Head vs Heart

[MasterAuron]

No point arguing, because I'm right lol. Greater lift and duration won't increase your powerband, it'll just shift it higher up the rev range and possibly out of the efficiency range of your turbo (depending on which you use of course). What you're essentially trying to do, is turn it into a petrol.

1500rpm isn't a massive difference though, but I was being modest. A difference of 2300rpm in every gear however is a pretty big difference.

[MasterAuron]

Originally Posted by HDi fun

I dunno they're all that bad. My 406 was redlined at 5300.

Yes but it's not really about the redline, you've had your peak torque by about 3000rpm then it's just a fat lot of nothing especially with the relatively small turbos dervs roll out of the factory with. A petrol car will pull and pull hitting its peak power around 5000rpm or after.

[HDi fun]

Originally Posted by MasterAuron

Yes but it's not really about the redline, you've had your peak torque by about 3000rpm then it's just a fat lot of nothing especially with the relatively small turbos dervs roll out of the factory with. A petrol car will pull and pull hitting its peak power around 5000rpm or after.

I know all this. I just happen to be fond of the midrange slam. I also like leggy revvy petrol engines such as in the E39 I have at the moment but in general I find that diesely 1500-3500 wallop more useable.

Yet I'm not a great fan of the VW PD 1.9 units for the reasons stated here. It's all over by 3000rpm. There are better 4 cylinder diesels on offer.

[MasterAuron]

I know you know mate, you're very well balanced and knowledgable about pretty much everything lol. Just pointing it out generally.

[HDi fun]

Originally Posted by MasterAuron

I know you know mate, you're very well balanced and knowledgable about pretty much everything lol. Just pointing it out generally.

[jarrus]

Bigger torque and longer ratios will make up for it without a doubt but my car is heavier that a punto though

[HDi fun]

Originally Posted by jarrus

Bigger torque and longer ratios will make up for it without a doubt but my car is heavier that a punto though

It does in the case of some of the more recent common rail engines. Funnily enough the biggest weakness I find with modern diesels is not the lack of 'revability' but more the fact that they really don't wanna know at idle speed.

I think this might be due to the current fad with modern diesels for lowering the compression ratio to reduce the clatter at cold idle. Even my 406 (2002 year model) was only about 19.5:1 compared to the more usual 22-24:1 ratio. Once under way the turbo sorts things out nicely but there is that latency below about 1300-1400rpm so you have to be pretty methodical with your choice of gears. Most petrols will tolerate being 1 cog too high at low speed.

The old 1.9 litre NA diesel Seat we had, however, pulled superbly from idle. Of course, things went downhill thereon in.

It is becoming more subjective all the time, and diesel engines have had massive investment made in the last decade. Blimey, even I've taken a liking to the things and I was the original diesel hater.

It is largely down to personal preference now regarding what you choose to drive.

Let's not kid ourselves, however.

No car is cheap to run anymore. The governemntal rules have made sure of this.

[jarrus]

I'd quite like to fit the GTI6 gearbox to my 1.9, I know it's fits on but the ratios are way out,

If I could some how equip it with a longer (much longer) final drive then I could make a very entertaining car...

[Dan2587]

I thought diesels had longer gear ratios than petrols ive driven my nan vauxhall zafira 1.9 cdti 120bhp and it goes quite well you really feel the turbo boost in 1st 2nd and 3rd but only revvs to about 4k its not slow but my laguna II 1.8 16v with about same bhp dont have brilliant lowdown revvs under 2k not as good as the zafira but once there it will pull away from it up to 80-90mph

[HDi fun]

Originally Posted by Dan2587

I thought diesels had longer gear ratios than petrols ive driven my nan vauxhall zafira 1.9 cdti 120bhp and it goes quite well you really feel the turbo boost in 1st 2nd and 3rd but only revvs to about 4k its not slow but my laguna II 1.8 16v with about same bhp dont have brilliant lowdown revvs under 2k not as good as the zafira but once there it will pull away from it up to 80-90mph

It's all about torque at the driven wheels when it comes to acceleration. Gears just trade revs/torque at the flywheel for torque/revs at the roadwheels. The total power transmitted in the whole system is the same either side of the box.

A diesel has higher gear ratios but the payback is that they don't have the revability of a petrol engine. But diesels do generally pull much harder from much lower revs.

You shouldn't really be aware of boost on/off with the 120 CDTi; it should be pretty linear across the rev range if the engine is running properly and is well maintained. Not my favourite 4 cylinder diesel units either, they can be quite rough, as can VAG's 4 cylinder PD units.

[MasterAuron]

Originally Posted by Dan2587

I thought diesels had longer gear ratios than petrols ive driven my nan vauxhall zafira 1.9 cdti 120bhp and it goes quite well you really feel the turbo boost in 1st 2nd and 3rd but only revvs to about 4k its not slow but my laguna II 1.8 16v with about same bhp dont have brilliant lowdown revvs under 2k not as good as the zafira but once there it will pull away from it up to 80-90mph

That's like comparing a dog poo with a cat poo though

[HDi fun]

Originally Posted by MasterAuron

That's like comparing a dog poo with a cat poo though

The analogy presented here by MA might be a little harsh; in practice neither car has any pretentions of performance.

Yet neither is inadequate for daily usage - they'll both do it well, even if they each do so in an uninspiring fashion.

They'll both get on with the job at hand in an unoffensive way.

[Dan2587]

It could just be mostly the torque that pulls it well working with the turbo. Remapped diesels can be impressive when pushing over 180 bhp with big torque.

[HDi fun]

It's roadwheel torque which makes a car accelerate. It matters not how it's derived or transmitted.

[MasterAuron]

Originally Posted by HDi fun

The analogy presented here by MA might be a little harsh; in practice neither car has any pretentions of performance.

Ah yes, that's what I meant to say. Sometimes all maturity just escapes me