Xantia 1.9 TD Economy at speed

[KP]

Ill soon(fingers crossed!) in the next month be starting a new job thats circa 40-45miles each way everyday, nearly all of which is on the motorway at normal cruising speeds. I know the veg oil makes the tank nice and cheap to run but i was wondering if there is anything better i can do at the higher speeds to help make the car more economical on these runs, i already try my best to remain at a constant speed, keep the car reasonably clean to minimise drag, keep tyres(205/60/15 Mich energy E3A and the old Pilot XSE) at 35psi front and 33rear and keep the wieght low, kwwp the tank about 1/2=>1/4 full and check fluids often, oil change every4-5k and keep the airfilter nice and clean.

The only things i can think of are possibly an Cone Airfilter thats washable to save on servicing costs in the long run.

The clutch is due in the next 6 months and getting some form of 6speed box or one with a higher ratiod 5th gear.

Getting larger profile tyres, ie 65's or 70's but would'nt like to think how badly they would handle!

Some form of boost controller that i could plumb in so that on the motorway it would have a very low(lower than standard boost level) and then for more power hungry moments having a higher boost level available.

Lowering the ride hieght a few CM's front and rear for the normal ride hieght setting so its bit lower than standard.

Getting the Injectors and the pump timing checked over by a bosch diesel specialist as from posts ive read on the veggie forum some experienced users think 60k for injectors is about their service life before pulling them out to be cleaned up or just replaced.

Does anyone have any experience of the above as im guessing the airfilter would be the cheapest way to save money in the long run and the gearbox if its possible to fit a better one without LOTS of hassle straight into the xantia when its clutch is being done??

PS, speed average we are talking about on this private track is approx 79-85 on my gps not on the xantia speedo I have done the 60mph thing in the slow lane behind the lorries with some overtaking me and got my magical 808miles out of a tank before the fumes ran dry but going slower isn't an option in this scenario as the time in bed is very valuable

[XantiaMan]

Use thinner engine oil, new filters, dont bother with a cone it will pick up warm air (so reduce your performance) and give increased noise, its more than efficent enough for a standard engine.

The gearbox really is an expense you'll never get back in a reasonable time scale, if it is actually available.

I see 40+mpg from my Xantia with 45mpg more normal on mixed driving and getting on for 50mpg on a run. If you have seen 800 from a tank you wont get more out of it, 800 miles is about 56mpg which is great for a heavy car with an IDI engine.

If you want more than that you'll need an HDi but then that wont run on veg. In fact you'll be lucky to find any car that is cheaper to run than your current one!

A boost controller wont give you better mpg it will only make it worse, it will come on boost sooner = more fuel. A tweak of the actuator and fuelling works wonders, dont go too far, these engines can and will pick up from 13-1400rpm and pull strongly from 2000rpm, you wont need to go over 2000rpm and that will save fuel. This is how i have set mine up but i cannot resist the urge to blow out the cobwebs every day

Higher profile tyres would not do the handling any good, and there is a chance of scrubbage too, its close enough with 205/60's.

[AndersDK]

There is one issue in particular you will start to notice, when doing such daily long runs : speed, performance, overtaking etc. is by far replaced by a sheer wish on the best possible drive comfort.

meaning :
You will soon start to bother on even the slightest extra noise or any other stress while driving. I talk from sad experience having driven 3 different makes of cars over a period of close to 3 yrs daily distances of 132miles round trip.

It gives no sense with a 6gear box - you want to minimise gearshifting as much as possible - and there is nothing to gain with any 6.th gear ratio.

The best you can do is to install a speedpilot.
This will ease any stress on you and save as much as possible on fuel by the constant speed.
It also has the added security on keeping you within legal speed limits. An issue that becomes quite important doing daily long trips, as you tend to lose patience with the speed over time.
Provided its set at correct speed of course.
Universal speed pilots are easy to fit and integrate into any make of car. I've just decided for a "Cruise" pilot, which is the usual stalk control variant, with an electric servomotor for very easy pulling on the throttle control.
It will need an electromagnetic pickup coil on either the flywheel or drive axle, to sense the actual speed on a diesel. (on a petrol you simply sense on the ignition coil breaker points signal)

The longer trips will do your engine good, as it will always reach a healthy working temperature. But be prepared the first few weeks may present all kinds of minor problems as any weaknesses are stressed into daylight.
That may be leaking cooling sytem (rotten hoses), burnt out exhaust piping, any need for tracking of steering, wobbling & rumbling wheel bearings etc. etc. etc.

[Xaccers]

Does anyone know if there is a compatible gearbox for the 1.9TD with a higher top gear? (heck even a higher 1st would be better as it's so damn low!)
My car needs a new gearbox along with clutch early next year.

[AndersDK]

The BE g/b is about the most commonly available g/b on scrapyards. Think about how many commercial vans & private cars by the make of PSA in all their XU variants with BE boxes stuck around.

Must be easy peasy finding a different matching set of 5.th gear cogs to replace with the ones you've got.
The 5.th gear cogs are located just behind the steelsheet end cover of the box. Easy to get at in-situ.

google peugeout and citroen sport sites. Many of these club sites holds a table of engine & g/b variants with their different gear ratios according to exact model and year.

[KP]

Cheers guys.

I will give the acetone trick a try as the reports seem to indicate better mpg as well but i guess the major thing will be having to slow down to lorry speeds again but by god it does make a journey drag more

Cruise control is a good option but i dont think i could shell out more than £100 on anything at the moment.

Another option instead ofthe cone filter was a replacement panel filter as they seem to cost about £30 this would equate to about 30k worth of services which im sure ill do in about a year and can always put in another xantia.

The tracking will soon also be done as well as when i get some spare pennies the rear anti sink sphere as well as i know thats on its way out

Losing the spare wheel seems a good idea as well as i have AA membership i can just get them to tow me home instead and thus leave it and the jack in the garden shed

Also a flat plate heat exchanger seems a good idea. Anyone got one of these in a Xantia at all and could take some pics of the install for me please??

At the place im currently temping at i have to use back roads that are mainly B class or face a double the length journey and time and the mpg has dropped massively as im getting just over 400miles to just a simdge under a full tank.

When i managed to get 808 the car had just had the oil and filters changed, 2 new tyres and i was sat on the motorway in lazy mode behind lorrys(mostly on the A1M which is a nightmare to overtake on anyway but the tank had been filled so much that it was upto the level of the filler cap and a tiny smidge came out but it alsohad about 6-7litres of the BP Ultimate stuff in and i tried some normal petrol(3 litres) in the last tank and the posts ive read on that could help point to some of my big MPG drop as well

Any other ideas welcome and certainly ones onthe better ratio'd 5th gear cogs if anyone could find them please

[XantiaMan]

I've tried acetone in mine and i've not noticed any difference. I also have petrol in my mix and it improves mpg because the oil is thinner and atomises better, not too much or it will affect the cetane rating and decrease performance.

This time of year mpg will be lower anyway, you can lose 5mpg just because of this.

[CitroJim]

Driving style has a heck of a lot to do with economy. The Xantia handbook has a lovely picture of a feather on the accellerator pedal and there is a lot of truth in this. Keep your foot light and economy will result. This does not mean you have to crawl along either. Speed and economy can co-exist.

Get up to speed quickly fully using the gears (but not much exceeding 3500rpm) and then, once up to crusing speed, feather off the throttle to just maintain that pace. It is easy on a diesel to put your foot down further than it needs to go when crusing at speed. At other times accelerate and brake gently.

Make sure your rolling resistance is low. Check the brakes are releasing fully and not causing any drag. Don't carry excess weight around in the boot unnecessarily. Don't have a roofrack or roofbox on.

Although you say you'll be using the 1.9TD on this commute, try your 2.1 as well. OK, I know it won't run veg but the EPIC system on the 2.1 can give excellent economy on motorway runs if you're careful to feather the throttle. I've had approaching 55mpg at 70mph on a long, clear motorway run. The 2.1TD is more sensitive to feathering than the 1.9TD, I suspect because of the rather coarse nature of its "fly-by-wire" throttle.

I honed a lot of my economy driving skills on my Activa. I once had 39mpg out of her on a 70mph motorway run

[KP]

Unfortunately the 2.1 is a xantia that was a Cat C that i gave to my dad a while back so isnt usable for testing really though he does run a few litres of veg thru it.

I have been thinking when i could afford it to move upto one and twin tank it but they only seem to have made them upto about S/T plate where the HDI's have crept in and superseded it and the 1.9td but then again i did get my 1.9 on a V plate.... I think im just really waiting for the right Exclusive 2.1td to come along as i have a turbo, pump, set of pistons and a clutch for one that could be used in the future if needed

I guess ill see how the acetone works out as i have added 11 litres of Pura Veg oil with acetone to the tank that was into the reserve half way so ill get a good judge of it's benefits as im doing, doncaster to manvers to sheffield to doncaster again tomorrow. in total about 90-100 miles all round

[XantiaMan]

Fail to see how an HDI will be cheaper to run when the cost of veg is still virtually half that of diesel it would have to do 70-80 mpg to be worthwhile and thats not going to happen in the real world.

You can try acetone but apart from cleaning the system out it wont make any difference, get the viscosity of the oil down and you will see improvements.

[KP]

Sorry i meant that if i moved onto a hdi varient xantia i would have to get it converted to run on svo. This would likely cost as much as the car which is why the 2.1td option but like i said it would be moving to an older car so unless i found an estate with a nice low mileage, superb nick and in exclusive trim it wouldn't be worth it.

[Kowalski]

For about 7 years now, I've been doing similar sort of driving to what your new commute sounds like. I've been a bit pedantic in keeping records of what fuel I've bought, when and what fuel economy I got.

The most effective thing I found for saving fuel was driving slowly, 55mph was as slow as I tried, at that sort of speed I would be getting better than 55mpg with the added bonus that you're going so slowly nobody is holding you up and you don't get stressed!

I also discovered that when you accelarate, if you don't press that accelarator to the carpet and accelarate a bit more gently I'd add at least 3 mpg to my economy. A turbo can be using 5% of your engine power to give boost pressure and that impacts your fuel economy.

The viscosity of your oil has very little to do with fuel economy, if the oil was using any significant amount of your engine power it would be getting very hot indeed. Once your oil gets up to temperature a 0w40 oil should have the same viscosity as a 15w40 i.e. the second number represents its hot viscosity. I tried playing with different oils and the difference in economy wasn't measureable.

Tyres not just their pressure but the tyre itself makes a difference to fuel economy. I have an autoexpress article on tyres, they claim that the difference in rolling resistance between the best and worse tyres they tested would equate to a 7% difference in fuel economy i.e. 3.5mpg for a 50mpg car. Michelin Energy were the best in that test, but thes best of the others were within 1%

[KP]

Cheers for the tyre info Kowalski as i have the Mich's fitted already though 1 is near the limit a new one is on its way

I guess really i am going to have bring the speed down and make more time for the trip once ive settled into it after a few days and see how it goes as i reckon it would add another 10-15minutes onto the trip which is already about 40-45mins

Unless i can find a magical cheap gearbox to bring the gearing ratio up a bit more as id really like 2000-2500 revs at 75mph on the dash as the engine is quite loud above these revs in my experience

Thanks all for your advice i will be trying bits and pieces from it over the coming weeks to see how things improve.

The one thing I'd note is that the acetone mix so far(1.5ml per Litre) seems to have helped performance a bit and most especially cold starting

[fastandfurryous]

Unless i can find a magical cheap gearbox to bring the gearing ratio up a bit more as id really like 2000-2500 revs at 75mph on the dash as the engine is quite loud above these revs in my experience

A higher gear ratio won't make very much difference to your fuel economy at all. By far the largest used of fuel at motorway speeds is overcoming wind resistance. Weight is fairly irrelevant, rolling resistance isn't significant, and the engine speed is also a minor consideration.

Pumping losses, rolling resistance and lifting weight up hills might account for somewhere between 10% and 20% of the fuel you burn on the motorway. The remaining 80% to 90% is all used countering wind resistance.

Thus, if you manage to reduce your pumping losses in the engine by say 20%, that's only 20% of 20% of your total power, so that's a 4% gain.

Conversely if you drop your speed from 80mph to 70mph, that's a 24% reduction in power requirement, which is then 24% of 80%, or 19% actual improvement.

Put simply, just drive slower.

[howiedean]

Unless i can find a magical cheap gearbox to bring the gearing ratio up a bit more as id really like 2000-2500 revs at 75mph on the dash as the engine is quite loud above these revs in my experience

A higher gear ratio won't make very much difference to your fuel economy at all. By far the largest used of fuel at motorway speeds is overcoming wind resistance. Weight is fairly irrelevant, rolling resistance isn't significant, and the engine speed is also a minor consideration.

Pumping losses, rolling resistance and lifting weight up hills might account for somewhere between 10% and 20% of the fuel you burn on the motorway. The remaining 80% to 90% is all used countering wind resistance.

Thus, if you manage to reduce your pumping losses in the engine by say 20%, that's only 20% of 20% of your total power, so that's a 4% gain.

Conversely if you drop your speed from 80mph to 70mph, that's a 24% reduction in power requirement, which is then 24% of 80%, or 19% actual improvement.

Put simply, just drive slower.

Your right a higher ratio didn't increse my MPG however it did reduce stress and make high speed cruising a doddle.
Here is a link regarding gearboxes:
http://www.frenchcarforum.co.uk/forum/v ... ight=howie

There are stacks around now as the hdi engine is in lots of applications, I managed to pick up a gearbox for £50.

Regards