What fuel for TB45E?

[Gerrit Loubser]

Since I got my 4.5 GRX I have always fed it unleaded petrol (ULP), but I was wondering if anyone has experimented with both lead replacement petrol (LRP) and ULP in the TB45E motor? Which is best and why?

According to the NAAMSA database, the TB45E should be run on ULP and LRP is not recommended. Does anyone know why? I can't see how LRP can do any harm to this motor; it has no oxygen sensor as far as I can see and I will replace the plugs long before they become fouled. What am I missing? Could gases ventilated from the crankcase contaminate the air mass meter when running LRP?.

[JG Shields]

Iteressante vraag Gerrit. In dieselfde asem wonder ek wat die verskil in effektiwiteit is tussen 93 en 95 oktaan in die 4.8 enjin. Die Toyota manne glo dat 95 oktaan 'n beter brandstof verbruik tot gevolg het in die V8 Cruiser.

[AndriesS]

If the vehicle is fitted with knock sensors and actively change timing then in theory 95 should allow for better performance as the timing does not have to be retarded by the ECM to prevent/stop knocking. Older fuel injections would have been set-up for specific environments (fuel, altitude etc) and thus would not utilize the fuel's ability to ignite at a higher pressure/temp.

Newer high compression or turbo engines should benefit more from the higher octane fuels.

[JG Shields]

Thanks Andries. I accept that the 2007 model 4.8 is fitted with the knock sensors and will therefore benfit from the 95 octane?

[AndriesS]

We should benefit but I think the performance increase will be marginal and maybe not worth the extra money. I know my plat kar a high pressure Volvo S60R did have better consumption.

[tour de frans]

Good day.This is a interested topic and can carry on for ages.
Andries,you are spot on with the knock device for the ecu,but it only pull timeing when the enjin suffer from ping.It do not control the timeing during normal circumstances or driving,only when the fuel are bad or its very hot etc.It only sit there and wait for ping.When it hear ping (microfhone on the block)The ecu will pull timeing up to 10 deg.It wil put the timeing back slowly so the car wont feel jerky.(if that is what you ment,sorry for the long story )
They use ulp with additives to get lrp,For what its worth if I can recomend a fuel to a custommer,use the highest octane available and unleaded.

Gerrit,the crankcase gas have more oil depossits than the "wrong fuel",no need to worry.
Rdgs
Frans

[Gerrit Loubser]

Thanks a lot Frans .

So, it seems fair to say that it is safe to use either LRP or ULP in the TB45E, but has anyone experimented with the differences between the two? On some other vehicles users report differences in things like fuel consumption when comparing LRP and ULP. I am not sure if this is reality or due to unscientific methods or wishful thinking .

[AndriesS]

Normally the driver will measure the performance improvement with his "gat-so-meter" or rather with the seat of his pants and this tends to be deceiving. As for fuel consumption, the guys using it their rigs as daily drivers should be able to give a good indication after about 4 tanks of each, of which the cost would be about R110 extra. I get between 5.5 and 6km/l on my 4.8GL, will give it ago in the coming month

[tour de frans]

Gerrit,I never tried to experiment with the fuel we buy at the pump,I dit not bother to see the difference between two of the same octane fuels.Yes I have tuned and worked on vehicles with the different fuel,and most of the older ones made the factory spec power with the new fuel.And the other way arround.
Like you say,before the sparkplug foul,you replaced them already.
What I have noticed before,a car that only start in the morning and drive 500m without reving it and at night or later the day,the same thing.A pannel shop /workshop moving cars in and out.After 4 to 5 days no more start.Sparkplugs dead,only the LRP ones.

[Gerrit Loubser]

Thanks again, Frans.

I just want to confirm that I have my facts straight: The TB45E as sold in SA does not have an oxygen sensor, does it? As I understand it, it was only the ones with catalytic converters that got the oxygen sensor.