stick with rez gas.
good call…actually in my owners manual it recommneds nothing lower than 91 beciase of the compression of my high performance motor
:withstupi
After a point that’s true if you don’t tune for it, but that point is not 89 octane. Just about any newish NA engine benefits from 91-93 and almost all forced induction cars OBD1+ benefit from 93-95 octane.
When mixing fuels, averaging their octane ratings will get you in the ballpark, but you can’t assume they’ll mix completely evenly.
-Mike
Yeah, you have to go over a lot of bumps and sharp turns.
Sorry but this is COMPLETELY WRONG. If a vehicle was designed to run on 87 octane how do you think it will make more power with 93 octane. Gas isn’t magic. Take for example a 2004 trailblazer which I have. It runs fine on 87 octane and make good power. It doesn’t get anymore power or mpg on higher octane so therefore it is just a waste of money
It depends on the car. A lot of the newer cars have ECU’s that adjust the timing to take advantage of a higher octane. I know a lot of Toyotas reccomend premium in order to achieve the best performance, and that’s what the top power output on the stock car was achieved using, but they will still run fine on 87 octane.
I’m sure the gains aren’t all that much when you’re talking about a stock NA car, but still, there is a difference.
RSX Type-S = 91 octane preferred.
Not saying I want your 93 dropped to 91, but I can only get 91 at Sunoco. So when I go elsewhere, I’m paying a bit more for slightly higher octane that I don’t need.
My f’en Ranger has to have 91+ octane in the summer to keep the engine from knocking…
17 gallon tank + 17-19 mpg + 91 octane fuel = rape
im a ford truck man, that’s all I drive, king of the raping built ford tough!
-Cheater-
Andy, you might want to read this article. it was written by Patrick bedard of car & Driver in 1992.
PATRICK
BEDARDSave valuable money.
The big oil companies have been trying to buy this column for months. Apparently, it took a check for six figures—that was a long time ago.—to get the 100-mpg carburetor. And you’ve heard about those gas-tank pills: just drop one in the tank with every fill and your mileage quadruples. That buyout had so many zeros it looked like a Hollywood movie deal.
The oil barons do what they have to do: over the counter, under the table, cash by the Samsoniteful, check, or money order. But I have to stay lily-white, be cause I’m neither confirming nor denying a run for the presidency in ‘92.
What the oil companies didn’t want me to write—because it would put a heckuva dent in their profits—is the tip that could save you up to a shiny quarter cash money on every gallon of gas you buy. It’s easy: no wrenches required. Just roll on by the super-premium pump and fill up with no-lead regular.
Some cars benefit from fuel higher in octane than the 87 PON (pump octane number) of regular unleaded. But not many. In fact, one of the most exotic engines on the market today runs happily on regular: the 24-valve V-6 in the Taurus SHO. Above 3600 rpm, it delivers its full output on 87 PON gasoline. Premium and super premium add nothing but gravy for the oil companies.
Ford recommends premium fuel for the SHO V-6. It’s plainly a high-performance engine, and Ford decided upon premium way back in the concept stage to avoid design constraints on power out put. But when the job was finished, the resulting engine worked fine on regular fuel, primarily because modern engine technology eliminates the bungling operation that, in past engines, could only be smoothed over by high-octane fuel.
Detonation—the “ping” we’ve all heard—is the sound of out-of-control combustion. The spark plug’s job is to start the fire. As the flame front travels across the chamber, the pressure and temperature rise in the mixture yet to be burned. The farther the flame has to travel, the higher the temperature and pressure rise. If they rise high enough, or if there is a hot spot, spontaneous ignition can occur somewhere in the remaining mixture. That’s trouble.
But four-valve engines usually have the spark plug centered in the chamber, which means a short flame path to all the extremities. Therefore, the intentional fire completes its job before spontaneous combustion has a chance. Port fuel injection delivers a more uniform mixture to all cylinders, which means there isn’t one somewhere that’s way ahead of the others in its propensity to ping. And electronic engine-management systems are more apt to spark each cylinder at exactly the right time, which also cuts the chances of an early pinger.
David Beatty, a product-design engineer on Ford’s SHO project, likens premium to a log and regular to sawdust. Both will burn, but sawdust—with any excuse—goes off in a flash. A log, like high-octane gasoline, resists immoderate combustion. A truly modern engine, however, controls combustion more by design than by fuel…
Above 3600 rpm, the SHO has no need for premium. But what about at lower engine speeds? In laboratory tests under adverse conditions, premium fuel allows a little more spark advance with out ping. That advance translates into a torque increase of about three percent at lower speeds. But out of the lab and on the road, SHOs don’t ping on regular. Beatty said that last summer Ford engineers drove several test cars with the knock detectors disconnected and never heard a sound. The factory-set ignition timing is right for best torque with premium fuel. Lf you have regular in the tank and the engine pings, the electronics will pull back the spark, thereby reducing torque. But if the engine doesn’t ping, the spark stays where it was set and you get all the torque there’s ever going to be. Beatty says spark pullback is a possibility—maybe if you’re towing a trailer through Death Valley with a carboned up engine—but not likely.
Contrary to what most motorists think, premium fuel doesn’t contain more power per gallon than regular. They’re the same. The power comes from having enough octane to allow optimum spark advance. If your engine doesn’t ping on regular, premium will do nothing for you. Moreover, most engine engineers will tell you that a modest amount of part-throttle ping bothers you more than it hurts the engine.
Although I haven’t talked to engineers from every company, I think it’s likely that most modern car engines have no more need for premium fuel than the SHO’s does. Turbos are a major exception. Some turbos are has-been engines being squeezed for a last bit of juice be fore retirement. They have outdated combustion chambers. Add to that the extreme temperatures and pressures from the turbo and you’ll want all the detonation insurance you can get.
Other turbos are highly sophisticated. Saab’s system, for example, listens for the onset of detonation and sets boost accordingly. Hose in a dose of Mexican regular and power will drop to the mañana level. Buy the good suff and power will climb in lock step with octane up to 92 PON. Octane ratings above that may make you feel like you’re giving the engine a treat, but the engine won’t notice.
So, unless you’re driving a turbo, premium is largely a placebo. But, hey, people like placebos. That’s why such a word had to be installed in the dictionary. And that’s why extra pumps are springing up at gas stations. The oil companies have discovered, to their delight, that people will pay up to twenty cents a gallon more for a gasoline better than the premium they already don’t need. Hence we now have super premium. Financial analysts say oil companies are harvesting 50 to 60 percent of their gasoline income from these placebos.
Within the trade, this deft mining of customer psychology is called “retailing.” The art of retailing is why when you stop, for example, at one of Ashland’s Super America stations, you have to walk through a maze of display racks thrusting at you Charms, Chuckles, Chiclets, Cheese Doodles. and Chattanooga Chew before you can get to the cashier to pay for your gas.
Perhaps this is only right, because if you spend the money for a chew instead of premium, your engine will never know the difference.
Mine runs just fine on 87.
-T
^^^ Great freakin’ read
very tru too
nice read
excellent statement…for example…my maxima has a knock sensor that listens for knock…the ECU continues to advance timing until it detects knock then it backs off timing appropriatly…now i am sure there is a limit to how far advanced the timing would go…i would probably not benefit much from race gas…and for those of u who dont know Octane is the fuels anti-knock index so the higher the octane the more resistant to knock it is…so if ur ECU does such as to advance timing until it dtects knock then u benefit…if it doesnt becuase some cars with have set timing and it doesnt change then dont worry use what is recomended by ur manufacturer
A little searching on J-body.org, and I learned that 87 is the best according to the majority of people.
A few said 92 will yield minor hp gains, but have no proof to back it up.
Although boosted cars, they suggest running 91/93 because of it’s higher combustion resistance.
One members post:
“I want some proof that 92 octane adds horse power to a stock N/A engine. 87 burns faster and easier. People that are running forced induction or high compression need higher octance because that gas doesn’t ignite as easily. Lower octane gas will pre-ignite on those cars.”
I’m sure for the most part (if this is true) this arguement holds true for most NA cars, and most boosted cars.
I didn’t say that running lower than 91 was bad. I said most newer vehicles would benefit from running 91 vs. 87/89. As people have already said, many newer stock ECU’s automatically advance timing based on knock readings so they DO make more power and run more efficienctly when you run 91 octane vs. 87.
I have dyno charts and tested by recording gas mileage to back me up. What evidence do you have that running an octane higher than 87 in a new vehicle doesn’t provide HP gains?
-Mike
excellent read. I have a question tho, might be dumb…my timing is advanced, not sure by how many degrees , I def have to run premium, correct?
You should say very few or some newer vehicles. Please elaborate and tell me which vehicles have these advanced computers. If they advance the ignition timing all the time do they even have spark load tables. The fact is the vehicles that require high octane fuel state so in the owners manual. For example the older generation GM DOHC northstar engine. Also what dyno charts do you have and on what car. Like I said before gasoline IS NOT magic. Just because a vehicle runs better on 91 octane vs. 87 octane isn’t always a function of the fuel. You do know that heavy carbon deposits on the tops of pistons can cause knock. The 91 octane fuel might help this situation out, but so would a bottle of seaform (GM topend cleaner)
Many newer vehicles run what are called spark difference maps. They give the computer a base timing map and run algorithms which increase timing off that base map based on current and historic readings from the knock sensor(s) and other sensors.
The majority of newer imports do this. For example: VW, Audi, Subaru, Honda, Mitsubishi, etc. Perhaps some new US don’t do this, but I’d be surprised if the higher performance ones didn’t.
I guess you’re saying that 91 octane fuels have extra cleansing agents that remove carbon deposits? Is that what you’re saying?
-Mike