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Goldenstate · 03-05-2014, 01:36 AM

Installed a set of CNC machined under-drive pulleys on the 1999 F150 4.6 engine yesterday. I immediately noticed a decrease in noise from the engine area as everything was spinning slower. The first driving experience was interesting as I quickly realized I had more power not being lost to the serpentine belt. Most of the reports I have read say one can feel the difference in power with the under-drive installation.

I did a short road test this evening and was disappointed to only achieve 22.95 MPG. Last fall before we went to the winter fuel mixture, I had test runs that achieved 25.5 MPG. I was hoping for at least breaking the 26 MPG barrier but that may have to wait until the Summer blend fuel is once again part of our life here in CA.

My other thought is to fill the tank with some Chevron Supreme and see if the higher octane fuel will improve my results. A Scangauge has been ordered and it may well give me some more credible results.

03-05-2014, 01:36 AM	#1 (permalink)
Goldenstate Heilopower Join Date: Oct 2013 Location: Central California Posts: 70 Platinum Ghost - '14 Ford Fusion SE 90 day: 33.44 mpg (US) Thanks: 8 Thanked 12 Times in 10 Posts	Under-drive pulley installation test drive Installed a set of CNC machined under-drive pulleys on the 1999 F150 4.6 engine yesterday. I immediately noticed a decrease in noise from the engine area as everything was spinning slower. The first driving experience was interesting as I quickly realized I had more power not being lost to the serpentine belt. Most of the reports I have read say one can feel the difference in power with the under-drive installation. I did a short road test this evening and was disappointed to only achieve 22.95 MPG. Last fall before we went to the winter fuel mixture, I had test runs that achieved 25.5 MPG. I was hoping for at least breaking the 26 MPG barrier but that may have to wait until the Summer blend fuel is once again part of our life here in CA. My other thought is to fill the tank with some Chevron Supreme and see if the higher octane fuel will improve my results. A Scangauge has been ordered and it may well give me some more credible results.