Used Turbo questions - How to avoid an abused car?
#18
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Originally Posted by ltc
It is virtually impossible for a stock Cayenne to record a Type 2 over rev....the TCU/ECU will not allow this. Type 1 overrevs will be recorded and are again goverened by the ECU/TCU and not normally an issue; new engines built at Zuffenhausen are assembled, filled with fluids, rolled into the dyno cell and put into the Rev limiter for a predetermined period of time.....just to make sure everything holds together.
#19
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Originally Posted by hk_usp9f
What are Type 1 and Type 2 over revs?
Difficult to do in an automatic transmission since it will shift right before redline all by itself.
Type 2 over rev is a mechanically induced over rev, say you are downshifting and go from 5th to 1st instead of 5th to 3rd. The engine is MECHANICALLY forced to over rev and there is nothing the ECU can do to prevent it (i.e cutting spark/fuel does nothing), valve damage normally ensues and you lose the motor.
As I mentioned a Type 2 is easy to do in a manual transmission (you simply miss a gear when downshifting); but it is damned near impossible to do in a Cayenne/Automatic transmission......you can be driving in "Manual" Tiptronic mode in 6th, and flick the thumb switches down 5 times.......the TCU and ECU will NOT let you drop down into a much lower gear.
Go ahead, try it sometime.
#20
Originally Posted by ltc
but it is damned near impossible to do in a Cayenne/Automatic transmission......you can be driving in "Manual" Tiptronic mode in 6th, and flick the thumb switches down 5 times.......the TCU and ECU will NOT let you drop down into a much lower gear.
Go ahead, try it sometime.
Go ahead, try it sometime.
#21
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Originally Posted by TimC.
LOL This reminds me of a post a while back where the guy said Try This: Put your Cayenne in Neutral and FLOOR IT !!! Yet another example of how the computer cuts out the engine at redline.
I think in that scenario it is not really a proper rev limiter, but rather the eGas and ECU simply acting as if you only pressed the accelerator enough to go 4200RPM.
#22
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Originally Posted by ltc
Type 1 over rev is when you hit the rev limiter under acceleration; the ECU responds by cutting spark and/or fuel to prevent over revving the engine.
Difficult to do in an automatic transmission since it will shift right before redline all by itself.
Type 2 over rev is a mechanically induced over rev, say you are downshifting and go from 5th to 1st instead of 5th to 3rd. The engine is MECHANICALLY forced to over rev and there is nothing the ECU can do to prevent it (i.e cutting spark/fuel does nothing), valve damage normally ensues and you lose the motor.
As I mentioned a Type 2 is easy to do in a manual transmission (you simply miss a gear when downshifting); but it is damned near impossible to do in a Cayenne/Automatic transmission......you can be driving in "Manual" Tiptronic mode in 6th, and flick the thumb switches down 5 times.......the TCU and ECU will NOT let you drop down into a much lower gear.
Go ahead, try it sometime.
Difficult to do in an automatic transmission since it will shift right before redline all by itself.
Type 2 over rev is a mechanically induced over rev, say you are downshifting and go from 5th to 1st instead of 5th to 3rd. The engine is MECHANICALLY forced to over rev and there is nothing the ECU can do to prevent it (i.e cutting spark/fuel does nothing), valve damage normally ensues and you lose the motor.
As I mentioned a Type 2 is easy to do in a manual transmission (you simply miss a gear when downshifting); but it is damned near impossible to do in a Cayenne/Automatic transmission......you can be driving in "Manual" Tiptronic mode in 6th, and flick the thumb switches down 5 times.......the TCU and ECU will NOT let you drop down into a much lower gear.
Go ahead, try it sometime.
#23
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Originally Posted by mjw930
Still turned a 51 (autocross), beat a 996TT by half a second (bad driver).
#24
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Originally Posted by mjw930
I can tell you from experience that you can bang the rev limiter with a type 1 hit when the tip is in manual mode..
#25
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Originally Posted by ltc
9PA beats a 996TT in an AX, and you say (bad driver).......who was behind the wheel of the 996TT? Bernie from Weekend at Bernies?
As a point of reference my best time in the Boxster S was 45.1 which put me second to a 44.5 in class. A well driven 997C4S was at 43.9. I did a 51.2 in the CTT with full depth Toyo Proxes tires. As you can see from the times it favored the higher power over handling. 2 weeks later that same 997C4S was slower than our 986S's on a different course.
So far NO 996TT has been able to touch the new 997S
#26
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Good advice in many of the above posts. Having had a CTT for two years now I would say the biggest risk factor is lack of service, and your candidate car looks like it passes the test. Don't worry about the tires - I bought my Toyos primarily for longer life as opposed to the soft rubber OEM Continentals that came with the car.
The other risk factor is oil consumption. At the risk of over-generalizing, I have noticed many more "S" owners than Turbo owners complaining about excessive oil consumption. Perhaps better QA on the Turbo engines? My CTT burns a quart every ~2,000 miles.
I agree it is very difficult to push the Cayenne into a mode where engine parts are being damaged. All of the computers work against that happening. Furthermore, the CTT engine is designed to deliver at least 520 hp - just look at the CTT S. So we might consider the 450 hp CTT a "de-tuned" version with extra design margin built in.
My opinions only - no science behind these statements.
The other risk factor is oil consumption. At the risk of over-generalizing, I have noticed many more "S" owners than Turbo owners complaining about excessive oil consumption. Perhaps better QA on the Turbo engines? My CTT burns a quart every ~2,000 miles.
I agree it is very difficult to push the Cayenne into a mode where engine parts are being damaged. All of the computers work against that happening. Furthermore, the CTT engine is designed to deliver at least 520 hp - just look at the CTT S. So we might consider the 450 hp CTT a "de-tuned" version with extra design margin built in.
My opinions only - no science behind these statements.
#27
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re: pig with lipstick-back in the 60-70's some Porsche driver was asked about the handling of his car and he said: "You can't make a race horse out of a pig, but you can make a real fast pig!" Believe it was a factory driver. Sure someone out there remember who it was.