ethanol additives and plastic fuel tanks

[Kaleid]

Any truth to ethanol additives present in gas not cooperating long term with plastic (i.e. RS plastic fuel tank)?

[911MRP]

I've had this for a while. See link to UK report below. Will vary by market. Not the most interesting read but may help with your question. Seem to recall report touches on some material compatibility issues but haven't read it in a while. Maybe more recent info exists. There is some issue wrt to fuel line degradation for some materials.



Author QinetiQ was formed in July 2001, set up,as as business out of the UK Ministry of Defence (MOD) Defence Evaluation and Research Agency (DERA)
http://www.volksbolts.com/faq/bioethanolstudyreport.pdf
Steve

PS The British market 73 RS had a steel tank

[Kaleid]

Thanks Steve, appreciate it- will give it a read

[MoparBoy72]

The Euro market plastic tanks are some type of polyethylene, correct?

[911MRP]

IIRC high density polyethylene (HDPE) from BASF and these so called RS tanks were made by K Kurtz...suggest you double check spec, MSDS etc because fuel tank is an important / safety critical item positioned upfront and quite low on early 911

[RSTarga]

I've had this for a while. See link to UK report below. Will vary by market. Not the most interesting read but may help with your question. Seem to recall report touches on some material compatibility issues but haven't read it in a while. Maybe more recent info exists. There is some issue wrt to fuel line degradation for some materials.

PS The British market 73 RS had a steel tank

Did they have a space saver tire?

[MoparBoy72]

IIRC high density polyethylene (HDPE) from BASF and these so called RS tanks were made by K Kurtz...suggest you double check spec, MSDS etc because fuel tank is an important / safety critical item positioned upfront and quite low on early 911

As long as this holds true, I would say this tank is a good fit for ethanol fuels. HDPE is quite good at handling alcohol, most modern gasoline tanks are made out of this material as well as the bottles most rubbing alcohol comes in.

I would worry more about all of the natural rubber products and seals once the fuel exits the tank.

[911MRP]

Did they have a space saver tire?

Hi David

No spacesavers under 73 911 bonnets here!

All RS spares were Fuchs 6 x15 predominantly with 185/70 15 Pirelli Cinturato CN 36 for country code c16/EG for early spec RS (later RS series also interchangeably used Dunlops).

In fact only steel tank / no spacesaver originally sold and permitted this side of pond for all model year 73 911 cars.

Below is wording from the original Porsche Cars GB price and spec sheet for MY 73 that came with my car that confirms this. The earlier 73 price list for new model year was quickly updated specifically for the RS launch event in October 1972, it includes a NOTE about the British-market the spec of the fuel tank. I posted this image elsewhere on the forum but reproducing it here given your question:


As I understand it, the space saver tyre was the thing that caused the British vehicle licencing authorities the problem at end of 72. Not the bigger plastic tank per se. Spacesaver wheel and tyre concept was not approved by UK regulators until much later. I seem to recall post impact cars here had warnings about them when first supplied and used. The RS was the first road-car in UK (and maybe other country-markets too?) to have different size front rear wheel tyre combo. So that model exacerbated the spare tyre size regulatory issue here in Britain. The practical solution the Porsche Cars Great Britain importer and factory chose was simply to provide an extra front 6 Fuchs / 185/70 tyre in the steel fuel tank. Probably technically illegal here at that time to run the front 6 inch 185/70 tyre spare to replace a punctured 7 215/60 rear too becase at that time wheels tyres on same axle must match. That was the owners risk in an event of an emergency but the spacesaver spare innovation was simply not regulator approved for use here back in 73 era. Plastic tank shape didn't accommodate the regular series front wheel/ tyre hence plastic tank not available in UK spec RS or TES per the NOTE. British market 911 cars from that time have a separate small "BS AU nn" tag riveted just above the front latch aluminium type plate relating to the country specific specification and approvals.

The original Mexico blue wheels on my 12/72 DOB RHD British market RS are earlier stamp than December date but the car's Fuchs spare was apparently put in as car was being finished off so it is dated a bit later than the other four road-wheel date code stamps.

U.K. Authorities in 72 were not alone in having some quibbles with spec RS. Germany authorities didn't like/ permit RS rear spoiler deeming it unsafe so they were fitted after the fact not by factory as I understand it, France didn't allow RS front spoiler so their examples used series S version instead. Probably not optimal aero balance in these mismatched cases. Less obviously, Swiss authorities required different type horns, a pair of mirrors not single were required in certain Scandinavian countries, Italian cars had differences on lights / flashers, and so on. Lots of little country regulator challenges. Some quite specific due to the innovations found only on the RS model but some were 911-wide variations required by European country regulators and or importers.

When RS model was being designed in 1972, Great Britain had yet to join the European "common market" experiment. Britain only joined January 1973 and a referendum confirmed continuation in 1975, so harmonised European product standards for a common marketplace didn't always apply as strongly back then -- although there were of course some auto industry European standards. (Back to the future, post BREXIT?)

Regarding the thread's original point of bioethanol perishing fuel systems, I like Andrew would very carefully watch the rubber lines etc because we have seen some problems with rapid deterioration over here. That is why I happened to have the QinetiQ research to hand. As already mentioned strongly recommend the OP should double check the plastic tank's material from a factory or original supplier source as my fallible memory may be wrong. Much better to research the actual material type to be safe if there is a risk of plastic perishing and leaking due to modern fuel formulation -- car fuel blends may vary in composition by geography so the risk of perishing might be more of an issue for some members than others.

The plastic tank innovation and its benefits are referenced in a Porsche KG publication that I have on my shelf (undated but est 71/2) promoting Porsche engineering services and technical capabilities in B2B markets.




Steve