interesting video reg vs premium

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6,222
Location
KY
I run Top Tier premium fuel in every vehicle but the Wrangler. The only vehicle that doesn't spec premium is the Club Sport, but it is now required since I installed a Turner/Conforti chip. If I didn't want to pay for premium fuel wouldn't buy a car that requires it.
 
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1,118
Location
Vancouver
We have probably the highest gas prices in North America and for me to run premium instead of regular is about $25 - 30 a month. I don't see the big deal* *Assuming the vehicle actually specs 91, otherwise just use 87
 
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1,502
Location
US
When I had a car(Lincoln LS) that said 91+ on the fuel filler door and in the manual, I ran it. I never had issues, per se, with running on regular but at the same time I could feel it retarding the timing(especially in terms of a seeming "hesitation" off the the line) and could measure a difference of 1-2mpg less on regular. We don't get 91 here-it's usually 92 at "budget" stations and 93 at name brand stations. I understand this is a regional thing, and 91 is premium in some parts of the country. My MKZ says 87, and I run 87 in it. I've run a few tanks of premium back to back in it in the past, and could not see any difference in power or economy. The MG is a bit of a different story. I tend to like how it runs with the timing a bit more advanced than normally specified(a lot of sources will say 32º BTDC max advance no vac-I usually run it 35º or so). I'm set up with a head/piston combination that pushes the C/R higher than stock(9.5:1 vs. 8.8:1) which, without a knock sensor, generally dictates 89 as a bit of a safety factor. I just go with 92/93 and enjoy the benefits of the timing a bit more advanced. BTW, when I first started paying attention to premium in '08 or so, when I got the LS, typically premium was 20-25¢ more than regular. Now it's 50-70¢ at most stations.
 
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Messages
1,118
Location
Vancouver
Originally Posted by bunnspecial
BTW, when I first started paying attention to premium in '08 or so, when I got the LS, typically premium was 20-25¢ more than regular. Now it's 50-70¢ at most stations.
Yeah, this is the part that bugs me. In 2010 when I first got a car requiring 91, up here in Canada it was 12-13 cents per litre more than regular. Today it's 22-25 cents, and the price of base 87 gas is basically the same.
 
i experimented running regular gas in my former mb c280 and glk 350 each several years back in both eastern canada and eastern usa. both performance and mpg were a bit, but noticeably, lower. i am frugal, but the savings at the gas pump were not worth trying regular gas in engines that are specifically spec'd for premium. my younger son used used midgrade gas in his two successive, former acura tlx 4 cylinder sedans. i dont recall exactly which gas is spec'd for the tlx but his two did best on midgrade.
 
Messages
1,465
Location
Richmond, VA area
Current GTIs have 87/reg as the min - amazing that the manufacturer actually knows what fuel will work. Sure, you will get a few extra hp out of a turbo car's motor with higher octane which will prevent some timing pull under WOT but simply not worth it for DD/commuting around but folks will stomp their feet that you will damage it doing this...so funny. In my current Golf wagon I run 93 b/c I have a software tune for 93, before, 87 all day with no drama. Also funny...the "run on the knock sensor" crowd" - let me tell you...you are probably pulling some timing on premium as well - just less so. Until you spend some time logging, you don't really know. The point of the closed-loop ECU is so you can have you cake and eat it too - push timing safely. Folks think you are getting substantial knock when timing is pulled...that is not the case. Interesting bit from one of the VAG tuning companies on this topic:

91_93.jpg
 
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Messages
1,527
Location
California
Octane numbers aside, different vehicles have different sensors and ECM/PCM systems, resulting in widely different abilities to take advantage of higher octane fuels. After testing just one vehicle, it's definitely not fair to say that the higher octane is not worth the cost. I have read many accounts here on BITOG where the user was trying premium 91 octane and they stated the increase in fuel economy alone was more than breaking even with the increased cost, let alone the increased performance (potential).
 
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10,035
Location
OH
It really isn't about HP, it's about preventing predetonation (knocking) in high compression engines...
 
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226
Location
YYC
Originally Posted by grampi
It really isn't about HP, it's about preventing predetonation (knocking) in high compression engines...
That's one of the tasks of the ECU, and the ECU is very good at doing its job.
 
Messages
1,776
Location
Kingston
I only run 87 octane in my 83 Caprice with an 8.5:1 Cr 305, and my Cutlass with a 76 350 with 8:1 compression ratio and my 2005 Silverado. No fuel related issues with any of them. The 305 in the Caprice will ping a little bit at light throttle on hot days because the EGR valve is dead. I should run 91 in it or fix the EGR valve, but it's too pricy for 91 octane here to run it daily in old cars that don't get great gas mileage, and it would literally be a weekend to replace the motor with my spare 305 if it ever died on me. I doubt that little bit of pinging will hurt it.
 
Messages
1,132
Location
ottawa
My mazda 6 specs 87.....with 13:1 compression on a NA engine. In very hot weather with the AC blasting I can feel the engine start to pull back on the timing with a slight loss of power. Especially during acceleration take off from start. 91 eliminates this completely. I now run 91 all the time in this engine. People on the forums say it's stupid. Honestly its night and day. Oh my intake valves are spotless....I checked with a boroscope. I run redline si-1 and top tier fuel. Engine is babied with early oil changes. I believe it's the 87. In such a high comp engine.
 
Messages
1,005
Location
Wash, DC
Originally Posted by nicholas
In very hot weather with the AC blasting I can feel the engine start to pull back on the timing with a slight loss of power. Especially during acceleration take off from start. 91 eliminates this completely. I now run 91 all the time in this engine. People on the forums say it's stupid. Honestly its night and day.
I have the same experience with my 2017 2.0 Tucson, and previous 2006 Toyota Matrix. I normally run 87, but when I know a heat wave is coming, when the tank drops to halfway, I fill it with 91/93. Around here it's cheaper to blend 87 and 91/93 50:50 than to buy 89, which costs nearly as much as premium. Re dyno tests: they don't tell the whole story about octane needs in hot weather. The operating conditions are not real world. The vehicle is standing still with the hood open and a big fan blowing at it. They only do a run up to redline at full throttle, denoting peak HP and torque. Totally different than creeping along stop-and-go in hot weather with the AC cranking.
 
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Messages
13,528
Location
Kendall, FL
Supposedly my VW gains 20hp when using 93 (according to APR). I've never felt a difference in cooler or hot Temps. The Hyundai turbo either after 8 yrs.
 
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