solid tensioners for 3.0?
03-09-2005, 03:16 PM
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solid tensioners for 3.0?
There was a thread a few weeks ago where tensioners were brought up. There was a vehement negative reaction to the use of solid tensioners. I have had solids in my 2.2E for 10+ years with no trouble, but very low mileage.
I am putting together a 3.0 and currently have solids in it. I put them in just for safety because it had not run in ~10 years, and I did not want to trust the stock units, and I did not want to put money into it if it had other problems.
Are the solids not a good long term bet for a 3.0 where the cylinders might change length more than the biral types in the 2.2?
I am putting together a 3.0 and currently have solids in it. I put them in just for safety because it had not run in ~10 years, and I did not want to trust the stock units, and I did not want to put money into it if it had other problems.
Are the solids not a good long term bet for a 3.0 where the cylinders might change length more than the biral types in the 2.2?
03-09-2005, 04:19 PM
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It's got nothing to do with displacement, etc. The chains stretch about 2mm in length from cold start to full running temp. A solid tensioner can't have it both ways, the chains will be either too loose or too tight, depending on engine temp. Oil fed Carrera tensioners have solved the tensioner problem and are completely reliable. They also will deliver the long life that's expected from a 911 engine.
Pete
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03-09-2005, 05:37 PM
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I might be answering my own question here:
Aluminum expands 1.24 x 10-5 in/in/°F, steel expands 6.33 x 10-6 in/in/°F.
If the temp change is 200F, the chain will grow by .029" assuming the chain is 2' long.
The engine (assuming all aluminum) will grow by .030". assuming 12" c-c from crank to cam.
This means that the effective c-c length of the chain has only grown by .015". I guess this means the chain needs to be loose when cool. I would assume that the chain runs cooler than the rest of the engine, so the effect may be compunded, but the chain makes a longer path through the tensioner, so that might mitigate.
I was hoping someone would have experience with this.
Aluminum expands 1.24 x 10-5 in/in/°F, steel expands 6.33 x 10-6 in/in/°F.
If the temp change is 200F, the chain will grow by .029" assuming the chain is 2' long.
The engine (assuming all aluminum) will grow by .030". assuming 12" c-c from crank to cam.
This means that the effective c-c length of the chain has only grown by .015". I guess this means the chain needs to be loose when cool. I would assume that the chain runs cooler than the rest of the engine, so the effect may be compunded, but the chain makes a longer path through the tensioner, so that might mitigate.
I was hoping someone would have experience with this.
03-09-2005, 11:51 PM
#4
RL Technical Advisor
Art:
Pete Z offered you VERY sound advice and I'd also strongly suggest that you install pressurized tensioners or at least the older Turbo tensioners with stop collars and wide idlers.
Solid tensioners are nothing but trouble and truly accelerate chain and sprocket wear. Remember, engine disassembly is required to install a new intermediate shaft when that item wears out,......
Pete Z offered you VERY sound advice and I'd also strongly suggest that you install pressurized tensioners or at least the older Turbo tensioners with stop collars and wide idlers.
Solid tensioners are nothing but trouble and truly accelerate chain and sprocket wear. Remember, engine disassembly is required to install a new intermediate shaft when that item wears out,......
03-10-2005, 02:39 AM
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Steve,
I have read over the last year about the virtues and nearly unanimous support of the oil-fed tensioner update. Thus, when looking for my track-meister SC, this was on my "list" of goodies.
If I may ask a question that may require you to speculate:
Why have I read so much lately (from some other sources) that this is not the best way to go. Quite a few, (actually, a bunch), mention that they have seen the carrera tensioners fail, or otherwise extol the benefits of standard tensioners with the wider rails and/or stop collars as the "real" and better alternative fix. I've already got the press-feds so I ain't gonna change, but can't help but wonder which is the better solution. You mind my asking you what has your experience been in this regard? Thanks a bunch!!
Edward
I have read over the last year about the virtues and nearly unanimous support of the oil-fed tensioner update. Thus, when looking for my track-meister SC, this was on my "list" of goodies.
If I may ask a question that may require you to speculate:
Why have I read so much lately (from some other sources) that this is not the best way to go. Quite a few, (actually, a bunch), mention that they have seen the carrera tensioners fail, or otherwise extol the benefits of standard tensioners with the wider rails and/or stop collars as the "real" and better alternative fix. I've already got the press-feds so I ain't gonna change, but can't help but wonder which is the better solution. You mind my asking you what has your experience been in this regard? Thanks a bunch!!
Edward
03-10-2005, 04:02 AM
#6
RL Technical Advisor
Edward:
Everyone becomes the end result of their experiences so you might see a lot of opinions on these kinds of things. I can only caution you to consider all the sources and put everything into context. There are VERY few people in the repair industry that post on these and other BBS's so one sees a somewhat skewed view of things based on individual experiences. I will also unequivocably state that many problems occur from installation mistakes by DIY'ers. Keep that one in mind!
FWIW, I've installed hundreds and hundreds of the Carrera tensioner kits since 1984 and I've not have one failure.......not one. For me, these are dead reliable and FAR better than anything else. The MTBF exceeds anything else,.......
I'd also suggest that you contact Bruce Anderson who gets a lot of feedback from shops all over the US and he'll tell you similar things.
Everyone becomes the end result of their experiences so you might see a lot of opinions on these kinds of things. I can only caution you to consider all the sources and put everything into context. There are VERY few people in the repair industry that post on these and other BBS's so one sees a somewhat skewed view of things based on individual experiences. I will also unequivocably state that many problems occur from installation mistakes by DIY'ers. Keep that one in mind!
FWIW, I've installed hundreds and hundreds of the Carrera tensioner kits since 1984 and I've not have one failure.......not one. For me, these are dead reliable and FAR better than anything else. The MTBF exceeds anything else,.......
I'd also suggest that you contact Bruce Anderson who gets a lot of feedback from shops all over the US and he'll tell you similar things.
03-10-2005, 09:26 AM
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Actually, I just realized that I remembered incorrectly what I put in this engine! I put a set of collars on the stock tensioners. I'll run it for a while and then check them.
I have seen some of the comments about failures of pressure fed tensioners, and I think the conclusion was that everything fails to some degree, and the number of these failures was small.
I have seen some of the comments about failures of pressure fed tensioners, and I think the conclusion was that everything fails to some degree, and the number of these failures was small.
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03-10-2005, 11:41 AM
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Steve,
Thanks!!! I figured that the "anecdotal" responses were just that: anecdotal, and not an accurate reflection of real-world circumstances. As always, thanks for your expert opinion! ...Funny how I always feel better about my porsche ownership after talking to you!
Edward
Thanks!!! I figured that the "anecdotal" responses were just that: anecdotal, and not an accurate reflection of real-world circumstances. As always, thanks for your expert opinion! ...Funny how I always feel better about my porsche ownership after talking to you!
Edward
03-11-2005, 08:02 AM
#9
Burning Brakes
Porsche didn't move from solid to oil pressure fed for nothing - I believe you would struggle real hard to find an engine shop in the UK that would recommend the old style tensioners. It is the engine shops that have to deal with these things letting go - individuals have relatively little experience in comparison.
PJC
PJC