Good, short article on premium fuel

[decypher44]

Scientific American

Here's a short article on premium fuel. So, am I wasting my money?

[blkbelt65]

good article, thanks. myself, I run 87, our engine is designed to run 87. I don't have nor have I ever had any issues with it so I for one will continue to use it until a problem warrants that I shouldn't.

[ambiguousanomaly]

I don't think so, a compression ratio of 9.8:1 (our motor) is fairly high. It would not be unreasonable to imagine the Titan pinging on 87 under a heavy foot. I run premium because I drive the truck pretty hard and I don't want it to ping and thus retard my timing. If you want to find out for sure, run a couple of tanks of 87 and pay close attention to whether or not you notice any pinging. Let us know what you find out, I'm going to give it a try myself, will update after the first tank.

Cheers

[CVTITAN]

Interesting I heard some of that before. I have a supercharged benz and it calls for 91 octane. I guess its because its a sports car?

[Quartz]

I've never had have any problems or issues with regular in my Titan. The engine is designed for it and runs fine on it. I have owned vehicles that needed premium but the manufacturer always recommended it.

I think the running premium instead of regular debate is one of those issues like the DIY airbox mod. It might help, it might not. But it won't do any damage and if it makes you happy, do it.

[Antihero]

I run regular and have no problems.

[Xcheckme]

I've always followed manufacturers spec, i.e. in the case of the Titan regular 87 is fine.
AFAIK generally only turbo-charged or high performance engines require higher grade. My wife's Audi needs (again, according to the manual) 91 minimum.

[chunko]

Originally Posted by ambiguousanomaly

I don't think so, a compression ratio of 9.8:1 (our motor) is fairly high. It would not be unreasonable to imagine the Titan pinging on 87 under a heavy foot. I run premium because I drive the truck pretty hard and I don't want it to ping and thus retard my timing. If you want to find out for sure, run a couple of tanks of 87 and pay close attention to whether or not you notice any pinging. Let us know what you find out, I'm going to give it a try myself, will update after the first tank.

Cheers

Are you implying that someone could "try" 87

I think that test is ran all day every day by most titan owners...maybe I'm missing something. Neverheard of the titan having problems with pre-detonation.

[37L1]

"If you think you need it," Green says, "you're being very eccentric."

[Yahooligan]

Some things to consider about fuel grades:

Octane rating doesn't have anything to do with the energy potential of the fuel.

A higher octane fuel is harder to ignite and has a slower frame front (burns slower)

From this, it's not very difficult to draw some basic conclusions about using 87 vs 91 octane fuel.

If 87 octane fuel doesn't result in your timing being retarded then running a higher octane fuel will have no benefits. Equal amounts of 87 and 91 octane fuel have the same energy potential, so the 91 octane fuel by itself doesn't provide any additional power.

If 87 octane is getting a complete burn per ignition cycle then your burn efficiency is 100%. If you run 91 and, due to a slower burn, it only burns 95% then you've lost 5% of your energy potential per cycle, which means you're blowing unburned fuel out the exhaust and are actually losing power and wasting fuel compared to 87.

On the other hand, if your timing is being retarded (The knock sensor can and does pick up preignition that your ears won't hear) with 87 then going to 89 or 91 will give you an improvement.

Octane should be selected as part of how your engine is performing, not as a performance enhancer itself.

[Quartz]

Originally Posted by Yahooligan

Octane should be selected as part of how your engine is performing, not as a performance enhancer itself.

Nicely put.

[abmobil]

Most vehicles that call for 87 need nothing more.
The Titan can operate fine on regular ,but I do beleive the Titan is one of the few that can see some benefit with premium.

The infinit QX56 shares the same engine with the same compression ratio ,but calls for premium and for 04 through 06 models its rated 10 hp more.

For 07 its rated only 3 hp more at 320hp vs 317 for the Titan.

There has been some speculation on this board if the tuning and ECU,s are the same.
I have no proof ,but im prety sure they are tuned the same.

The Titan makes loads of power on either grade ,but if your looking to extract all of its potential I do think it will benefit from premium.

[myTtitan]

Going through my owners manual and found recommended unleaded regular gasoline with an octane rating of at least 87 (anti- Knock Index) number(Research octane number 91).

[Mr.TEE]

In the mid-80's, Chrysler's 2.2L engines were equipped with a knock sensor. The ECU would advance the timing until knocking was sensed and then retarded the timing by 2 degrees. If any type of knocking was sensed it would automatically retard timing in 2 degree increments. Every few minutes it would advance timing slightly until knocking was sensed and would go through the cycle again. I don't know if Nissan's ECU follows the same logic, but if it does then one would benefit from use of higher octane. On the other hand, if no advance in timing takes place and the engine is operated near redline (high RPMs), higher octane fuel is slower burning thus it would be burning while exhaust valve begins to open (piston at bottom of stroke just as it is coming up) which may cause burning of exhaust valves. So your best bet is to follow the manufacturer's recommendation on grades of fuel.

[Footloose301]

I run 93 just because its only a $0.20 difference between the 87 and 93...so basically if my tank is empty and 20 gallons goes in.... thats only $4.00 more per fill up.... and its not breaking my bank by doing it. And I'll tell ya what, that $4 I'm using to keep my conscience in good standing is keeping me from eating that extra McDonalds that I don't need each week.