Louis Ott's full valve cover video now on youtube
06-18-2010, 10:38 PM
#121
Nordschleife Master
Thread Starter
The GTR is stated to have used a select example of the GTS engine with fine tuning performed on it. The GTS had emissions cams in it, whether "fine tuning" involved swapping in the GT cams I do not know.* The S4 GT engines immediately prior were raced to 7200 rpms, despite the peak output being at 6600 rpm and max torque at 4500 rpm (Gruppe H). Stated modifications to the S4 racing engines which would come under tuning were the use of a pressure limiting (to 3Bar) valve to the heads (from the 944 S2). This slowed oil throughput and the volume of oil in the heads and had the effect of increasing the oil level in the sump. The mentioned modifications to the sump using sheet metal aluminum most likely refers to the subsequently introduced GTS baffle. The GTS engine was raced in the GTR for almost a complete season without failure and another engine was obtained with the same tuning done to it.
All this aside, you're simply in a bit over your head technically and grasping at any and all straws to try to avoid answering the questions. You keep appealing to Occams Razor despite the very well established fact that demanding parsimony as an arbitor in answers is a logical and empirical fallacy. It is a guide for rational thinking -- not a rule for rational thinking. You throw aeration out the window despite it being a well established physical characteristic of lubricating oil. What is that? Do you really think you're helping people with that?
I say that the intermittent pressure drops in fast, high rpm corners are caused by the pickup being uncovered. I furthermore say that this is mainly caused by the crankshaft whipping the oil to the heads and to the top of the crankcase in fast, high rpm corners, and the oil therefore not returning fast enough into the sump. Note that I am not saying that aeration isn't a problem that one should worry about once the problem of pickup being uncovered is solved. What I am saying is that worrying about aeration when the pickup is being uncovered is analogous to rearranging deck chairs on Titanic.
06-19-2010, 05:00 AM
#122
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Here is an excerpt from the 928 wikipedia entry; my emphasis:
Originally Posted by wikipedia
Lagaaij reports, that the car was very competitive and able to hold most 993GTR down, although the engine was no more than fine-tuned after chosen from a set of high power output specimen in Weissach.In the last race of the season at Hockenheim a crank-bearing ran dry. As the car was supposed to race in 1995 as well, she was made ready to continue her successful competition in the 1995 season. A fresh engine was installed, selected from the same lot of high output engines and tuned as before. In 1995 Porsche's 928 production came to an end, and the car consequently was not raced in the new season.
Harm Lagaaij (Den Haag, 28 december 1946) is autodesigner en heeft in de loop van zijn carrière de vormgeving van veel succesvolle auto’s beïnvloed. Na zijn opleiding, met een afgeronde studie aan de TU in Delft begon hij zijn loopbaan in 1967 bij het bedrijf Olyslager in Soest. Eind zestiger jaren werkte Lagaaij voor Simca.
Vanaf 1971 werkte hij op de design-afdeling van Porsche in Weissach (Duitsland) en was hij betrokken bij de vormgeving van de modellen 911, 924 en 928.
Na zes jaren werd hij hoofd van de design-afdeling bij Ford in Keulen. Daar droegen meerdere modellen, zoals de Escort en de Sierra zijn handschrift.
In 1985 stapte hij over naar BMW en werd daar hoofdontwerper. Een van de bekendste projecten uit deze tijd is de in 1987 op de IAA gepresenteerde BMW Z1 Roadster.
Van 1989 tot zijn pensionering op 1 juli 2004 was hij daarna hoofd van de designafdeling van Porsche in Weissach. Naast de studiemodellen Porsche Panamericana en Porsche 989 werden de seriemodellen Porsche Boxster, Porsche Cayman, Carrera GT, Cayenne en de 911 (modelnummers 964, 993 en 996) grotendeels door hem stilistisch gedefinieerd. Zijn laatste opgave was de Porsche 911 (modelnummer 997), die vanaf 2004 op de markt is. Sinds 1 november 2004 zijn zijn taken overgenomen door Michael Mauer, die daarvoor hoofddesigner bij Saab was.
Vanaf 1971 werkte hij op de design-afdeling van Porsche in Weissach (Duitsland) en was hij betrokken bij de vormgeving van de modellen 911, 924 en 928.
Na zes jaren werd hij hoofd van de design-afdeling bij Ford in Keulen. Daar droegen meerdere modellen, zoals de Escort en de Sierra zijn handschrift.
In 1985 stapte hij over naar BMW en werd daar hoofdontwerper. Een van de bekendste projecten uit deze tijd is de in 1987 op de IAA gepresenteerde BMW Z1 Roadster.
Van 1989 tot zijn pensionering op 1 juli 2004 was hij daarna hoofd van de designafdeling van Porsche in Weissach. Naast de studiemodellen Porsche Panamericana en Porsche 989 werden de seriemodellen Porsche Boxster, Porsche Cayman, Carrera GT, Cayenne en de 911 (modelnummers 964, 993 en 996) grotendeels door hem stilistisch gedefinieerd. Zijn laatste opgave was de Porsche 911 (modelnummer 997), die vanaf 2004 op de markt is. Sinds 1 november 2004 zijn zijn taken overgenomen door Michael Mauer, die daarvoor hoofddesigner bij Saab was.
...
That's an interesting way to look at this conversation we've had. Nobody else cares at this point, but just for the sake of completeness let me just write out what I think so we can contrast it with your misrepresentations.
I say that the intermittent pressure drops in fast, high rpm corners are caused by the pickup being uncovered. I furthermore say that this is mainly caused by the crankshaft whipping the oil to the heads and to the top of the crankcase in fast, high rpm corners, and the oil therefore not returning fast enough into the sump. Note that I am not saying that aeration isn't a problem that one should worry about once the problem of pickup being uncovered is solved. What I am saying is that worrying about aeration when the pickup is being uncovered is analogous to rearranging deck chairs on Titanic.
That's an interesting way to look at this conversation we've had. Nobody else cares at this point, but just for the sake of completeness let me just write out what I think so we can contrast it with your misrepresentations.
I say that the intermittent pressure drops in fast, high rpm corners are caused by the pickup being uncovered. I furthermore say that this is mainly caused by the crankshaft whipping the oil to the heads and to the top of the crankcase in fast, high rpm corners, and the oil therefore not returning fast enough into the sump. Note that I am not saying that aeration isn't a problem that one should worry about once the problem of pickup being uncovered is solved. What I am saying is that worrying about aeration when the pickup is being uncovered is analogous to rearranging deck chairs on Titanic.
Since we know that, isolated from the system, the pickup will already be fully uncovered at 1G laterally by the angle of repose (probably much earlier -- at .58G the pickup begins to be exposed laterally) the engine has only the volume of oil present in the tube and being recirculated by the pump. This would suffice for perhaps a second or two. Every second the engine is rotating about 100 times (6000 rpm). Within one race, perhaps even within one or two hard corners under power, you could expect bearing failure.
This uncovering of the pickup does not require oil being whipped up to the heads or the top of the engine. Your "mainly caused by the crankshaft whipping the oil to the heads and to the top of the crankcase in fast, high rpm corners, and the oil therefore not returning fast enough into the sump" shows that you do not understand this. It also shows that overly simplistic approaches to the problem do not address what is actually happening. This transfer of the oil occurs even with the sump being fully filled with the normal running level of oil.
Why do we know that such a simplistic approach is incorrect? Because the engine did not always immediately fail. Mark Kibort can attest to this and so can the team running the GTR.
This means that some sort of dynamic system is present that is continually throwing or pushing oil to the opposite side of the pickup so that as the engine moves through space accelerating laterally that oil will migrate and become available to the pickup.
That also means that the fundamental problem in the bearing failure was aeration. Porsche had the issue of the pickup being covered addressed up to a fairly high level of performance. What was vexing was that aeration bulk was often helpful in the sump feeding the pickup but it would ultimately destroy the engine.
To suppress the underlying problem of aeration which helped in some ways but ultimately would kill the engine, i.e. a complex problem, a complex solution was required.
06-19-2010, 09:35 AM
#124
Nordschleife Master
Thread Starter
Your pan angle and capacity calculations are incorrect and/or rely on unverifiable assumptions.
It's not enough to take a loose pan, fill it with water, and tilt it to see in which angle the water flows out of the pan and uncovers the pickup. The reason why it's not enough is that when the pan is installed on the block, the girdle and block walls extend the pan. If you look at the static (crank not spinning) combination of the pan, girdle, and the block, whether the pickup gets uncovered or not depends not only on the angle but also on the volume of the oil in the sump. In extreme, you could think of an absurd example of tilting the engine 90 degrees and filling up the entire engine with oil -- the pickup wouldn't uncover.
Thus, for every tilt angle of the engine, one would need to measure the critical volume of oil, defined as the smallest volume of oil in the sump that keeps the pickup covered. That's a lot of measurements with minimally the girdle bolted on the pan, but it is measurable.
Then, for every tilt angle of the engine and rpm, we have to assume (or measure, if someone figures out how) both the net rate at which the pump ingest oil and the oil return rate. The oil return rate depends on the volume of oil in circulation, which is the total oil capacity minus the volume in sump. The relation is almost certainly monotonic, more oil in circulation means higher return rate. It's enough to only assume/measure the return rate when the sump is at critical volume (and total oil capacity minus the critical volume is in circulation) in order to figure out whether the pickup uncovers.
For a given rpm and tilt angle, the net ingestion rate is either lower than the return rate at critical volume, in which case the pickup stays submerged, or the net ingestion rate is higher than the return rate at critical volume, in which case the pickup uncovers.
Is this how you came up with your precise 0.58g estimate? Or did you just fill a loose pan with fluid, tilt the pan sideways until the pickup uncovered while some of the fluid poured out of the pan, and back out the g-force from the resulting angle? This short-cut method would be pretty stupid and give the wrong answer, don't you agree?
It's not enough to take a loose pan, fill it with water, and tilt it to see in which angle the water flows out of the pan and uncovers the pickup. The reason why it's not enough is that when the pan is installed on the block, the girdle and block walls extend the pan. If you look at the static (crank not spinning) combination of the pan, girdle, and the block, whether the pickup gets uncovered or not depends not only on the angle but also on the volume of the oil in the sump. In extreme, you could think of an absurd example of tilting the engine 90 degrees and filling up the entire engine with oil -- the pickup wouldn't uncover.
Thus, for every tilt angle of the engine, one would need to measure the critical volume of oil, defined as the smallest volume of oil in the sump that keeps the pickup covered. That's a lot of measurements with minimally the girdle bolted on the pan, but it is measurable.
Then, for every tilt angle of the engine and rpm, we have to assume (or measure, if someone figures out how) both the net rate at which the pump ingest oil and the oil return rate. The oil return rate depends on the volume of oil in circulation, which is the total oil capacity minus the volume in sump. The relation is almost certainly monotonic, more oil in circulation means higher return rate. It's enough to only assume/measure the return rate when the sump is at critical volume (and total oil capacity minus the critical volume is in circulation) in order to figure out whether the pickup uncovers.
For a given rpm and tilt angle, the net ingestion rate is either lower than the return rate at critical volume, in which case the pickup stays submerged, or the net ingestion rate is higher than the return rate at critical volume, in which case the pickup uncovers.
Is this how you came up with your precise 0.58g estimate? Or did you just fill a loose pan with fluid, tilt the pan sideways until the pickup uncovered while some of the fluid poured out of the pan, and back out the g-force from the resulting angle? This short-cut method would be pretty stupid and give the wrong answer, don't you agree?
Since we know that, isolated from the system, the pickup will already be fully uncovered at 1G laterally by the angle of repose (probably much earlier -- at .58G the pickup begins to be exposed laterally) the engine has only the volume of oil present in the tube and being recirculated by the pump. This would suffice for perhaps a second or two. Every second the engine is rotating about 100 times (6000 rpm). Within one race, perhaps even within one or two hard corners under power, you could expect bearing failure.
This uncovering of the pickup does not require oil being whipped up to the heads or the top of the engine. Your "mainly caused by the crankshaft whipping the oil to the heads and to the top of the crankcase in fast, high rpm corners, and the oil therefore not returning fast enough into the sump" shows that you do not understand this. It also shows that overly simplistic approaches to the problem do not address what is actually happening. This transfer of the oil occurs even with the sump being fully filled with the normal running level of oil.
Why do we know that such a simplistic approach is incorrect? Because the engine did not always immediately fail. Mark Kibort can attest to this and so can the team running the GTR.
This means that some sort of dynamic system is present that is continually throwing or pushing oil to the opposite side of the pickup so that as the engine moves through space accelerating laterally that oil will migrate and become available to the pickup.
That also means that the fundamental problem in the bearing failure was aeration. Porsche had the issue of the pickup being covered addressed up to a fairly high level of performance. What was vexing was that aeration bulk was often helpful in the sump feeding the pickup but it would ultimately destroy the engine.
To suppress the underlying problem of aeration which helped in some ways but ultimately would kill the engine, i.e. a complex problem, a complex solution was required.
This uncovering of the pickup does not require oil being whipped up to the heads or the top of the engine. Your "mainly caused by the crankshaft whipping the oil to the heads and to the top of the crankcase in fast, high rpm corners, and the oil therefore not returning fast enough into the sump" shows that you do not understand this. It also shows that overly simplistic approaches to the problem do not address what is actually happening. This transfer of the oil occurs even with the sump being fully filled with the normal running level of oil.
Why do we know that such a simplistic approach is incorrect? Because the engine did not always immediately fail. Mark Kibort can attest to this and so can the team running the GTR.
This means that some sort of dynamic system is present that is continually throwing or pushing oil to the opposite side of the pickup so that as the engine moves through space accelerating laterally that oil will migrate and become available to the pickup.
That also means that the fundamental problem in the bearing failure was aeration. Porsche had the issue of the pickup being covered addressed up to a fairly high level of performance. What was vexing was that aeration bulk was often helpful in the sump feeding the pickup but it would ultimately destroy the engine.
To suppress the underlying problem of aeration which helped in some ways but ultimately would kill the engine, i.e. a complex problem, a complex solution was required.
06-19-2010, 12:11 PM
#125
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Originally Posted by ptuomov
Your pan angle and capacity calculations are incorrect and/or rely on unverifiable assumptions.
It's not enough to take a loose pan, fill it with water, and tilt it to see in which angle the water flows out of the pan and uncovers the pickup. The reason why it's not enough is that when the pan is installed on the block, the girdle and block walls extend the pan. If you look at the static (crank not spinning) combination of the pan, girdle, and the block, whether the pickup gets uncovered or not depends not only on the angle but also on the volume of the oil in the sump. In extreme, you could think of an absurd example of tilting the engine 90 degrees and filling up the entire engine with oil -- the pickup wouldn't uncover.
Thus, for every tilt angle of the engine, one would need to measure the critical volume of oil, defined as the smallest volume of oil in the sump that keeps the pickup covered. That's a lot of measurements with minimally the girdle bolted on the pan, but it is measurable.
Then, for every tilt angle of the engine and rpm, we have to assume (or measure, if someone figures out how) both the net rate at which the pump ingest oil and the oil return rate. The oil return rate depends on the volume of oil in circulation, which is the total oil capacity minus the volume in sump. The relation is almost certainly monotonic, more oil in circulation means higher return rate. It's enough to only assume/measure the return rate when the sump is at critical volume (and total oil capacity minus the critical volume is in circulation) in order to figure out whether the pickup uncovers.
For a given rpm and tilt angle, the net ingestion rate is either lower than the return rate at critical volume, in which case the pickup stays submerged, or the net ingestion rate is higher than the return rate at critical volume, in which case the pickup uncovers.
Is this how you came up with your precise 0.58g estimate? Or did you just fill a loose pan with fluid, tilt the pan sideways until the pickup uncovered while some of the fluid poured out of the pan, and back out the g-force from the resulting angle? This short-cut method would be pretty stupid and give the wrong answer, don't you agree?
It's not enough to take a loose pan, fill it with water, and tilt it to see in which angle the water flows out of the pan and uncovers the pickup. The reason why it's not enough is that when the pan is installed on the block, the girdle and block walls extend the pan. If you look at the static (crank not spinning) combination of the pan, girdle, and the block, whether the pickup gets uncovered or not depends not only on the angle but also on the volume of the oil in the sump. In extreme, you could think of an absurd example of tilting the engine 90 degrees and filling up the entire engine with oil -- the pickup wouldn't uncover.
Thus, for every tilt angle of the engine, one would need to measure the critical volume of oil, defined as the smallest volume of oil in the sump that keeps the pickup covered. That's a lot of measurements with minimally the girdle bolted on the pan, but it is measurable.
Then, for every tilt angle of the engine and rpm, we have to assume (or measure, if someone figures out how) both the net rate at which the pump ingest oil and the oil return rate. The oil return rate depends on the volume of oil in circulation, which is the total oil capacity minus the volume in sump. The relation is almost certainly monotonic, more oil in circulation means higher return rate. It's enough to only assume/measure the return rate when the sump is at critical volume (and total oil capacity minus the critical volume is in circulation) in order to figure out whether the pickup uncovers.
For a given rpm and tilt angle, the net ingestion rate is either lower than the return rate at critical volume, in which case the pickup stays submerged, or the net ingestion rate is higher than the return rate at critical volume, in which case the pickup uncovers.
Is this how you came up with your precise 0.58g estimate? Or did you just fill a loose pan with fluid, tilt the pan sideways until the pickup uncovered while some of the fluid poured out of the pan, and back out the g-force from the resulting angle? This short-cut method would be pretty stupid and give the wrong answer, don't you agree?
I will paste in the text from the speedtalk forum further down below. I did not try to conceal anything whatsoever about what I did.
So, yes, let’s be a little more realistic ! I do a lot of tests on pans and so I have a fair amount of modeling clay sitting around. I constructed a supported clay dam several inches high around the perimeter of the 928 pan. I again filled it with 6 quarts of water which represents the maximum dynamic amount of oil that would be in the sump. This wall contained all the water flowing out of the sump and would be like the bedplate and block forming higher walls to the pan.
Instead of simply tilting the pan straight over parallel to its longitudinal axis (and the crankshaft) as before I tilted it at an angle biased to the rear corner as this is where the oil collects in high G turns. I was using a hand held protractor so this is not super accurate but I got a set of angles that arise as the edge of the pickup becomes exposed. The angle to the corner was ~25 degrees while the simultaneous angle to the side of the pan was ~18 degrees. So, let’s be generous and call it ~.47 G.
Hey – thanks! That reinforces what I wrote – I guess I was right on target.
Your thesis above is cute – but you neglect in your ingestion and rate of return musings the oil that is being thrashed around by the rotating assembly. So, the critical volume with maximal oil in the sump begins to arrive at ~.47 G laterally. Again, you are left with the onus of demonstrating why the engine does not fail virtually immediately in a turn exceeding this level.
You really, really don’t seem to like that GTR.
Hey, lets let YOU pick the 928 !
I think pretty much any of them are capable of more than .5 G laterally.
Lots of swings and misses – but at least I can see you’re putting that thinkin cap on when you're up at bat. Progress !
Have a good weekend.
Best, Kevin
~~~~~~~~~~~~~~~~
Re: Possibly non-standard oil viscosity question
by Kevin Johnson » Tue May 25, 2010 11:13 pm
Very busy day.
It has been a few years so I dragged out one of the oil pans.
Capacity is 7.9 quarts -- figure 1.9 quarts circulating through the engine normally.
Plug all the holes with clay and fill up the pan with 6 quarts of water.
Tilt the pan to the right side and note at what angle the surface of the water approaches the edge of the pickup opening. This is 30 degrees. A whole bunch of water has poured out the side. I unplug the drain hole and measure the amount of water left in the pan: 3 quarts.
Except that in real life three quarts of oil above the oil pan rail would have virtually the full length of the crank spinning and swimming in oil. This is why a spacer helps. This is why Porsche doubled the gasket thickness in the 928. This is why Porsche quadrupled the gasket thickness in the 944.
Except that in real life it would not be 6 quarts of oil in the pan; at, say, 30% aeration from the constant churning it would be 7.8 quarts of aerated oil by volume in the pan. So about 4.8 quarts of oil being thoroughly thrashed to death. Some of it making its way to the heads, of course. That can be seen in the video.
Pretty much that whole side of the motor would be churning away. The decreased volume of the rear of the sump would ensure that the churned oil would be forced forward by the combined furies of over 3000gs ( ! ).
Now the function of the cloverleaf overlay on the floor of the pan becomes very clear.
With so much aerated oil being thrown/churned at it and settling over it, this design serves to delay the ingestion of aerated oil/foam by drawing as distantly as possible from underneath it -- plus no vortexes leading to the pickup opening.
At 45 degrees (1G) the pickup opening would surely still be engulfed in foam/aerated oil. Hence the flow of finely entrained air bubbles in the white-brown foam ejecting from the cam bearings and thrown up at the window.
Perhaps at a steady 60 degrees the pickup would become sporadically uncovered more often than not -- time to start considering a dry sump.
No doubt the oil in Mike's [Simard] car was over 300 degrees. I believe that happens with the Nissan SR20 when you overfill it (with a stock oil cooler too, I think?). I know it can happen in a Honda D-series as well, from working with a racer. I think he was also running a cooler.
Kevin Johnson
Last edited by Kevin Johnson; 06-19-2010 at 03:11 PM.
06-21-2010, 10:56 AM
#126
Nordschleife Master
Thread Starter
Here we go again.
First, you tilt the pan in one meaningless experiment and get a meaningless 0.58g figure. Then, you do something potentially less stupid, but don't like the answer. Because you don't like the answer, you alter the experiment until you get a figure less than 0.58g. You're just a fundamentally dishonest guy.
Is the second experiment meaningful? It seems that you've uncovered the fact that if the one can forward accelerate the car while cornering, the pickup gets uncovered. But given your history of making stuff up, I am not putting much weight on this observation.
Apart from measurements (actual or fictional), there's the question of logic. Overall, your strategy of arguing that the source of intermittent oil pressure drops in fast, high rpm corners is not the pickup being uncovered is perverse. You take (mostly flawed and/or fictional) measurements which indicate that the pickup gets uncovered quite easily. To a normal person, this would be support of the hypothesis that indeed it is the pickup being uncovered that is the likely source of problems.
To you, "Mr. Aeration", this is an unacceptable conclusions. Therefore, you attempt to build a rather perverse chain of logic saying that the results from your (mostly flawed and/or fictional) experiments indicate pickup being uncovered so easily that the car shouldn't be able to run a single lap, from which you (incorrectly) infer that the pickup being uncovered is NOT the problem. A normal person would infer from your (mostly flawed and/or fictional) measurements that some combination of the following two are true: (1) The 928 oil pressure problems are caused by the pickup uncovering and/or (2) you are very bad at taking and reporting measurements accurately.
I couldn't make this stuff up. There's a whole stand up comedy routine waiting to be discovered in your posts.
First, you tilt the pan in one meaningless experiment and get a meaningless 0.58g figure. Then, you do something potentially less stupid, but don't like the answer. Because you don't like the answer, you alter the experiment until you get a figure less than 0.58g. You're just a fundamentally dishonest guy.
Is the second experiment meaningful? It seems that you've uncovered the fact that if the one can forward accelerate the car while cornering, the pickup gets uncovered. But given your history of making stuff up, I am not putting much weight on this observation.
Apart from measurements (actual or fictional), there's the question of logic. Overall, your strategy of arguing that the source of intermittent oil pressure drops in fast, high rpm corners is not the pickup being uncovered is perverse. You take (mostly flawed and/or fictional) measurements which indicate that the pickup gets uncovered quite easily. To a normal person, this would be support of the hypothesis that indeed it is the pickup being uncovered that is the likely source of problems.
To you, "Mr. Aeration", this is an unacceptable conclusions. Therefore, you attempt to build a rather perverse chain of logic saying that the results from your (mostly flawed and/or fictional) experiments indicate pickup being uncovered so easily that the car shouldn't be able to run a single lap, from which you (incorrectly) infer that the pickup being uncovered is NOT the problem. A normal person would infer from your (mostly flawed and/or fictional) measurements that some combination of the following two are true: (1) The 928 oil pressure problems are caused by the pickup uncovering and/or (2) you are very bad at taking and reporting measurements accurately.
I couldn't make this stuff up. There's a whole stand up comedy routine waiting to be discovered in your posts.
Since we know that, isolated from the system, the pickup will already be fully uncovered at 1G laterally by the angle of repose (probably much earlier -- at .58G the pickup begins to be exposed laterally) the engine has only the volume of oil present in the tube and being recirculated by the pump.
I do a lot of tests on pans and so I have a fair amount of modeling clay sitting around. I constructed a supported clay dam several inches high around the perimeter of the 928 pan. I again filled it with 6 quarts of water which represents the maximum dynamic amount of oil that would be in the sump. This wall contained all the water flowing out of the sump and would be like the bedplate and block forming higher walls to the pan.
Instead of simply tilting the pan straight over parallel to its longitudinal axis (and the crankshaft) as before I tilted it at an angle biased to the rear corner as this is where the oil collects in high G turns. I was using a hand held protractor so this is not super accurate but I got a set of angles that arise as the edge of the pickup becomes exposed. The angle to the corner was ~25 degrees while the simultaneous angle to the side of the pan was ~18 degrees. So, let’s be generous and call it ~.47 G.
Hey – thanks! That reinforces what I wrote – I guess I was right on target.
Instead of simply tilting the pan straight over parallel to its longitudinal axis (and the crankshaft) as before I tilted it at an angle biased to the rear corner as this is where the oil collects in high G turns. I was using a hand held protractor so this is not super accurate but I got a set of angles that arise as the edge of the pickup becomes exposed. The angle to the corner was ~25 degrees while the simultaneous angle to the side of the pan was ~18 degrees. So, let’s be generous and call it ~.47 G.
Hey – thanks! That reinforces what I wrote – I guess I was right on target.
06-21-2010, 11:48 AM
#127
Supercharged
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Here we go again.
First, you tilt the pan in one meaningless experiment and get a meaningless 0.58g figure. Then, you do something potentially less stupid, but don't like the answer. Because you don't like the answer, you alter the experiment until you get a figure less than 0.58g. You're just a fundamentally dishonest guy.
Is the second experiment meaningful? It seems that you've uncovered the fact that if the one can forward accelerate the car while cornering, the pickup gets uncovered. But given your history of making stuff up, I am not putting much weight on this observation.
Apart from measurements (actual or fictional), there's the question of logic. Overall, your strategy of arguing that the source of intermittent oil pressure drops in fast, high rpm corners is not the pickup being uncovered is perverse. You take (mostly flawed and/or fictional) measurements which indicate that the pickup gets uncovered quite easily. To a normal person, this would be support of the hypothesis that indeed it is the pickup being uncovered that is the likely source of problems.
To you, "Mr. Aeration", this is an unacceptable conclusions. Therefore, you attempt to build a rather perverse chain of logic saying that the results from your (mostly flawed and/or fictional) experiments indicate pickup being uncovered so easily that the car shouldn't be able to run a single lap, from which you (incorrectly) infer that the pickup being uncovered is NOT the problem. A normal person would infer from your (mostly flawed and/or fictional) measurements that some combination of the following two are true: (1) The 928 oil pressure problems are caused by the pickup uncovering and/or (2) you are very bad at taking and reporting measurements accurately.
I couldn't make this stuff up. There's a whole stand up comedy routine waiting to be discovered in your posts.
First, you tilt the pan in one meaningless experiment and get a meaningless 0.58g figure. Then, you do something potentially less stupid, but don't like the answer. Because you don't like the answer, you alter the experiment until you get a figure less than 0.58g. You're just a fundamentally dishonest guy.
Is the second experiment meaningful? It seems that you've uncovered the fact that if the one can forward accelerate the car while cornering, the pickup gets uncovered. But given your history of making stuff up, I am not putting much weight on this observation.
Apart from measurements (actual or fictional), there's the question of logic. Overall, your strategy of arguing that the source of intermittent oil pressure drops in fast, high rpm corners is not the pickup being uncovered is perverse. You take (mostly flawed and/or fictional) measurements which indicate that the pickup gets uncovered quite easily. To a normal person, this would be support of the hypothesis that indeed it is the pickup being uncovered that is the likely source of problems.
To you, "Mr. Aeration", this is an unacceptable conclusions. Therefore, you attempt to build a rather perverse chain of logic saying that the results from your (mostly flawed and/or fictional) experiments indicate pickup being uncovered so easily that the car shouldn't be able to run a single lap, from which you (incorrectly) infer that the pickup being uncovered is NOT the problem. A normal person would infer from your (mostly flawed and/or fictional) measurements that some combination of the following two are true: (1) The 928 oil pressure problems are caused by the pickup uncovering and/or (2) you are very bad at taking and reporting measurements accurately.
I couldn't make this stuff up. There's a whole stand up comedy routine waiting to be discovered in your posts.
06-21-2010, 12:23 PM
#128
Rennlist Member
mine pulls close to 1.5g's, has been doing this for over 10 years of racing, and the 2-3 engines we took apart and looked at, the bearings were perfect. If there was a problem,wouldnt my "miracle " motors have some sign of wear? no mods, no coolers,no spacers, no accusump, no scrapers, baffles, etc.
How long would you expect my engine to last, barring some kind of supernatural intervention?
we need some camera action inside the pan to see what the oil does on those 1.5g turns at 5000rpm. I bet all is just fine, as the oil pressure I see would relate. If the pick up is being uncovered, I woudlnt have 5bar all the time with only 4 bar at extreme constant high g loading turns at a min. (and at 260f oil temp)
How long would you expect my engine to last, barring some kind of supernatural intervention?
we need some camera action inside the pan to see what the oil does on those 1.5g turns at 5000rpm. I bet all is just fine, as the oil pressure I see would relate. If the pick up is being uncovered, I woudlnt have 5bar all the time with only 4 bar at extreme constant high g loading turns at a min. (and at 260f oil temp)
06-21-2010, 12:34 PM
#129
Nordschleife Master
If the pickup uncovered with only .58 G then we would have a lot of failures on street tires.
And at every corner regardless of left/right one would see pressure drops.
And at every corner regardless of left/right one would see pressure drops.
06-21-2010, 01:49 PM
#131
Nordschleife Master
Thread Starter
I get irritated by snake-oil salesmen, especially by ones that initially fooled me.
Kevin initially measured the 0.58g lateral acceleration figure by assuming that the pan is not bolted to the girdle in a race car. That's where the non-sensical 0.58g comes from. (A strong alternative for the source of this figure is that he just made it up.) You should pay zero attention to it.
Then, when he repeated the measurements with pan walls extended, simulating the girdle, he couldn't get the pickup to uncover at a low enough side angle / lateral g force. So he started tilting the pan backwards as well. (Or he again made all the numbers up.)
Tilting the pan backwards corresponds to forward acceleration. Well, the edge of the pickup will uncover below 1g of forward acceleration. Furthermore, given the shape of the gridle and the pan, the critical forward acceleration g-force / backward tilt angle is not very sensitive to the amount of oil in the pan. This is however irrelevant for explaining the survival of stock or near stock 928s, because none of the cars mentioned in this thread can sustain anywhere near 1g forward acceleration for any meaningful periof of time.
So some more smoke and mirrors from Kevin. Let's see how many bottles of aeration snake oil this obfuscation effort sold.
Why don't you shed some light on your theory of how oil aeration is necessary for keeping the 928 pickup covered? I mean, this has already turned into a comedy routine, so why not blow it off in the end with the biggest joke!
"Aeration -- the source of and solution to all of lifes problems." (Adapted from Homer Simpson.)
Then, when he repeated the measurements with pan walls extended, simulating the girdle, he couldn't get the pickup to uncover at a low enough side angle / lateral g force. So he started tilting the pan backwards as well. (Or he again made all the numbers up.)
Tilting the pan backwards corresponds to forward acceleration. Well, the edge of the pickup will uncover below 1g of forward acceleration. Furthermore, given the shape of the gridle and the pan, the critical forward acceleration g-force / backward tilt angle is not very sensitive to the amount of oil in the pan. This is however irrelevant for explaining the survival of stock or near stock 928s, because none of the cars mentioned in this thread can sustain anywhere near 1g forward acceleration for any meaningful periof of time.
So some more smoke and mirrors from Kevin. Let's see how many bottles of aeration snake oil this obfuscation effort sold.
"Aeration -- the source of and solution to all of lifes problems." (Adapted from Homer Simpson.)
Last edited by ptuomov; 06-21-2010 at 04:18 PM.
06-21-2010, 05:44 PM
#133
Racer
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Yup.
I will drag out the pan AGAIN.
Tuomo is apparently used to having people do just what he wants. Laugh.
One of the other effects not considered is how much the suspension compresses as this will generate apparent Gs. On other forums I tell people to measure the wheel lift on drag racing launches as this needs to be considered as well.
I have never ever heard of someone accelerating through a turn. Centripetal or otherwise.
I will drag out the pan AGAIN.
Tuomo is apparently used to having people do just what he wants. Laugh.
One of the other effects not considered is how much the suspension compresses as this will generate apparent Gs. On other forums I tell people to measure the wheel lift on drag racing launches as this needs to be considered as well.
I have never ever heard of someone accelerating through a turn.
Centripetal or otherwise.
06-21-2010, 05:56 PM
#134
Nordschleife Master
Thread Starter
06-21-2010, 06:22 PM
#135
Rennlist Member
You must never heard or seen anyone go though turn 8 at willow springs.
Not drag racing, but in road racing, the acceleration Gs are very light, braking, differenent story.
Not drag racing, but in road racing, the acceleration Gs are very light, braking, differenent story.
Yup.
I will drag out the pan AGAIN.
Tuomo is apparently used to having people do just what he wants. Laugh.
One of the other effects not considered is how much the suspension compresses as this will generate apparent Gs. On other forums I tell people to measure the wheel lift on drag racing launches as this needs to be considered as well.
I have never ever heard of someone accelerating through a turn. Centripetal or otherwise.
I will drag out the pan AGAIN.
Tuomo is apparently used to having people do just what he wants. Laugh.
One of the other effects not considered is how much the suspension compresses as this will generate apparent Gs. On other forums I tell people to measure the wheel lift on drag racing launches as this needs to be considered as well.
I have never ever heard of someone accelerating through a turn.
Centripetal or otherwise.