2/6 rod bearing flow tests
12-24-2012 | 02:10 AM
#241
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Yet more points to consider...
1. That oil starvation is part of the 2/6 failure process must be a given.
2. Having seen what I have experienced [limited as it may be] I am inclined to think that engine knocks may be contributing more to big end failure than perhaps has been given credit for- the knock control system can only do so much and if 2/6 lead the charge then logic says they run out of steam first.
3. The tendency to knock mid range is there but my recent investigations suggested that was no more prevalent than normal with minor events on stockish settings- implication being that oil lifting is not prevalent at that rpm point.
4. There is what seems to me to be a very clear point [5300 rpm] for onset of pings on my motor. That it happens mostly on 6 then 2 is one thing but it seems if those two were not pinging I suspect I could run the stock timing on the other cylinders no problem, my perception being that 6/2 generally lead the charge by 4 or 5 degrees [sometimes].
5. Given the post on the motor with sensors on all 8 cylinders, more air flow thourgh those two cylinders goes part way to explaining the problem but it seemed to me that when I richened up the mix to circa 11.5 to 11.9 it made no difference to the pings. This leads me to conclude that enrichment can only do so much.
6. I have no way of knowing whether 6/2 runs significantly hotter than other cylinders [and for sure one would not expect it to run cooler] -all I can say is that I believe my cooling is optimal if not a little overdone at the moment with the 75C thermostat.
7. I would be interested to know what kind of temperature increase inlet air has to see before that starts to cause some issues. It would be interesting to log inlet air temperature to see what temperature the inlet air temp rises to on its journey through the inlet tract. Much as I like the EIS system a metal shell is going to allow more heat to pick up compared to plastic duct work.
8. it would be interesting to remove the inlet plenum spacers to see if ST2 can detect any signs of a difference [ve or -ve]. I am wondering if these may facilitate an increment of mal-distribution of air compared to the stock set up?
if this oil consumption and the knock problem werre occurring on other cylinders I would be thinking in terms of a knackered motor and although I do not discount that possibility, this thread keeps my hopes alive that it is no more than a breathing problem that just may be soluble without major mechanical intervention.
For sure it is a complex interactive problem and if Porsche could not solve it then enthusiastic DIY hacks like myself have no chance.
Thank goodness we now have some options
Regards
Fred
1. That oil starvation is part of the 2/6 failure process must be a given.
2. Having seen what I have experienced [limited as it may be] I am inclined to think that engine knocks may be contributing more to big end failure than perhaps has been given credit for- the knock control system can only do so much and if 2/6 lead the charge then logic says they run out of steam first.
3. The tendency to knock mid range is there but my recent investigations suggested that was no more prevalent than normal with minor events on stockish settings- implication being that oil lifting is not prevalent at that rpm point.
4. There is what seems to me to be a very clear point [5300 rpm] for onset of pings on my motor. That it happens mostly on 6 then 2 is one thing but it seems if those two were not pinging I suspect I could run the stock timing on the other cylinders no problem, my perception being that 6/2 generally lead the charge by 4 or 5 degrees [sometimes].
5. Given the post on the motor with sensors on all 8 cylinders, more air flow thourgh those two cylinders goes part way to explaining the problem but it seemed to me that when I richened up the mix to circa 11.5 to 11.9 it made no difference to the pings. This leads me to conclude that enrichment can only do so much.
6. I have no way of knowing whether 6/2 runs significantly hotter than other cylinders [and for sure one would not expect it to run cooler] -all I can say is that I believe my cooling is optimal if not a little overdone at the moment with the 75C thermostat.
7. I would be interested to know what kind of temperature increase inlet air has to see before that starts to cause some issues. It would be interesting to log inlet air temperature to see what temperature the inlet air temp rises to on its journey through the inlet tract. Much as I like the EIS system a metal shell is going to allow more heat to pick up compared to plastic duct work.
8. it would be interesting to remove the inlet plenum spacers to see if ST2 can detect any signs of a difference [ve or -ve]. I am wondering if these may facilitate an increment of mal-distribution of air compared to the stock set up?
if this oil consumption and the knock problem werre occurring on other cylinders I would be thinking in terms of a knackered motor and although I do not discount that possibility, this thread keeps my hopes alive that it is no more than a breathing problem that just may be soluble without major mechanical intervention.
For sure it is a complex interactive problem and if Porsche could not solve it then enthusiastic DIY hacks like myself have no chance.
Thank goodness we now have some options
Regards
Fred
12-25-2012 | 12:17 AM
#242
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From: MA
This discussion remains me about one old thread, where Todd installed eight O2 sensors to monitor A/F-ratio on each cylinder separately. He found that #2 and #6 were running the most lean.
https://rennlist.com/forums/928-foru...ne-spacer.html
"From Todd's data logging he's mentioned 2 & 6 are the most prone to knock due to going lean, in the stock (batch fire) configuration. He has the fuel trim turned up the most on these two, backed off on #5 more then any other cylinder. His fuel trim adjustments are not "fixed" through the RPM range. Where one cylinder might be lean at 3,000rpm, it might be rich at 5,500. This might give an idea of how much time Todd has spent on the dyno tuning each cylinder. He said #2 is the most efficient, moving the most air consistently throughout the RPM range"
https://rennlist.com/forums/928-foru...ne-spacer.html
"From Todd's data logging he's mentioned 2 & 6 are the most prone to knock due to going lean, in the stock (batch fire) configuration. He has the fuel trim turned up the most on these two, backed off on #5 more then any other cylinder. His fuel trim adjustments are not "fixed" through the RPM range. Where one cylinder might be lean at 3,000rpm, it might be rich at 5,500. This might give an idea of how much time Todd has spent on the dyno tuning each cylinder. He said #2 is the most efficient, moving the most air consistently throughout the RPM range"
Inside cylinders:
2: 27 cm
3: 28 cm
6: 32 cm
7: 28 cm
Average: 29 cm
Outside cylinders:
1: 19 cm
4: 23 cm
5: 20 cm
8: 23 cm
Average: 21.25 cm.
I don't think it's a coincidence that the outside cylinders have much shorter runners. It could be that the cooler-running outside cylinders were tuned to fill better at the knock-prone rpms and the hotter-running inside cylinders were tuned to fill better at less knock-prone rpms.
If anyone has flow coefficients or whatnot for the stock manifold runners, I'd be interested.
12-25-2012 | 02:12 AM
#243
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From: Oman
I don't think it's a coincidence that the outside cylinders have much shorter runners. It could be that the cooler-running outside cylinders were tuned to fill better at the knock-prone rpms and the hotter-running inside cylinders were tuned to fill better at less knock-prone rpms.
If anyone has flow coefficients or whatnot for the stock manifold runners, I'd be interested.
Tuomo,
You have triggered a thought here- if you remember I said that I was experiencing knock events at quite a distinct boundary of 5300 rpm and upwards. I believe that is the trigger point above which the flappy reverts back to its base position so in effect there are three "zones" of operation from the flappy perspective so perhaps that explains why there may be a "trigger point" at that rpm not that it explains why knock events start to occur on my motor on stock advance settings.
As I understand, besides geometry considerations, the runners have different lengths to produce a series of "mini peaks" to flatten out the torque distribution rather than get it all at one operating point, thus logic suggests that maybe 6/2 having longer runs peak at lower rpm's within each flap zone compared to the other cylinders- is that logical? I presume that in the base state there is a primary set of flow harmonics, then as the flappy swings, a different set and eventually as it swings back, a secondary set of resonant harmonics based on the primary which, being of lower value, do not show up much in the scale of things.
Whatever way you look at it those lengths have quite a spread. It would be interesting to know what kind of flow distribution would be predicted at different operating points. From the little I know about this aspect of design I understand longer runners place the torque lower down the rev range compared to shorter ones.
Anyone fancy shark tuning on 8 cylinders? I suppose configuring the system to to put some suppression on individual cylinder timing at specific hot spots is just not possible [JDS/JC?]. Just makes me wonder if the brain that is in there can apply retard in reaction to knock events on specific cylinders whether it could be programmed to adapt based on event history and de-facto apply a bit of retard in advance of a specifc operating point arriving?
Perhaps this is getting way off topic?
Regards
Fred
12-25-2012 | 02:23 PM
#244
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From: Finland
Hmm, perhaps we are going too far and wrong direction, but let's continue bit more...
By looking yesterday my removed S4 intake I found, that #2, #3 and #6 are the most straight intake pipes going from plenum to appropriate cylinders.
Perhaps #3 is also very close to #2 and #6 what comes to flow and filling of the cylinder, but not enough to cause most of the knocks..
Inside cylinders:
2: 27 cm
3: 28 cm
6: 32 cm
7: 28 cm
Average: 29 cm
"Air has a mass and it doesn't want to turn quickly"
Now the most straight pipes and intake ports will produce the best flow and velocity to ram-fill the appropriate cylinders. This is the reason, why race engine builders likes to make straight, tapered intake pipes and straight intake ports.
By doing this this way, they eliminate the turbulence and different velocity zones in pipe, which will badly distrubt the cylinder filling and VE. The shape of intake pipe bellmouth is just minimal tuning compared to pipe straightness.
http://www.profblairandassociates.co...mouth_Sept.pdf
Thinking about stroker engine with stock intake. The engine with larger displacement tries desperately to draw air through undersized stock intake pipes. The velocity in straight pipe must get very high value, compared to pipe with numerous, tight curves in it.
In this case, the VE and A/F- ratios across different cylinders have even higher dispersion. Therefore the larger displacement engine with stock intake may suffer more about #2 & #6 knocking issue... Same basically could happen with high rpm engines.
Of course, the other discussed aspects may have some additional coincidences for explained brainchaild
I'll stop for no. Happy Christmas, need to go back with rest of family...
By looking yesterday my removed S4 intake I found, that #2, #3 and #6 are the most straight intake pipes going from plenum to appropriate cylinders.
Perhaps #3 is also very close to #2 and #6 what comes to flow and filling of the cylinder, but not enough to cause most of the knocks..
Inside cylinders:
2: 27 cm
3: 28 cm
6: 32 cm
7: 28 cm
Average: 29 cm
"Air has a mass and it doesn't want to turn quickly"
Now the most straight pipes and intake ports will produce the best flow and velocity to ram-fill the appropriate cylinders. This is the reason, why race engine builders likes to make straight, tapered intake pipes and straight intake ports.
By doing this this way, they eliminate the turbulence and different velocity zones in pipe, which will badly distrubt the cylinder filling and VE. The shape of intake pipe bellmouth is just minimal tuning compared to pipe straightness.
http://www.profblairandassociates.co...mouth_Sept.pdf
Thinking about stroker engine with stock intake. The engine with larger displacement tries desperately to draw air through undersized stock intake pipes. The velocity in straight pipe must get very high value, compared to pipe with numerous, tight curves in it.
In this case, the VE and A/F- ratios across different cylinders have even higher dispersion. Therefore the larger displacement engine with stock intake may suffer more about #2 & #6 knocking issue... Same basically could happen with high rpm engines.
Of course, the other discussed aspects may have some additional coincidences for explained brainchaild
I'll stop for no. Happy Christmas, need to go back with rest of family...
12-25-2012 | 04:33 PM
#245
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From: Guelph, Ontario, Canada
Didn't Todd put 8 O2 sensors on an engine and showed which ones ran lean? I am too lazy to find that thread, but if we are saying for the sake of argument, that knock events are causing the 2/6 bearing issue, that data would be extremely useful.
I am not as convinced that this is the problem. Detonation usually causes ring and piston failures in my limited exposure to these types of failure.
I did have a Datsun P/U the had bearing failure once.... someone
forgot to tighten the oil plug and it fell out while doing 100km/h....yes it was capable of reaching that speed...barely
I am not as convinced that this is the problem. Detonation usually causes ring and piston failures in my limited exposure to these types of failure.
I did have a Datsun P/U the had bearing failure once.... someone
forgot to tighten the oil plug and it fell out while doing 100km/h....yes it was capable of reaching that speed...barely
04-25-2013 | 10:53 PM
#246
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From: Calgary North
After reading through all this and the European water bubble thread, I am wondering if a cyclonic system like this would work.
http://www.triple-r-europe.com/index...quicktron.html
If so, where would the best place to tie into the sump system be?
http://www.triple-r-europe.com/index...quicktron.html
If so, where would the best place to tie into the sump system be?
04-26-2013 | 08:45 AM
#247
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Evac-Breather
Interesting stuff..
I'll be testing my breather/evac setup I designed in 2005 after penning my twin Screw system, with a GZ vacuum pump and post results for others to see after testing, as the system is installed in the car now..
Basically, I thought that if all the oil in the heads that gets there at higher RPM's can be directed to the crankcase, then oiling should improve in the engine. The vacuum differential pressure between the case and atmo should allow this to happen by the vac pump sucking the crankcase and heads of the oil mist, and draining to the pan while keeping the head drains less clogged than they are on a stock setup.
That way, the pickup has something to pressurize the galleys and the bearings don't spin..
We shall see... There are a few details I am not mentioning yet, as I want to test first. They have to do with hose size and the pro vent..
Actually, I think the Pro vent 200 I have may be too small, or may need to have 2 units to deal with the vac pump flow rate. So, I may need to switch to a 400 or plumb in two 200 units... If the flow is an issue, I may probably plumb in a 400 unit due to space considerations..
This picture is also on my SC setup post, and can be followed there..
Hope it is helpful...
I'll be testing my breather/evac setup I designed in 2005 after penning my twin Screw system, with a GZ vacuum pump and post results for others to see after testing, as the system is installed in the car now..
Basically, I thought that if all the oil in the heads that gets there at higher RPM's can be directed to the crankcase, then oiling should improve in the engine. The vacuum differential pressure between the case and atmo should allow this to happen by the vac pump sucking the crankcase and heads of the oil mist, and draining to the pan while keeping the head drains less clogged than they are on a stock setup.
That way, the pickup has something to pressurize the galleys and the bearings don't spin..
We shall see... There are a few details I am not mentioning yet, as I want to test first. They have to do with hose size and the pro vent..
Actually, I think the Pro vent 200 I have may be too small, or may need to have 2 units to deal with the vac pump flow rate. So, I may need to switch to a 400 or plumb in two 200 units... If the flow is an issue, I may probably plumb in a 400 unit due to space considerations..
This picture is also on my SC setup post, and can be followed there..
Hope it is helpful...
04-26-2013 | 12:45 PM
#248
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Richard,
From what you describe you have to be careful about a few things.
Evacuating from the heads may itself create reversals up the head drains as in the stock configuration. It is very important where, how many ports and how you scavenge the heads. Using the top mounted stock breather ports unmodified won't really work - because the heads could still be approximately full of oil even when scavenging effectively from there. With a single stage pump you may not effectively scavenge all ports very well either, a balance issue due to flow differences between air/mist/liquid oil. I'm not sure the GZ pump is really designed as a liquid pump either...?
You may do better encouraging flow the other way around - drive net pumped flow down the head drains. Stock cam ports would be fine for that (if all are opened up)...
I do know that the Provent 200 alone isn't big enough for this usage - and the more heavily oiled it gets the worse it both performs (i.e. separates) and flows. I think its actually probably the wrong kind of separator for this application - since you will recycle most of the flow & oil back to the pan you may really need either: nothing (possible?) or a non-filter (low restriction) centrifugal separator in the pump recirculator loop followed by maybe a Provent style filter separator only on the output side e.g. handing only the net blowby out - not the whole pump loop flow..?.
Alan
From what you describe you have to be careful about a few things.
Evacuating from the heads may itself create reversals up the head drains as in the stock configuration. It is very important where, how many ports and how you scavenge the heads. Using the top mounted stock breather ports unmodified won't really work - because the heads could still be approximately full of oil even when scavenging effectively from there. With a single stage pump you may not effectively scavenge all ports very well either, a balance issue due to flow differences between air/mist/liquid oil. I'm not sure the GZ pump is really designed as a liquid pump either...?
You may do better encouraging flow the other way around - drive net pumped flow down the head drains. Stock cam ports would be fine for that (if all are opened up)...
I do know that the Provent 200 alone isn't big enough for this usage - and the more heavily oiled it gets the worse it both performs (i.e. separates) and flows. I think its actually probably the wrong kind of separator for this application - since you will recycle most of the flow & oil back to the pan you may really need either: nothing (possible?) or a non-filter (low restriction) centrifugal separator in the pump recirculator loop followed by maybe a Provent style filter separator only on the output side e.g. handing only the net blowby out - not the whole pump loop flow..?.
Alan
04-26-2013 | 01:33 PM
#249
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From: Monterey Peninsula, CA
Richard,
From what you describe you have to be careful about a few things.
Evacuating from the heads may itself create reversals up the head drains as in the stock configuration. It is very important where, how many ports and how you scavenge the heads. Using the top mounted stock breather ports unmodified won't really work - because the heads could still be approximately full of oil even when scavenging effectively from there. With a single stage pump you may not effectively scavenge all ports very well either, a balance issue due to flow differences between air/mist/liquid oil. I'm not sure the GZ pump is really designed as a liquid pump either...?
You may do better encouraging flow the other way around - drive net pumped flow down the head drains. Stock cam ports would be fine for that (if all are opened up)...
I do know that the Provent 200 alone isn't big enough for this usage - and the more heavily oiled it gets the worse it both performs (i.e. separates) and flows. I think its actually probably the wrong kind of separator for this application - since you will recycle most of the flow & oil back to the pan you may really need either: nothing (possible?) or a non-filter (low restriction) centrifugal separator in the pump recirculator loop followed by maybe a Provent style filter separator only on the output side e.g. handing only the net blowby out - not the whole pump loop flow..?.
Alan
From what you describe you have to be careful about a few things.
Evacuating from the heads may itself create reversals up the head drains as in the stock configuration. It is very important where, how many ports and how you scavenge the heads. Using the top mounted stock breather ports unmodified won't really work - because the heads could still be approximately full of oil even when scavenging effectively from there. With a single stage pump you may not effectively scavenge all ports very well either, a balance issue due to flow differences between air/mist/liquid oil. I'm not sure the GZ pump is really designed as a liquid pump either...?
You may do better encouraging flow the other way around - drive net pumped flow down the head drains. Stock cam ports would be fine for that (if all are opened up)...
I do know that the Provent 200 alone isn't big enough for this usage - and the more heavily oiled it gets the worse it both performs (i.e. separates) and flows. I think its actually probably the wrong kind of separator for this application - since you will recycle most of the flow & oil back to the pan you may really need either: nothing (possible?) or a non-filter (low restriction) centrifugal separator in the pump recirculator loop followed by maybe a Provent style filter separator only on the output side e.g. handing only the net blowby out - not the whole pump loop flow..?.
Alan
Thanks for the input...
Few things about the way I am plumbing stuff..
The pump is a vacuum pump that is meant to have oil in it.. (I ftrst posted on this in 2005 on RL in a discussion with Louie Ott), it turns out Colin is now using the same pump..
The head will be drained into the oil filler, and the vacuum pump will scavenge from there, and return through a modified tap on the oil pan like Louie did..
The vac pump exits to the Provent, and the Provent drains to the sump.. The pro vent exits to the intake, but before the MAF, as the vac pump pulls too much air, and will upset the MAF reading and not have an accurate airflow reading otherwise..
It is a closed system, where the differential pressure in the crankcase and heads is regulated by the size of the hoses of the drains and the scavenge hoses..
The vacuum pump needs oil to run, or it will break... My concern on the provent 200 is that it may not flow enough due the the pump pushing through it as the flow rating (CFM) is low compared to what the pump can do.
I understand what Greg has done, and why he did things his way. my design is similar, except I do not use a barnes or such as Greg is using.
In addition, the vacuum pump I am using looks very much like the stock airpump I removed.. (This is for smog eyeballs in CA..)
The basic idea is to keep excess oil out of the heads, or make it much easier for it to get back to the sump..
HTH,
04-26-2013 | 01:44 PM
#250
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This is for smog eyeballs in CA..
Your only hope is that the Porsche font and crest on the laminova covers distracts him from the fact that he's looking at a supercharger....FWIW, and a big knock on wood, my smog guy never batted an eyelash at the Dailey pump on my GTS- we did specify a black anodized pulley in lieu of the polished aluminum one. Nor did any of the scavenging lines. Or the headers, for that matter. Stock-colored intake, stock air tubes,old school rubber hoses, and belly pans do wonders towards hiding things in plain sight.
04-26-2013 | 02:37 PM
#251
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Richard, I can't help but think that once your Friendly Local Smog Guy raises the hood on your monster, he's never going to even get as far as the vacuum pump masquerading as an air pump. Your only hope is that the Porsche font and crest on the laminova covers distracts him from the fact that he's looking at a supercharger....
FWIW, and a big knock on wood, my smog guy never batted an eyelash at the Dailey pump on my GTS- we did specify a black anodized pulley in lieu of the polished aluminum one. Nor did any of the scavenging lines. Or the headers, for that matter. Stock-colored intake, stock air tubes,old school rubber hoses, and belly pans do wonders towards hiding things in plain sight.
Your only hope is that the Porsche font and crest on the laminova covers distracts him from the fact that he's looking at a supercharger....FWIW, and a big knock on wood, my smog guy never batted an eyelash at the Dailey pump on my GTS- we did specify a black anodized pulley in lieu of the polished aluminum one. Nor did any of the scavenging lines. Or the headers, for that matter. Stock-colored intake, stock air tubes,old school rubber hoses, and belly pans do wonders towards hiding things in plain sight.
Yes, the monster will be hoping to "hide in plain sight" with the big porsche fonts and medallion stuck to the top cover of the setup as the SC will be living underneath it all. (I was also thinking of hard anodizing the setup all black as well to hide more....)
I will see if I get lucky... In past I have been lucky with the headers, x pipe and such... Then again, snakes were not living under the bonnet then....
I need to actually smog it next month so I can test it, as it has been on a non op for a bit... That will buy me two years before the moment of truth.
But, in Monterey, it is a small area, and not like LA or SF etc.. So, maybe I'll have the lucky goddess smiling on me afterall..
04-26-2013 | 02:38 PM
#252
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Richard - to be clearer. I am driving my GTS with a GZ-VP102 installed in place of the air pump - sucking out of a Greg Brown baffle, modified filler port and discharging through a Provent 200.
These were not hypothetical comments
It works- but only sort of.. (as expected - this was known to be an interim configuraion). Don't follow this path without other mitigation plans:
1) It isn't clean enough to go back in the airbox (will kiill your MAF) - Though like you I do intend to do this eventually as a closed system -but it will need a lot more work
2) It's too restrictive at high RPM - I've been taking it very easy (<4K rpm)- Provent filter is far too wet. I've been running an NA Provent for a long time and the pump hugely changed the results (hence comment on total pumped flow Vs. net blowby flow). Ducman has seen the same thing even on an early car (<< displacement). Colin gave up on a Provent and made his own separator.
3) If the only return port is the Provent drain - that doesn't work so well - you want to be able to easily vary the bypass/recuirculation to control vacuum/balance
4) There is no fresh air crank flushing at all - exactly none. The stock Porsche system has part time fresh air flushing for a reason
5) There is no longer a simple means to remove water vapor - think about how you would get rid of it (the oil separator separates out the water -> crank pretty good also).
Stock system just ingests this with no serious vapor separation so its gone (along with a bunch of oil of course...)
6) GZ pump needs oil in suspension for sure - but not sure how it will deal with a significant quantity as a liquid - much more difficult to pump a liquid Vs. a gas out of the reducing chamber at high RPM
7) Your configuration of heads to filler & evacuate there sounds effectively similar to the stock configuration but with more flow - I don't see how that really helps eliminate the head drain restrictions - I could see how with the pump flow it might actually make it worse.
Did you already drive it this way?
Also:
8) Give some though to what would happen if the GZ pump fails:
a) Keep the catastrophic junk out of the crank (you must still have a recirculation path...)
b) If say the belt were to fail or the pump sieze - where would the blowby go?
Alan
These were not hypothetical comments
It works- but only sort of.. (as expected - this was known to be an interim configuraion). Don't follow this path without other mitigation plans:
1) It isn't clean enough to go back in the airbox (will kiill your MAF) - Though like you I do intend to do this eventually as a closed system -but it will need a lot more work
2) It's too restrictive at high RPM - I've been taking it very easy (<4K rpm)- Provent filter is far too wet. I've been running an NA Provent for a long time and the pump hugely changed the results (hence comment on total pumped flow Vs. net blowby flow). Ducman has seen the same thing even on an early car (<< displacement). Colin gave up on a Provent and made his own separator.
3) If the only return port is the Provent drain - that doesn't work so well - you want to be able to easily vary the bypass/recuirculation to control vacuum/balance
4) There is no fresh air crank flushing at all - exactly none. The stock Porsche system has part time fresh air flushing for a reason
5) There is no longer a simple means to remove water vapor - think about how you would get rid of it (the oil separator separates out the water -> crank pretty good also).
Stock system just ingests this with no serious vapor separation so its gone (along with a bunch of oil of course...)
6) GZ pump needs oil in suspension for sure - but not sure how it will deal with a significant quantity as a liquid - much more difficult to pump a liquid Vs. a gas out of the reducing chamber at high RPM
7) Your configuration of heads to filler & evacuate there sounds effectively similar to the stock configuration but with more flow - I don't see how that really helps eliminate the head drain restrictions - I could see how with the pump flow it might actually make it worse.
Did you already drive it this way?
Also:
8) Give some though to what would happen if the GZ pump fails:
a) Keep the catastrophic junk out of the crank (you must still have a recirculation path...)
b) If say the belt were to fail or the pump sieze - where would the blowby go?
Alan
Last edited by Alan; 04-26-2013 at 03:33 PM.
04-26-2013 | 03:46 PM
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Richard - to be clearer. I am driving my GTS with a GZ-VP102 installed in place of the air pump - sucking out of a modified filler port and discharging through a Provent 200.
These were not hypothetical comments
It works but only sort of... don't follow this path without mitigation:
1) It isn't clean enough to go back in the airbox (will kiill your MAF) Is this because you are overpowering the ability of the provent, or ? How can you tell my setup has unbalanced flow, and will be the same as your situation? I am very curious about this, as I really want to know what people are doing so we can all improve..
2) It's too restrictive at high RPM - I've been taking it very easy - Provent filter is far too wet. Wet from water or oil? Or both? Again, is the PV200 being overpowered compared to NA mode...? Then again, I do not know what size lines, pulley ratio, and how the lines are run on your setup, so I cannot comment on why you are experiencing these issues. (I've been running an NA Provent for a long time and the pump hugely changed the results (hence comment on total pumped flow Vs. net blowby flow). Ducman has seen the same thing even on an early car (<< displacement). Don't know what he is doing, and how his setup is constructed, so I can't comment here either..
3) If the only return port if the Provent drain - that doesn't work so well - you want to be able to easily vary the bypass/recuirculation to controll vacuum/balance What size is the drain, how long are the lines, and where is it plumbed on your setup? How did you decide the single drain is inadequate? How much load was on the motor, and for how long before the drain was overwhelmed?
4) There is no fresh air crank flushing at all - exactly none.Not sure what you are saying here.. I don't want any fresh air in the crankcase. I want as much of the air out, but not enough that too much oil is taken out, and then I gall the piston pins and rod bushings, but enough to have better ring seal. This is the balance bit that keeps me wondering, not the other bits...
5) There is no longer a simple means to remove water vapor - think about how you would get rid of it
(the oil separator separates out the water -> crank pretty good also). So why do I want water vapour in my crankcase?? Not sure I understand your point here.. There is no water separator on my S4 other than when the engine ingests it with oil as it does in NA form currently..
6) GZ pump need oil in suspension for sure - but not sure how it will deal with a significant quantity as a liquid I plan to test and find out, this is part of my development plan, design, develop, test, redesign, cycle again..
Also:
7) Give some though to what woiuld happen if the GZ pump fails: See my comments below
a) Keep the catastrophic junk out of the crank (you must still have a recirculation path...)
b) If say the belt were to fail or the pump sieze - where would the blowby go?
Alan
These were not hypothetical comments
It works but only sort of... don't follow this path without mitigation:
1) It isn't clean enough to go back in the airbox (will kiill your MAF) Is this because you are overpowering the ability of the provent, or ? How can you tell my setup has unbalanced flow, and will be the same as your situation? I am very curious about this, as I really want to know what people are doing so we can all improve..
2) It's too restrictive at high RPM - I've been taking it very easy - Provent filter is far too wet. Wet from water or oil? Or both? Again, is the PV200 being overpowered compared to NA mode...? Then again, I do not know what size lines, pulley ratio, and how the lines are run on your setup, so I cannot comment on why you are experiencing these issues. (I've been running an NA Provent for a long time and the pump hugely changed the results (hence comment on total pumped flow Vs. net blowby flow). Ducman has seen the same thing even on an early car (<< displacement). Don't know what he is doing, and how his setup is constructed, so I can't comment here either..
3) If the only return port if the Provent drain - that doesn't work so well - you want to be able to easily vary the bypass/recuirculation to controll vacuum/balance What size is the drain, how long are the lines, and where is it plumbed on your setup? How did you decide the single drain is inadequate? How much load was on the motor, and for how long before the drain was overwhelmed?
4) There is no fresh air crank flushing at all - exactly none.Not sure what you are saying here.. I don't want any fresh air in the crankcase. I want as much of the air out, but not enough that too much oil is taken out, and then I gall the piston pins and rod bushings, but enough to have better ring seal. This is the balance bit that keeps me wondering, not the other bits...
5) There is no longer a simple means to remove water vapor - think about how you would get rid of it
(the oil separator separates out the water -> crank pretty good also). So why do I want water vapour in my crankcase?? Not sure I understand your point here.. There is no water separator on my S4 other than when the engine ingests it with oil as it does in NA form currently..
6) GZ pump need oil in suspension for sure - but not sure how it will deal with a significant quantity as a liquid I plan to test and find out, this is part of my development plan, design, develop, test, redesign, cycle again..
Also:
7) Give some though to what woiuld happen if the GZ pump fails: See my comments below
a) Keep the catastrophic junk out of the crank (you must still have a recirculation path...)
b) If say the belt were to fail or the pump sieze - where would the blowby go?
Alan
Thanks for the coments again.. I am looking at testing the setup to see what happens. As I mentioned, I think the 200 is too small for the GZ pump I have, that's why I may switch to a Provent 400.. I also do not know how the ratio of your pump is setup compared to what I have, and also what lines you have compared to the plumbing I have. Although I suspect mine is very different to anyone who is using a Provent in a 928.
If the pump fails on my setup, the pieces will not get into the crankcase unless they are a few microns thick there is a metal filter on my setup after the pump, and that is dirt size, same as old rubber and plastic bits now. If the belt fails, the blowby will just stay in the crankcase, and be vented as it is now with one small exception of the ingestion into the engine, it will vent to the lines and into the intake. AN-16 lines hold a lot of liquid, and so do AN-12 lines.
On another note, The car will not have a MAF in future, and may end up with a dry sump.. I am not worried about the belt failing. If it does, lots worse can happen than worrying about the oil from blowby. If the belt fails, and takes out a coolant hose, you will destroy the engine anyway, and that can happen with the steering belt, or the alternator belt, or the AC belt for that matter.
Oil will be the least of the problem in this failure mode. I choose not to worry about things like that. Granted the kevlar lines I have installed have better chance of surviving that situation compared to a stock rubber coolant hose..
Testng will see what happens.. I described my setup as simply as I can, so everyone can get an idea of what i am doing. There are many details that are very important that are technical, that I have not written in here, as it is overwhelming to most people, and pretty boring as well.. However, the devil is actually in the details, and unless everything is analyzed, something will not be correct.
Granted, after all this, the engine may blow up, and I will have to put in my spare motor and rebuild the current motor. However, I'm ok with that.. Part of the process, and hobby with this car..
Thanks again for the feedback
04-26-2013 | 04:44 PM
#254
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Richard I think you may be assuming things here that I didn't say or mean...
Didn't say anything about your system. Its a default nature - the CFM flow to develop whatever vacuum you target (likely 10-12 "Hg) will be broadly similar to any other 928 engine - that is the flow through the Provent - even changing the pully ratio won't change it much without fresh air flushing. So I think the results will be about the same. If your blowby is less/more then the high load/rpm may be better/worse - but what I see happens at mid rpm (~4k). So I think you will have this problem too. I'm not even sure waht you mean by 'unbalanced' flow in this context? it's not something I said?
Wet from oil primarily of course, the filter medium is totally soaked with oil from top to bottom. When fully loaded like this (heavy) it is restrictive and tends to blow off oil to the outer Provent casing where it can find its way out of the (low) output vent line. Would have been a better design if the vent was at the top.
I honestly don't think it matters much how its plumbed. I feed from the crank vent (only) via a precision motorwerks crank baffle to the pump - to the Provent - shortest possible path. I'm not asking for comment or solutions - the issues I see are almost exactly what I expected to see. This is only an interim installation. As I mentioned I think the Provent is the wrong kind of separator to be in the high flow pump loop , I do think its quite good at lower flow levels for good cleaning (based on what I saw in NA mode)
its exactly like Colin's set up but with a Provent AOS - also over oiling at high rpm.
The drain is the size of the Provent drain - this is not just the drain its also the recirculation flow path and if its the only one - its small. How you plumb it can't make it bigger. I didn't say it was overwhelmed with oil - this is the way you will modulate crank vacuum unless you have a secondary output recirculation return or install VLVs.
Porsche wanted fresh air through the crankcase... I think the general idea was to help flush out water vapor & toxic gasses that otherwise would end up contaminating your oil. So it might be a good idea. You don't want to boost the total Provent flow at high rpm & max blowby - so you need a method where it only flushes part time (low rpm, coast, idle...).
You don't - but since its a combustion product and blows by the rings along with other noxious stuff - you get it in the crank anyway. Best to have a way to get it out. In stock form the water vapor stays as a vapor and is routinely ingested - the flushing helps with this. Oil separators tend to also condense & strip out the water vapor and drain it to the pan bottom = bad.
Maybe the GZ guys have an answer already?
Again if your crank is otherwise sealed then the flow is pretty much defined by the recirculation flow needed to restrict to 10-12 "Hg.
Good
If the pump seizes and the crank is otherwise sealed - then I think the blowby will blow out seals somewhere.. where else is there to go? I don't understand what other paths exist?
My only goal is to save you some experimentation time here... you of course will do as you wish - but I do think you will see very similar results.
Alan
I honestly don't think it matters much how its plumbed. I feed from the crank vent (only) via a precision motorwerks crank baffle to the pump - to the Provent - shortest possible path. I'm not asking for comment or solutions - the issues I see are almost exactly what I expected to see. This is only an interim installation. As I mentioned I think the Provent is the wrong kind of separator to be in the high flow pump loop , I do think its quite good at lower flow levels for good cleaning (based on what I saw in NA mode)
4) Not sure what you are saying here.. I don't want any fresh air in the crankcase. I want as much of the air out, but not enough that too much oil is taken out, and then I gall the piston pins and rod bushings, but enough to have better ring seal. This is the balance bit that keeps me wondering, not the other bits...
Hi Alan,
Thanks for the coments again.. I am looking at testing the setup to see what happens. As I mentioned, I think the 200 is too small for the GZ pump I have, that's why I may switch to a Provent 400.. I also do not know how the ratio of your pump is setup compared to what I have, and also what lines you have compared to the plumbing I have. Although I suspect mine is very different to anyone who is using a Provent in a 928.
Thanks for the coments again.. I am looking at testing the setup to see what happens. As I mentioned, I think the 200 is too small for the GZ pump I have, that's why I may switch to a Provent 400.. I also do not know how the ratio of your pump is setup compared to what I have, and also what lines you have compared to the plumbing I have. Although I suspect mine is very different to anyone who is using a Provent in a 928.
My only goal is to save you some experimentation time here... you of course will do as you wish - but I do think you will see very similar results.
Alan
Last edited by Alan; 04-26-2013 at 05:57 PM.
04-26-2013 | 07:03 PM
#255
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Richard I think you may be assuming things here that I didn't say or mean...I am trying to decipher it, but I am missing so many details, that it is difficult to ask all the questions I want to ask without writing a book here, and bore everyone reading..
Didn't say anything about your system. Its a default nature - the CFM flow to develop whatever vacuum you target (likely 10-12 "Hg) will be broadly similar to any other 928 engine - that is the flow through the Provent - even changing the pully ratio won't change it much without fresh air flushing. I disagree, as the vacuum increases with rpm of the pump, as does the cfm of the pump. depending on the condition of the engine seals, the air could be leaking into the crankcase from more than just combustion blowby. For example, a leaky dipstick tube..
The flowchart of the GZ pump from the mfr confirms that the cfm will increase with rpm as well. The Provent 200 can only flow 200Liters/min, and depending on the gearing of the GZ pump rpm to the engine rpm, or the pulley ratio, you will overpower the provent once the GZ pump reaches a certain RPM depending on how and where the vacuum is restricted if any, as the PV200 will not be able to flow the air or oil mist you are pushing through the it, and it will also pressurize, and the valve will possibly open on the exhaust port to relieve the excess, and you will have blowby in the exit of the PV200 line and ruin the MAF.
A PV400 flows 400L/Min, and can handle much more airflow, to be exact double.. I am sure you can calculate the cfm to liters/min as I did and see why the PV200 may be overwhelmed when placed in the pressure side of a pump at certain RPM's.
So I think the results will be about the same. If your blowby is less/more then the high load/rpm may be better/worse - but what I see happens at mid rpm (~4k). So I think you will have this problem too. The same only if there is a restriction in the line from the pump through the PVent.. This is why I suggest the PV400. However, your system setup is determining what you see at 4k RPM engine speed
I'm not even sure waht you mean by 'unbalanced' flow in this context? it's not something I said? Yes, it was something you wrote, I am not sure what you meant by that either..
Wet from oil primarily of course, the filter medium is totally soaked with oil from top to bottom. When fully loaded like this (heavy) it is restrictive and tends to blow off oil to the outer Provent casing where it can find its way out of the (low) output vent line. Would have been a better design if the vent was at the top. I highly suspect that you are pressurizing the PV 200. Please look at the GZ pump flow data, convert CFM to Liters per minute and see that the PV is out of capacity, so the pressure is causing the gases to go to the outer case, as the safety valve opens on the outer casing on the lower line. FYI, The PV400 has in and out on the top of the case.
I honestly don't think it matters much how its plumbed. It absolutely does matter, and it also matters what size lines you use on the pump intake, as well as how long the lines are. GZ supplies AN-10 fittings as standard.. I am not using AN-10, although I have the fittings. The smaller fittings on the intake side if the pump causes a restriction and limits the amount of airflow and vacuum the pump can produce in the crankcase. GZ clearly states this in their literature as well.
I feed from the crank vent (only) via a precision motorwerks crank baffle to the pump - to the Provent - shortest possible path. I'm not asking for comment or solutions - the issues I see are almost exactly what I expected to see. This is only an interim installation. As I mentioned I think the Provent is the wrong kind of separator to be in the high flow pump loop , A PV200 is like you have stated, and I agree with you on some things. However, this is why I suggest you look at the flow data for the other PV models they have some that can flow 800 Liters/min of gases, In addition, a lot depends on how it is set up.
I do think its quite good at lower flow levels for good cleaning (based on what I saw in NA mode) its exactly like Colin's set up but with a Provent AOS - also over oiling at high rpm. I haven't see Colin's setup, so I can't comment on it..
The drain is the size of the Provent drain - this is not just the drain its also the recircution flow path and if its the only one - its small. How you plumb it can't make it bigger. No, you can't make the PV drain bigger, nor you may not want to, depending on what your goal is. But, you can use delta pressures to increase velocity such that oil flow exiting the PV over time is greater than flow at standard sea level pressure. That is a key bit... Think about what a compressor does when it compresses air.. Vacuum is created on the inlet side of the compressor..
I didn't say it was overwhelmed with oil - this is the way you will modulate crank vacuum unless you have a secondary output recirculation return or install VLVs. My misunderstanding, I agree that this is one of the ways to modulate the crankcase vacuum, there are others such as bleed valves, pulley and pump speed etc as well..
Porsche wanted fresh air through the crankcase... I think the general idea was to help flush out water vapor & toxic gasses that otherwise would end up contaminating your oil. So it might be a good idea. You don't want to boost the total Provent flow at high rpm & max blowby - so you need a method where it only flushes part time (low rpm, coast, idle...). The crankcase is not perfectly sealed, so my thoughts are that it will leak lots of air without having to put in more. I however, have not done a leakdown test on the crankcase to see how much it leaks.. However, it is interesting to note Porsche wanted to flush the case..
You don't - but since its a combustion product and blows by the rings along with other noxious stuff - you get it in the crank anyway. Best to have a way to get it out. In stock form the water vapor stays as a vapor and is routinely ingested - the flushing helps with this. Oil separators tend to also condense & strip out the water vapor and drain it to the pan bottom = bad. You can put a water separator filter on the line if it is that much of an issue to you, although I doubt it will be. I have one on my boat, and it works pretty well.
Maybe the GZ guys have an answer already? Not that I know of...
Again if your crank is otherwise sealed then the flow is pretty much defined by the recirculation flow needed to restrict to 10-12 "Hg. Yes, b ut it depends where you plumb the restriction..
If the pump seizes and the crank is otherwise sealed - then I think the blowby will blow out seals somewhere.. where else is there to go? I don't understand what other paths exist?The Pro vent valve will let go if pressurized too much, long before the engine seals let go. I don't understand why you would not shut the car off when the pump siezes and makes all that racket... This is also why I asked what size pump inlet lines, and how long they are. You can fill lots of oil in that line if the pump dies and you have to shut it down... Calculate the volume of fluid in a 1 inch ID line that is 30+ inches long.. Or a 0.5 inch line for that matter.. It's a lot..
My only goal is to save you some experimentation time here... you of course will do as you wish - but I do think you will see very similar results.Thanks, I appreciate all comments from everyone, even if untowardly, and I don't take yours as untowardly in any way. I want to understand what is going on, and what can be done to solve the problems. That's my goal. My setup is modeled on a dry sump setup without the multi stage scavenge and the pressure/gravity feed to the oil pickup
Alan
Didn't say anything about your system. Its a default nature - the CFM flow to develop whatever vacuum you target (likely 10-12 "Hg) will be broadly similar to any other 928 engine - that is the flow through the Provent - even changing the pully ratio won't change it much without fresh air flushing. I disagree, as the vacuum increases with rpm of the pump, as does the cfm of the pump. depending on the condition of the engine seals, the air could be leaking into the crankcase from more than just combustion blowby. For example, a leaky dipstick tube..
The flowchart of the GZ pump from the mfr confirms that the cfm will increase with rpm as well. The Provent 200 can only flow 200Liters/min, and depending on the gearing of the GZ pump rpm to the engine rpm, or the pulley ratio, you will overpower the provent once the GZ pump reaches a certain RPM depending on how and where the vacuum is restricted if any, as the PV200 will not be able to flow the air or oil mist you are pushing through the it, and it will also pressurize, and the valve will possibly open on the exhaust port to relieve the excess, and you will have blowby in the exit of the PV200 line and ruin the MAF.
A PV400 flows 400L/Min, and can handle much more airflow, to be exact double.. I am sure you can calculate the cfm to liters/min as I did and see why the PV200 may be overwhelmed when placed in the pressure side of a pump at certain RPM's.
So I think the results will be about the same. If your blowby is less/more then the high load/rpm may be better/worse - but what I see happens at mid rpm (~4k). So I think you will have this problem too. The same only if there is a restriction in the line from the pump through the PVent.. This is why I suggest the PV400. However, your system setup is determining what you see at 4k RPM engine speed
I'm not even sure waht you mean by 'unbalanced' flow in this context? it's not something I said? Yes, it was something you wrote, I am not sure what you meant by that either..
Wet from oil primarily of course, the filter medium is totally soaked with oil from top to bottom. When fully loaded like this (heavy) it is restrictive and tends to blow off oil to the outer Provent casing where it can find its way out of the (low) output vent line. Would have been a better design if the vent was at the top. I highly suspect that you are pressurizing the PV 200. Please look at the GZ pump flow data, convert CFM to Liters per minute and see that the PV is out of capacity, so the pressure is causing the gases to go to the outer case, as the safety valve opens on the outer casing on the lower line. FYI, The PV400 has in and out on the top of the case.
I honestly don't think it matters much how its plumbed. It absolutely does matter, and it also matters what size lines you use on the pump intake, as well as how long the lines are. GZ supplies AN-10 fittings as standard.. I am not using AN-10, although I have the fittings. The smaller fittings on the intake side if the pump causes a restriction and limits the amount of airflow and vacuum the pump can produce in the crankcase. GZ clearly states this in their literature as well.
I feed from the crank vent (only) via a precision motorwerks crank baffle to the pump - to the Provent - shortest possible path. I'm not asking for comment or solutions - the issues I see are almost exactly what I expected to see. This is only an interim installation. As I mentioned I think the Provent is the wrong kind of separator to be in the high flow pump loop , A PV200 is like you have stated, and I agree with you on some things. However, this is why I suggest you look at the flow data for the other PV models they have some that can flow 800 Liters/min of gases, In addition, a lot depends on how it is set up.
I do think its quite good at lower flow levels for good cleaning (based on what I saw in NA mode) its exactly like Colin's set up but with a Provent AOS - also over oiling at high rpm. I haven't see Colin's setup, so I can't comment on it..
The drain is the size of the Provent drain - this is not just the drain its also the recircution flow path and if its the only one - its small. How you plumb it can't make it bigger. No, you can't make the PV drain bigger, nor you may not want to, depending on what your goal is. But, you can use delta pressures to increase velocity such that oil flow exiting the PV over time is greater than flow at standard sea level pressure. That is a key bit... Think about what a compressor does when it compresses air.. Vacuum is created on the inlet side of the compressor..
I didn't say it was overwhelmed with oil - this is the way you will modulate crank vacuum unless you have a secondary output recirculation return or install VLVs. My misunderstanding, I agree that this is one of the ways to modulate the crankcase vacuum, there are others such as bleed valves, pulley and pump speed etc as well..
Porsche wanted fresh air through the crankcase... I think the general idea was to help flush out water vapor & toxic gasses that otherwise would end up contaminating your oil. So it might be a good idea. You don't want to boost the total Provent flow at high rpm & max blowby - so you need a method where it only flushes part time (low rpm, coast, idle...). The crankcase is not perfectly sealed, so my thoughts are that it will leak lots of air without having to put in more. I however, have not done a leakdown test on the crankcase to see how much it leaks.. However, it is interesting to note Porsche wanted to flush the case..
You don't - but since its a combustion product and blows by the rings along with other noxious stuff - you get it in the crank anyway. Best to have a way to get it out. In stock form the water vapor stays as a vapor and is routinely ingested - the flushing helps with this. Oil separators tend to also condense & strip out the water vapor and drain it to the pan bottom = bad. You can put a water separator filter on the line if it is that much of an issue to you, although I doubt it will be. I have one on my boat, and it works pretty well.
Maybe the GZ guys have an answer already? Not that I know of...
Again if your crank is otherwise sealed then the flow is pretty much defined by the recirculation flow needed to restrict to 10-12 "Hg. Yes, b ut it depends where you plumb the restriction..
If the pump seizes and the crank is otherwise sealed - then I think the blowby will blow out seals somewhere.. where else is there to go? I don't understand what other paths exist?The Pro vent valve will let go if pressurized too much, long before the engine seals let go. I don't understand why you would not shut the car off when the pump siezes and makes all that racket... This is also why I asked what size pump inlet lines, and how long they are. You can fill lots of oil in that line if the pump dies and you have to shut it down... Calculate the volume of fluid in a 1 inch ID line that is 30+ inches long.. Or a 0.5 inch line for that matter.. It's a lot..
My only goal is to save you some experimentation time here... you of course will do as you wish - but I do think you will see very similar results.Thanks, I appreciate all comments from everyone, even if untowardly, and I don't take yours as untowardly in any way. I want to understand what is going on, and what can be done to solve the problems. That's my goal. My setup is modeled on a dry sump setup without the multi stage scavenge and the pressure/gravity feed to the oil pickup
Alan
On another note, If you look at what Greg did, it is pretty obvious why, once you really look.. Same with a dry sump setup, if you know what you are looking at, and why things are placed in certain ways.
I remember seeing Louie's pics on how much oil was in the head, and thinking jeez, that can't be good, and there has got to be an oil drain problem in these motors... Same thing when I saw the catch can on the DEVEK car at the track after going for a spin around the track in it..
Dry sumps pull all the oil out of the motor case and put it back in certain places... Greg drains the heads and puts the oil back in the sump at certain places... What is similar and what is different... More importantly, why....?
Ok, thanks again, have a great one!