Rec 90 Fuel?

[fisheye]

Someone recently told me I should try running Rec 90 in my 91 nsx. Is this a bad idea? I know the manual calls for 91 octane but gas with no ethanol sounds interesting.

 

[JD Cross]

What would you hope to gain by running 90 octane in your engine?

 

[mrdeadman]

What would you hope to gain by running 90 octane in your engine?

He's get better fuel mileage running gas without ethanol in it.

 

[JD Cross]

He's get better fuel mileage running gas without ethanol in it.

Then why not 89 or 87 octane. Better mileage and cheaper too?

 

[mrdeadman]

Then why not 89 or 87 octane. Better mileage and cheaper too?

Octane isn't the reason he'd get better mileage the lack of ethanol is.

 

[Old Guy]

As with all things in life, it will be a trade-off. The slightly higher energy content in gasoline versus ethanol would theoretically result in slightly lower fuel consumption. However, the energy difference between a gallon of 90/10% gas / ethanol and a gallon of 100% gas is small - do the math. That improvement could be offset by the loss in efficiency if the EMS pulls the ignition timing to prevent knock. That will depend on how the OP drives. If they never drive aggressively enough to induce detonation on the REC 90, then there might be no down side.

The OP is from Florida, so this is probably not an issue for them; but, if you live in a colder climate and store your car for a significant period of the year, pure gas as opposed to an ethanol blend can prevent the nasty effects of phase separation that can occur if the ethanol component in the gas has taken on any moisture.

- - - Updated - - -

Then why not 89 or 87 octane. Better mileage and cheaper too?

Updated avatar JD - does that mean you have taken delivery of your new wheels?

 

[JD Cross]

Octane isn't the reason he'd get better mileage the lack of ethanol is.

I understand that.

In Oct 2013 I drove from Belle Vernon PA to Raleigh NC for NSXPO and back to Vancouver on 10 % ethanol 91 octane.
The mileage was less than 1% lower than driving on 91 octane ethanol free for the previous 3420 miles.

Would rather have the protection of higher octane (with or without ethanol) than risk detonation.