This relates to Spud's horror at HJ's treatment of the Yaris diesel.
All of the Road Tests I read on the new breed of high performance turbo diesels stress the huge amount of torque available at very low revs. They emphasise that a new driving technique is required for rapid progress and stress the need to change gear early at the peak of the torque curve.
Has anyone got any statistics on the difference in performance, say 0-60mph and overall economy, between taking it to the red line in each gear and changing gear at 2000-3000rpm.
C
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No, I have no stats but I have some experience.
I have an MG ZR-TD fitted with a TuningBox. This unit ups the power by 25BHP and sees a huge rise in torque.
There is no point in revving a diesel past its torque peak; industrial engines have a torque peak of 1500-1800RPM, trucks are a good example of this.
I find it best to change up just past the max torque peak; this appears to cointribute towards good fuel consumption, too.
The saying 'With a Diesel, use the available Torque and forget the power' rings very true
MG-Rover Questions? Click on www.mg-rover.org
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Two reasons for revving diesels to the guv'nor are to self-clean the injectors and blow the soor out of the exhaust which inevitably accumulates from driving diesel as low revs. Another reason to give a diesel a bit of stick a few times a week it to free it up. This can actually solve oil consumption problems in diesels, as Flat in Fifth has testified. I never advocated revving them for performance. See Golf TDI PD 130 test in VW Triple Test on the Road Tests Menu to your left. And Dr Dave is right about truck diesels. The latest engines are designed to offer peak torque at around 1,500rpm and drivers who habitually rev them harder waste a lot of fuel.
HJ
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HJ,
I have read your tests and wasn't implying you advocated the 'rev to the red line' treatment for diesels as normal - and the benefits of the 'Italian tune up' have been posted here many times.
I am just interested if the difference in performance and economy between the different techniques has been quantified.
C
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Diesel Car magazine is bound to have done something. One of the writers on Commercial Motor told me about the truck diesel problem with older drivers who can't get used to not revving their engines.
HJ
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There is actually some proper science to back this up, I'll take a look for the papers during the week and post a proper answer.
It explains scientifically why HJ's advice on how to run in diesels and operate them is actually spot on.
HJ's comment about my comment is that I did have oil cons problems, GM ecotec 2.0 DTi.
Three things have between them cured it.
1) Dipping the oil exactly per handbook, ie engine hot, leave it for up to an hour, then dip thus avoid overfilling.
2) Stop being pussy footed and deliberately give it a blat several times a week. eg take it to governor in 2nd, hold it at 70 in 3rd which is over 4k.
These two measures got rid of most of the problem, the last bit was
3) changing to VX dealer semi-synth, since when I've not topped it up.
Quite willing for my conclusions to be questioned.
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FIF,
You might be interested to hear Vauxhall semi-syn is the oil I'm using for the Xantia TD now. I didn't have any problems before with the car and I'm not looking for any improvements but of all the oils I use it is the one I like.
Good balance of quality vs price, flows from the can nicely and smells good (!).
David W
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See GTI International thread in Discussion for the best revs to get a Golf GTI PD 150 off the line in order to record a low 0-60. Totally irrelevant to everyday motoring, of course. But 0-60 in 7.61 seconds isn't too bad for an oil burner. (All I could manage was 7.95 seconds dropping the clutch at 2,250rpm, but I did better in the petrol 1.8T.)
HJ
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DW using GM Oil??? Is that because it's on special at £5.99/can through the Trade Club? ;-)
MG-Rover Questions? Click on www.mg-rover.org
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I regularly rev my '93 xantia (110K miles) to the limit. It never smokes or uses much oil between changes. At the last MOT, the exhaust readings were incredibly good and that was without any special additives to clean out the crud. The engine is beautifully loose and pulls very well. I took the car to Euro Disney last year and averaged 100 mph from the french end of the tunnel to Disney and achieved 32mpg.
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Can you give some more details about your TuningBox? I have a 530d and I am not 100% happy with the power delivery as it is a little uneven. What benefits do you get and is there any risk to your gearbox being damaged with the increase in torque?
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