early dyno results
02-20-2011, 09:46 PM
#376
Race Director
02-21-2011, 12:40 AM
#378
Rennlist Member
Hello Alll
I have some results posted from the dyno session.
I have measured 2 points one from the hose that drains from the oil filler horn to the sump , and the from the horn itself , all other hoses blocked to maintain the integrity of the original system .
At idle the gauges show 40 kpa (idle vacuum) at full load both of rise to 100 kpa our sea level pressure , at full load there is no further rise from sea level pressure .
So thinking about it this I would think that supports what GB has been saying all along in which I agree that the sump pressure is not linear , therefore cannot be the major problem , as in my case the heads are limited to a line pressure of 3 bar (944 valves) this does in no way limits flow . To which I believe the rise in engine speed , causes a rise in oil flow which overwhelms the cavity in the rocker cover until the sump pickup is uncovered (ie no oil) at that point the engine is severly damaged .
After doing some very quick calculations , the volume of spare space in the rocker covers is easily more than the capacity of the sump , as it explains why the sump is emptied at a long time at high engine speed.
As the oil in the rocker cover has no pump tp force it down , ie the cavity is not at oil line pressure but at sea level, the flow back the the sump or pressure obviously does not allow the oil to return at the same rate , with the obvious result .
THis folllows now with the conclusion how do we now have enough oil for the system to be reliable , it needs to be a closed loop so that the flow from the sump equals the return . A secound pump scavenging the heads to the sump (Dave Os idea), or a dry sump system that will fit in the stock cars .
One thing that I observed that I found odd was the fact that I had a vacuum at idle , in my case the inlet manifold is completely isolated from the pcv system as all the breathers are drained into the catch tank . I will check the routing of the hoses shortly .
Ok i welcome all the comments .
I have some results posted from the dyno session.
I have measured 2 points one from the hose that drains from the oil filler horn to the sump , and the from the horn itself , all other hoses blocked to maintain the integrity of the original system .
At idle the gauges show 40 kpa (idle vacuum) at full load both of rise to 100 kpa our sea level pressure , at full load there is no further rise from sea level pressure .
So thinking about it this I would think that supports what GB has been saying all along in which I agree that the sump pressure is not linear , therefore cannot be the major problem , as in my case the heads are limited to a line pressure of 3 bar (944 valves) this does in no way limits flow . To which I believe the rise in engine speed , causes a rise in oil flow which overwhelms the cavity in the rocker cover until the sump pickup is uncovered (ie no oil) at that point the engine is severly damaged .
After doing some very quick calculations , the volume of spare space in the rocker covers is easily more than the capacity of the sump , as it explains why the sump is emptied at a long time at high engine speed.
As the oil in the rocker cover has no pump tp force it down , ie the cavity is not at oil line pressure but at sea level, the flow back the the sump or pressure obviously does not allow the oil to return at the same rate , with the obvious result .
THis folllows now with the conclusion how do we now have enough oil for the system to be reliable , it needs to be a closed loop so that the flow from the sump equals the return . A secound pump scavenging the heads to the sump (Dave Os idea), or a dry sump system that will fit in the stock cars .
One thing that I observed that I found odd was the fact that I had a vacuum at idle , in my case the inlet manifold is completely isolated from the pcv system as all the breathers are drained into the catch tank . I will check the routing of the hoses shortly .
Ok i welcome all the comments .
02-21-2011, 01:11 AM
#379
Race Director
John
What was the RPM at full load?
I think the crankcase pressure is directly correlated to piston speeds....it makes sense that a faster moving piston (why a stroker is higher) would displace more air & oil as it moves down.....compared to a slower piston speed engine....however for every piston that moves down to pressurize the sump, another is moving UP, which would in theory pull a bit of vacuum with it too?
What was the RPM at full load?
I think the crankcase pressure is directly correlated to piston speeds....it makes sense that a faster moving piston (why a stroker is higher) would displace more air & oil as it moves down.....compared to a slower piston speed engine....however for every piston that moves down to pressurize the sump, another is moving UP, which would in theory pull a bit of vacuum with it too?
02-21-2011, 01:20 AM
#380
Rennlist Member
5000 rpm and than 6000 rpm held at that engine speed on the dyno and increaseing the throttle position up to 100 % , SO the engine is fully loaded at this the catch can began to fill from the cam covers .
02-21-2011, 01:23 AM
#381
Addict
Lifetime Rennlist
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Lifetime Rennlist
Member
Hello Alll
I have some results posted from the dyno session.
I have measured 2 points one from the hose that drains from the oil filler horn to the sump , and the from the horn itself , all other hoses blocked to maintain the integrity of the original system .
At idle the gauges show 40 kpa (idle vacuum) at full load both of rise to 100 kpa our sea level pressure , at full load there is no further rise from sea level pressure .
So thinking about it this I would think that supports what GB has been saying all along in which I agree that the sump pressure is not linear , therefore cannot be the major problem , as in my case the heads are limited to a line pressure of 3 bar (944 valves) this does in no way limits flow . To which I believe the rise in engine speed , causes a rise in oil flow which overwhelms the cavity in the rocker cover until the sump pickup is uncovered (ie no oil) at that point the engine is severly damaged .
After doing some very quick calculations , the volume of spare space in the rocker covers is easily more than the capacity of the sump , as it explains why the sump is emptied at a long time at high engine speed.
As the oil in the rocker cover has no pump tp force it down , ie the cavity is not at oil line pressure but at sea level, the flow back the the sump or pressure obviously does not allow the oil to return at the same rate , with the obvious result .
THis folllows now with the conclusion how do we now have enough oil for the system to be reliable , ...........
I have some results posted from the dyno session.
I have measured 2 points one from the hose that drains from the oil filler horn to the sump , and the from the horn itself , all other hoses blocked to maintain the integrity of the original system .
At idle the gauges show 40 kpa (idle vacuum) at full load both of rise to 100 kpa our sea level pressure , at full load there is no further rise from sea level pressure .
So thinking about it this I would think that supports what GB has been saying all along in which I agree that the sump pressure is not linear , therefore cannot be the major problem , as in my case the heads are limited to a line pressure of 3 bar (944 valves) this does in no way limits flow . To which I believe the rise in engine speed , causes a rise in oil flow which overwhelms the cavity in the rocker cover until the sump pickup is uncovered (ie no oil) at that point the engine is severly damaged .
After doing some very quick calculations , the volume of spare space in the rocker covers is easily more than the capacity of the sump , as it explains why the sump is emptied at a long time at high engine speed.
As the oil in the rocker cover has no pump tp force it down , ie the cavity is not at oil line pressure but at sea level, the flow back the the sump or pressure obviously does not allow the oil to return at the same rate , with the obvious result .
THis folllows now with the conclusion how do we now have enough oil for the system to be reliable , ...........
02-21-2011, 02:51 AM
#385
Drifting
When I built a high HP engine for a drag car I had to run a high vol oil pump.
Because of that I installed restrictors between the block and head to limit oil at high RPM.
I don't think this is a good idea with a twin dual over head cam.
Porsche engineers have that high pressure there for a reason and it is more then likly so that the cams don't tear themselves out of the head.
Like I said many post ago, windage or crank case pressure must be reduced.
Blow by when Supercharging I bet is a compounding problem or during high RPM when the rings do not have time to spring back.
The extra volume can be put inline with the cooler. Thats where I would add a gallon.
Is there a schematic of the oil channels on a 32V block?, even though I bet nothing can be done there, except for opening up oil return as suggested.
This may also equalize pressure.?
Leaning the engine forward a few deg, front lower then the rear, may help by changing the direction of the G-force to assist the oil in returning to the pan.
Again I hope that I have not spoken out of line because I know you guys have been working on these things for some time.
Because of that I installed restrictors between the block and head to limit oil at high RPM.
I don't think this is a good idea with a twin dual over head cam.
Porsche engineers have that high pressure there for a reason and it is more then likly so that the cams don't tear themselves out of the head.
Like I said many post ago, windage or crank case pressure must be reduced.
Blow by when Supercharging I bet is a compounding problem or during high RPM when the rings do not have time to spring back.
The extra volume can be put inline with the cooler. Thats where I would add a gallon.
Is there a schematic of the oil channels on a 32V block?, even though I bet nothing can be done there, except for opening up oil return as suggested.
This may also equalize pressure.?
Leaning the engine forward a few deg, front lower then the rear, may help by changing the direction of the G-force to assist the oil in returning to the pan.
Again I hope that I have not spoken out of line because I know you guys have been working on these things for some time.
02-21-2011, 03:00 AM
#386
Rennlist Member
At all times off idle the oil gauge is pegged at full scale , I wouild expect that if you ran the engine long enough at high enough load to see a flucturation in the gauge, you will have already critically damaged it .
02-21-2011, 03:22 AM
#387
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02-21-2011, 03:54 AM
#388
Track Day
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e-mail from 2000
http://members.rennlist.com/pirtle/z...ng_failure.txt
message appears to be from Marc Thomas [mmthomas@ix.netcom.com]
Sent: Friday, October 27, 2000 4:32 PM
in part
"An addition item is to decrease the amount of oil available to the head by
increasing the spring pressure or my favorite, decreasing the feed orifice."
message appears to be from Marc Thomas [mmthomas@ix.netcom.com]
Sent: Friday, October 27, 2000 4:32 PM
in part
"An addition item is to decrease the amount of oil available to the head by
increasing the spring pressure or my favorite, decreasing the feed orifice."
02-21-2011, 04:16 AM
#389
Nordschleife Master
http://members.rennlist.com/pirtle/z...ng_failure.txt
message appears to be from Marc Thomas [mmthomas@ix.netcom.com]
Sent: Friday, October 27, 2000 4:32 PM
in part
"An addition item is to decrease the amount of oil available to the head by
increasing the spring pressure or my favorite, decreasing the feed orifice."
message appears to be from Marc Thomas [mmthomas@ix.netcom.com]
Sent: Friday, October 27, 2000 4:32 PM
in part
"An addition item is to decrease the amount of oil available to the head by
increasing the spring pressure or my favorite, decreasing the feed orifice."
The oil starvation, or lack of oil in the pan is caused by the fact that oil
is pumped into/upto the head in large quantities by high rpm and the head
acts as a oil "pan" of its own. The crank also spins up a batch of oil and
keeps it in suspension, especially at high rpm. This oil cloud circles the
crank and is the reason most race engine have "scrapers" in the case. Up to
two quarts of oil can be circling the crank at high rpm! In some cases it
can be more as the S4 is known to "pump" oil up the oil filler tower and
keep it there!
When there is not enough oil in the pan (caused by the high rpm pumping of
oil to other areas, like the head, etc.), then under cornering at 1 g, the
oil pickup is uncovered!
is pumped into/upto the head in large quantities by high rpm and the head
acts as a oil "pan" of its own. The crank also spins up a batch of oil and
keeps it in suspension, especially at high rpm. This oil cloud circles the
crank and is the reason most race engine have "scrapers" in the case. Up to
two quarts of oil can be circling the crank at high rpm! In some cases it
can be more as the S4 is known to "pump" oil up the oil filler tower and
keep it there!
When there is not enough oil in the pan (caused by the high rpm pumping of
oil to other areas, like the head, etc.), then under cornering at 1 g, the
oil pickup is uncovered!
Interesting comment by Marc on reducing the oil feeds in the heads. That might explain Tim Dey's engine longevity? (as lets face it, 17s benefit from the accusump doesn't go far at 200mph
).