I know that there are plenty of similar posts so don't flame me.

My question is a bit different- actually the opposite of the previous one.

Not to far from where I live I have the opportunity to buy 103 octane. I know what happens when you ran a car on it (better combustion,more power, etc...)

I've read that about 7 HP get more to the wheels when compared to 91 octane.

My question is if anyone has ran there car on higher octanes, what are your impressions of it.

 

no way. absolutely not. BS. and anything else you can think of. If someone is claiming 7whp from using 103 octane, ask them to show you the dyno sheets before and after. If it is a stock VQ engine - not meaning intake and exhaust, but actual engine parts - 103 will not produce 7whp. I challange anyone to PROVE me wrong. BTW proof is not just saying so, it's documentation.

'04 coupe6mt
ivory premium aero

92 plymouth laser AWD
heavily modified for solo II
11.51@118 on 215/55 goodyear eagles

03 dodge ram quadcab 4X4 Hemi

 

Wax on wax of...

Try it - its only what $8.00 or more a gallon?


NY G SQUAD<font color=red>&lt;---Official Website

 

if you had a turbo kit then you would see some serious hp gains in the double digits

 

With a turbo(depending on the PSI) its sometimes almost very neccesary for a high octance (octane boosters) for a good combustion.

As for the 7whp thing, I'll try to find the article- I believe it was online from a "reliable" source about the 350z

 

Octane is only one measure of fuel performance. Suggest you google VP Race Fuels to learn more. As far as octane alone is concerned, once you reach the point where bang is happening at the intended time, not before due to pre-ignition/detonation caused by low octane, that's it, you're done. Higher octane than that (alone) is of little benefit. As a motorcycle racer, I will tell you that if you mod your bike, say, shave the head to up the compression, then now it's time to go looking for more octane to combat the higher compression ratio. A diesel works by having compression high enough and fuel volatility high enough (think lower octane) that compression of the fuel mixture generates enough heat to "bang" the charge without a spark. That's why old guys sometimes refer to detonation as "dieseling". Back to regular IC engines, unlike simply raising the octane level (I remember people being all wowed by aviation fuel), race gas like VP or Klotz is far more stabile, thus results in more consistent flame, which results in more consistent burn, which reduces heat in the engine, which allows more efficient/optimised combustion, which again results in more power. Tests of a midsize race bike with race fuel yielded a 7% (yes percent!) increase in power versus 93 octane Exxon, but that's because these bikes are in a much higher state of tune, tweaked, (more air can be safely put into the charge with race gas) and really need good fuel. And a race bike gets it's engine rebuilt every 20-25 hours of use. Your car, on the other hand, has a wonderful computer which compensates for crap fuel by reducing the ratio of air to fuel (more fuel less air), which yields less power and crap gas mileage to protect the engine from harm. It's also is one of the many factors that that explains why across the continent we see wild differences in dyno results (dynos themselves are also to blame, along with a bunch of other stuff). Buy your hi-test at a place that turns over a lot of fuel each week. That way you know it's still close to the number on the pump. Short of buying race fuel, which no one would do for their car, I think that's the best approach to take.

Cheers,
Derek

DB

 

Good points by derek above on Octane and what's it's all about... If I can offer my own spin: In modern street EFI applications, the ECU has been calibrated to only allow a certain amount of spark advance. Basically, the computer doesn't know what to do with 100+... It can't take advantage of the higher octane because it's already at it's max allowable advance when you're running 94.

In my turbo application, the higher octane the better as it allows me to run a few more PSI with the same amount of fuel delivered and keep EGT's in a good range. (for the reasons Derek mentioned).

Side note/useless (for here) fact: my vintage '80's turbo Dodge MPFI application calls for +12^ base (mechanical) timing and the computer can add/subtract 40^ for a maximum advance of 52^

To make this relevant to this forum in some way, I guess I'll just say that running 102 in your G is basically useless, as someone mentioned in 10 words or less above. ;-P