Use Only High Octane Gas in High Compression Engine ?

[BMWTurboDzl]

My Hyundai GDI 2.4L non- turbo engine has a 11.3.1 compression ratio . Not sure if this is considered high compression or not and if such an engine benefits from or needs high octane gas ? The owners manual just states 87 octane minimum .

It's high compression but with DI they've tuned the car to run fine on 87.

 

[Mackelroy]

Things are happening in the fuel market, and with trucking, bad loads of fuel, and unscrupulous tactics.

Careful where you get fuel, a blown motor can be very expensive.

 

[JohnnyG]

Things are happening in the fuel market, and with trucking, bad loads of fuel, and unscrupulous tactics.

Careful where you get fuel, a blown motor can be very expensive.

Some things never change.

 

[Kestas]

I take care of four cars that recommend 91 octane fuel. This is different from "required." I run 87 octane fuel for economy, because premium fuel costs 28% more where I fill up. Each car has knock sensors. I lose a little top end performance, but I lose very little in fuel economy... certainly not a 28% hit! I've been doing this for many years.

 

[Olds394]

I try 92 in every vehicle I own, and if it runs better that’s what I buy. They’re almost always quieter, or have better throttle response on 92.

 

[RDY4WAR]

Being non-turbo, you're unlikely to notice any significant difference. If you come from an old school background of wedge chambers and smog heads, the thought of 11.3:1 SCR on 87 octane seems unfathomable. With that newer engine though, which I'm assuming is direct injection, with pentroof chambers and runner design that induces good tumble, and a centrally located spark plug, you can get away with more compression.

 

[CDNozzle]

One issue with GDI engines is, the "cleaning benefit" only applies to injector tips. Using fuel like Chevron with Techron will keep injector tips clean which IS an issue with DI engines, but does nothing for the backs of the intake valves.
MAC and SNAP-ON both make a tool setup that cleans the carbon off the valves. It's pretty cool, but labor-intensive. Pull the intake manifold back, position the vacuum snorkel next to the valve, and there's a device that looks similar to a airbrush gun that sprays crushed walnut shells onto the valves as the vacuum collects them.
This tool was originally intended for MINI Cooper engines, but now with Hynudai, Kia, GM and nearly everyone else using GDI it's finally making money for the shops that invested in them!!

True for DI-only engines. I'm lucky to have both port and DI in my A25A-FKS. I never ever want to have to hot soak B12 or use walnut shells

 

[Chris142]

An old carburetor or port fuel injected engine needs higher octane because the Fuel is in the cylinder before the plug fires.

The direct injected ones squirt the fuel in at the Iast split second before the plug fires and don't need high octane.

 

[Mackelroy]

One issue with GDI engines is, the "cleaning benefit" only applies to injector tips. Using fuel like Chevron with Techron will keep injector tips clean which IS an issue with DI engines, but does nothing for the backs of the intake valves.

unless you buy an engine with both DI and Port injection.

too many manufactures behind on this