rr1982

Does anyone know if the computer will advance ignition timing if I use 89 or higher octane gas?

my06tc

iTrader: (2)

you can use 89 or higher,only difference will be is youll pay more....as far as the computer is concern,ill ajust to it over time....

criminaltc

The car will run a tad bit hotter, but you won't really notice. The only reason you'd put 93 in or something is because of the quality. 87 is pure garbage. 93 is a good gasoline. That's the only reason you'd use it.

draxcaliber

It will make no difference. You'll just be wasting money. It isn't like the Hyundai Tau V8 that will adapt and make more power with higher octane gas.

You don't need higher octane unless you rebuild the engine with higher compression pistons, or you go forced induction.

rr1982

I also have a Mazda Protege 5 and I switched to the Mazda Protege MP3 ECU because it added about 5hp if you ran 91 octane or higher, because the computer would advance the ignition timing based on knock sensing and they only had 9.1:1 compression. These TC's actually have moderately high compression,10.4:1, so I was hoping that these computers could advance ignition like the MP3 computer. Thanks

Brichard0625

i run 93 in my tc2 and even tho i paying more..it has seemed to do postive things..notice my car doesnt vibrate when i idle....no hesitation at low rpms...and i runs alot smoother..i been using 93 for about 6000 miles and i put a fuel cleaner in every 1000 miles!

KidJustin

i've been using 87 and have no issues. basically my tC2 is feeling exactly how you described yours...

draxcaliber

it's all in your mind dude. Toyota engineered and optimized the engine to run on 87 octane.

5.0 liter ford mustangs make 414 horsepower on 87 octane because it was built to do it.

KidJustin

also...keep in mind the engine in the tC2....is a CAMRY ENGINE

...would u put high octane in a camry?

dm1336

I filled up from almost empty (light on) with 93 one time. Felt no difference at all. Went back to 87.

ashtc2

I've been using 93 octane since I got my Camry 20 years ago. (around the same time I was born). And do the same with the tC. At this point its just a matter of habit, but I think its beneficial in the long run.

draxcaliber

octane rating is just a rating of detonation resistence. It doesn't mean the gas is of higher quality. you're just wasting money.

engifineer

You're not getting what the octane number means.

A higher octane fuel can resist pre-ignition due to higher compression better than low octane fuels. If your engine is lower in compression (like ours) and does not require a higher octane fuel, then there will be no difference in running high or low octane.

The other qualities of the fuel are going to be the same (comparing 2 ratings for the same fuel maker) including the additives and the energy content.

If you run a lower octane level in a car designed to run a higher one, and the system is able to change the timing enough to prevent knock, then you will have lower power output, but possibly nothing else. Worst case is that you start having knock (pre-ignition) and lower power output. But if a system is designed to run on 87, then you wont gain anything by running 91.

engifineer

So you were driving your camry the day you were born ... ?

Brichard0625

ever since i put headers intake and exhaust of my car my car feels weird on 87...im not sure maybe it is in my head but on 87 my car tends to feel sluggish when im pushing pass 60 and in 93 its drives smoother..i know its just breathing mods but im spending about 2.70 extra which isnt that serious so i rather spend the 2.70 and feel better

ashtc2

No, its been in the family since I was born and maintained with 93 octane even today.

Deathscythe40

Any time there's an increase in gas prices you'll often see news stories posing the question: "Is premium fuel worth the premium price?" After the "expert" gives his two cents, the reporter will often conclude thus: "There you have it-if your vehicle runs fine on regular, stop throwing your money away on premium!" The average consumer can easily be lulled to the conclusion that there are no benefits whatsoever from running gasoline that costs a premium price of 20 cents more per gallon. The logic experts use to justify their claims is straightforward: If you run 87 octane and your car doesn't knock or ping, you'll see no difference if you use 89 or 91 octane. There are also claims that if your vehicle is only designed to run on 87 octane, you could possibly encounter problems from using higher octane.

To test the "premium gasoline is a waste of money" theory, we borrowed an unmodified Jetta 2.5L designed to run on 87 octane. In order to get a more accurate read on performance and pick up on any drivability differences, we decided to do more than just dyno tests. We performed the various tests using four tanks of gasoline. Under real-world driving conditions, the tank was run from full to empty first on 87, then on 91, and then back to 87. With the last remnants of 87 the car was dynoed until completely empty, then refilled with 91 and dynoed again.


Vehicle Data
Engine: 2.5-liter I5, dohc, 20-valve
Transmission: Six-speed automatic
Mileage: 4,520
Current modifications: None Dyno Type:
Six-speed automatic
Baseline : 87 octane

Performance
Temperature: 66° F
Humidity:15% Peak Power: 133 hp @ 5976 rpm
Peak Torque: 134 lb-ft @ 3444 rpm

Test Notes
All testing was performed on the same day. All horsepower and torque numbers are quoted at the wheels. Keep in mind that the properly calibrated "Mustang" dyno produces more accurate real world numbers. While these numbers might seem low when compared to figures gathered from a Dynojet, what is important is the differences between each dyno run. When we strapped the Jetta to the dyno the needle of the fuel gauge was right at the red marks and we dynode until the fuel light appeared. All five of the Jetta's 87 octane runs were virtually identical with no major variations and at no time did the vehicle experience any knocking or pinging.


Graph 1: Baseline 87 Octane vs. 91 Octane
Test 1
Performance
Peak power: 138 hp @ 5908 rpm
Peak torque: 146 lb-ft @ 4060 rpm
Peak power gain: 7 hp @ 5790 rpm
Peak torque gain: 13 lb-ft @ 4150 rpm
Temperature: 67° F
Humidity: 13%

Pros
• Increase of 1-2 mpg
• Increased throttle response and smoother power transitions
• Reduce risk of knocking or pinging
• Reduce risk of horsepower loss from heat soak

Cons
• $0.20 per gallon price premium

Test Notes
We took the Jetta to a gas station about a mile away from the dyno facility and filled it up with 13.74 gallons of 91 octane gasoline. We then drove the vehicle for 25 miles to give the vehicle a chance to adapt to the octane increase and make sure there was no 87 octane left in the lines.



Read more: http://www.europeancarweb.com/tech/p...#ixzz1npBWr21I




This is the closet test that I could compare with our cars.
The Jetta doesn't need 91 but as the test shows it benefited from it.

2010 Jetta 2.5l
Engine: 2.5L in-line 5 double overhead cam ( 9.5 :1 compression ratio ; four valves per cylinder)
Fuel: unleaded ( 87 octane)
Fuel consumption: city= 23 (mpg); highway= 30 (mpg); combined= 25 (mpg); vehicle range: 364 miles
Multi-point injection fuel system
14.5 gallon fuel tank
Power: 170 HP ( 127 kW) @ 5,700 rpm; 177 ft lb of torque ( 240 Nm) @ 4,250 rpm


2011 Scion TC

Engine: 2.5L in-linefour-cylinder DOHC with variable valve timing and four valves per cylinder
Unleaded fuel
Fuel economy: EPA (0:, 23MPG city, 31 MPG highway, 26 MPG combined and 378 mi. range
Multi-point fuel injection
14.5gallon fuel tank
Power (SAE): 180 hp @ 6,000 rpm; 173 ft lb of torque @ 4,100 rpm

Deathscythe40

My thread on this
https://www.scionlife.com/forums/sho...d.php?t=202103

engifineer

And that gives you results for one car in one case. Some cars, for example, are designed to run best on 93 or even higher, but are rated for 91 since that is more common. They simply change timing to run on that fuel, thus if you find 93 they will perform better. Other cars may have no effect at all. It depends on whether or not the timing is advanced or not. The energy in the fuel is the same. I have had cars that seemed to avg a couple mpg better with higher octane, although changes that small an also be lost in the statistical noise. But considering a 12000 mile year, 2 mpg improvement and .20 a gallon difference that would have netted in an $18 a year LOSS. So even if I saw a slight improvement it was negated.

draxcaliber

and yes, some cars are designed to run a range of tunes based on octane of gas. A lot of european cars are for instance, but not so much Japanese cars.