Drilled Crank Thoughts...
10-08-2007, 07:13 PM
#181
Nordschleife Master
Wow!
The odd thing is that #2 or #6 fails repeatedly. I've heard of other rod bearing failures but it seems the 90%+ it's that #2/6 journal. Why, why why? Since one pick-up feeds the whole engine it's got to be in the way the oil is distributed. That re-drilling the crank shows progress it backs up that conclusion. However, a drilled crank is not a panacea as there have been failures with them.
I believe there are two problems with the engines:
1) Aerated oil (foam) or simply no oil
2) High RPM causing starvation at the bearing.
The posters on this thread are mainly old hands with this car and we've heard the approaches and tracked the failures. Yes, blew mine with a scraper and sump cover installed. Do note that the engine was having ejection problems before that. Too much blow-by even after a re-build was my assessment...along with a tendency to run +6K rpms. Things are very much different with a fresh bore to new pistons and a full windage set.
What works? Here's a list:
Accusump to supplement pressure especially when cornering
Windage set to control foam and keep oil in the sump
Dry sump for consistent pressure and de-aerating the oil
Drilled crank for high RPM running
Staying in the garage
Doubling up a drilled crank and accusump has been effective as a combo. I'd like to know if those engines are getting bearings periodically as that combo has been done by the few really serious guys who are likely to rebuild the engines every year or three.
I suspect that the drilled crank may improve aerated oil by feeding the rod journals from two places. This would provide extra oil in starvation or aeration conditions.
The odd thing is that #2 or #6 fails repeatedly. I've heard of other rod bearing failures but it seems the 90%+ it's that #2/6 journal. Why, why why? Since one pick-up feeds the whole engine it's got to be in the way the oil is distributed. That re-drilling the crank shows progress it backs up that conclusion. However, a drilled crank is not a panacea as there have been failures with them.
I believe there are two problems with the engines:
1) Aerated oil (foam) or simply no oil
2) High RPM causing starvation at the bearing.
The posters on this thread are mainly old hands with this car and we've heard the approaches and tracked the failures. Yes, blew mine with a scraper and sump cover installed. Do note that the engine was having ejection problems before that. Too much blow-by even after a re-build was my assessment...along with a tendency to run +6K rpms. Things are very much different with a fresh bore to new pistons and a full windage set.
What works? Here's a list:
Accusump to supplement pressure especially when cornering
Windage set to control foam and keep oil in the sump
Dry sump for consistent pressure and de-aerating the oil
Drilled crank for high RPM running
Staying in the garage
Doubling up a drilled crank and accusump has been effective as a combo. I'd like to know if those engines are getting bearings periodically as that combo has been done by the few really serious guys who are likely to rebuild the engines every year or three.
I suspect that the drilled crank may improve aerated oil by feeding the rod journals from two places. This would provide extra oil in starvation or aeration conditions.
Last edited by GlenL; 10-08-2007 at 09:02 PM. Reason: Failed on #6 actually
10-08-2007, 08:20 PM
#183
Rennlist Member
Wouldnt one of the solutions be amzoil? 
seriously, i do have the oldest racing 928 engines on the planet, probably with the most amount of racing hours on it as well, yet no accusump, no drilled crank (that we know of) and it has over 90 race days on it now!
maybe we are on to something with the foaming, and oil ejecting reduction characteristics of specific types of oils. after all, rev limiter banging racing for over 6 years now, and the only thing that i have done is run Amzoil. pretty good testimonial if you ask me! (scots is still racing, no issues with his 5 liter euro as well, my 4.7 liter lasted 170,000miles and still looked fine when disassembled as well. )
Maybe the drilled crank and accusump allow for foaming oils and their issues to be less of a factor.
When we pull my engine, we will certainly see what is behind the success.
Mk
[/QUOTE]QUOTE=GlenL;4653886]Wow!
The odd thing is that #2 fails repeatedly. I've heard of other rod bearing failures but it seems the 90%+ it's that #2 rod. Why, why why? Since one pick-up feeds the whole engine it's got to be in the way the oil is distributed. That re-drilling the crank shows progress it backs up that conclusion. However, a drilled crank is not a panacea as there have been failures with them.
I believe there are two problems with the engines:
1) Aerated oil (foam) or simply no oil
2) High RPM causing starvation at the bearing.
The posters on this thread are mainly old hands with this car and we've heard the approaches and tracked the failures. Yes, blew mine with a scraper and sump cover installed. Do note that the engine was having ejection problems before that. Too much blow-by even after a re-build was my assessment...along with a tendency to run +6K rpms. Things are very much different with a fresh bore to new pistons and a full windage set.
What works? Here's a list:
Accusump to supplement pressure especially when cornering
Windage set to control foam and keep oil in the sump
Dry sump for consistent pressure and de-aerating the oil
Drilled crank for high RPM running
Staying in the garage
Doubling up a drilled crank and accusump has been effective as a combo. I'd like to know if those engines are getting bearings periodically as that combo has been done by the few really serious guys who are likely to rebuild the engines every year or three.
I suspect that the drilled crank may improve aerated oil by feeding the rod journals from two places. This would provide extra oil in starvation or aeration conditions.[/QUOTE]
seriously, i do have the oldest racing 928 engines on the planet, probably with the most amount of racing hours on it as well, yet no accusump, no drilled crank (that we know of) and it has over 90 race days on it now!
maybe we are on to something with the foaming, and oil ejecting reduction characteristics of specific types of oils. after all, rev limiter banging racing for over 6 years now, and the only thing that i have done is run Amzoil. pretty good testimonial if you ask me! (scots is still racing, no issues with his 5 liter euro as well, my 4.7 liter lasted 170,000miles and still looked fine when disassembled as well. )
Maybe the drilled crank and accusump allow for foaming oils and their issues to be less of a factor.
When we pull my engine, we will certainly see what is behind the success.
Mk
[/QUOTE]QUOTE=GlenL;4653886]Wow!
The odd thing is that #2 fails repeatedly. I've heard of other rod bearing failures but it seems the 90%+ it's that #2 rod. Why, why why? Since one pick-up feeds the whole engine it's got to be in the way the oil is distributed. That re-drilling the crank shows progress it backs up that conclusion. However, a drilled crank is not a panacea as there have been failures with them.
I believe there are two problems with the engines:
1) Aerated oil (foam) or simply no oil
2) High RPM causing starvation at the bearing.
The posters on this thread are mainly old hands with this car and we've heard the approaches and tracked the failures. Yes, blew mine with a scraper and sump cover installed. Do note that the engine was having ejection problems before that. Too much blow-by even after a re-build was my assessment...along with a tendency to run +6K rpms. Things are very much different with a fresh bore to new pistons and a full windage set.
What works? Here's a list:
Accusump to supplement pressure especially when cornering
Windage set to control foam and keep oil in the sump
Dry sump for consistent pressure and de-aerating the oil
Drilled crank for high RPM running
Staying in the garage
Doubling up a drilled crank and accusump has been effective as a combo. I'd like to know if those engines are getting bearings periodically as that combo has been done by the few really serious guys who are likely to rebuild the engines every year or three.
I suspect that the drilled crank may improve aerated oil by feeding the rod journals from two places. This would provide extra oil in starvation or aeration conditions.[/QUOTE]
10-08-2007, 08:45 PM
#184
Former Sponsor
We've already established that Greg Brown doesn't know his *** from a hot rock on this thread. Building tried and proven stuff has no place in this thread. Using examples of what Porsche did to fix the oiling problems in the dry sumped, windage trayed, scraper equiped 944 GTRs has no place in this thread. Theory is the only thing that holds water, here.
10-08-2007, 08:59 PM
#185
Nordschleife Master
Greg, The problem is that no one can explicitly prove the cause with concrete evidence. There's no camera inside the bearing and oil analyser in the ladder. Gotta have theories to work againt. Solutions are welcome, of course.
I'd like to correct something. My engine actually failed on #6!
I'd forgotten that and a sharp-eyed guy pointed that out.
I'd like to correct something. My engine actually failed on #6!
I'd forgotten that and a sharp-eyed guy pointed that out.
10-08-2007, 09:02 PM
#186
In Your Face, Ace
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10-08-2007, 09:09 PM
#187
Under the Lift
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Blue = 15mm wide round feed pipe from oil filter = 177mm^2
Green = 8.5mm wide x 16mm deep = 136mm^2
Yellow = 8.5mm wide x 10mm deep = 85mm^2
Light yellow = 7.5mm wide x 11 deep = 83mm^2
Red = 5mm wide x 5 mm deep = 25mm^2
Yellow means both short straight thing from blue feed to #1 main bearing and from green to end of #3 main bearing and towards #4 and #5. Light yellow is from #3 main to input to upper half of block for right head.
Left head takes its oil from green area IIRR or maybe more likely from forward yellow. Anyone remember exact position for it? How close it is to red input of #2 main?
4x25mm^2 + 85mm^2 = 185mm^2. Should total area for 5 main bearings be larger or smaller than feed from filter? Does it make any difference in to this relationship that feed is round while channels are rectangle? Obviously feed to left head needs to be added also. So total area for all channels is significantly larger than feed.
Should light yellow feed to head be smaller or larger in size when using stroker crank where #3 is feeding two rods too?
Could and should feeds to both head be made slightly smaller or larger in order to leave more oil for main and rod bearings?
Green = 8.5mm wide x 16mm deep = 136mm^2
Yellow = 8.5mm wide x 10mm deep = 85mm^2
Light yellow = 7.5mm wide x 11 deep = 83mm^2
Red = 5mm wide x 5 mm deep = 25mm^2
Yellow means both short straight thing from blue feed to #1 main bearing and from green to end of #3 main bearing and towards #4 and #5. Light yellow is from #3 main to input to upper half of block for right head.
Left head takes its oil from green area IIRR or maybe more likely from forward yellow. Anyone remember exact position for it? How close it is to red input of #2 main?
4x25mm^2 + 85mm^2 = 185mm^2. Should total area for 5 main bearings be larger or smaller than feed from filter? Does it make any difference in to this relationship that feed is round while channels are rectangle? Obviously feed to left head needs to be added also. So total area for all channels is significantly larger than feed.
Should light yellow feed to head be smaller or larger in size when using stroker crank where #3 is feeding two rods too?
Could and should feeds to both head be made slightly smaller or larger in order to leave more oil for main and rod bearings?
10-08-2007, 09:23 PM
#188
Three Wheelin'
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As a relative newbie to the 928 community, seeing this thread is incredibly SAD ! Come on guys, please leave the egos at the door. What on earth is the point ? Are you competing for something here ???
FWIW, I have been assisting another 928 owner with an engine rebuild and we just fit one of Kevin's windage / scraper systems to the bottom end. For the money, this windage setup is one of the most completely thought through setups I have seen. From past experience, to get something this complete requires a LOT of DIY-ing and specific fitment.
IMHO, you guys should be appreciative that someone is offering this kit, particularly if folks who are on this thread antagonizing Kevin are not offering anything to 928's as an alternative.
From the perspective of a DIY-er 928 owner, I sure hate to see the forum used to drive away potential solutions to the all so obvious issues of "hot-rodding" the 928 engine. The issues are known, but solutions can be many... all depending on what each of us believes is the cause(s) vs. effect(s).
For my own larger displacement engine project, I plan to use Kevin's kit, plus a few more breather improvements and pan mods... that is, if this thread does not drive Kevin away from supporting the 928 crowd. Given this thread, who would blame him.
I sure hope that those of you who want to be considered experts in this area of windage and crank case breathing are willing to fill the gap here once we lose another source of assistance. If you are not, please bow out and let the rest of us take this info for what it is... Rant off.
FWIW, I have been assisting another 928 owner with an engine rebuild and we just fit one of Kevin's windage / scraper systems to the bottom end. For the money, this windage setup is one of the most completely thought through setups I have seen. From past experience, to get something this complete requires a LOT of DIY-ing and specific fitment.
IMHO, you guys should be appreciative that someone is offering this kit, particularly if folks who are on this thread antagonizing Kevin are not offering anything to 928's as an alternative.
From the perspective of a DIY-er 928 owner, I sure hate to see the forum used to drive away potential solutions to the all so obvious issues of "hot-rodding" the 928 engine. The issues are known, but solutions can be many... all depending on what each of us believes is the cause(s) vs. effect(s).
For my own larger displacement engine project, I plan to use Kevin's kit, plus a few more breather improvements and pan mods... that is, if this thread does not drive Kevin away from supporting the 928 crowd. Given this thread, who would blame him.
I sure hope that those of you who want to be considered experts in this area of windage and crank case breathing are willing to fill the gap here once we lose another source of assistance. If you are not, please bow out and let the rest of us take this info for what it is... Rant off.
10-08-2007, 09:40 PM
#189
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The key issue of contention as I see it, is that Kevin promotes too much that his kit is THE solution and anything else is not needed. This is NOT known to be true and will NOT be known to be true until many many hours of on track use without any issues.
I don't want the unwary to think this is a proven solution until there is more proof that it is.
In the meantime we do have significant proof that a drilled crank and dry sump are the best KNOWN 928 motor solutions.
I applaud Kevin for his efforts and will certainly consider his product, but not as a sole solution until more proof is available.
10-08-2007, 10:01 PM
#190
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In the meantime we do have significant proof that a drilled crank and dry sump are the best KNOWN 928 motor solutions.
Yes... but at what cost to the owner, or even at what value to the car being "hot-rodded" ???
Comparing custom one-off dry sump setups to a readily available $650-ish dollar windage improvement is exactly how this thread is going off base.
Unless I am missing something, I have not seen any vendor (let alone the contributors to this thread) offer a complete dry sump solution for the 928 engine. How many owners can afford to develop a dry sump system, let alone correctly ? How about folks who want to keep their HVAC setups or still have a street / DE car ???
From searches on various 928 sites (including RL), there has been some discussion of one off DS pans being built, but no commercial kit. So who's offering this "known" solution ? And at what cost ?
IMHO, comparing a custom dry sumping setup as the only "known" solution for us 928 enthusiasts is a great example of how this thread is so far a field from what it could be.
How about some mediation to discuss resonable solutions for the hobbiest 928 owner who wants to do DE's and keep to a hobbiest budget ???
IN the mean time, I guess I'll go back to lurking since this solution is "known".
10-08-2007, 10:18 PM
#191
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Comparing custom one-off dry sump setups to a readily available $650-ish dollar windage improvement is exactly how this thread is going off base.
Unless I am missing something, I have not seen any vendor (let alone the contributors to this thread) offer a complete dry sump solution for the 928 engine.
Unless I am missing something, I have not seen any vendor (let alone the contributors to this thread) offer a complete dry sump solution for the 928 engine.
10-08-2007, 10:26 PM
#193
In Your Face, Ace
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You're missing the fact that dry sump setups are proven, drilled cranks are proven, and Kevin's setup is not.
And I have spoken with Mark A. who mentioned someone that lost an engine with a dry sump. Can't remember who he said it was.
10-08-2007, 10:35 PM
#194
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A few runs up Pike's Peak is a good start, but really isn't the long term proof I would be looking for. I could run a new motor for quite a while without drilled crank or accusump as it does take a while for the bearings to wear out. It wouldn't be instant catastropic failure.
10-08-2007, 10:38 PM
#195
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Great point, Stan.
I found it interesting that Carl does not cross drill his crank.
For me, I decided to go with drilled crank, scraper-tray and the accusump with EPCV and also the baffle upgrade....and strongly considering Amzoil too
Also put in fresh bearings.
I found it interesting that Carl does not cross drill his crank.
For me, I decided to go with drilled crank, scraper-tray and the accusump with EPCV and also the baffle upgrade....and strongly considering Amzoil too
Also put in fresh bearings.