SURVEY: How many people have suffered catastrophic engine failure on their 944/68?
01-25-2002, 06:50 PM
#17
Here is my 89 944S2 with 65k on it.......
Always changed the oil at 3-4k and always ran 20-50 amsoil, Had my head reworked and it was burnin a bunch of oil after that, so i pulled the head to send it back and this is what i found.....Engine was NEVER overheated....I will pull the bottom end apart this weekend and get a look at the bearing.......Car has seen mostly track use sense the head was redone......
Motor still ran good, just smoked like hell...
Always changed the oil at 3-4k and always ran 20-50 amsoil, Had my head reworked and it was burnin a bunch of oil after that, so i pulled the head to send it back and this is what i found.....Engine was NEVER overheated....I will pull the bottom end apart this weekend and get a look at the bearing.......Car has seen mostly track use sense the head was redone......
Motor still ran good, just smoked like hell...
01-26-2002, 09:30 PM
#20
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Destroyed engine in a high water situation. Low visibility on a rainy night. Ended up trudging through mid door deep water. Car held up like a trooper, though I did park it about 10 miles further down the road because of knocking noises. The engine was still running!! When my mechanic pulled it from the car, you could see straight through the block...!
01-28-2002, 02:26 AM
#22
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first had the belts replaced, and the front end wasnt sealed properly (i forget wut seal). Oil saturated the belts for the 3 weeks it was running and at a stop sign, the car simply died. When i tried to start it, big time clunk. When the car was towed back home, we took off the timing belt cover to find its teeth laying at the bottom. We did the second rebuild ourselves, time wasnt an issue that time and we wanted it done right.
01-28-2002, 04:56 AM
#23
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Huntley Racing had done a lot of research over the years into EXACTLY why 944 cars spin rod bearings. What we found out over several years of searching was that there is much more miss-information that actual facts. First we found that whether in a track car, streetcar or even a weekend show car all 944 based cars including the 968 can spin a rod bearing. Second this has nothing to do with HP or TQ. Third it has nothing to do with uncovering the oil pick-up (This is a common miss-conception promoted by many many shops). Forth is that extra oil, like a half quart over the dipstick, does nothing. Fifth the Accusump and other systems don't fix this issue (other possible problems yes, but not the common rod bearing failures). Sixth no matter how many baffles you have put in your pan they will not help. I can go on and on but to get to the 'meat' of the matter....
What causes rod-bearing failures is 99% of the time centrifugal force. We found the solution to the mystery in an uncommon place, the Chevy world. It turns out a Chevy motor has the same problem, the 454 big block. Chevy 454 big blocks, which were designed for lower RPM operation, later became popular for drag racers. The drag racers started to turn more and more rpm's in search of more HP, which resulted in a 'new' problem developing, spun rod bearings. It took years to figure out why. The reason turned out to be so basic that the likes of Chevy and Porsche simply 'missed' it.
As a crankshaft rotates it has many forces acting upon it. It is obvious that the pistons push on the rods, which push on the crank and so forth and so on. What was missed was centrifugal force acting on the oil within the crank. High-pressure oil is fed thru the center of the crank to the main and rod bearings. Oil passing thru each journal is forced out of the crank onto the surface of the bearing thru the oil feed, which is nothing more than a hole in the surface of the journal. Where the 'mistake' was made was in the placement of the hole. The single oil feed hole can be drilled at any point 360 deg around on the journal, this is a decision dictated during the production of the crank. When the 944 crank design was made there was no attention given to the placement of this hole and the effect centrifugal force might have on the oil within it. Where the feed was placed just so happens to be one nearly opposite the direction centrifugal force pulls the oil when the crank is in motion. As the RPMs increase the centrifugal force goes up, eventually to the point where the oil pumps pressure simply can't overcome it. When this happens the rod bearings are starved of oil. The reason more track cars have this failure is because they are at high RPMs more often and for longer periods of time. Also track cars tend to have relatively high oil temperatures which thins the oil and causes the oil pressure to drop which lowers the RPM point where oil starvation at the rod bearings occurs. Further the high RPMs and often overfilled oil pans (to supposedly save the rod bearings) cause high windage that aerates the oil, further reducing its lubricating potential. Older motors spin rod bearings more often than newer motors since they have had more high RPM time than new motors and they usually have less oil pressure. Baffles, Accusumps, overfilling etc... do nothing to stop this failure mode.
Cross-drilling came out several years ago as a remedy for this issue but not because the problem was understood but because the idea was that a second oil feed hole would add more oil. There was a positive benefit from crossdrilling. The new oil feed opposite the original oil feed was not either hurt or helped by centrifugal force due to its position. This meant that the oil pump could generally keep up with the oiling needs of the rod bearings. Huntley Racing however took the cross-drilling to the next level and developed the Perp drilled crank. We perpendicularly bore a new feed into the rod journal, which is actually taking the nemesis, 'centrifugal force' and working with it to help to actually scavenge oil to the rod bearing as the RPMs go up!! Since we have machined cranks with this technique we have 'NEVER' had a rod bearing failure in any car, ever! We started offering these in 1998.
This subject and its relevance to the 944 world is obvious but it is only one of many possible failures, which can and do occur to these cars. Cars that suffer rod failure generally can trace this to the above mentioned rod bearing problem as the catalyst. Main bearings generally don’t have this problem simply because they are centrally located on the centerline of the crank and have a much smaller ‘arm’ to their outer diameter which makes them far less susceptible to oil starvation from centrifugal force
What causes rod-bearing failures is 99% of the time centrifugal force. We found the solution to the mystery in an uncommon place, the Chevy world. It turns out a Chevy motor has the same problem, the 454 big block. Chevy 454 big blocks, which were designed for lower RPM operation, later became popular for drag racers. The drag racers started to turn more and more rpm's in search of more HP, which resulted in a 'new' problem developing, spun rod bearings. It took years to figure out why. The reason turned out to be so basic that the likes of Chevy and Porsche simply 'missed' it.
As a crankshaft rotates it has many forces acting upon it. It is obvious that the pistons push on the rods, which push on the crank and so forth and so on. What was missed was centrifugal force acting on the oil within the crank. High-pressure oil is fed thru the center of the crank to the main and rod bearings. Oil passing thru each journal is forced out of the crank onto the surface of the bearing thru the oil feed, which is nothing more than a hole in the surface of the journal. Where the 'mistake' was made was in the placement of the hole. The single oil feed hole can be drilled at any point 360 deg around on the journal, this is a decision dictated during the production of the crank. When the 944 crank design was made there was no attention given to the placement of this hole and the effect centrifugal force might have on the oil within it. Where the feed was placed just so happens to be one nearly opposite the direction centrifugal force pulls the oil when the crank is in motion. As the RPMs increase the centrifugal force goes up, eventually to the point where the oil pumps pressure simply can't overcome it. When this happens the rod bearings are starved of oil. The reason more track cars have this failure is because they are at high RPMs more often and for longer periods of time. Also track cars tend to have relatively high oil temperatures which thins the oil and causes the oil pressure to drop which lowers the RPM point where oil starvation at the rod bearings occurs. Further the high RPMs and often overfilled oil pans (to supposedly save the rod bearings) cause high windage that aerates the oil, further reducing its lubricating potential. Older motors spin rod bearings more often than newer motors since they have had more high RPM time than new motors and they usually have less oil pressure. Baffles, Accusumps, overfilling etc... do nothing to stop this failure mode.
Cross-drilling came out several years ago as a remedy for this issue but not because the problem was understood but because the idea was that a second oil feed hole would add more oil. There was a positive benefit from crossdrilling. The new oil feed opposite the original oil feed was not either hurt or helped by centrifugal force due to its position. This meant that the oil pump could generally keep up with the oiling needs of the rod bearings. Huntley Racing however took the cross-drilling to the next level and developed the Perp drilled crank. We perpendicularly bore a new feed into the rod journal, which is actually taking the nemesis, 'centrifugal force' and working with it to help to actually scavenge oil to the rod bearing as the RPMs go up!! Since we have machined cranks with this technique we have 'NEVER' had a rod bearing failure in any car, ever! We started offering these in 1998.
This subject and its relevance to the 944 world is obvious but it is only one of many possible failures, which can and do occur to these cars. Cars that suffer rod failure generally can trace this to the above mentioned rod bearing problem as the catalyst. Main bearings generally don’t have this problem simply because they are centrally located on the centerline of the crank and have a much smaller ‘arm’ to their outer diameter which makes them far less susceptible to oil starvation from centrifugal force
01-28-2002, 08:08 AM
#24
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Having sold several engines, we have quite a few cores showing catastrophic failure.
The typical failure is a damaged #2 rod bearing, but we have had scored cylinders, broken rods, burned pistons, cracked cylinders, etc.
Keep enough oil in your car and watch your oil pressure. If you do track events, drop the oil pan and check your rod bearings every couple of years. If you race, have a competent engine builder make your engine bulletproof (yes, it can be done!).
Good luck...
The typical failure is a damaged #2 rod bearing, but we have had scored cylinders, broken rods, burned pistons, cracked cylinders, etc.
Keep enough oil in your car and watch your oil pressure. If you do track events, drop the oil pan and check your rod bearings every couple of years. If you race, have a competent engine builder make your engine bulletproof (yes, it can be done!).
Good luck...
01-28-2002, 08:34 AM
#25
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[quote]Originally posted by 944Ecology:
<strong>Having sold several engines, we have quite a few cores showing catastrophic failure.
The typical failure is a damaged #2 rod bearing, but we have had scored cylinders, broken rods, burned pistons, cracked cylinders, etc.
Keep enough oil in your car and watch your oil pressure. If you do track events, drop the oil pan and check your rod bearings every couple of years. If you race, have a competent engine builder make your engine bulletproof (yes, it can be done!).
Good luck...</strong><hr></blockquote>
How did you get an avatar?
<strong>Having sold several engines, we have quite a few cores showing catastrophic failure.
The typical failure is a damaged #2 rod bearing, but we have had scored cylinders, broken rods, burned pistons, cracked cylinders, etc.
Keep enough oil in your car and watch your oil pressure. If you do track events, drop the oil pan and check your rod bearings every couple of years. If you race, have a competent engine builder make your engine bulletproof (yes, it can be done!).
Good luck...</strong><hr></blockquote>
How did you get an avatar?
01-28-2002, 09:46 AM
#26
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I spun the #2 rod bearing at 98k miles (8k after purchasing the car). I have Huntley's crank in there now, so hopefully that will make a difference. I think I'll still change the rod bearings (or at least check them) after a couple years to see where things are -- seems like cheap insurance compared to what it costs to rebuild the entire motor.
01-28-2002, 03:06 PM
#27
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[quote]Originally posted by Huntley Racing:
<strong> ...Third it has nothing to do with uncovering the oil pick-up (This is a common miss-conception promoted by many many shops). Forth is that extra oil, like a half quart over the dipstick, does nothing. Sixth no matter how many baffles you have put in your pan they will not help.
...Baffles, Accusumps, overfilling etc... do nothing to stop this failure mode. </strong><hr></blockquote>
While you've completely made a case for the approach of drilling, shouldn't we still be just as concerned with getting oil to the destination? Doesn't starvation still occur if the pickup is uncovered? And, couldn't that starvation even cause problems with a properly drilled crank? My thought is that all these things help, but are certainly not the holy grail.
[quote]<strong> Huntley Racing however took the cross-drilling to the next level and developed the Perp drilled crank. We perpendicularly bore a new feed into the rod journal, which is actually taking the nemesis, 'centrifugal force' and working with it to help to actually scavenge oil to the rod bearing as the RPMs go up!!</strong><hr></blockquote>
Do you block the original hole(s)? Are you drilling all the way thru? Does the use of multiple holes in the crank need any increased pressure (because there's more relief now)? With the addition of holes, are there any fatiguing issues that may arise?
Thanks for the detailed response!
Skip
<strong> ...Third it has nothing to do with uncovering the oil pick-up (This is a common miss-conception promoted by many many shops). Forth is that extra oil, like a half quart over the dipstick, does nothing. Sixth no matter how many baffles you have put in your pan they will not help.
...Baffles, Accusumps, overfilling etc... do nothing to stop this failure mode. </strong><hr></blockquote>
While you've completely made a case for the approach of drilling, shouldn't we still be just as concerned with getting oil to the destination? Doesn't starvation still occur if the pickup is uncovered? And, couldn't that starvation even cause problems with a properly drilled crank? My thought is that all these things help, but are certainly not the holy grail.
[quote]<strong> Huntley Racing however took the cross-drilling to the next level and developed the Perp drilled crank. We perpendicularly bore a new feed into the rod journal, which is actually taking the nemesis, 'centrifugal force' and working with it to help to actually scavenge oil to the rod bearing as the RPMs go up!!</strong><hr></blockquote>
Do you block the original hole(s)? Are you drilling all the way thru? Does the use of multiple holes in the crank need any increased pressure (because there's more relief now)? With the addition of holes, are there any fatiguing issues that may arise?
Thanks for the detailed response!
Skip
01-28-2002, 11:39 PM
#28
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IMHO - as to the cause of the misterious #2 rod bearing failure and Huntleys' fix is based on what is common lore in the 928 world.
Keep in mind that the 928 experiences the same problems under hard throttle and high rpms - this may be the same situation for the 944 (given the closeness of our engine designs).
Mark Anderson (928 International) and Mark Thomas (DEVEK) have both (claimed) expored this territory and concluded that cross drilling the craknshaft with a seperate oil port to the #2 (& #6 on a V8 application) rod bearing location that the centrifugal forces are abated in the oil flow direction under the conditions mentioned above. Seems to require a shift in the paradigm - but whatever - it seems to work for the 928 motors.
I have read of NO failures on motors that have implemented this change n the 928's - and I'm not sure who came up with the fix first - but no matter, it seems to work (at least in the 928 realm).
hth-
Now, about those valves sizes....
Keep in mind that the 928 experiences the same problems under hard throttle and high rpms - this may be the same situation for the 944 (given the closeness of our engine designs).
Mark Anderson (928 International) and Mark Thomas (DEVEK) have both (claimed) expored this territory and concluded that cross drilling the craknshaft with a seperate oil port to the #2 (& #6 on a V8 application) rod bearing location that the centrifugal forces are abated in the oil flow direction under the conditions mentioned above. Seems to require a shift in the paradigm - but whatever - it seems to work for the 928 motors.
I have read of NO failures on motors that have implemented this change n the 928's - and I'm not sure who came up with the fix first - but no matter, it seems to work (at least in the 928 realm).
hth-
Now, about those valves sizes....
01-29-2002, 07:40 AM
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[quote]Originally posted by Jay Wellwood:
<strong>IMHO - as to the cause of the mysterious #2 rod bearing failure and Huntleys' fix is based on what is common lore in the 928 world.
Keep in mind that the 928 experiences the same problems under hard throttle and high rpms - this may be the same situation for the 944 (given the closeness of our engine designs).
Mark Anderson (928 International) and Mark Thomas (DEVEK) have both (claimed) expored this territory and concluded that cross drilling the craknshaft with a seperate oil port to the #2 (& #6 on a V8 application) rod bearing location that the centrifugal forces are abated in the oil flow direction under the conditions mentioned above. Seems to require a shift in the paradigm - but whatever - it seems to work for the 928 motors.
I have read of NO failures on motors that have implemented this change n the 928's - and I'm not sure who came up with the fix first - but no matter, it seems to work (at least in the 928 realm).
hth-
Now, about those valves sizes.... </strong><hr></blockquote>
<strong>IMHO - as to the cause of the mysterious #2 rod bearing failure and Huntleys' fix is based on what is common lore in the 928 world.
Keep in mind that the 928 experiences the same problems under hard throttle and high rpms - this may be the same situation for the 944 (given the closeness of our engine designs).
Mark Anderson (928 International) and Mark Thomas (DEVEK) have both (claimed) expored this territory and concluded that cross drilling the craknshaft with a seperate oil port to the #2 (& #6 on a V8 application) rod bearing location that the centrifugal forces are abated in the oil flow direction under the conditions mentioned above. Seems to require a shift in the paradigm - but whatever - it seems to work for the 928 motors.
I have read of NO failures on motors that have implemented this change n the 928's - and I'm not sure who came up with the fix first - but no matter, it seems to work (at least in the 928 realm).
hth-
Now, about those valves sizes....
</strong><hr></blockquote>
01-29-2002, 01:25 PM
#30
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quote:
--------------------------------------------------------------------------------
Originally posted by Huntley Racing:
...Third it has nothing to do with uncovering the oil pick-up (This is a common miss-conception promoted by many many shops). Forth is that extra oil, like a half quart over the dipstick, does nothing. Sixth no matter how many baffles you have put in your pan they will not help.
...Baffles, Accusumps, overfilling etc... do nothing to stop this failure mode.
--------------------------------------------------------------------------------
While you've completely made a case for the approach of drilling, shouldn't we still be just as concerned with getting oil to the destination? Doesn't starvation still occur if the pickup is uncovered? And, couldn't that starvation even cause problems with a properly drilled crank? My thought is that all these things help, but are certainly not the holy grail.
>>>Concerned yes, but the reality is that uncovering the pickup is rare. We have allways gone with the later 88+ pans and pickups with baffles on track cars but mainly because of the nice scapers and chaneling for the oil.
quote:
--------------------------------------------------------------------------------
Huntley Racing however took the cross-drilling to the next level and developed the Perp drilled crank. We perpendicularly bore a new feed into the rod journal, which is actually taking the nemesis, 'centrifugal force' and working with it to help to actually scavenge oil to the rod bearing as the RPMs go up!!
--------------------------------------------------------------------------------
Do you block the original hole(s)? Are you drilling all the way thru? Does the use of multiple holes in the crank need any increased pressure (because there's more relief now)? With the addition of holes, are there any fatiguing issues that may arise?
>>>The original hole is left open. We dont drill all the way thru just to the oil galley. There is no percevable oil pressure loss with the added feed. There is so little material removed during this procedure that fatigue is not an issue, of course the hoe is chamafered and such.
Thanks for the detailed response!
Skip
>>>Any time.
--------------------------------------------------------------------------------
Originally posted by Huntley Racing:
...Third it has nothing to do with uncovering the oil pick-up (This is a common miss-conception promoted by many many shops). Forth is that extra oil, like a half quart over the dipstick, does nothing. Sixth no matter how many baffles you have put in your pan they will not help.
...Baffles, Accusumps, overfilling etc... do nothing to stop this failure mode.
--------------------------------------------------------------------------------
While you've completely made a case for the approach of drilling, shouldn't we still be just as concerned with getting oil to the destination? Doesn't starvation still occur if the pickup is uncovered? And, couldn't that starvation even cause problems with a properly drilled crank? My thought is that all these things help, but are certainly not the holy grail.
>>>Concerned yes, but the reality is that uncovering the pickup is rare. We have allways gone with the later 88+ pans and pickups with baffles on track cars but mainly because of the nice scapers and chaneling for the oil.
quote:
--------------------------------------------------------------------------------
Huntley Racing however took the cross-drilling to the next level and developed the Perp drilled crank. We perpendicularly bore a new feed into the rod journal, which is actually taking the nemesis, 'centrifugal force' and working with it to help to actually scavenge oil to the rod bearing as the RPMs go up!!
--------------------------------------------------------------------------------
Do you block the original hole(s)? Are you drilling all the way thru? Does the use of multiple holes in the crank need any increased pressure (because there's more relief now)? With the addition of holes, are there any fatiguing issues that may arise?
>>>The original hole is left open. We dont drill all the way thru just to the oil galley. There is no percevable oil pressure loss with the added feed. There is so little material removed during this procedure that fatigue is not an issue, of course the hoe is chamafered and such.
Thanks for the detailed response!
Skip
>>>Any time.
