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Discussion Starter #1
One thing I've always loved about Nissan vehicles is that when you put a higher octane gas in the tank than the vehicle really needs, the computer tends to figure it out and dial in more power. This was especially true with my Titan when I had it. The first time I put premium gas in the thing, it had a whole lot of power it didn't have before.


My question is: has anybody tried this with the 2nd gen X yet and noticed a power gain or mpg difference?

Just curious...
 

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I've used a few tanks of premium and "felt" like I noticed a difference but I can't be positive.
 

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Duck said:
One thing I've always loved about Nissan vehicles is that when you put a higher octane gas in the tank than the vehicle really needs, the computer tends to figure it out and dial in more power. This was especially true with my Titan when I had it. The first time I put premium gas in the thing, it had a whole lot of power it didn't have before.


My question is: has anybody tried this with the 2nd gen X yet and noticed a power gain or mpg difference?

Just curious...
I believe the Toyota FJ and the new Tacoma's do this. When Toyota advertises the 235 HP engine, that figure is based on the vehicles ability to detect hi octane fuel and advance the timing accordingly.

Somebody smack me around if I'm incorrect. I'll take my medicine. :blackeye:
 

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I alternate between and regular and premium all the time. If anything, the detergents in the premium can't hurt, right?
 

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Oh boy! This is a touchy subject. A engineer that works for GM Well, retired now, swears that if it will run on lower octane, use it! He made his case used a slew of technical terms and charts and all that over on Caddyinfo.com. But, I have to agree that when you burn the better stuff it pumps a little easier. I been doing a test with the amsoil gas additive, something that same guy swears don't use. (Additives) I think the best thing is, all opinion, is keep the injectors and fuel related things as clean as you can for best longevity, once it gets gummed up, you never get it clean again.

MC
 

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This is what I have about this:

When my tank was almost empty, I disconnected the battery for more than 20 minutes, then filled up with regular and kept records for three tanks:

1st 17.28 mpg
2nd 17.36 mpg
3rd 17.55 mpg

Then repeated the process with premium and got:

1st 18.03 mpg
2nd 18.01 mpg
3rd 18.64 mpg

I always filled at the same pump.

So basically, I got a consistent higher mpg with premium than regular, not much though.
 

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a guy on a forum around here proved all that false.

with real dyno testing. he ran 91 octane for two tanks, and dynoed before and after. Gained NOTHING from higher octane, even lost 1-2.
 

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So will the timing adjust with higher octane?
 

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Discussion Starter #12
burnout said:
Interesting indeed. It is worth noting that the only significant thing one gains with the higher octane is a little more torque in the low rpms. This is something that I am willing to try simply because I have a manual tranny and it just seems that the truck needs a little punch in the low end before I see it really take off after the engines spins up a bit.

Thanks for the great link.
 

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Wow, thanks for the dynos, burnout. Wonder how the graphic is bellow 3,500 rpm.

I usually shift at 3,500 rpm or bellow, and cruise at 2,000 rpm.

According to the dynos, at 3,500 rpm torque is 135 with 87 octane gas and 155 with 91 octane, that's about 15% more juice.

That extra power at the low end is highly appreciated at daily driving and rockcrawling :cheers:
 

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The dyno's he posted re-enforce all that the GM power train engineer told us on Caddyinfo.com The octane and the K&N. Bruce, founder of Caddyinfo Swore a K&N was better, he did the testing and posted a factory paper filter actually did better. Amsoil also says no K&N, lets too much dirt to the oil. So, pretty much factory has things right out of the box. Not sure the Gibson exhaust is really worth it now. I really like his testing procedures. MC
 

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Offroad said:
Wow, thanks for the dynos, burnout.
ah you know theyre not mine, theyre some priest dudes. but very valuable none the less. it helped me decide to not waste money on mid grade gas.
 

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I try to use the mid grade or high end octanes every like 3rd fill up. For some reason i figure it cleans out the injectors. But wha the hell do i know. I have a race car driver as a client. He told me its all a bunch of bs, and to use the cheap stuff. Unless its some exotic sports car, it doesnt make a difference.
 

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Some interesting results.
I think the exhaust is still worth it, especially if you're loading it down, towing or running at high altidude. Every bit helps plus it makes it sound better.
 
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