Last post on Nov 17, 2010 at 10:29 AM
You are in the Acura RDX
What is this discussion about?
Acura RDX, Concept Cars, SUV
#2728 of 2732 Re: 91 octane gasoline [cowboy7]
Nov 15, 2010 (10:10 am)
I'm sure the ECU will retard spark timing to compensate and prevent knocking, but the engine would be running out of its ideal tune for that whole tank.
Even if you had to use regular, because that's the only gas available, I'd only put enough to reach another gas station that had premium.
Turbos increase the effective compression ratio so they are far more vulnerable to knock.
#2729 of 2732 Re: 91 octane gasoline [ateixeira]
Nov 16, 2010 (11:01 am)
There is "spark" knock, which can often be compensated for via timing change, and there is compression/dieseling/detonation knock.
The latter is compensated for via the use of EFI to enrich the mixture.
#2730 of 2732 Re: 91 octane gasoline [wwest]
Nov 16, 2010 (12:30 pm)
If so, mileage would drop and defeat the purpose of using lower-cost fuel in the first place....
Stick with premium.
#2731 of 2732 Re: 91 octane gasoline [cowboy7]
Nov 16, 2010 (6:07 pm)
So it sounds like 87 octane does no harm to the engine, if it was used a few times by mistake. Do I interpret it correctly?
#2732 of 2732 Re: 91 octane gasoline [ateixeira]
Nov 17, 2010 (10:29 am)
"..mileage will drop.."
Not necessarily, it depends both on the price differential and the driving style. Price issue is obvious and if the driver doesn't go WOT very often the A/F mixture need never be enriched. And we can forget about detonation due to (uphill, towing)engine lugging with an automatic.
When we picked up our '01 Porsche at the factory we were told that fueling with regular would do no harm.