[JantzenOKC]

Originally Posted by Mr. Stacy

Maybe for a turbo.

You can't get more power from more octane. You can compress higher octane fuel more before it ignites by itself. That is all.

If your engine is designed to highly compress the fuel (as in a turbo or other such high performance performance feature) then you actually NEED a higher octane rating.

Octane rating is a measure of it's ability to compress before spontaneous combustion. If your engine (LFX) does not compress the fuel enough to cause spontaneous combustion, the money you spend on a higher octane rating is wasted.

GM 3.6L V6 LFX Engine Specs
Type: 3.6L V6
Displacement: 3564 cc (217 ci)
Engine Orientation: Longitudinal and Transverse
Compression ratio: 11.5:1
Valve configuration: Dual overhead camshafts
Valves per cylinder: 4
Assembly site/s: St. Catharines, ON; Flint, MI; Melbourne, Australia; Ramos Arizpe, Mexico
Valve lifters: Roller follower with hydraulic lash adjusters
Firing order: 1-2-3-4-5-6
Bore x stroke: 94.0 x 85.6 mm
Bore Center (mm): 103
Bore Area (cm2) (total engine bore area): 416.37
Fuel system: Direct Injection
Fuel Type: Regular Unleaded, E85 capable

http://www.nicoclub.com/archives/gas...ane-myths.html


Read more: http://gmauthority.com/blog/gm/gm-en...#ixzz41a28ujoA

I'm talking about the LFX in stock form. I've never ran less than 93 since being boosted, as I'm tuned for 93.

A stock LFX runs fine on 87, but it pulls timing (knock reduction) to be able to do it. If you run 91 it will pull a lot less timing if any at all. Less timing = less power, more timing = more power. So yes 91 will make more power in our cars than 87 will. But not because "91 makes more power" but because 91 allows the ecm to run the timing it was designed to run. It just has the ability to instantly reduce the timing as soon as knock is detected. That way the masses can fill up with 87 and be happy.