Smooth gear shifting

[akirk]

I used to love my Alfa's handbook - which instead of telling you not to go into the red simply said - don't stay there too long! Brilliant attitude

Alasdair

The problem I used to have with the Alfas I've owned was that I kept activating the rev limiter.

The rev limiter presumably being whichever piston had decided to escape through the side of the engine block.

not sure that would make an Alfa any more or less reliable!

Alasdair

[gannet]

The problem I used to have with the Alfas I've owned was that I kept activating the rev limiter.

The rev limiter presumably being whichever piston had decided to escape through the side of the engine block.

not sure that would make an Alfa any more or less reliable!

Alasdair

to be fair to Alfas (at least reasonably current ones)... the one I had never actually broke down - the engine was reliable and very sonorific (made that up )... not terribly thirsty... if only the car felt better put together and it's electrics were better we might still have it...

ours was a 2.0 twinspark engine in the 147...

back on topic I don't tend to struggle with smooth shifting and find a slight pause to stabilise the engine revs before coming off and on to the clutch can be beneficial...

[Garrison]

If any one were to drive a car of mine like that they would only do it once as I would never let them drive one of my cars again.

+1

I do not like anyone to use wide open throttle and slam the revs into the limiter, which is very easy to do in 1st and somewhat easy to do 2nd, or slip the clutch massively in between gear change.

The fact that the engine can/may register over-revs will 1) render the car pretty much unsaleable, as well as 2) might reduce its resale value noticeably.

[Silk]

The fact that the engine can/may register over-revs will 1) render the car pretty much unsaleable, as well as 2) might reduce its resale value noticeably.

I don't understand. Are you saying that a record is kept somewhere that the engine has been over-rev'd and a future purchaser can find out? I'm not sure how this makes a car unsaleable.

[WhoseGeneration]

The fact that the engine can/may register over-revs will 1) render the car pretty much unsaleable, as well as 2) might reduce its resale value noticeably.

I don't understand. Are you saying that a record is kept somewhere that the engine has been over-rev'd and a future purchaser can find out? I'm not sure how this makes a car unsaleable.

Yup, it also might render any warranty void. Amazing what those ecus can store and reveal to those able to interrogate.

Eta, as SD said, OP needs to go out with someone who can help with the gearchange problems.

[Garrison]

The fact that the engine can/may register over-revs will 1) render the car pretty much unsaleable, as well as 2) might reduce its resale value noticeably.

I don't understand. Are you saying that a record is kept somewhere that the engine has been over-rev'd and a future purchaser can find out? I'm not sure how this makes a car unsaleable.

All Mezger Porsche engine (GT1, GT2, GT3 and Turbo), although immensely strong, are liability to give terminal failure if it has been over-rev. Most likely happened on missed down shift or you spin out with your throttle open wide-ish. Given I have the slowest one of the lot and it will still do 0-30 in about 1 second meant you are quite likely to spin up the wheels and hit the limiter in first or maybe second.

Data logged will indicate number of ignitions when the engine has been over-rev., in which rev ranges, operating date and time since inception (but not mileage). Unless the number of ignitions are very low, well over 200 operating hours ago and in the lower band of the over-rev rev range, buyers will be recommended to reject the car during the pre-purchase inspection (PPI) by specialists.

I don't know exact technical details but it is something to do with the disintegration of the timing gear, rod or crank. The fact that Porsche will not allow you to buy extended warranty over 2 years old on your purchase if there is any over-rev in the upper half of the rev. ranges suggest to me that this is a serious enough issue to be considered by the specialist and the manufacturer themselves.

The upshot is that all PPIs will include interrogating the ECU. This means that as well as logging any fault and over-rev, the specialist can do the maths and see if you purchase is likely to have been clocked based on the mileage in the cluster (which can be clocked) and the operating hours and time stamps (which cannot be changed). Clocked cars tend to have abnormally low calculated average speed over its life. Mine was 36 mph, which given it lived in the south east most of its life, is above average.

[waremark]

In my manual car it is often either 1st to 4th at about 20 or 2nd to 6th at about 30. I am not a great one for the traffic lights grand prix, but if you do want to get ahead of the car next to you holding onto first gear for longer than they do is a good way to achieve it.

[akirk]

interesting Garrison - I had heard that about the Porsches - a good reason to take care of them... the intriguing question for me though is if a car has a rev-limiter (i.e. it stops you going above a certain number of revs) how can it possibly be over-revved? If pushing into the top part of the revs is likely to damage the car, then I would consider that a manufacturing issue, the rev limiter should be lower... it begins to sound as though Porsche have engines which are vulnerable at high revs and they don't limit them lower as to do so would be to contradict their sports car image... something wrong there...

I appreciate you wouldn't wish to drive a car continually at the top end of the rev range - but to feel you can't go there or somehow you will damage it suggests that it is not built very well!

I would always respect an owner's wishes if driving someone else's car - that is simple polite courtesy... but for personal ownership would not wish to own a car where I couldn't use the full rev range - I keep the revs down unti lthe temperature is up / and a bit of time for oil - after that anyone driving the z3 is welcome to use the full rev range (having said that the auto box will change up if you accelerate at the top end of the range nothing like the nanny state keeping control!

Alasdair

[WhoseGeneration]

interesting Garrison - I had heard that about the Porsches - a good reason to take care of them... the intriguing question for me though is if a car has a rev-limiter (i.e. it stops you going above a certain number of revs) how can it possibly be over-revved? If pushing into the top part of the revs is likely to damage the car, then I would consider that a manufacturing issue, the rev limiter should be lower... it begins to sound as though Porsche have engines which are vulnerable at high revs and they don't limit them lower as to do so would be to contradict their sports car image... something wrong there...
Alasdair

Does seem to be incongrous, doesn't it?
Me, in lesser stuff, I often hit the limiter, with to date, no adverse effects. Then in olden days, pre the electronics, just till it's screaming no.
Perhaps it's to do with lowish volume manufacturers not being truly able to fully develop.

[Garrison]

interesting Garrison - I had heard that about the Porsches - a good reason to take care of them... the intriguing question for me though is if a car has a rev-limiter (i.e. it stops you going above a certain number of revs) how can it possibly be over-revved? If pushing into the top part of the revs is likely to damage the car, then I would consider that a manufacturing issue, the rev limiter should be lower... it begins to sound as though Porsche have engines which are vulnerable at high revs and they don't limit them lower as to do so would be to contradict their sports car image... something wrong there...

I appreciate you wouldn't wish to drive a car continually at the top end of the rev range - but to feel you can't go there or somehow you will damage it suggests that it is not built very well!

I would always respect an owner's wishes if driving someone else's car - that is simple polite courtesy... but for personal ownership would not wish to own a car where I couldn't use the full rev range - I keep the revs down unti lthe temperature is up / and a bit of time for oil - after that anyone driving the z3 is welcome to use the full rev range (having said that the auto box will change up if you accelerate at the top end of the range nothing like the nanny state keeping control!

Alasdair

The red-line is set at 6,600 rpm and limiter at 6,800 rpm.

There is nothing actually wrong with the limiter and I certainly all the revs to the red-line in the higher gears. It is just that with twin turbo and in the 1st and 2nd gears, revs will flare pass the limiter with the twin turbo and momentum because the revs rises so quickly on full boost, unless you start to back off the throttle as you approach the red-line. Bear in mind that the car would not stop boosting instantaneously the millisecond the limiter cuts in.

The car will revs from idle to the limiter in just over a second in 1st gear, covering 5 mph to 35 mph, and 40-60 mph in 2nd will be again covered in just over a second. I would not be surprise if the revs over-shoots the limiter. Situation is worse on track when you spin off from a high-grip tarmac onto wet grass with the throttle wide open in lower gears. Again, the revs will flare.

In 3rd, 4th, 5th and 6th gear, the revs will not be rising fast enough and the limiter will catch the revs in time.

My practice is to start changing up around 5,500-6,000rpm in 1st and 2nd so I would not slam into the limiter and trigger a data-log for over-revs.

I guess a work around is for the drive-by-wire throttle to start tapering the revs at it approaches the limiter, depending on how much throttle is applied at the pedal. Alternatively, they can set different rev limiter for each gear, lower limiter for lower gears. Neither of which I like as I prefer to control the throttle as manually as possible.

[RobC]

The fact that the engine can/may register over-revs will 1) render the car pretty much unsaleable, as well as 2) might reduce its resale value noticeably.

I don't understand. Are you saying that a record is kept somewhere that the engine has been over-rev'd and a future purchaser can find out? I'm not sure how this makes a car unsaleable.

All Mezger Porsche engine (GT1, GT2, GT3 and Turbo), although immensely strong, are liability to give terminal failure if it has been over-rev

The original poster has a Volvo V50 diesel though and not the highest performance version of the Porsche 911 which are often bought with track days in mind.
I was put of buying a 911 after speaking to people about intermediate shaft, cylinder cracking and catastrophic engine failure and £10K engine rebuilds as well as rear main oil seal problems and bought a Mercedes SL instead.

I know that all modern cars have ECUs that store fault codes, however would the Volvo V50s diesels ECU pick up the same things as a 911?

[IcedKiwi]

the intriguing question for me though is if a car has a rev-limiter (i.e. it stops you going above a certain number of revs) how can it possibly be over-revved? If pushing into the top part of the revs is likely to damage the car, then I would consider that a manufacturing issue, the rev limiter should be lower... it begins to sound as though Porsche have engines which are vulnerable at high revs and they don't limit them lower as to do so would be to contradict their sports car image... something wrong there...

My understanding is providing you're on a level road, the ECU should be able to stop all over revs by cutting fuel. Not 100% sure about the really fast stuff like 1st WOT and low grip. But if you down change into 2nd instead of 4th (or 6th if you have 7sp!) or at the top of 3rd then the car's inertia will obviously drag the rev's beyond the limiter. Similarly if you're at the top of a gear going down hill then gravity may pull you over the rev limiter and the ECU can't do anything about it.

This post explains the rev ranges pretty well. Suggest for a 997 turbo, only over revs in range 3 (>7200) or above are deemed damaging (Where the limiter is at 6800)
http://www.911virgin.com/porsche/rev-range-information/

[akirk]

very interesting - thank you Garrison / icedKiwi
that suggests that the limiter is set correctly and therefore in theory you shouldn't be able to harm the engine - if you can, then I think Porsche have got it wrong... I do understand that for an out and out sports car it is better to have less control and expect the driver to drive it more accurately but to be honest the 911 in all guises is often sold to those who will drive it hard, but not necessarily have the skills needed to be more discerning - in recognition of that it is sensible to have built in controls - with today's computerised systems there is nothing to stop the computer having the ability to change the limiter - pre-set to safety first and then if the owner chooses to change it that is a conscious action from the owner...

I am lucky with the z3 - the 3litre straight six BMW engine is possibly one of the more bullet proof engines around - equally it is a very cheap car and one where I would rather have fun with it than worry about resale value - I know that is not the same with a classic such as Garrison's 911... For me it does highlight that in enjoying cars, choosing deliberately and knowing whether you need to retain value etc. is a part of how we approach our driving... my car having been bought very cheaply, having little commercial value, lots of grin factor means I can be more relaxed - I am happy for pretty much anyone to drive it and if it breaks I just mend it having said that it still doesn't sound quite as good as Harrison's 911!!!

Alasdair

[Garrison]

I was put of buying a 911 after speaking to people about intermediate shaft, cylinder cracking and catastrophic engine failure and £10K engine rebuilds as well as rear main oil seal problems and bought a Mercedes SL instead.

I know that all modern cars have ECUs that store fault codes, however would the Volvo V50s diesels ECU pick up the same things as a 911?

I don't know but I doubt the V50 TDCi ECU would log gear shift which is not smooth.

I'm not sure what type of data that series of TDCi ECU would log now - I left Ford R&D back in 2000.

Regarding 996/997 Carrera engines, unfortunately they can be liable to bore scoring, intermediate shaft (IMS) failure and oil leaks. U.S. Class Action request for disclosure indicated the failure rate which requires a new engine is c.5% of all cars under Porsche warranty in the U.S.

Fortunately, the repair would only be c.£10K as you said. The Mezger engine in mine would be £39K + fittings, although it does not suffer bore scoring, IMS, etc. and the failure rate is almost nonexistent for stock cars. The X50 engine is in excess of £43K and I think the GT2 engine is north of £50K. The failure mode has been the engine throwing its timing chains after the over-rev, but I don't know whether the damage was caused by the chains or crank or rod or camshaft side.

[Garrison]

... and bought a Mercedes SL instead.

On one hand I agree, I ran a S-Class which is not liable to sudden and extremely costly failure and is very nice with engine pre-heater for the winter and double glazing. On the other hand I disagree, as the ongoing servicing and repair costs are as costly as my 911 and has a lot more small faults.

The most annoying and/or costly items are (all parts only, not including labour)
- Bilstein suspension struts (I change my spring and dampers every 60k regardless of cars in case I lend them to others to drive so I want the cars to be mechanically great) - £1,500 per corner
- Alternator (120A, water-cooled in mine) - £700
- Air leak on boot lock - £200 for new boot lock as I can't open the boot
- Air leak on boot lock which caused the Pneumatic soft closing boot and doors pump to burn out - £500 (got to be done as it also controls some seat adjustments and my wife is a lot shorter than me)
- Argument between the glass fitter and his manager because the fitter is reluctant to fit a pattern double glazed screen due to the poor quality and that I'd have problems soon after. His manager want the cheap screen fitted because of the low cost (insurance covered)
- front ball joints every 2 year due to rubbish qualify of the part and rubbish quality of central London pot holed and speed bumps roads