– Why are you supposed to put high octane gas in some (typically luxury brand) cars?
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It is mostly for cars with turbos. The higher octane fuel burns more cleanly and there are less leftover bits of fuel in the exhaust. This is important because the manifold exhaust is what spins the turbo, which in turn pushes more air in to the engine making more power.
Anyways, turbos get really hot, and if there is unburned fuel vapor still in the exhaust, it can ignite and blow up the turbo. This is the main reason that I’m aware of.
Im no expert but I’ve heard that if your car doesn’t need high octane it could be beneficial to switch up the fuel grades because each type will cause buildup in different parts of the engine
I have a 20 yr old 225 TT that only runs on 97 octane. if you dont run 97 it don run well. dunno why
Octane number indicates how much can you compress the air and fuel mixture without causing it ignite spontaneously. Higher octane number means you can apply higher compression. Increased compression ratio means that the same amount of air + fuel mixture will generate more force for every revolution of the engine. So to generate more power luxury cars use high compression ratio engines that requires higher octane number fuel to resist the spontaneous ignition before actual ignition by the spark plug. Some cars also use direct gasoline injection to avoid spontaneous ignition.
Who knew? Luxury cars need fancy fuel for their high-maintenance engines. Guess even cars have expensive taste!
There’s a good video by Engineering Explained that explains this on YouTube but I can’t find it right now. Great channel for questions like this!
Thank you for the many thoughtful responses!
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