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Discussion Starter · #1 ·
Hey,

I'm literally about to buy one of these cars this week. Searched the forums first but didn't locate my answer easily.

What octane is required for this car? 87, 89, 91, 93? Thanks in advance and hope to join the ranks officially soon.
 

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Discussion Starter · #3 ·
Thanks man. I see that thread and I feel as though the opinions are mixed. I can see why people use 93. But why wouldn't Hyundai make you use 93 if it could run better or smoother?
 

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Because it's typically not a popular decision for a manufacturer to do this when selling a compact car.
Yes,
Lower operational costs are a selling point/feature.
 

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I personally run 91 because I want the added protection against knock (especially in 115 degree Arizona summers) and the car runs a bit smoother with it. The stock tune is pretty crap to begin with. Sure it's more expensive, but where I am at it's about $5 extra per tank and in the grand scheme of things that is hardly anything when you are buying a $20k+ car.
 

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2018 Hyundai Elantra Sport DCT w/TECH
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Is using 93 octane fuel make changes to the engine's output? It is said stock hp/tq numbers are based on 91 octane and power is reduced on 87 octane, hence using higher octane gas makes changes as well ?
 

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Is using 93 octane fuel make changes to the engine's output? It is said stock hp/tq numbers are based on 91 octane and power is reduced on 87 octane, hence using higher octane gas makes changes as well ?
Power doesn't change from one to the other. However you may notice the car will run smoother on the higher octane.
 

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The stock tune of this car needs only 87 Octane with the stock boost and timings. Using higher grades should bring about no differences in the performance but might probably make a difference due to the better purity or quality of the gas itself and it does no harm to use higher grade. Will be a different story if modded with advanced timing and higher boost. Now THAT would require the higher grade fuels so that the engine stays alive.
The higher the Octane number the lower will be its tendency to flame spontaneously. In the stock tune the fuel injection happens closer to when the piston reaches the top of the cylinder. So by the time the fuel ignites by the spark the piston is already at the top and moving back down. If the boost pressure is increased and timing is advanced, meaning the fuel injection is modded to start earlier and stay longer before the piston reaches the top, this fuel will ignite before the spark due to the pressure much like a diesel engine and expand and push against the piston which is still moving up. Not good. Due to this modded engines need fuels that have a lower tendency to spontaneously ignite and this is a job for the higher octane fuels. 'Required' use of high octane fuels only depend on the application.
 

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For an otherwise stock car, 87 is fine. Regardless of what you run I鈥檇 make an effort to stick with a top tier gas. The extra additives do make a difference.

Personally, I run 93 in all my vehicles. Even the dang lawnmower.
 

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Higher octane only helps if you have any kind of detonation, I highly doubt you are going to get any kind of donation at 14 -16pounds of boost unless that car is not running very good meaning you mechanical problems.
 

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Higher octane only helps if you have any kind of detonation, I highly doubt you are going to get any kind of donation at 14 -16pounds of boost unless that car is not running very good meaning you mechanical problems.
Stock boost can spike to 18 psi.
 

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I installed a lower motor mount on my 2018 ES and I can feel so much more when at idle and lower speeds. I decided to switch to 91 after using 87 for a couple months. I immediately noticed how much smoother the car felt at idle. Just because of that I'm not going to switch back.
 

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Used 87 my first 2 tanks. Car didn't seem to run very smoothly. Mostly noticed the hesitation under acceleration. Since then I've switched to 93 and I haven't had any of those issues since.
 
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