Oil pan baffle archeological find: totally useless or answer to acillies heel?
#61
so as the oil piles up at 16.7degrees, (and whatever volume that creates) the oil falls in to the sump. I guess draw a picture of a 16.7 degree angle the length of the high area of the pan and see how high it is at the back of the engine. I would say it would be near 2" high, maybe just hitting the crank counterweights.
anyway, I havent seen any oil pressure loss anytime the car has been pointed straight and accelerating as long as the longest straight at Road America. (about 20 seconds)
The only time Ive seen oil pressure problems with my old bugger or scots racer was when we used Mobil 1 or a cheap oil.
again, doesnt emperical testing mean anything anymore?
anyway, I havent seen any oil pressure loss anytime the car has been pointed straight and accelerating as long as the longest straight at Road America. (about 20 seconds)
The only time Ive seen oil pressure problems with my old bugger or scots racer was when we used Mobil 1 or a cheap oil.
again, doesnt emperical testing mean anything anymore?
It is relatively easy to figure out the resultant vector for any given longitudinal or lateral acceleration. it is mearly the arctan(acc/G)= vector angle.
.2G gives 11.3
.3G gives 16.7
.4G gives 21.8
.6G gives 31.0
one thing to consider is as oil piles up at the rear of the engine it increases the effective angle of the pan. A way to envision this is to imagine an oil bottle put at the end of an arm with the lid facing the center of rotation rotating and along the bottom edge, and the edge of the bottle is parallel to the ground. The arm rotates in the horzontal plane. If the arm is rotating to give a lateral acceleration of .2G and you remove the lid oil WILL puor out even though the bottom of the container is flat. The oil will contine to flow until the oil has reached a level when it forms the 11.2 degree ange as dictated by the vector of the combined accel and G force, so even with little to no drain angel most of the oils will pour out.
.2G gives 11.3
.3G gives 16.7
.4G gives 21.8
.6G gives 31.0
one thing to consider is as oil piles up at the rear of the engine it increases the effective angle of the pan. A way to envision this is to imagine an oil bottle put at the end of an arm with the lid facing the center of rotation rotating and along the bottom edge, and the edge of the bottle is parallel to the ground. The arm rotates in the horzontal plane. If the arm is rotating to give a lateral acceleration of .2G and you remove the lid oil WILL puor out even though the bottom of the container is flat. The oil will contine to flow until the oil has reached a level when it forms the 11.2 degree ange as dictated by the vector of the combined accel and G force, so even with little to no drain angel most of the oils will pour out.
#62
MK
look at the "design" of the late 928 oil pan......then look at the wetsump oil pan of other engines that hold up well on track.....it looks NOTHING like the 928 pan...it is just too shallow and wide to work effectively......the other wetsump pans have actual baffling or trapdoors or a VERY deep sump (ford 5.0 is 7" deep)...
The current lemons racer setup is just an old pan-baffle-screen-pickup with a 3/8th pan spacer...thats it...no cooler, no accusump...nothing.....it appears to be working....BUT I was intentionally keeping the RPM's low in left hand turns.....until I get a real oil pressure gauge working...that will be the plan...
once the autometer gauges are installed....then I can conduct some higher G testing to see how the oil pressure holds up....but I will need some R comps for that
look at the "design" of the late 928 oil pan......then look at the wetsump oil pan of other engines that hold up well on track.....it looks NOTHING like the 928 pan...it is just too shallow and wide to work effectively......the other wetsump pans have actual baffling or trapdoors or a VERY deep sump (ford 5.0 is 7" deep)...
The current lemons racer setup is just an old pan-baffle-screen-pickup with a 3/8th pan spacer...thats it...no cooler, no accusump...nothing.....it appears to be working....BUT I was intentionally keeping the RPM's low in left hand turns.....until I get a real oil pressure gauge working...that will be the plan...
once the autometer gauges are installed....then I can conduct some higher G testing to see how the oil pressure holds up....but I will need some R comps for that
#63
That tray is clearly designed to address a windage problem.
Mark: Isn't the oil cooler up-stream from the pressure relief valve? That's why you pumped it dry right away.
Also, some oil return to the pan as it's below the front two pistons.
#65
#66
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I remember from when I had the pan of my euro S motor out, it had a decent baffle in the lower part of the pan. It looked like the crosshairs of a scope, with a circle in the middle where the oil pickup tube inserted. The whole thing was about as tall as the deep part of the pan IIRC. I don't think the US motor had that.
It didn't have any part of the baffle traveling up the shallow part though.
It didn't have any part of the baffle traveling up the shallow part though.
Last edited by Erik N; 02-22-2010 at 11:10 PM.
#67
Don't you think that the expensive part would be the very first one? It seems like it would be really cheap to make more, once the mold was made.
Because it appears that the GTS rods would not clear it, I'm going to guess that the part number is correct and that Porsche paid to have this developed, in the 80's. Must not have accomplished what they intended it to do and the manufacturer was left with some expensive molds.
Everyone needs to keep in mind that racing the 928 was always verboten...the Alan Johnson 928 effort is very well known. I think Porsche knew all along that the oiling system was not up to snuff and didn't want engines blowing up on race tracks. They certainly knew enough not to try and run the 944 race engines with stock cranks or stock oiling system, way back in 1986.
#68
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Roughly how much oil does the deep front part of the pan hold?
And how long before that gets pumped out with the engine, at say 4500-5000 revs.
Just curious.
And how long before that gets pumped out with the engine, at say 4500-5000 revs.
Just curious.
#69
The info I have heard is the engine needs 3-4 quarts pumped through it....so that leaves 5-6 in the sump at all times...... The amount of oil the oil pump flows can vary quite a bit..... I also heard anywhere from 9 gallons a minute to 21 gallons a minute....so between .6 to 1.5 qts per second.....which means it will empty in 2-3 seconds at high rpm....which is also exactly what I heard (2.6 seconds)
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#71
#73
Yes, it would be expensive to develop the part but actually using it in production vehicles would have required disruptive changes to other even more expensive parts.
Because it appears that the GTS rods would not clear it, I'm going to guess that the part number is correct and that Porsche paid to have this developed, in the 80's. Must not have accomplished what they intended it to do and the manufacturer was left with some expensive molds.
I think maybe some clever people backdated the part number to make it appear that it was paid for (perhaps to soothe the accountants) and developed (to soothe any race parts inspection) back in the 1980s. Why would an official Porsche part number immediately preceding the production piece part number require changes to the casting not present with the production piece number???
One company I know of (which will go un-named) developed a product with a well-known trademarked name. The name used was the street name reversed on which the mistress to the company president lived. Ha ha. There is a lot that goes on secretly behind the scenes at big companies and you reference the restriction on racing the 928 below.
Black Ops with muffled helicopters in the water cooled engineering section.
Everyone needs to keep in mind that racing the 928 was always verboten...the Alan Johnson 928 effort is very well known. I think Porsche knew all along that the oiling system was not up to snuff and didn't want engines blowing up on race tracks. They certainly knew enough not to try and run the 944 race engines with stock cranks or stock oiling system, way back in 1986.
Last edited by Kevin Johnson; 02-23-2010 at 08:54 AM.
#74
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Lots of speculation around this part... As of now, the most plausible seems to be that it was made for the marine engine. But who knows? Maybe a call to Porsche could clarify. Aryan is on it.