944 2006

[John Sims]

Ah! But I've already said that I think it should have the Boxer 6 'cos I like the Porscheness of the noise. I agree, a V8 is out of the question. In reality I don't think a current Porsche boxer engine would fit in the front as it is too wide.

4 cylinders just don't sound nice when being pushed (unless it is a Kent engine on twin 45s, or a rally car []), and who wants a high revving screamer in a sports GT? 4 cylinder screamers are for lightweight sports racers and Rice Rockets, not something with understated class.

Having thrown out the boxer 6 for being too wide, I guess I'm lumbered with a V6. A 944 with the engine from a VW Golf - well you said that you wanted to stick with tradition. []

 

[TTM]

ORIGINAL: pikey7

C. Belts are 100 times more reliable than chains and more effiecient than gears. The 944 engine just misses out as the belt is not automatically tensioned, and so the intervals are shorter than say Honda. Equally though, manufacturers like Alfa or Ford have roughly the same interval. The difference (with Ford anyway), is that they are not interference engines, so a broken belt is just a nuisance rather than a bank manager job.

Sorry but I disagree 100 %.
1/ Timing chains are 100% more reliable in that they don't need changing every 60k miles like a bl**dy timing belt. On a Porsche flat 6 you normally don't replace them between engine rebuilds (that would be every 160k miles for a well treated engine). I'd be as bold as to say that timing belts are perhaps the most stupid thing "engineers" ever come up with on the internal combustion engine as we know it.
2/ 944 engines are very much indeed interference engines. The only front engined car from Porsche with a non interference engine is the first 928 with the 4.5 V8.

 

[Guest]

ORIGINAL: TTM

Sorry but I disagree 100 %.
1/ Timing chains are 100% more reliable in that they don't need changing every 60k miles like a bl**dy timing belt. On a Porsche flat 6 you normally don't replace them between engine rebuilds (that would be every 160k miles for a well treated engine). I'd be as bold as to say that timing belts are perhaps the most stupid thing "engineers" ever come up with on the internal combustion engine as we know it.
2/ 944 engines are very much indeed interference engines. The only front engined car from Porsche with a non interference engine is the first 928 with the 4.5 V8.

1. Chains are noisy, and they stretch MUCH easier than belts. The difference is that the belt can be made to stretch over a reasonable range. The chain stretches immediately, and then wears over time, meaning intermediate services to take the slack out of a chain. Even though they may last 3 times as long, the cost of a chain is 3 times as much as a belt. No saving. The problem with the 944 system is that without a proper tensioner, the only benefit that you get from belt to chain is the decrease in noise. With a proper tensioner, you would get rid of the need for the 1500mile tension check, AND increase the belt life.
2. I know. My example was that the Ford engine is non-interference and is the way that "the new" engine should be made.

 

[TTM]

ORIGINAL: pikey7

1. Chains are noisy, and they stretch MUCH easier than belts. The difference is that the belt can be made to stretch over a reasonable range. The chain stretches immediately, and then wears over time, meaning intermediate services to take the slack out of a chain. Even though they may last 3 times as long, the cost of a chain is 3 times as much as a belt. No saving. The problem with the 944 system is that without a proper tensioner, the only benefit that you get from belt to chain is the decrease in noise. With a proper tensioner, you would get rid of the need for the 1500mile tension check, AND increase the belt life.
2. I know. My example was that the Ford engine is non-interference and is the way that "the new" engine should be made.

1. I'd rather spend 3 times more money in a timing chain than having to have the timing belt replaced 3 times as often. This is a great time saving as far as I'm concerned.
I have never heard of any intermediate chain tension check required on any 911s and do not see why it would be required on an in-line 4. There are loads of in-line 4s that have run chains troublefree for very high mileages with no specific check. See Mercedes taxis of all sorts.
The "proper" tensioner somewhat already exists and it is the hydraulic one from the 968, which is supposed to compensate the stretch of the timing belt. However replacement of the timing belt on the 968 is officially recommended to be as often as on a 944, from which I conclude the hydraulic tensioner is no better than the 944's on the durability front.
If you prefer belts though, you can have them of course. I'd even give you mine for free []

2. Sorry, I had misunderstood your post. [8|]

 

[Guest]

ORIGINAL: TTM

If you prefer belts though, you can have them of course. I'd even give you mine for free []

As soon as I take delivery of my 2006 944, I'll hold you to that! []

 

[sawood12]

The advantage a modern 4-potter would give is compactness. A modern high revving twin turbo 2.5ltr 4-pot would be much more compact than a V6 and V8 and provide a much better power to weight ratio. Yes they don't sound as good as a V6 or V8 but I'd gladly trade that in for performance. It's true that it's not as easy to drive as a V engine but if you want a large easy lumbering engine then go for a 928. The 944 in my view is a much more focussed drivers car and we should expect to have to work the gearbox to get the best out of the engine. The addition of an Audi DSG style gearbox (up and coming new Tiptronic?) will make easy work of chaning gear and will mean no interruption to power throughout the gear change and since no clutch is needed it leaves your left foot for the brake.

One thing I wouldn't want to see is PCCB. What a complete and utter waste of time they seem to be. By Porsches own admission they don't stop you any quicker and from various reports i've read seem to get knackered prematurely at hard track days so don't last any longer and cost an extortionate amount. The only benefit seems to be looks and unsprung weight.

I'm not so sure that any modern engines have a non-interference design. I don't think this could be achieved with the high compression ratio's needed these days to achieve emmissions and fuel economy. Fords last generation of engines (the CVH) certainly was an interference design as the belt in my dad's Orion gave way and knackered a few pistons and valves. The best way is to get rid of the mechanical drive altogether and have F1 style pneumatic actuation of the valves. With this type of system 9,000 rpm is only tickover!

 

[Guest]

Well i may as well jump in here.

I think porsche is already building this car, its called the Caymen. Just that someone has put the final drive the wrong way round!!!

Despite others dislike of a v8, i would say a 4.0l v8 would be nice in the 944. Around 300bhp and 260lbft. Rev to 7,500. Mmm nice.

And a turbo version with 450bhp and 400lbft

You know it makes sense

 

[carlmthompson]

ORIGINAL: pikey7


1. Chains are noisy, and they stretch MUCH easier than belts.

Err, no they aren't. They stretch more? Chains are metal. Belts are made of rubber......
My current BM (as well as the last two) uses a chain. It ain't noisy, has done 125K and will most likely do the same again - without (chain)ging it!
The only controversy about chains was the E30 M3. That was also a load of bollocks made up by a certain garage who wanted to keep the prices of 100k milers down!! Oh and that stupid cam chain on the 944 16valvers - more poor development than bad idea!
I've never heard of a chain snapping - although just like belts, the pulleys sometimes let go.

Got to agree with TTM - Belts are a stupid idea, and prove to be the weak link in the (you guessed it) chain[8D]

 

[Guest]

OK, let me rephrase slightly. Chains are noisIER than belts. They have to be. The sound of metal on metal is louder than rubber on metal.

As for wear issues, I can't be bothered to argue, but in my mind, the wear for a given mileage would be roughly the same. to thow away a £20 belt after 50k miles, or to replace a £100 chain after 250k miles is irrelevant..I'd just rather go the belt route.

Then there is the question of efficiency. It is a well known fact that belts are more effiecient at reducing drivetrain losses than chains..........

 

[TTM]

ORIGINAL: pikey7
OK, let me rephrase slightly. Chains are noisIER than belts. They have to be. The sound of metal on metal is louder than rubber on metal.

The sound of metal is better than the whine of belts that makes you feel someone is killing a pig below the hood. []

ORIGINAL: pikey7
As for wear issues, I can't be bothered to argue, but in my mind, the wear for a given mileage would be roughly the same. to thow away a £20 belt after 50k miles, or to replace a £100 chain after 250k miles is irrelevant..I'd just rather go the belt route.

With belts you end up spending 5 times the price in labour (and/or hassle) when you do it only once with chains.

ORIGINAL: pikey7
Then there is the question of efficiency. It is a well known fact that belts are more effiecient at reducing drivetrain losses than chains...

In older days certainly, but not anymore, if it's properly designed. The Cayenne V8 with 4.5 L, has chains and puts out roughly as much power & torque as the 928 32V engine, with belts and 5.4 L.
Belts are a technical solution that was adopted because it is technically more simple than chains and is conveniently less reliable because it forces people going back to the garage every once in a while for having the belt replaced.
I remember of a Citroën engine that had a belt from the start but they redesign it with a belt so that people would HAVE to spend more money on maintenance. They changed the design for that very purpose.

BMW nowadays build perhaps the best engines and they run chains. Designing a proper design with a timing chain requires abilities a timing belt set up does not. The belt is a "third world" (as in "cheap") technical solution, hence why you find them on most mainstream cars, because it's cheap it brings back Joe Public to the garage for additional maintenance.

 

[danmason]

ORIGINAL: TTM
944 engines are very much indeed interference engines. The only front engined car from Porsche with a non interference engine is the first 928 with the 4.5 V8.

How about the 924? Not only does it say in my 'big Porsche book' that it has a non-interference engine [], the belt once stripped bare on mine at circa 100mph and my total cost of repair was £5 for the belt (the free ride back from Devon on a recovery truck was a bonus too).

Back on-topic, I can scarcely believe how many items some of you have on your list of changes - basically asking for a different car altogether! My list would be much shorter; in fact I feel my Turbo is just about perfect the way it is. Perhaps reduce the lag so I don't need to fit a Boost Enhancer. As for things I wouldn't want to change: steering (including wheel!), suspension (M474 or M030), gears, number of cylinders [], front seats, driving position, instrument cluster, supercool styling.... etc. etc. and I daresay etc..

Thank goodness there isn't going to be a 2006 944 - I have a feeling it would be a massive disappointment regardless of how each of us might feel about the 'old one'.

 

[TTM]

ORIGINAL: danmason
How about the 924? Not only does it say in my 'big Porsche book' that it has a non-interference engine []

Very true, I stand corrected [8|]