944ja väntvõll ja kepsusaale probleemid
944ja väntvõll ja kepsusaale probleemid
Tehase manualis kulumise piirid
Haynes manualis kulumise piirid
Nii raam- kui ka kepsusaaled on saadaval standard, oversize 0,25 mm ja oversize 0,5 mm.
Kuid millise n.ö. siseläbimõõduga on näiteks standard kepsusaale?
Milline võiks olla "oil clearance"? 0,020 mm?
Ehk kui suur peaks olema väntvõlli kaelte läbimõõt oversize 0,5 mm saalede jaoks?
Haynes manualis kulumise piirid
Nii raam- kui ka kepsusaaled on saadaval standard, oversize 0,25 mm ja oversize 0,5 mm.
Kuid millise n.ö. siseläbimõõduga on näiteks standard kepsusaale?
Milline võiks olla "oil clearance"? 0,020 mm?
Ehk kui suur peaks olema väntvõlli kaelte läbimõõt oversize 0,5 mm saalede jaoks?
Re: 944ja väntvõll ja kepsusaale probleemid
Kas keegi on näinud mujal kui Lindsey Racingu lehel "Oil pan baffel kit" sarnast toodet?
Linsay Racing
On sellel ka reaalset mõtet? Aitaks see reaalselt õlitusprobleeme vähendada?
Linsay Racing
On sellel ka reaalset mõtet? Aitaks see reaalselt õlitusprobleeme vähendada?
Re: 944ja väntvõll ja kepsusaale probleemid
Õlitusprobleeme peaks parandama n.ö. "Cross drilling".
Paistab, et tasuks läbi puurida väntvõlli teise ja kolmanda kepsu kaelad?
http://forums.rennlist.com/rennforums/s ... od+bearing
Peale seda peaks väntvõlli tasakaalustama?
Paistab, et tasuks läbi puurida väntvõlli teise ja kolmanda kepsu kaelad?
http://forums.rennlist.com/rennforums/s ... od+bearing
Peale seda peaks väntvõlli tasakaalustama?
Re: 944ja väntvõll ja kepsusaale probleemid
Kas on võimalik/mõistlik kasutada näiteks 0,25 oversize raamsaalesid ja 0,50 oversize kepsusaalesid?
Re: 944ja väntvõll ja kepsusaale probleemid
Ikka on võimalik. Iseenesest ei tee see midagi hullu.joonas kirjutas:Kas on võimalik/mõistlik kasutada näiteks 0,25 oversize raamsaalesid ja 0,50 oversize kepsusaalesid?
Re: 944ja väntvõll ja kepsusaale probleemid
selles pole midagi erilist ja nii tehaksegi Tihti on lugu nii, et kepsusaaled kuluvad kiiremini ja kui raamid pole veel sajandikkugi kulunud on kepsu kaelad 3 sajandikku kulunud ja lihvitakse vaid need....säästab vantvõlli ressursse. Kui jutub nii, et 1 kael on nii kannatada saanud, et järgmine remont ei vea välja siis võib tolle ka ülejärgmisse remonti teha ja saale puudumise korral saab lasta saale ka teha vastavalt mõõdule Soovitan soojalt vänt kaasa võtta ja spetsialisti juurde minna, neil on ülitäpsed riistad ja kõik mõõdud peas tegelikult....lisaks on ka kataloogid kus on mõõdud, millega tuleb asi tehasest ja mis saalesid sellele vändale saada on Ise olen teinud Tartus Astro motos ja neil oli kataloog, kus minu autole näitas isegi nelja eri remonti ja mõnele usakale kuute eri saalemõõtu, sama kataloogi järgi saab tellida astro moto kõrvalt auto eksperdi poest. Ise pole mõõtnud ja olen spetsialisti abi kasutanud aga kas pole mitte nii, et std mõõt on täis millimeeter (diameeter) ja remondid siis vastavalt nende tähistuste järgi peenemad. Konsultatsiooni eest pole raha küsitud, küll aga olen nelipaki jagu andnud ja seda peetakse paljuks. Lihvimise teemaga tartus nii, et kui mitteametlikult paluda siis saab põhitöö kõrvalt isegi kuni 4x odavamalt. Ploki hoonimine tehti mul põhi töö kõrvalt koguni 20x odavamalt kui se oleks läinud ametlikult Tean ka seda et nii tallinnast kui ka kaugemalt käiakse väntadega viljandisse ja teistesse odavamatesse kohtadesse. 4 silindrilisel porschel pole vahe ehk nii suur aga mingi 8 silindrilise mootori väntvõlli korral on võit mitmeid tuhandeid.joonas kirjutas:Kas on võimalik/mõistlik kasutada näiteks 0,25 oversize raamsaalesid ja 0,50 oversize kepsusaalesid?
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- Postitusi: 818
- Liitunud: 19 Sept 2005 16:48
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Re: 944ja väntvõll ja kepsusaale probleemid
Kuna sa põhiliselt autot ringraja otstarbel kasutad, siis äkki oleks mõttekas karter ümber ehitada kuivkarteriks?
http://aremfg.com/pan28.htm" onclick="window.open(this.href);return false; näiteks on täitsa olemas 944-le karter. Samalt tootjalt ka pump http://aremfg.com/oilpump.htm" onclick="window.open(this.href);return false;
Ideeliselt võiks see kokku tulla odavam kui tihti mootorit saale pöörlemisest taastada?
http://aremfg.com/pan28.htm" onclick="window.open(this.href);return false; näiteks on täitsa olemas 944-le karter. Samalt tootjalt ka pump http://aremfg.com/oilpump.htm" onclick="window.open(this.href);return false;
Ideeliselt võiks see kokku tulla odavam kui tihti mootorit saale pöörlemisest taastada?
Re: 944ja väntvõll ja kepsusaale probleemid
Kuiv karter tundub esialgu nagu overkill.
Crasnk scraper osas leidsin sellise
ja sellise
http://www.crank-scrapers.com/Porsche.html
variandi. Kui keegi on kuskil veel näinud midagi sobivat, siis palun postitage linke. Samas ootan ka arvamusi, et milline tasuks valida.
Crasnk scraper osas leidsin sellise
ja sellise
http://www.crank-scrapers.com/Porsche.html
variandi. Kui keegi on kuskil veel näinud midagi sobivat, siis palun postitage linke. Samas ootan ka arvamusi, et milline tasuks valida.
Re: 944ja väntvõll ja kepsusaale probleemid
Pildid mida keegi ei taha oma auto juures näha. Õlikorgi "kaunistused".
Lasin täna õli välja ja oletused leidsid kinnitust. Jälle on saale ringi tõmmanud.
Lasin täna õli välja ja oletused leidsid kinnitust. Jälle on saale ringi tõmmanud.
Re: 944ja väntvõll ja kepsusaale probleemid
Pakutakse ploki õlikanalite modifitseerimise varianti.
http://forums.rennlist.com/rennforums/s ... 038&page=2
http://forums.rennlist.com/rennforums/s ... 038&page=2
Re: 944ja väntvõll ja kepsusaale probleemid
Huntley racing arvamus
Huntley on Rod Bearings
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.
So in summary if you have your crank out have the process done. If your motor is still together and you want to avoid spinning a bearing without the Perp drilled crank,
keep your oil temps down, limit your RPMs a bit (look at your HP peak and avoid revving past it), run a higher viscosity oil, avoid over filling, and keep the oil fresh.
Derrek Huntley Khajavi
Huntley Racing
Huntley on Rod Bearings
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.
So in summary if you have your crank out have the process done. If your motor is still together and you want to avoid spinning a bearing without the Perp drilled crank,
keep your oil temps down, limit your RPMs a bit (look at your HP peak and avoid revving past it), run a higher viscosity oil, avoid over filling, and keep the oil fresh.
Derrek Huntley Khajavi
Huntley Racing
Re: 944ja väntvõll ja kepsusaale probleemid
Üks postitus järgnevalt lingilt http://forums.rennlist.com/rennforums/s ... fle&page=2
Good information from Jon Milledge.
He does neglect to inform you that the exit angle of oil really does matter. I have built a large number of 944 engines over the years and have seen many failed rod bearings and punched blocks from broken rods.
The 944 and 968 cranks all have the same oiling angle.
The one reason that I can think that the 968 cars have less failure is that they can't pull out of the turns like a 951 and they also have a better limiting valve in the head that keeps more oil on the bottom end.
The best way to avoid bearing failure is to:
1) place a scraper plate like that one pictured above in place
2) add an oil cooler with a thermosate inline and get the engine up to full operating temperature prior to running it hard
3) install baffles in the oil pan with a modified sump pickup
4) use a better air oil separator on the oil filler neck assembly
5) run a good dry sump....costs a lot of money
6) examine the check valve in the cylinder head and install a later 944S type
7) run a good quality motor oil
8 ) have the crank feed passages modified for straight shot oiling.
These are the problems that over the years I have addressed in problem engines.
Good luck.
Good information from Jon Milledge.
He does neglect to inform you that the exit angle of oil really does matter. I have built a large number of 944 engines over the years and have seen many failed rod bearings and punched blocks from broken rods.
The 944 and 968 cranks all have the same oiling angle.
The one reason that I can think that the 968 cars have less failure is that they can't pull out of the turns like a 951 and they also have a better limiting valve in the head that keeps more oil on the bottom end.
The best way to avoid bearing failure is to:
1) place a scraper plate like that one pictured above in place
2) add an oil cooler with a thermosate inline and get the engine up to full operating temperature prior to running it hard
3) install baffles in the oil pan with a modified sump pickup
4) use a better air oil separator on the oil filler neck assembly
5) run a good dry sump....costs a lot of money
6) examine the check valve in the cylinder head and install a later 944S type
7) run a good quality motor oil
8 ) have the crank feed passages modified for straight shot oiling.
These are the problems that over the years I have addressed in problem engines.
Good luck.
Re: 944ja väntvõll ja kepsusaale probleemid
"Perp drill" the #2 and #3 rod bearing journals in the crank. "Perp" rather than cross, as the hole is drilled perpendicular to the original, facing radially outward. Centripital force (or lack thereof) helps draw the oil out into the bearing. Its done to #2 and #3 only, as its been proven #1 and #4 are almost never starved for oil, while #2 always goes first, and #3 is usually following about 50% behind it.
Ehk puurida lisakanal olemasolevaga risti.
Ehk puurida lisakanal olemasolevaga risti.
Re: 944ja väntvõll ja kepsusaale probleemid
Lugesin kõik lingitud teemad läbi. See Huntley racingu variant tundub päris usutav. Teisalt ka Jon Milledge variant, et mitte õhku lasta õlivõttu on õige. Kokkuvõttes on aga ikkagi suur segadus.
Ise laseksin praegu vist küll nii lisaaugud teha, kui karterisse õli loksumise jm vastased vahendid panna. Ja siis korralik õli, jahutus jm. Ja ka sel juhul jääb ikkagi oht, et äkki...
Ise laseksin praegu vist küll nii lisaaugud teha, kui karterisse õli loksumise jm vastased vahendid panna. Ja siis korralik õli, jahutus jm. Ja ka sel juhul jääb ikkagi oht, et äkki...