Highest Octane For Stock ECU??

DEpointfive0 · 11-21-2013, 12:28 AM

Quote:

Originally Posted by Driftomodachi

From what I have heard, 100 octane in Japan is like the 91 octane here and 91 octane there is like the 87 octane here. And since the z is a "world car" the ecu should compensate and performance should improve with the highest octane the car was designed to run on which is 100 octane.

Not sure how true that is

The US doesn't use Octane, we use AKI, average knock index. You cannot compare it to the rest of the world

Jordo! · 11-21-2013, 12:58 AM

Quote:

Originally Posted by DEpointfive0

The US doesn't use Octane, we use AKI, average knock index. You cannot compare it to the rest of the world

We do refer to octane, but it's rated a bit differently -- RON+MON/2 = AKI, whereas most of the rest of the world uses RON.

You can get a close approximation on RON vs AKI tho'; typically .95*RON = approximately equivalent AKI.

Example: The Z recommended octane is 91 AKI and 96 RON

96 RON*.95 = 91.2, very close to the AKI value.

DEpointfive0 · 11-21-2013, 01:07 AM

Quote:

Originally Posted by Jordo!

We do refer to octane, but it's rated a bit differently -- RON+MON/2 = AKI, whereas most of the rest of the world uses RON.

You can get a close approximation on RON vs AKI tho'; typically .95*RON = approximately equivalent AKI.

Example: The Z recommended octane is 91 AKI and 96 RON

96 RON*.95 = 91.2, very close to the AKI value.

Yeah, that's close.

If the RON is 100 in Japan, 95~ AKI

My money would be something like 94 on America's AKI system because that's probably the highest you CAN find at a normal pump in the US (I think I've seen 94 at the pump in Ohio, or Illinois, or Michigan)

Mt Tam I am · 11-21-2013, 09:37 AM

All this had to do with octane wars years ago (1970's ??). This ended once they settled on the RON+MON/2 = AKI formula.

Driftomodachi · 11-21-2013, 01:35 PM

Quote:

Originally Posted by DEpointfive0

The US doesn't use Octane, we use AKI, average knock index. You cannot compare it to the rest of the world

I'm sure Nissan considered all this when they put parameters on the ecu so that it could be a world car.

So can a z34 run "100 octane" or whatever it's called from the local 76 station pump here in So Cal and will it improve performance?

When I had my 240sx with an sr swap it ran ok on 91 but felt much livelier when I put in 100 but the vq is a different motor. Sorry for the noob question just trying to learn. It's funny google actually pulls up better results than the forum but I haven't found a thread that confirmed anything

DEpointfive0 · 11-21-2013, 01:58 PM

Quote:

Originally Posted by Driftomodachi

I'm sure Nissan considered all this when they put parameters on the ecu so that it could be a world car.

So can a z34 run "100 octane" or whatever it's called from the local 76 station pump here in So Cal and will it improve performance?

When I had my 240sx with an sr swap it ran ok on 91 but felt much livelier when I put in 100 but the vq is a different motor. Sorry for the noob question just trying to learn. It's funny google actually pulls up better results than the forum but I haven't found a thread that confirmed anything

I doubt it. And you'd probably "gain" only if you reset your ECU too

Jordo! · 11-21-2013, 02:36 PM

Quote:

Originally Posted by DEpointfive0

I doubt it. And you'd probably "gain" only if you reset your ECU too

Basically, if it wasn't running full advance, it would be more likely to do so on higher octane fuel.

And I say "more likely" rather than definitely because other sensor data affects how much advance it runs (e.g., oil temp).

Of course, you could always fill it up with a full tank of >100 AKI, and with Uprev try and dial in more advance, then save it as a "track day/High Octane" tune...

DEpointfive0 · 11-21-2013, 04:11 PM

Quote:

Originally Posted by Jordo!

Basically, if it wasn't running full advance, it would be more likely to do so on higher octane fuel.

And I say "more likely" rather than definitely because other sensor data affects how much advance it runs (e.g., oil temp).

Of course, you could always fill it up with a full tank of >100 AKI, and with Uprev try and dial in more advance, then save it as a "track day/High Octane" tune...

Yes, for sure, that is a different story. You can of course do that.

chops · 11-21-2013, 07:53 PM

Quote:

Originally Posted by Driftomodachi

I'm sure Nissan considered all this when they put parameters on the ecu so that it could be a world car.

So can a z34 run "100 octane" or whatever it's called from the local 76 station pump here in So Cal and will it improve performance?

When I had my 240sx with an sr swap it ran ok on 91 but felt much livelier when I put in 100 but the vq is a different motor. Sorry for the noob question just trying to learn. It's funny google actually pulls up better results than the forum but I haven't found a thread that confirmed anything

full tank of 100 octane is definitely overkill unless you have a tune for it. but i throw in a few gallons to hit about 93-95 octane whenever i go to the track or do some spirited driving

11-21-2013, 09:37 AM	#4 (permalink)
Mt Tam I am A True Z Fanatic Join Date: Jun 2010 Location: California Posts: 10,709 Drives: 370Z T/S/N 6MT & XKE Rep Power: 3844	All this had to do with octane wars years ago (1970's ??). This ended once they settled on the RON+MON/2 = AKI formula. __________________ "Does the carpet match the drapes? NO!!! I don't date bald women." Nissan Motorsports 34R Oil Cooler. Stillen CBE. Hotchkis Sport Sway Bars. KW Variant 3 Coilover System. Stillen Gen3 CAI. Michelin Pilot Super Sport. Stillen Brake Ducts. Carbotech™ XP10/XP8 Pads. Z1 Front Rotors. Z1 Stainless Brake Lines. Two degrees of camber

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