Any 944 Rod bearing failures WITH drilled crank?
11-07-2003, 09:33 AM
#61
Pro
Join Date: Jan 2002
Location: Toronto
Posts: 523
Likes: 0
Received 0 Likes
on
0 Posts
I had my 951 engine rebuilt at about 100,000 miles, and the #2 rod bearing was showing copper. I installed the oil pick-up collar, knife-edged the crank, and installed the trap-door on the right side. The engine has the Jon Milledge 290 hp system with a K26/8. When I got it on the track, the oil pressure would drop to 3 bar or even less after about three laps, and I discussed it with Jon. He said that you need 10 psi per 1,000 rpm, i.e. 4 bar at 6,000 rpm. I installed a large oil cooler, and the pressure never drops below 4 bar with Mobil 1 20W50. So far, so good with about 10,000 track miles. I may try Amsoil next year, though.
My mechanic worked on the Rothmans 944's in the 1980's, and they never had any rod bearing problems, although they were rebuilt after each season. He said the key was to keep the oil topped up. With high oil consumption, the oil level can drop very quickly on the track, and this may lead to the rod bearing problems. We've had a number of these go at Mosport, but that was before we realized the importance of the oil level.
My mechanic worked on the Rothmans 944's in the 1980's, and they never had any rod bearing problems, although they were rebuilt after each season. He said the key was to keep the oil topped up. With high oil consumption, the oil level can drop very quickly on the track, and this may lead to the rod bearing problems. We've had a number of these go at Mosport, but that was before we realized the importance of the oil level.
11-10-2003, 01:12 AM
#62
Rennlist Member
Join Date: Dec 2002
Posts: 1,051
Likes: 0
Received 0 Likes
on
0 Posts
Greetings from V-8 land. 
That's one of the things I've been wondering about on the 928. Why 2/6? Since I know almost nothing about 944s, would somebody mind posting a picture of a 944 oil pan? I'm curious as to what the inside of one looks like. Any changes to them over the years, with any apparent effect on the rod bearing issue occuring?
My thinking as far as the 928 engine goes is that there are more than one kind of failure, caused by different issues, that all get lumped into one general rod bearing failure catagory.
Originally posted by Al P.
The real question remains why #2?
The real question remains why #2?
My thinking as far as the 928 engine goes is that there are more than one kind of failure, caused by different issues, that all get lumped into one general rod bearing failure catagory.
11-10-2003, 08:19 AM
#63
Pro
Join Date: May 2001
Location: North Jersey
Posts: 674
Likes: 0
Received 0 Likes
on
0 Posts
Good morning from 1/2 of a V8 land
I don't have any pics at the moment but either I'll try to take some or maybe someone else has some already.
Z wrote
"My thinking as far as the 928 engine goes is that there are more than one kind of failure, caused by different issues, that all get lumped into one general rod bearing failure catagory."
I think that there may be numerous "triggers" that cause the failures but my concern is the one underlying cause of the #2 failures or in the case of the 928 the #2/6 failures. They tend to always be these particular journals that fail first indicating to me at least that there is an oiling problem to them rather than an across the board problem otherwise there would be random failures.
I don't have any pics at the moment but either I'll try to take some or maybe someone else has some already.
Z wrote
"My thinking as far as the 928 engine goes is that there are more than one kind of failure, caused by different issues, that all get lumped into one general rod bearing failure catagory."
I think that there may be numerous "triggers" that cause the failures but my concern is the one underlying cause of the #2 failures or in the case of the 928 the #2/6 failures. They tend to always be these particular journals that fail first indicating to me at least that there is an oiling problem to them rather than an across the board problem otherwise there would be random failures.
11-10-2003, 06:29 PM
#64
Pro
Join Date: Jun 2003
Location: Bjärred Sweden
Posts: 600
Likes: 0
Received 0 Likes
on
0 Posts
it occures to me that I've never herd of a 968 motor or an S2 for that mater blowing up! Now of course it may just be that I didn't get the memo but then again it does have a different crank. Think maybe the engineers at Porsche actually did fix the problem?
So you racers, what oil temperatures do you see when the pressure drops to 3 bars? ( I suppose you have a temp gauge?)
Bengt
11-10-2003, 06:32 PM
#65
Rennlist Member
Mobil 1, thats the reason!!
try amzoil NOW!!! cheapest insurance you will ever buy.
some of the best engine builders , no nothing about oil. they are amazed when I tell them the oil pressure problem only when using mobil 1 in race conditions.
MK
try amzoil NOW!!! cheapest insurance you will ever buy.
some of the best engine builders , no nothing about oil. they are amazed when I tell them the oil pressure problem only when using mobil 1 in race conditions.
MK
Originally posted by smokey
I had my 951 engine rebuilt at about 100,000 miles, and the #2 rod bearing was showing copper. I installed the oil pick-up collar, knife-edged the crank, and installed the trap-door on the right side. The engine has the Jon Milledge 290 hp system with a K26/8. When I got it on the track, the oil pressure would drop to 3 bar or even less after about three laps, and I discussed it with Jon. He said that you need 10 psi per 1,000 rpm, i.e. 4 bar at 6,000 rpm. I installed a large oil cooler, and the pressure never drops below 4 bar with Mobil 1 20W50. So far, so good with about 10,000 track miles. I may try Amsoil next year, though.
My mechanic worked on the Rothmans 944's in the 1980's, and they never had any rod bearing problems, although they were rebuilt after each season. He said the key was to keep the oil topped up. With high oil consumption, the oil level can drop very quickly on the track, and this may lead to the rod bearing problems. We've had a number of these go at Mosport, but that was before we realized the importance of the oil level.
I had my 951 engine rebuilt at about 100,000 miles, and the #2 rod bearing was showing copper. I installed the oil pick-up collar, knife-edged the crank, and installed the trap-door on the right side. The engine has the Jon Milledge 290 hp system with a K26/8. When I got it on the track, the oil pressure would drop to 3 bar or even less after about three laps, and I discussed it with Jon. He said that you need 10 psi per 1,000 rpm, i.e. 4 bar at 6,000 rpm. I installed a large oil cooler, and the pressure never drops below 4 bar with Mobil 1 20W50. So far, so good with about 10,000 track miles. I may try Amsoil next year, though.
My mechanic worked on the Rothmans 944's in the 1980's, and they never had any rod bearing problems, although they were rebuilt after each season. He said the key was to keep the oil topped up. With high oil consumption, the oil level can drop very quickly on the track, and this may lead to the rod bearing problems. We've had a number of these go at Mosport, but that was before we realized the importance of the oil level.
11-10-2003, 06:35 PM
#66
Rennlist Member
the 928 gets around 260F oil temp on a hot day (90 degrees plus)
It can have peaks toward the end of a race of 270ish)
at 270ish, the oil pressure of my back up 928 track car that was running mobil 1, was at 3bar in some turns. idling in the red zone for pressure as we came into the pits. with amzoil, none of that happens.
fact or fiction???Its your engine!!
MK
QUOTE]Originally posted by Bengt Sweden
I would guess that those engines run much lower oil temperatures than a 951.
So you racers, what oil temperatures do you see when the pressure drops to 3 bars? ( I suppose you have a temp gauge?)
Bengt [/QUOTE]
It can have peaks toward the end of a race of 270ish)
at 270ish, the oil pressure of my back up 928 track car that was running mobil 1, was at 3bar in some turns. idling in the red zone for pressure as we came into the pits. with amzoil, none of that happens.
fact or fiction???Its your engine!!
MK
QUOTE]Originally posted by Bengt Sweden
I would guess that those engines run much lower oil temperatures than a 951.
So you racers, what oil temperatures do you see when the pressure drops to 3 bars? ( I suppose you have a temp gauge?)
Bengt [/QUOTE]
11-12-2003, 05:56 PM
#69
Pro
Join Date: May 2001
Location: North Jersey
Posts: 674
Likes: 0
Received 0 Likes
on
0 Posts
The case I ordered was 20w50 "racing" oil they also make a 20w50 "severe service" for all I know the only difference may be the label.
unfortunately I won't have a chance to test this on the track till Spring.
that seems like such a long time from now I think I need to move to a climate that allows year round fun. Although it could be worse I could live in Sweden, does it even get light there in the winter? brrrrr.......cold
unfortunately I won't have a chance to test this on the track till Spring.
that seems like such a long time from now I think I need to move to a climate that allows year round fun. Although it could be worse I could live in Sweden, does it even get light there in the winter? brrrrr.......cold
11-12-2003, 07:13 PM
#70
Pro
Join Date: Jun 2003
Location: Bjärred Sweden
Posts: 600
Likes: 0
Received 0 Likes
on
0 Posts
Sweden is large. Up in the north the sun do not come up for a few months but you get some indirect daylight for a few hours a day. In the south where I live it is not that bad although I do not use the Porsche for some months. A good period for upgrading and the car is perceived dramatically faster in the spring just by not driving it for some time.
Cheers
Cheers
11-13-2003, 10:16 AM
#71
Race Director
Thread Starter
Originally posted by Bengt Sweden
What viscosity Amsoil?
Bengt
What viscosity Amsoil?
Bengt
I have race next weekend with 2hr enduro so I get chance to test it out quickly!
11-13-2003, 12:12 PM
#73
Race Director
Thread Starter
Originally posted by Al P.
Arizona
Hmmm.... year round racing, 944 spec racing
Arizona
Hmmm.... year round racing, 944 spec racing
We don't race from the middle of may to the middle of september. Racing in 114F just aint any good!
11-14-2003, 03:23 PM
#74
Pro
Join Date: Jun 2003
Location: Bjärred Sweden
Posts: 600
Likes: 0
Received 0 Likes
on
0 Posts
I visited a tuner today who told me that it was a well known fact that engines with large diameter main journals had problems at high rpms and that high oil pressure is required to overcome centrifugal forces. He told me about some Chrysler engine where they had shifted to cranks with larger journals and thereby induced the problem.
It used to be a rule of thumb to have 10psi per 1000rpm. This can of course not be strictly correct but perhaps is good enough within a certain rpm span.
So keep the pressure high with cold thick oil!
Bengt
It used to be a rule of thumb to have 10psi per 1000rpm. This can of course not be strictly correct but perhaps is good enough within a certain rpm span.
So keep the pressure high with cold thick oil!
Bengt
11-18-2003, 01:16 PM
#75
Pro
Join Date: Jun 2003
Location: Bjärred Sweden
Posts: 600
Likes: 0
Received 0 Likes
on
0 Posts
On this page it is claimed that the Turbo Cup had reinforced bearings ( verstärkte Motorlager). Does anyone know what is done?
http://content3.eu.porsche.com/prod/...e=rennwagen&19
http://content3.eu.porsche.com/prod/...e=rennwagen&19