Anybody tried 100 octane in 2nd Gen?

[BadQ45t]

There is a gas station here in California that someone on the board pointed out for me. I stopped there and saw 100 octane. I was too scared to try it, thinking it was so high. Anybody try it? I was thinking maybe use 1/4 tank of it and 3/4 of the Cali 91.....thoughts?

[jnever1]

Some 100+ is leaded. I would be VERY careful of such significant additives. For example: there is a 110 octane pump at my local BP. It is, however, leaded. The Michigan International Speedway is about 10 miles from my door, so demand for leaded race fuel is locally present, as it is likely with the station you have visited.

Here is an excerpt from wikipedia on octane:

Many high-performance engines are designed to operate with a high maximum compression, and thus demand fuels of higher octane. A common misconception is that power output or fuel efficiency can be improved by burning fuel of higher octane than that specified by the engine manufacturer. The power output of an engine depends in part on the energy density of the fuel being burnt. Fuels of different octane ratings may have similar densities, but because switching to a higher octane fuel does not add more hydrocarbon content or oxygen, the engine cannot develop more power.

Source: http://en.wikipedia.org/wiki/Octane_rating

With leaded fuel you must consider your injectors, spark plugs, and O2s (really, your engine in general). Such parts can accumulate lead deposits and essentially deaded their respective abilities. Also, lead can destroy your catalytic element.

For what it's worth, the Speedways and BPs in Michigan offer 93 octane. I use it exclusively but have not noticed a difference from the 89 or 91 rated fuel oil I've purchased from California, Arizona, New Mexico...

[BadQ45t]

interesting, well I know it wasn't leaded because it said "Unleaded" on the pump and there is leaded gas in the state of California. It had the smaller pump like all unleaded, back in the day the leaded pump was 1/4" biger, I made that sucker fit my old Celica

I was just wondering if pumping up the volume a little or yield some better gas mileage, sounds like it wouldn't given your results.

[jnever1]

It would be an interesting comparison (I'm a chemical engineering student) to test the density of the 100 octane versus what you normally buy. A hydrometer and a thermometer could be used to simply determine whether the density of the 100 octane is significantly greater than your regularly purchased fuel. If so then, yes, you would "get more power" from the higher density fuel. IF you could manage a lighter foot then, theoretically, you might see a tiny improvement in MPG. Of course, then your fuel pump has to work harder, and your injectors may be exposed to higher pressure, etc...

You might also want to consider the additional cost of the higher grade fuel. The 110 race gas by me costs 3X the price of 93 octane and you would be a damn fool to believe the Q will EVER get 60 MPG!

FWIW, I have been trying to affect something similar with a Stillin conical air cleaner in place of the original air cleaner. So far all I've managed is a throatier engine growl. ;-) Apparently my foot isn't receptive to change!

Good luck.

[jnever1]

By the way... I noticed your 84 300ZX... I shed tears the day my 86's transmission took a crap on me... To this day I have never seen a more efficient use of dashboard electronics than the digital instrument cluster that my 86 had.

[SanCarlosQ45]

Kings 76 on woodside road right. I think I mentioned it awhile ago. Anyways the 100 at the pump is unleaded, but the higher octane gas in the barrels in the back are leaded. I believe they have 108 and 116 which are leaded.

I put about half a tank in about two years ago and it definitely felt different. Idle was more smooth and it had better throttle response. I would recommend after you do that try the car on Canada road, I think I hit about 135 on the second half! Its on your way home anyways.

[paranoidjack]

By the way... I noticed your 84 300ZX... I shed tears the day my 86's transmission took a crap on me... To this day I have never seen a more efficient use of dashboard electronics than the digital instrument cluster that my 86 had.

\

Wow! Never seen that.

[BadQ45t]

Thanks for the tip....I do still have a cherry 84' 300zx with that exact dash. While based (by several on this board) as the "Disco Danny" dash it only shows their lack of understanding. There have been very few digital dash boards produced that actually were worthwhile, this is one of them. I have retrofitted it with a 85' Turbo dash as I enough issues with my original 84 NA that I had to get working one in there. I love how you can see the tach come up to show production of tourque and the fuel gauge is quite simply the most accurate one ever to this day made.

It wasn't easy to get it all working but when it does (and mine is) perfect it rocks!

[BadQ45t]

Thanks for the tip....I do still have a cherry 84' 300zx with that exact dash. While based (by several on this board) as the "Disco Danny" dash it only shows their lack of understanding. There have been very few digital dash boards produced that actually were worthwhile, this is one of them. I have retrofitted it with a 85' Turbo dash as I enough issues with my original 84 NA that I had to get working one in there. I love how you can see the tach come up to show production of tourque and the fuel gauge is quite simply the most accurate one ever to this day made.

It wasn't easy to get it all working but when it does (and mine is) perfect it rocks!