Just how good is our fuel?

[stroller]

I've often heard that certain manufacturers are not bringing certain vehicles into SA because our fuel simply does not meet the requirement of their engines.
Other manufacturers take their chances with a detuned spec or an extended maintenance plan to cover mishaps; hopefully the engine will pack up after the warranty or service plan has expired.

Some examples come to mind: Honda no longer offer a diesel engine and BMW's diesel engine does not have the output of its European siblings. Subaru motors can only perform at their best when an octane booster has been added. The pending arrival of the Suzuki Baleno will be with the 1.4 motor and that the turbo jobbie will not see our shores.

The local sulphur content of our diesel has also created much discussion for certain engines.

Is any of this true?

 

[froot]

I know from a friend in the fuel industry that there is a lot of BS'ing around what exactly our fuel contains. Mixtures being added to get the colour of the petrol right, and so forth.

 

[saturnz]

I've often heard that certain manufacturers are not bringing certain vehicles into SA because our fuel simply does not meet the requirement of their engines.
Other manufacturers take their chances with a detuned spec or an extended maintenance plan to cover mishaps; hopefully the engine will pack up after the warranty or service plan has expired.

Some examples come to mind: Honda no longer offer a diesel engine and BMW's diesel engine does not have the output of its European siblings. Subaru motors can only perform at their best when an octane booster has been added. The pending arrival of the Suzuki Baleno will be with the 1.4 motor and that the turbo jobbie will not see our shores.

The local sulphur content of our diesel has also created much discussion for certain engines.

Is any of this true?

yeah the fuel is pretty poor, cars can easily detonate if you try to run higher compressions (through more boost or otherwise)

If you have a knock detector in your car it lights up pretty quickly.

 

[LCBXX]

I doubt whether fuel quality alone will be a deciding factor as to whether a manufacturer brings in a certain model of car. Honda, for example, did not sell their diesels well at all because they were dabbling into the premium market with their prices (CRV DTEC was nudging R600,000, Civic 1.6 was entering GTi territory). Personally I blame both manufacturer greed as well are inflated import taxes - our car prices are ridiculous, remember how VWSA cocked up with Seat when they tried selling the brand for more than a VW when it is cheaper in Europe, by some margin, than a equivalent VW?

 

[FiestaST]

I doubt whether fuel quality alone will be a deciding factor as to whether a manufacturer brings in a certain model of car. Honda, for example, did not sell their diesels well at all because they were dabbling into the premium market with their prices (CRV DTEC was nudging R600,000, Civic 1.6 was entering GTi territory). Personally I blame both manufacturer greed as well are inflated import taxes - our car prices are ridiculous, remember how VWSA cocked up with Seat when they tried selling the brand for more than a VW when it is cheaper in Europe, by some margin, than a equivalent VW?

Agreed; more often that not is not a fuel story but a pricing vs demand story. 1L T in the Baleno is no being brought in initially due to a possible pricing conflict.

Fuel quality in ZAR has improved well in recent years but we still behind.

Sulfur content in our diesel has improved greatly over the years.

 

[Gordon_R]

You are asking a lot of vastly different questions at once (petrol and diesel), some of which are true, and some of which are irrelevant. The maximum octane rating of petrol is limited by legislation, introduced at the same time as leaded petrol was withdrawn from SA.

Ultra-low sulfur diesel is not available in SA, due to refinery constraints, and would be extremely expensive to introduce (edit: except Sasol with their gas to liquid conversion). The power output of a diesel engine has little to do with the sulfur content (edit: in fact ULSD has a lower energy content). In any case diesel engines in passenger cars should be banned IMO, since the emissions tests were so obviously rigged. See: https://en.wikipedia.org/wiki/Ultra-low-sulfur_diesel

Modern fuel injected engines systems can be tuned to deal with different grades of petrol (purely a software setting), so no reason why the same vehicle can't be imported. Under normal circumstances this would not cause any problems, other than a slight loss of power. You could add an octane booster to the petrol, and the owner could tamper with the settings, but this would clearly void the warranty

My brother (visiting from Australia) mentioned that the Subaru Outback turbo uses 98 octane petrol, which is definitely not available in SA. The performance penalty would amount to about 3% when using 95 unleaded.

 

[saturnz]

The performance penalty would amount to about 3% when using 95 unleaded.

how did you get to this number of 3%?

 

[Gordon_R]

how did you get to this number of 3%?

Probably an estimate. Since the compression ratio of most engines is fixed, retarding the timing to reduce the possibility of ignition knock would reduce the power of the combusion cycle. See: https://en.wikipedia.org/wiki/Engine_knocking

Edit: For a turbocharged engine the boost pressure would have to be reduced to prevent knocking, with an equivalent loss of performance.

 

[saturnz]

Probably an estimate. Since the compression ratio of most engines is fixed, retarding the timing to reduce the possibility of ignition knock would reduce the power of the combusion cycle. See: https://en.wikipedia.org/wiki/Engine_knocking

Edit: For a turbocharged engine the boost pressure would have to be reduced to prevent knocking, with an equivalent loss of performance.

yup reducing boost pressure will result in a lot more than a 3% reduction in performance.

 

[Gordon_R]

You can read more than you ever wanted to know about engine power and fuels worldwide on Wikipedia: https://en.wikipedia.org/wiki/Octane_rating
Note that elevation (highveld vs coastal) also makes a significant difference.

Many modern engines are equipped with a knock sensor (a small piezoelectric microphone), which sends a signal to the engine control unit, which in turn retards the ignition timing when detonation is detected. Retarding the ignition timing reduces the tendency of the fuel-air mixture to detonate, but also reduces power output and fuel efficiency. Because of this, under conditions of high load and high temperature, a given engine may have a more consistent power output with a higher octane fuel, as such fuels are less prone to detonation.

Australia: "regular" unleaded fuel is 91 RON, "premium" unleaded with 95 RON is widely available, and 98 RON fuel is also reasonably common.
........
South Africa: "regular" unleaded fuel is 95 RON in coastal areas. Inland (higher elevation) "regular" unleaded fuel is 93 RON; once again most fuel stations optionally offer 95 RON.