Kia Forum banner
41 - 46 of 46 Posts

·
Registered
2017 Kia Sportage
Joined
·
1,655 Posts
I'm not sure what horsepower has to do with spark knock or low rpm acceleration. Torque on the other hand is directly impacted by both. Low rpm acceleration is one of the peak conditions resulting in detonation. Detonation results in less sustained push on the piston, providing less torque at the crank. Retarding the spark, or any other means that the ECU can take to reduce detonation, results in a less efficient combustion versus piston position. Once again, less torque (the necessary force required for acceleration).

I do concur with the rest of your argument regarding not getting an increase in power (hp or torque) by using more than 87 octane in our engines. But, I error on the side of pumping a higher octane to ensure that I always am getting at least 87 octane (I can assure you that even at Tier 1 stations of the same brand, the octane rating of the fuel dispensed can vary from station to station.

Sent from my SM-N986U using Tapatalk
I've travelled across the country in many states and never have had a problem in Top Tier stations with 87 octane gas. Spending more money than I need to has never made me happy.... Petroleum refining today has really good controls. However, if you think a certain gas station is cheating on you, I'd go to a different station...
 

·
Registered
2021 Sportage SX 2.0T-GDI AWD
Joined
·
87 Posts
I'm not 100% sure if you're trying to suggest that 85 octane gas is not sold in the USA. I rather doubt that's what you were saying, but just in case... Here is a picture I took not 5 minutes ago. This is what you see at every pump in Denver for at least the last 40 years (for octane).

And... @deadrx7conv , I think you make some salient points but you don't need to demean others along the way.

Also for what it's worth, now starting my third tank of mid-grade on my 2021 SX turbo, it clearly runs much better on 87 octane than it did on 85 octane. And more surprisingly it actually seems to run better than it did on 91 octane (3 tanks tested). All top-tier.

I fully admit this is a test with a sample size of one ( me, my SX ), with a number of uncontrolled variables, and a fairly short duration so far. It is merely my subjective experience so far..


120059
 

·
Registered
2017 Kia Sportage
Joined
·
1,655 Posts
I'm not 100% sure if you're trying to suggest that 85 octane gas is not sold in the USA. I rather doubt that's what you were saying, but just in case... Here is a picture I took not 5 minutes ago. This is what you see at every pump in Denver for at least the last 40 years (for octane).

And... @deadrx7conv , I think you make some salient points but you don't need to demean others along the way.

Also for what it's worth, now starting my third tank of mid-grade on my 2021 SX turbo, it clearly runs much better on 87 octane than it did on 85 octane. And more surprisingly it actually seems to run better than it did on 91 octane (3 tanks tested). All top-tier.

I fully admit this is a test with a sample size of one ( me, my SX ), with a number of uncontrolled variables, and a fairly short duration so far. It is merely my subjective experience so far..
You're right, I'm not saying that 85 octane is not sold, only that when travelling, I only use 87 octane and have never had any issues or loss of power. Manufacturers today, with all of their computer magic, can keep their specs very tight. So when they maximize an engine for 87 octane, using 85 octane will cause issues -- even in Denver.... It's not like the old days when you heard a ping and then put in higher octane gas. Unfortunately, many gearheads are stuck in the past and think there is always more power in higher octane gas. It's a complicated subject because it depends on the manufacturer's engine design. Kia designed their engines to be maximized with 87 octane, so higher octane delivers no benefit. You also get all of the same important additives in both octane levels despite some oil companies claiming extra additives in premium which have not been proven to do anything. It's just like fuel additives which do virtually nothing if you use Top Tier gas (as it says in the Kia manual).

There are several of us here that use 87 octane gas and have no problems and no supernatural beliefs that their engine will last longer and do better with higher octane gas. Oh well, I'm glad your voice is added to the several of us who have experienced the same result.
 

·
Registered
2021 Sportage SX 2.0T-GDI AWD
Joined
·
87 Posts
Well after quite a few tanks and several thousand miles, using only 87 octane (or occasionally premium when it was cheaper at Costco than the mid-grade, LOL) ... I really don't think the overall driving experience has improved all that dramatically. SOME, yes. But not hugely. This turbo is still nearly impossible to drive smoothly. Very frustrating.
(and I consider smooth driving to be not only an expectation of any vehicle, but a life long practice and goal for myself, and I'm somewhere close to 1 million miles driven in my 37 years of driving, all in non-commercial personal vehicles)

< edited >

Also for what it's worth, now starting my third tank of mid-grade on my 2021 SX turbo, it clearly runs much better on 87 octane than it did on 85 octane. And more surprisingly it actually seems to run better than it did on 91 octane (3 tanks tested). All top-tier.

I fully admit this is a test with a sample size of one ( me, my SX ), with a number of uncontrolled variables, and a fairly short duration so far. It is merely my subjective experience so far..

< pic >
 

·
Registered
2020 Kia Sportage SX AWD and 1988 Mercedes 300CE
Joined
·
459 Posts
You do realize that the turbo spins up at a mere 1400 rpm don't you? That means that from idle at 750 rpm to an additional 650 rpm your running off boost, but then SUDDENLY you get virtually full boost. So yes, it's jumpy! Older turbo engines didn't hit boost until much further up the rev range, so take off from a stop was not nearly as jumpy.

The advantage of this low end boost is that additional low end torque that gives the ability to accelerate out of situations where vehicles with less torque could not. The obvious disadvantage is the jumpyness. But, some of us actually love the way it jumps out there.

Sent from my SM-N986U using Tapatalk
 
41 - 46 of 46 Posts
Top