tank is vented to the cam chest on purpose to remove condensate (that gets pumped in) from the oil tank. \\
 +Venting the oil tank \ cap also will negatively influence crankcase venting by letting in extra air. \\
 +1/2 of the return flow is air because the return pump is twice as big as the feed pump. ((ryder rick of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1904589&​page=4)) \\
 +That air is full of condensate. \\
 +A slightly negative (to atmospheric) pressure in the tank facilitates vaporization of the condensate. \\
  
  
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 (that'​s high performance enough.... not worn enough) \\ (that'​s high performance enough.... not worn enough) \\
 It will, in general, add some horse power, increase engine life and keep oil cleaner for longer (in a high performance engine). \\ It will, in general, add some horse power, increase engine life and keep oil cleaner for longer (in a high performance engine). \\
 +
 +The first thing that happens on downstroke is that positive pressure (greater than atmosphere) is generated due to the restrictions of:
 +  * Case volume
 +  * Path to the vents
 +  * Vent hole size
 +  * Vent line (if applicable) length
 +  * Any induced air from the breather valve(s) not closing properly
 +
 +These things will bring the pressure inside to higher than atmosphere, else there would be nothing to expel. \\
 +As the air is pushed out of the vent, at BDC, the air returns to atmospheric. \\
 +That is the problematic condition, the higher pressure before returning to atmosphere. \\
 +Blowby adds to positive pressure which throws out the balance.
 +  * Using X (+1) as positive and Y (-1) as negative pressure.
 +  * In a perfect world, X goes down and Y comes up ------ X+Y=0.
 +  * Add ring blowby and you get ------ X+1>​Y------ or the real result. \\ Balance is off by nature of the moving parts. \\ The pistons move up and down almost together. \\ That makes the push/pull environment more violent.
 +  * Now add a vacuum pump with Z (-1) amount of pull. \\ Now you get X+1=Y-Z... seems the balance (to zero) is restored even though positive pressure is compiled of blowby. \\ But the lower the negative pressure is at the beginning of the downstroke, the lower the next positive pressure will be.
 +  * If you are generating 2 psi of positive pressure on downstroke but reduce it's beginning surge to -1 psi (Z), \\ the result will be only 1 psi of positive pressure during downstroke. \\ -1 (+) + 2 equals +1.
 +
 +The more the vacuum, even lower the positive will begin. \\
 +The rings act as a buffer between these two conditions as excess pressure could run both directions. \\
 +But positive pressure aides in oil scavenging. \\
 +So lowering positive pressure by default also hinders scavenging. \\
 +That's why racers with vacuum pumps use multistage scavenge pumps to account for the imbalance to scavenge and improve it. \\
 +
  
 **Considerations for running a vacuum pump**: \\ **Considerations for running a vacuum pump**: \\