Real petrol

[axenige]

For those of you who live local to Kettering area, and are running old Dub's with soft valves and seats, well I notice today on my travels that Thrapston Rd Garage "Fina" sells leaded 4 Star petrol. I didn't dare ask the price but I'm going to treat the Golf to some as is always good to have lead in your pencil , Oh I mean your fuel tank ;D

[theanimalbus]

Nice

I was speacking to Andy smokeydub at the weekend and he said some garage up near them still sells it..................

2 bloomin quid a litre

thats like ...well expensive fuel eh !!!!

[axenige]

Yep sounds about right, but I'll still give it a go, mix a gallon or two with every tank full of 99 RON Un-leaded, as Tetra Ethyl lead also boosts the octane as well as lubricate and protect the valves.

[GravityGuru]

Well..........While were on the subject of fuel, If using a lead additive in your tank, what is the best petrol to use? Ive always put in normal unleaded but would super be any better??

[axenige]

Super in My golf yes , in your bus no . This is half the problem the VW OHV Air-cooled Boxer engine was designed back in the days of low Octane fuel with a 6-1 or there abouts compression ratio. In fact the petrol available during and after the war in Germany was $h!t, high octane suits high compression engines and low octane suits low compression engines. The Octane helps to reduce engine knock caused by pre-detonation of the fuel, before ignition by the spark plugs. Pre-detonation is a side effect of compressing an explosive gas mixer, by may times atmosphere, thus causing friction and heat in the process. The higher the engines compression ratio the more octane you need to stop pre-detonation taking place. TEL which was in **,***,****, and ***** was used for the same effect, it reduces the knocking but also lubricates the valves at the same time. Old **** has a similar octane rating to unleaded somewhere in the region of 70-90 RON this would depend on the lead content in the fuel.

The Open University in now closed for the evening

[theanimalbus]

(blimey i might have to move this into the tech section soon, or even start a new board/catergory...........Axenige motoring school )

yeah i would say if it aint broke dont fix it, you told me you were getting decent mpg outta her ,so if she runs sweet i'd leave her ,
but chucking a tenner of higher octane 99 every coupleo months or flushing her with some redex every 6 months or so, but i guess it depends on how often you use her..........

opinions welcome

[axenige]

theanimalbus said:

Axenige motoring school

LOL ;D

I did a lot of swatting up about fuel years ago, this was because of similar problems with the jeeps Side valve engine.
The Willy's "Go Devil" engine used in WW2 jeeps was also a low compression ratio of 6.88-1 and would not even run on **** to well due to being to high an octane rating. I got around this by skimming the cylinder head to increase the compression ratio to 9-1, however this can't been done on an old engine with a lot of wear on it as it will make things worse rather than better. However this is not an option on Vw air cooled pots, as each cylinder is a complete unit including the head, and so you can't machine it, and I would not recommend machining the base (I don't even think this is possible) as this will over stress the studs and you end up blowing a pot of the crankcase, which is what used to happen to modular construction Aircraft engines. However if there are after market shaped pistons available for VW boxers this would work, but again you would run the risk of stretching the studding and knackering the engine.

As to Redex it very good at keeping your fuel system clean, plus if you don't use your motor that much added some STP petrol treatment (not injector cleaner) to the mix as this is designed to stop the petrol from going off due to evaporation, and keeps it fresh for much longer.

If you have in-line fuel filers CHANGE them, don't wait until they become completely blocked with muck. I change my Fuel filter Cartridge every 18mths, its a lot cheaper then new injectors. Old cars always have fuel supply problems due to deterioration of fuel lines and rust flakes from the petrol tank, that if of course your tank steel and not plastic.

A good way to check if your fuel is the wrong grade for the job, is look at your spark plugs. The colour, deposits, and general condition of the Spark plugs this will tell you basically how your engine is running. I.E. To lean, to rich, wrong Octane fuel and a 100 other different things if you know what too look for