Tim_Carr

85 Octane is very low and would definetly cause performance issues. I guess I am saying that think about the lack of acceleration you already expirence, it will get much worse. I would also point out that poor detination causes deposits to build up and may cause the engine to need service sooner than expected. I don't think you should do it. Who in Austin sells 85? I have never noticed it?

Grateful11

That don't sell it in NC that I know of. I hit a major city daily and I've never seen it at the various stations I buy gas at.

jct

85 octane is only in the western part of the country

Persocon

I have been using 85 octane for 3,000 miles. but my elevation is mile high city, so the volume of air has less oxygen than lower elevation, and I'm broke. Most of the members of Scinergy Colorado runs 85 octane.

1NZ FE compression ratio is 10.5:1 I consider that pretty high so 91 octane would make sense

Zman

I've been buying 87 the whole time.
Would it be better to switch to 91?
I've wondered about that, it only adds up to maybe a dollar more anyway.

jct

stick with 87, thats what your knock sensor is for

Zman

Thanks.

boostedbox06

The higher the octane, the better IMHO I don't know for sure but I can vouch for the fact the the higher the octane the better your engine will perform, in San Jose, they have a station with 100octane and I use that when I can, makes my car rip! love that stuff, only difference is that its about five bucks a gallon, so I only use it once in a while.

vintage42

No, the engine cannot retard the timing enough for gas under 87 octane. The Owners Manual, Section 2, Page 114 says:
"OCTANE RATING
Select Octane Rating 87... or higher.
Use of unleaded gasoline with an octane rating or research octane number lower than (87 octane) stated above will cause persistent heavy knocking. If it is severe, this will lead to engine damage."

No, quality of gas is not related to its octane.

vintage42

No, Scion has emailed that higher octane is of no benefit:

Scion Customer Experience Discussion Thread
Scion xB horsepower and torque [Incident: 060901-000071]
From: Scion <scion_mail@scion.com>
Response (Vernon) 09/06/2006 04:09 PM
… The vehicle is engineered and tested using 87 octane fuel. We recommend that fuel for optimum performance, reliability, and fuel economy on the vehicle. The vehicle does make the same power at maximum throttle position on 87 octane as it would on higher octane fuel.

vintage42

No, the HP rating dropped because SAE standards changed to require that engines be tested with normal loads attached, i.e. the water pump and alternator, as in real life. Previously engines were tested bare on test stands.

vintage42

When Toyota makes an engine that can take advantage of higher octane, their Owners Manual will say so.

From the 2006 Tacoma Owners Manual:
(2TR-FE is the 2.7L I-4 and 1GR-FE is the 4.0L V-6)
"OCTANE RATING
2TR- FE engine - Select Octane Rating 87 or higher.
1GR- FE engine - Select Octane Rating 87 or higher. For improved vehicle performance, use premium unleaded gasoline with an Octane Rating of 91 or higher."

Toyota designed one engine to benefit from 91 octane, but not the other. And they put it in the Owners Manual.

boostedbox06

im boosted bro so i felt the difference, trust me i don;t know if you have ever tried putting the higher octane in your scion, but try it trust me its better, could be a few reasons why, one the lower octane has more additives and is goin to be less clean of certain elements and crap that can clog your injectors the higher octane should detonate at higher levels of heat, thereby cleaning out the injectors if needed, plus the 100octane is considered racing gas, so let me ask you this if there is truly no difference in performance, why is in considered "racing gas" and why would a higher performance engine need it as opposed to lower octane, kinda seems like there is a difference to me,...

Persocon

No difference. Higher performance engine cannot use lower octane. It needs higher octane to prevent detonation (instead of even burn lit by spark plugs, gasoline explodes with much force before spark plugs firing) With high engine compression ratio in high performance engines, during the compression stroke, lower octane gas will detonate whereas high octane gas will not.
So why would you, 1NZ FE engine with 10.5:1 compression ratio ECU retarded timing worry about detonation when the spark plugs fire BEFORE it deotnates? If the manufacture did not design the timing to be retarded in order to run lower octane gas, THEN I would worry about detonation and 91 octane would settle that. 100 octane is waste of your money.

Octane rating has nothing to do with performance rating. Your engine's performance determines which octane rating to use, that doesn't mean using 100 Octane will give you more power.

boostedbox06

it doesnt when you have a turbo, because the octane rich exhaust fumes require it to gain a decent amount of power, trust me I ran lower than 91 before and i had no spoolage or power to speak of my car with a turbo does require the higher octane say what you will but I know first hand

Persocon

octane rich exhaust what are you talking about. Do you adjust your fuel to air mixture ratio on the fly or what?

boostedbox06

i didn't but the guys that tuned my emanage did, and were very clear that I needed the 91 octane or higher, my gf borrowed my car once, and put regular in it and the turbo was pinging and wouldn't spool as soon as we got the 91 back in it was smooth sailing again, so been following their advice ever since

vintage42

Forced induction may be able to use 87 if you can stay out of the boost, but must have 91 octane when the boost is on, or the knock sensor will intervene to retard timing. Boosting into low octane on retarded ignition is not good for a turbocharged engine, and negates any extra power the forced induction can make.

My NA Subaru Forester LL Bean model is made to run on 87, but the turbocharged XT model must have 91, according to the manual and according to the poor experience of people who try to run them on 87.

boostedbox06

ya it sucks it usually starts to spool at like 3k and with our little engines it hard to get anywhere without crossing that point, so unfortunately I gotta stick with the 91, don't even have to know much about cars to realize that when you are driving and you hear the turbo pinging(literally that what is sounds like) that something is wrong lol