FWIW: My Mazda 2.5L has 13:1 CR and works perfectly on 87 octane. This summer, I started doing a test by mixing 93 and 87. I'm about 5 tanks into the test now and cannot tell any significant difference. Fuel economy is within 5% of last year.
High Compression GDI Engines With 87 Octane ?
- Thread starter ChrisD46
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As an aside, yesterday evening I filled the F-150 with 89. Was indicating 1/4 tank, took 16.8 gallons. $6 more cost than to fill w/ 87. I swear the truck lost just an edge in throttle response, which is the opposite of what might be expected, although the small bump plus the ratio of remaining 87 to new 89 would only put the full tank at 88 which should make zero diff. Impulsive, idiotic thing to do actually. $6 wasted. This was an instant blend (for 89) station-- only three storage tanks, 87, 93, and diesel.
Originally Posted by ChrisD46
I believe my Hyundai GDI Sonata 2.4L non-turbo has a compression ratio of 13:1 ... Makes me wonder how on earth Hyundai engineers can make 87 octane work in such a high compression engine ?
Also , even though 87 octane or higher is recommended in the OM - how would you tell what the best octane is for this engine ?
If you read your owners manual, it will say 87 or higher.
Given that is a high compression engine 13:1, using higher octane 91/93 will "some" increase power. This is a real sensitive topic, so to each their own. If you want maximum power, go with 91+.
I believe my Hyundai GDI Sonata 2.4L non-turbo has a compression ratio of 13:1 ... Makes me wonder how on earth Hyundai engineers can make 87 octane work in such a high compression engine ?
Also , even though 87 octane or higher is recommended in the OM - how would you tell what the best octane is for this engine ?
If you read your owners manual, it will say 87 or higher.
Given that is a high compression engine 13:1, using higher octane 91/93 will "some" increase power. This is a real sensitive topic, so to each their own. If you want maximum power, go with 91+.
Originally Posted by LoneRanger
As an aside, yesterday evening I filled the F-150 with 89. Was indicating 1/4 tank, took 16.8 gallons. $6 more cost than to fill w/ 87. I swear the truck lost just an edge in throttle response, which is the opposite of what might be expected, although the small bump plus the ratio of remaining 87 to new 89 would only put the full tank at 88 which should make zero diff. Impulsive, idiotic thing to do actually. $6 wasted. This was an instant blend (for 89) station-- only three storage tanks, 87, 93, and diesel.
Well, believe it or not, when I switch from one brand to the next or if I've been running 87 and switch to 89 in the summer, I swear I can feel the car behave oddly on that first tankful. It seems to settle-out and return to normal after 50-75 miles or so. I don't know for sure but suspect the ECU is doing some adaptive learning.
Just recently however, a tank of mid grade from a brand new station that just opened up ran noticeably poorer for the whole tank. Weather, environment conditions and commute pattern remained the same. Quite certainly though, I could feel a distinct vibration in the steering wheel and gear selector lever. Things cleared-up about 50-75 miles into my next fill-up at one of my regular stations.
I always fill-up when the gauge gets to (or slightly below) 1/4 tank.
Ray
As an aside, yesterday evening I filled the F-150 with 89. Was indicating 1/4 tank, took 16.8 gallons. $6 more cost than to fill w/ 87. I swear the truck lost just an edge in throttle response, which is the opposite of what might be expected, although the small bump plus the ratio of remaining 87 to new 89 would only put the full tank at 88 which should make zero diff. Impulsive, idiotic thing to do actually. $6 wasted. This was an instant blend (for 89) station-- only three storage tanks, 87, 93, and diesel.
Well, believe it or not, when I switch from one brand to the next or if I've been running 87 and switch to 89 in the summer, I swear I can feel the car behave oddly on that first tankful. It seems to settle-out and return to normal after 50-75 miles or so. I don't know for sure but suspect the ECU is doing some adaptive learning.
Just recently however, a tank of mid grade from a brand new station that just opened up ran noticeably poorer for the whole tank. Weather, environment conditions and commute pattern remained the same. Quite certainly though, I could feel a distinct vibration in the steering wheel and gear selector lever. Things cleared-up about 50-75 miles into my next fill-up at one of my regular stations.
I always fill-up when the gauge gets to (or slightly below) 1/4 tank.
Ray
I've been experimenting in my Silverado (L83, GDI, 11.0:1). Manual calls for a minimum of 87. When I run 87, the switch between V8 and V4 is VERY noticeable as well as the idle being rough. I ran a few tanks of 89, and it got better (much smoother, to the point that I can't feel it). MPG stayed the same though. I then ran a few tanks of 93 and it was no different than the 89. Went back to 87 just to make sure I wasn't crazy, and the roughness came back. Back to 89 and it seems to run great. It does seem to take about 2 tanks when going up in octane to feel the difference. It seems that the computer is slow to learn. Dropping down to 87 you can feel it almost immediately though.
Our 4Runner is not GDI, but port injected (10.0:1). The manual for it calls for 87. Running 89 and 93 make absolutely no difference that I can feel in this one. Idle us exactly the same and engine is smooth. So I save money and run 87 in this one.
Our 4Runner is not GDI, but port injected (10.0:1). The manual for it calls for 87. Running 89 and 93 make absolutely no difference that I can feel in this one. Idle us exactly the same and engine is smooth. So I save money and run 87 in this one.
Originally Posted by MParr
ChrisD46
My theory is that the fuel octane has more to do with LSPI than any oil. Could the blowing of engines have to do with fuel choice? I think so. Knock sensors, computer controlled timing and lugging the engine all factor in. We ran 93 octane in our ‘13 KIA Optima and we run 93 octane in our ‘17 Escape and ‘19 Tiguan. The extra cost of fuel beats the cost of a new engine.
Nope your theory is not correct LPSI has been documented with 87 octane to E85.
ChrisD46
My theory is that the fuel octane has more to do with LSPI than any oil. Could the blowing of engines have to do with fuel choice? I think so. Knock sensors, computer controlled timing and lugging the engine all factor in. We ran 93 octane in our ‘13 KIA Optima and we run 93 octane in our ‘17 Escape and ‘19 Tiguan. The extra cost of fuel beats the cost of a new engine.
Nope your theory is not correct LPSI has been documented with 87 octane to E85.
Running rich? Perhaps this is why every Hyundai/Kia seems to have an excessive amount of soot accumulation around the tailpipe area .
Never experienced an LSPI event in my non - turbo 2.4L Hyundai before ... While I'm running 89 octane in it now during hot , humid months - I experience a little extra pep but no real gas mileage improvement . I'll probably go back to 87 octane and drive in sport mode (higher RPM's for each gear) to keep the engine from lugging and running in the power band .
Our 2017 Equinox GDI has 11.2:1 ratio. It doesn't "ping" on regular 87, but the performance does suffer a little. The ECM monitors knock events and adjusts timing to prevent it. The vehicle is flex fuel, so we tend to use E85 more regularly as it has a 100 octane and allows the ECM to advance timing to the max of the map and deliver a better overall experience in driving. Less downshifting and gear hunting on hills and such and smoother operation under acceleration. I could use mid grade or premium to get the same result, but the cost per mile would be higher. Sure, using E85, the mpg takes a hit, but the actual cost per mile is substantially lower than using mid grade or premium. E85 is a buck cheaper per gallon than premium in my area.
wemay
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When using 87, about 80% of the time now, our 2013 Santa Fe Sport 2.0T runs just fine. No difference in mpg or noticable power, and approaching 200K miles. My Sportage uses the same 2.4L Thetta II and is run exclusively on 87.
Originally Posted by BMWTurboDzl
Running rich? Perhaps this is why every Hyundai/Kia seems to have an excessive amount of soot accumulation around the tailpipe area .
That's actually from oil been burned. Vehicle has oil consumption problem.
Running rich? Perhaps this is why every Hyundai/Kia seems to have an excessive amount of soot accumulation around the tailpipe area .
That's actually from oil been burned. Vehicle has oil consumption problem.
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