4000rpm @ 80MPH?

Gloomendoom

londonTiger wrote: »

Thats why your speedo and tach is completely wrong.

Wasn't that pic just posted for comparative purposes by someone other than the OP?

DUTR

londonTiger wrote: »

That is not a factory 00 bora clock. Just do an ebay search for "bora clock" and you'll see these what the factory ones looks like. The clock seems to be installed from a much newer car, maybe the 2005/06 golf.

Thats why your speedo and tach is completely wrong.

You are correct it is/was a 2005 Golf, was posting to show the OP what my revs were at the displayed speed (somewhat much less than 4000rpm) Sorry for the confusion.

Ultrasonic

forgotmyname wrote:

Except it would only apply to my car on that stretch of road, So putting a graph to show the fuelling would be boring and quite meaningless to others.

Dull perhaps, but this data would be of some use though, whereas the TPS data tells us absolutely nothing useful.

BINGO... Its the extra load required in a higher gear.. Thats why it uses more fuel.

No, not BINGO at all, but it does make me realise the crucial part of the argument that you seem to be missing. Let me try to explain...

First let's be clear that Brake Specific Fuel Consumption (BSFC) is a measure on engine efficiency. That is, how much fuel it takes to produce a given amount of mechanical energy. Low BSFC means high engine efficiency.

Now, as discussed in this link which I keep posting (please do look at it), driving along at a particular speed on a particular gradient takes a particular amount of power. You will get highest fuel efficiency (mpg) by operating the engine such that it generates this power most efficiently i.e. with the minimum BSFC. Changing up to a higher gear increases engine load, reducing BSFC and therefore increasing mpg.

Your cycling analogy is not helpful as it only covers half of the problem. YES, cycling up hill in a higher gear is more difficult, and this idea transfers to the engine being under higher load when you change up a gear. But this is a GOOD thing for mpg because it makes the engine run more efficiently (lower BSFC). I appreciate that this seems counter-intuitive, but it is FACT.

The advice to change up gears early to improve fuel economy is widespread for precisily this reason. Here for example is a very good booklet from VW advising this on page 11:

http://en.volkswagen.com/content/medialib/vwd4/vw_international/4_company/4_3_overview_sustainability/Nachhaltigkeit/Produkte/Recycling/effizient_unterwegs-pdf/_jcr_content/renditions/rendition.file/effizient_unterwegs.pdf

I'll be very surprised if you can find any manufacturer or motoring body advocating your 'keep revs higher so you're closer to the torque peak' approach. See if you can.

This is why if your car really does give the better mpg you describe it is very unusual, and offering this advice widely is likely to mislead others.

Finally, let's return to the idea of higher load using more fuel. At higher load more fuel will be used per engine cycle, but there will be fewer cycles per unit time due to lower engine rpm. The net result is therefore that the rate of fuel use (gallons per hour) is LOWER, and therefore fuel economy (mpg) is HIGHER.

Ultrasonic

Abu_Yoosha wrote: »

That's the negative thing about this forum, unlike other because you can't close a thread down after the OP has had their question answered.

Hopefully you said that in relation to the 80mph is over the speed limit nonsense, but if it was directed in part to me please just ignore the thread!

Ultrasonic

Abu_Yoosha wrote: »

Yes it has just been serviced.
In excellent condition for its age.
I only intended on buying it as a temporary car till next summer.

Now I'm seriously contemplating buying a newer one.

Why? You don't even know what sort of mpg you get with it yet.

Many people spend thousands of pounds to buy more economical cars that save them just a few hundred pounds a year in fuel and tax. Financially this just doesn't stack up.

Give your new car a fair go. Don't get rid of it purely on the basis of it's engine rpm, that would be daft!

(I've no idea why you were asked if it had been serviced recently BTW, that's not going to affect engine RPM. Well, not unless they caused the indicator to develop a fault!)

Shawn_Dark

Ultrasonic wrote: »

Why? You don't even know what sort of mpg you get with it yet.

Many people spend thousands of pounds to buy more economical cars that save them just a few hundred pounds a year in fuel and tax. Financially this just doesn't stack up.

Give your new car a fair go. Don't get rid of it purely on the basis of it's engine rpm, that would be daft!

(I've no idea why you were asked if it had been serviced recently BTW, that's not going to affect engine RPM. Well, not unless they caused the indicator to develop a fault!)

This whole RPM question was purely to see if there was something wrong with the car. After we had established that the car was fine the thread was finished for me.

With regards to getting another, the fact of the matter is that this was always going to be a temporary car (until the summer, next year). Remember I said I was going to buy a newer car next year and therefore this one was only temporary.

Having said that, the reason I would get a newer diesel is nothing to do with RPM, nor MPG. It simply more to do with the fact that I could get the things that this car lacks. Examples:

1) Turbo diesel engine (to me they always work out more economical and just quicker, more enjoyable to drive, etc.). The equivalent petrol always seems to be too costly to run. So the turbo diesel gives me the best of both worlds - economy and power, speed, etc.

This current car is surprisingly nice but far too sluggish for me. ***Spoiler alert: this does not mean I wish to break speed limits***

I know from colleagues that the Bora TDI's are just as quick as the Skoda I've been driving.

2) 6-speed gearbox. This car doesn't have one and it isn't worth getting a new one fitted (unless of course the gearbox went but not much chance of that).

3) Range. I always use the range indicator on my cars and this one doesn't have that feature.

4) Up-to-date features. Being thirteen years old it lacks some of the newer features that I am used to.

Ultrasonic

Abu_Yoosha wrote: »

1) Turbo diesel engine (to me they always work out more economical and just quicker, more enjoyable to drive, etc.). The equivalent petrol always seems to be too costly to run. So the turbo diesel gives me the best of both worlds - economy and power, speed, etc.

I totally agree . I drive a Skoda Octavia TDI precisely because I like the balance of economy and performance that it offers.

Abu_Yoosha wrote:

4) Up-to-date features. Being thirteen years old it lacks some of the newer features that I am used to.

At the point you come to look for a replacement car, be sure to read up on issues with DPFs. They are one 'new feature' you may want to be wary of depending on your driving pattern.

Ultrasonic

Abu_Yoosha wrote: »

3) Range. I always use the range indicator on my cars and this one doesn't have that feature.

Oh, and relying on a car range indicator is a BAD idea. They are not accurate.

Shawn_Dark

Ultrasonic wrote: »

I totally agree . I drive a Skoda Octavia TDI precisely because I like the balance of economy and performance that it offers.


At the point you come to look for a replacement car, be sure to read up on issues with DPFs. They are one 'new feature' you may want to be wary of depending on your driving pattern.

Yes I've had my own experience with the DPF on a diesel 307 I bought. Gained a wealth of knowledge from the experience.

Ultrasonic wrote: »

Oh, and relying on a car range indicator is a BAD idea. They are not accurate.

Its just to give me a rough guideline. I.e. I know roughly how many more miles I can travel.

Shawn_Dark

Considering the Bora (SE spec) is five years older than the Skoda (Elegance spec) the interior is far nicer in the Bora. I really enjoy driving it at night due to the cool blue and red interior display lighting.