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Old 12-19-2012, 12:52 AM   #55 (permalink)
RH77
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Join Date: Nov 2007
Location: Kansas City Area
Posts: 1,761

Teggy - '98 Acura Integra LS
Sports Cars
90 day: 32.74 mpg (US)

IMA - '10 Honda Insight EX
Team Honda
90 day: 34.76 mpg (US)

Tessie - '06 Acura TSX Base
90 day: 28.2 mpg (US)
Thanks: 31
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Quote:
Originally Posted by Ardent View Post
As a test subject, she and her car are near ideal as far as I can determine. ... I believe that the mileage increase is because of the octane reduction caused by adding oil to gasoline. An engine with safe/conservative ignition timing then benefits from the timing "advance" caused by the added oil. I expect that I could see the same mileage increase by more optimally dialing in the timing.
What kind of drivetrain is in your Wife's car -- does it require premium fuel (also the truck, is it a pushrod vs. OHC)? My testing is currently in a vehicle with full mechanical advance (distrubutor), warm/hot intake temps, and increased Winter coolant temps. I found that this combo requires premium fuel to prevent detonation year 'round (although it's not needed for this engine in stock form). I'm halfway into a tank and haven't noticed any pinging (including high loads -- didn't before either) -- I'll have to try high-RPM as well. My planned, "blinded" test vehicle (TSX) has been proven to need premium, as recommended. Lower octane fuels decrease FE and increase detonation across the board (loads, RPM, etc.) -- especially while under the i-VTEC's performance (high-RPM) valve lift/duration (rarely used).

So, I'm hoping the the 91-Octane fuel doesn't get reduced down to 87 as I'm pumping it into the tank along with the "blue-stuff". More investigation may be required if I try it in the "complicated engine".

Quote:
Originally Posted by nbleak21 View Post
I noticed very similar results in my Acura (2-3mpg gain on longer trips) prior to my VAFC install. I also noted similar gains using ethanol free gas (still 87octane) after my VAFC install...
Same question for you -- is it recommended that the CL use 91-Octane?

Just a hypothesis: maybe compression has something to do with it.

Only note of possible improvement -- I wish I could quantify "crank" time before the engine fires. It seems to be quicker to start now, but I have no way to communiate that legitimately.

RH77
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