Dodgy deisel or is Cassy now veg only?

[Xaccers]

Last weekend I went down to Portsmouth to catch up with some old school friends (one's off to volenteer in India for 3-12 months) and see my ex who now isn't (Kate).
By the time I managed to get away from work, it was too late to get to Costco, so I treated cassy to some v-power diesel (I'll often do this when I need fuel reciepts for expenses, my little treat to her).
Unable to get any veg in bulk down there, and needing some fuel to take Kate and her sister to Bexhill on sea for their sister-in-law's suprise birthday party, I stopped at Tescos on the A27 by Chichester and put some diesel in.
Now previously, before using veg, I ran Cassy pretty much all the time on Tesco's diesel up in MK without issue, but this time she became unresponsive, struggling to reach 70mph, as though my turbo just wasn't working.
No roughness or smoke, but no oomph either.
Put a fiver's worth of BP diesel in on the way home, then managed to get some v-power on the A3 at Liphook services (slightly cheaper than in MK too!) as I was nearly empty by then, and it made a little difference.
Added 20L of KTC genetically modified soya oil and woosh! She's back to her old self again.

Previously, under "testing", KTC gave +5mph to her top speed, and if I drive her sensibly I'm still getting approx 45mpg so the idea that SVO (or at least soya oil from ktc) is not as powerful as diesel seems to be not quite the case.

Or maybe Cassy has taken a "leaf" out of Jim's book and is now totally vegetarian?

[CitroJim]

That's a strange one Xac I can't get my head around that one, quite. It needs some thinking about. My initial thoughts is that the pump and injectors have become used to the thicker consistency of veg and have worn into it. I'd not be surprised if the pump and injectors have worm a little under the veg regime and clearances are now slightly larger and pumping efficiency has fallen with the thinner diesel. The pumps are such precision items, it would not take a lot of wear and how good the absolute lubricity of veg is compared to proper DERV is open to speculation. The otehr thing that may be worth a shot is to disconnect your battery for a bit so that the ECU "forgets" itself and then run on DERV to retrain it..

Next step will be to have your injectors serviced and calibrated and if that fails to resolve the issue, it'll be pump wear.

This is interesting as it is helping understand the long-term effects of being a veggie. I reckon if I ate meat now my performance would suffer somewhat

Or maybe Cassy has taken a "leaf" out of Jim's book and is now totally vegetarian?

I had a dream the other night that I ate some meat and ended up very, very violently sick Not quite a nightmare but not very pleasant either

[MikeT]

the idea that SVO (or at least soya oil from ktc) is not as powerful as diesel ......

I don't know where you first got that idea from but it's not been proven in my experience and I've since read that rapeseed oil has an equal cetane value to our pump diesel. Don't forgot, you're not diluting the veg oil with improvers and detergents like pump fuel has - even more with V-power I believe?

[Xaccers]

According to the blurb on v-power, they basically take some shell diesel, mix in some synthetic pure diesel, and add redex.
Does make the car go whooosh though, even Jim's 2.1

[XantiaMan]

Rapeseed does have a lower cetane value than diesel, that is proven and i have seen it written down someone but do the research as its out there.

Its possible the diesel has loosened off some residual crap from the lines or tank. V-Power is a very good fuel and has some excellent cleaning properties, so this is possible.


Fuel Heat of Cetan Viscosity
Weight Combustion Number Centistokes
___________________________________________________________________________
Lbs./gal. BTU/gal.

No. 2 diesel 7.05 140,000 48 3.0
100% Biodiesel (B100)
Methyl or ethyl ester 7.3 130,000 55 5.7
B20 mix (20/80) 7.1 138,000 50 3.3
Raw vegetable oil 7.5 130,000 35 to 45 40 to 50
____________________________________________________________________________

Cetane rating varies considerably among the listed fuels (table 1) and is a measure of the self-ignition quality of the fuel. No. 2 diesel fuel usually has a cetane rating between 45 and 50 while vegetable oil is 35 to 45. Biodiesel is usually 50 to 60. The ignition quality affects engine performance, cold starting, warm up and engine combustion roughness. Cetane rating is related to the volatility of the fuel where more volatile fuels have higher ratings. A high cetane fuel also may lead to incomplete combustion and smoke if the fuel ignites too soon by not allowing enough time for the fuel to mix with air for complete combustion.

The energy content of the fuels also vary. No. 2 diesel fuel typically contains about 140,000 BTU's per gallon while vegetable oil and biodiesel contain about 130,000 BTU/gal. A "BTU" stands for British Thermal Unit which is defined as the energy required to raise the temperature of water one degree fahrenheit. Fuels with a high heat of combustion will usually produce more power per pound of fuel than fuels with lower energy. As a result, an engine using a lower energy fuel will require more fuel to produce the same power as diesel fuel. As a result of the lower energy content, biodiesel will require about 1.1 gallons of fuel to do the same work as a gallon of diesel fuel.

[Xaccers]

Interestingly enough, something else I've noticed, the temperature of the engine is higher on veg than deisel.

[MikeT]

Rapeseed does have a lower cetane value than diesel

I stand corrected. It seems I was referring to rapeseed esters which has been cetane rated between 50 and 65 (depending on who measured it)

It transpires that the very method of calculating cetane value (ASTM D 613) is questionable and acknowledged as being not wholly accurate. It allows a tolerance of 0.7 - 0.9 (between same test equipment) or 2.5 - 3.3 (between different test equipment) which I find remarkable.

It's interesting to note that the quicker auto-ignition of high cetane fuels reduces the opportunity for the fuel and air to mix before combustion!)

It is also interesting to note that veg oil is acknowledged to provide superior lubrication over pump diesel.

[rory_perrett]

Slight digression, does V power make that much difference? For me its all about mpg and when V-power first came the 6p a litre extra represented a premium over “normal” diesel of about 6.5% so I wondered if it was worth it and never tried it. Now its still 6p per litre extra which is a 4.5% premium which would make it worthwhile if it gave an extra 2.5 mpg. Would anyone like to comment as to whether this is likely?

Regards

[XantiaMan]

Interestingly enough, something else I've noticed, the temperature of the engine is higher on veg than deisel.

I would agree that it runs slightly hotter too.

Slight digression, does V power make that much difference? For me its all about mpg and when V-power first came the 6p a litre extra represented a premium over “normal” diesel of about 6.5% so I wondered if it was worth it and never tried it. Now its still 6p per litre extra which is a 4.5% premium which would make it worthwhile if it gave an extra 2.5 mpg. Would anyone like to comment as to whether this is likely?

I would much rather run cheaper veg and save more, i ran it a few times in the Montego and it did go well but not worth the premium.

Gareth

[Xaccers]

No idea I'm afraid, I tend to be a little bit heavy footed around MK and don't do the long relaxing journies anymore.
At £90 a tank, and supposedly needing several tank fulls to get proper benefit from it (if the blurb is to be believed) that's a little out of my price range (when compared to SVO).

[weety]

Interestingly enough, something else I've noticed, the temperature of the engine is higher on veg than deisel.

yeah i noticed that as well...wonder why....

[reblack68]

Slight digression, does V power make that much difference? For me its all about mpg and when V-power first came the 6p a litre extra represented a premium over “normal” diesel of about 6.5% so I wondered if it was worth it and never tried it. Now its still 6p per litre extra which is a 4.5% premium which would make it worthwhile if it gave an extra 2.5 mpg. Would anyone like to comment as to whether this is likely?

Regards

I've used premium diesel before and if anything I think it reduced the mpg.

In my experience supermarket fuel gives the worst mpg and standard Shell diesel gives the best.

[lolingram]

No idea I'm afraid, I tend to be a little bit heavy footed around MK and don't do the long relaxing journies anymore.
At £90 a tank, and supposedly needing several tank fulls to get proper benefit from it (if the blurb is to be believed) that's a little out of my price range (when compared to SVO).
_________________
1.9TD+ SX Xantia Estate (Cassy) running on 100% veg oil

For what it is worth, my son has a company 407 Pug estate auto. Running it on no/low sulphur pump DERV, it returns 7.7L/100km, as opposed to 8.4L/100km on standard pump DERV. The fuel costs 4% more but consumes 8% less over carefully logged extended (7000km) similar routes.... point is does this apply to XUDs with mechanical pumps? These not being equipped with onboard computers doesn't help resolve the issue.