LR3 4.4 What octane?

[scottymcdonald]

Hey Guys,

I've been faithfully filling my LR3 with 93 octane since I've had it since last December. But permium is now around $4.40/gal in the Bay Area. Wondering if anyone has used 89 or 87 with ill affect? Is this something that might be adjusted with the GAP or iLand tool? Ive been getting around 17-19mpg.

 

[TexasTJ]

Gas mileage will drop and out way the benefits.

 

[Model97]

i run 89, getting ~17.8 mpg. runs fine.

 

[johnsoax]

I'm getting 14.8 average with 91 octane.

 

[merr1ca]

Purely anecdotal, but my buddy has two lr3's and has only run regular in them over the (combined) 400,000 miles they have on them. No ill effects.

Kinda freaks me out still, and it's generally considered a bad idea, but meh.

 

[krick3tt]

Using less octane rating than prescribed per the owners manual or your technician may decrease performance and possibly cause damage to the internals of your engine. It may also decrease your milage. I have had to go out of my way on trips to find stations that sell 91 octane petrol to maximize my vehicle's operation. These vehicles are specifically designed to operate on premium and although it might save you a few dollars per tank to use less you have to weigh the possible cost down the road (so to speak). I would not do that, you may wish to. Cheap petrol is like fast food for your vehicle, it may come back to bite you.
Just my opinion.

 

[dreadlocks]

are these boosted? if so you need the slower burn of higher octane to prevent pre-detonation under full boost in conditions when the ECU might not respond to quick enough.. if these are naturally aspirated, using lower octane will just result in ECU retarding the timing, resulting in a drop in power output but should otherwise be harmless.. unless a NA engine has a very high compression ratio, which would necessitate race fuel, it should safely adapt to any octane you provide it.. just with reduced performance.

Many new boosted european vehicles are being tuned on regular octane, since they are looking at the inevitable death of the diesel and need boosted eco gassers to compensate..

 

[TOUGE]

are these boosted? if so you need the slower burn of higher octane to prevent pre-detonation under full boost in conditions when the ECU might not respond to quick enough.. if these are naturally aspirated, using lower octane will just result in ECU retarding the timing, resulting in a drop in power output but should otherwise be harmless.. unless a NA engine has a very high compression ratio, which would necessitate race fuel, it should safely adapt to any octane you provide it.. just with reduced performance.

Many new boosted european vehicles are being tuned on regular octane, since they are looking at the inevitable death of the diesel and need boosted eco gassers to compensate..

No these aren't boosted but have a highish compression ratio for a V8(10.8ish).

I thought the higher octane requirement was to do with the lower sulfur content in the fuel compared with lower octanes to pass emissions. Running lower octane may(in extreme cases) clog the EGR and emissions systems. A quick search says 91/93 has to have a max of 30ppm of sulfur where anything under 91 octane is 50ppm of sulfur in the US. Europe in 10ppm, Australia is 50ppm.

Fuel consumption also depends on the ethanol content of the fuel. In California it is around 10% but you never know as it varies. E10 91 octane will get you around 3% less fuel economy than with pure gasoline 91, which generally you will only find near race tracks.

 

[Blaise]

Run the correct fuel. Premium.

Please don't try to out-engineer the engineers. Trust me, we don't make up recommendations.

 

[rgallant]

Just to added to the confusion octane ratings are different in Europe than North America. So take your best guess, but the owners manual says :

Premium unleaded gasoline with a CLC or AKI octane rating of 91 or higher. See TYPE OF FUEL, 168 Note: Mid or regular grade gasoline with a CLC or AKI octane rating of not lower than 87 may also be used, but performance and fuel economy will be reduced.

If you want to figure it out - get the chart from this web site Octane Info Then go to your gas station and see how they measure octane, in Canada at least it is on the pump and generally the AKI and Octane are the same so my old Disco II gets Shell 91 - no ethanol and the right gas. As a bonus it runs better smoother and is perkier (very scientific term).

 

[Model97]

A free snickers bar to whomever can describe exactly what may happen with lower-than-advised octane fuel. Hint: you will know it's happening. And if it isn't, no worries. There is no ultra secret long term damage occurring that only engineers can understand.

 

[dreadlocks]

on a modern EFI vehicle the fuel is going to detonate before the spark plug fires causing pinging (firing before its at the top of the stroke), which the knock sensor will detect and the ECU will respond to by retarding the timing, stopping the pre-detonation while reducing power output without any harm.. on an old fully mechanical engine, it'll go unchecked and the pinging will take its toll on the main bearings, piston and valvetrain unless someone manually pulls the timing advance (retarding timing) until the pinging stops.. back in the day we tuned the engine for the fuel type with a wooden dowel rod between our and the engines head, a timing light in one hand and the distributor in the other, today the ECU does all that for you automagically.

 

[Model97]

on a modern EFI vehicle the fuel is going to detonate before the spark plug fires causing pinging (firing before its at the top of the stroke), which the knock sensor will detect and the ECU will respond to by retarding the timing, stopping the pre-detonation while reducing power output without any harm.. on an old fully mechanical engine, it'll go unchecked and the pinging will take its toll on the main bearings, piston and valvetrain unless someone manually pulls the timing advance (retarding timing) until the pinging stops.. back in the day we tuned the engine for the fuel type with a wooden dowel rod between our and the engines head, a timing light in one hand and the distributor in the other, today the ECU does all that for you automagically.

Ding ding ding ding. And if there is pre-detonation happening, you can feel it. And the sensor will tell you as well. So it's all good and there is kumbayah in the valve train.

 

[Blaise]

A free snickers bar to whomever can describe exactly what may happen with lower-than-advised octane fuel. Hint: you will know it's happening. And if it isn't, no worries. There is no ultra secret long term damage occurring that only engineers can understand.

Correct. But still, run the right octane.

 

[Model97]

Correct. But still, run the right octane.

Missing the point. And I’m one of those engineers .