|12-16-2013 08:36 PM|
|dyn085||Merged with anyone using premium gas ?|
|12-16-2013 05:39 PM|
The MK3 will always run better the higher the octane with its compression , I never use anything but 93
|12-16-2013 05:03 PM|
|geneticjim||The research Ive done on octane for my motorcycle and cars over the years is summed up quickly -----> The higher the compression the higher the octane is needed so the engine will not knock and will not have pre-ignition. My motorcycle uses 87 octane better than 93 due to low compression. The 2012 focus I have seems to run better on 91+ octane.|
|12-16-2013 04:46 PM|
Hundreds of postings on the octane 'war'. Wherein some say the upgrade to Premium is well worth the expense (me included I use 93 all the time in my 2012)(( better idle, better tip in better acceleration...))
Another pontificating how 93 is a total waste of money and 'proof' it cannot make any difference for our dumpy little cars.... blah blah blah
One of the more entertaining sets of posts.. I would think your post should be merged into the others..
|12-16-2013 04:25 PM|
93 octane vs 87...
Anyone else get better mpgs/ performance with 93 octane vs the regular 87?? Ran regular for the first couple weeks of owning my focus then figured a couple bucks more a tank for premium wasnt a big deal. Been running it ever since, then recently switched back to regular for a good 3-4 tanks. Wow noticable difference in pep(lack of) and lower gas mileage about 2-3 mpgs less or about 30 miles less on the overall miles per tank.
Gas mileage may increase if I ran it for another couple tanks but I like the get up and go better with the 93. Just figured I'd share a bit of experience/difference in my case with the two.
I have a 2013 5 speed with just a CAI.
|12-05-2013 09:42 AM|
Yes, it can protect from fouling and/or hotspots or cylinder walls in air cooled aircraft engines. It's handy if you have individual cylinder head or exhaust gas temp readings. Lean of peak is very handy but has to be done precisely to avoid the obvious consequences of running too lean.
Aircraft engines are also often direct injected so much of the same practice is probably being used by car manufacturers in hopes of better fuel economy. My only beef with it is that AvGas is 100oct leaded fuel, and is much more conducive to it VS the 87oct Murphy USA junk that most Foci are fed. It's harder to pull off reliably in a car because of that.
|12-05-2013 09:33 AM|
|12-05-2013 09:32 AM|
|cessna1||While this is a little different, on airplane engines these terms are used Rich of Peak, Peak, and Lean of Peak exhaust gas temperatures. Generally it has been normal practice to run 100 degrees ROP. If you can balance the fuel injectors to make equal exhaust gas temps, you can run 100 degrees LOP at a lower power setting and get better fuel economy. Basically things go so lean that they cool off.|
|12-03-2013 02:33 PM|
I did not make the assertion that "...lean burn is the recipe for fuel economy these days".
I did ask a simple question.
Lean burn means that the engine operates (when cruising) with an air/fuel ratio significantly leaner than stoich.
|12-03-2013 12:56 PM|
Your definition of "lean burn engines" I feel is different from what is being discussed, I'm relatively positive that the main goal of GDI implementation as far as fuel economy is to enable lean burns in low load scenarios by a modified spray pattern (stratified charge during compression stroke) and piston -
Here's a photo of V6 Ecoboost piston:
Mazda SkyActiv Engines have similar characteristics, albeit more agressive piston cavity and higher compression ratio:
There are also patent documents from Ford which talk about how fuel type is sensed in their new Flex-Fuel vehicles which results in different fuel injection strategies for ethanol (E85) vs E10 and gasoline.
I'm not a fan of being so blunt. People lose respect quickly.
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