A veg oil question

[ProgRocker]

Dome's post on the 'What Makes you Grin?' thread...

 

I'll be back in the land of veg oil powered cars too, just bought a Mk1 Octavia Tdi. Needs some work to get it road ready then I'll be watching the cheap veg oil thread...

 

I know that using veg oil is OK in low tech normally aspirated diesel engines like the VAG SDi.

 

However, I thought using veg oil in turbo diesel engines wasn't good for the longevity of the car. Or am I getting confused with common rail diesel engines like mine? My owner's manual dissuades me from using it (Nissan/Renault dCi engine).

 

Please put me out of my misery. Metaphorically.

[skattrd]

Veg oil is fine in some low tech tdi`a which have a suitable fuel pump. Turbo or not has no bearing on it being able to run on veg.

[jonathan_dyane]

Turbo/non turbo has nothing to do with it, veg suits cars with old style injectors and Bosch injector pumps however indirect injection engines (pre sdi/tdi) are even more suitable.

 

As well as knackering up modern diesel injection systems it also tends to burn incompletely gumming up your piston rings and making your car fail to start or seize because the oil has turned to jelly

[ProgRocker]

Thanks for the replies!

[twosmoke300]

Dont do it , renault dci motors struggle on bloody diesel.

[ProgRocker]

Dont do it , renault dci motors struggle on bloody diesel.

 Mine certainly does!

[forddeliveryboy]

The VW TDi system is the only direct injection one which can be run safely on a single tanked system (ie cold starting on veg), partly because of the engine piston design. Just don't idle them from cold, or turn out of your drive into a traffic jam. Make sure there aren't constant tell-tale wisps of smoke, suggesting poor combustion. A little petrol (1-2%) helps enormously with the TDi system (several tiny injector holes rather than one bigger one), I always run with 5%+ diesel too and a dash of acetone as the icing on the cake.

 

The later VNT turbos give boost from lower revs and these engines seem among the best for veg. My old 80TDi with the old wastegate turbo is very slow until 1800rpm+ (and doesn't continue to boost much as revs rise above 3k), the 90hp Octy from garbaldy takes off like a jet aircraft in comparison as the turbo boosts from 1200rpm and keeps on pulling hard to 4k. I'd suggest there is less chance of unburnt fuel with the VNTs - they also make for a very flexible motor.

 

As to the turbo or not question, a smaller non-turbo engine will rev harder which is no bad thing on veg if the driver isn't the press-on sort. Equally, a turbo will increase compression, improve fuel/air mixing in the combustion chambers and often run at higher temps which are all good for veg fuels. The shortish stroke larger Mercedes (car) diesels (the ones meant to be ideal for veg because of the inline IP) are often used very gently (although they love revving) and have been known to be prone to ring-gumming. I'd imagine that the shorter stroke makes them more vulnerable to poor injector spray patterns, retarded timing and cylinder compressions which aren't as healthy as they ought to be. These need to be in full health before starting to run any engine on veg - but who checks any of them?

[willswitchengage]

As to the turbo or not question, a smaller non-turbo engine will rev harder which is no bad thing on veg if the driver isn't the press-on sort. Equally, a turbo will increase compression, improve fuel/air mixing in the combustion chambers and often run at higher temps which are all good for veg fuels. The shortish stroke larger Mercedes (car) diesels (the ones meant to be ideal for veg because of the inline IP) are often used very gently (although they love revving) and have been known to be prone to ring-gumming. I'd imagine that the shorter stroke makes them more vulnerable to poor injector spray patterns, retarded timing and cylinder compressions which aren't as healthy as they ought to be. These need to be in full health before starting to run any engine on veg - but who checks any of them?

 

Generally not true but I cba and the soccer's on.

[forddeliveryboy]

Generally not true but I cba and the soccer's on.

 

 

Enlighten us all when you can/footy's finished.