Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Can swapping in taller gearing result in worse fuel economy?

Christ · 11-20-2008, 02:45 PM

Stop for a minute and think about the ratios you're going to/from...

If you had changed your Si to a HF tranny, you'd have been dogging from day one.

The HF has more than 2x the gearing of a Si. Hence the reason your Si was at 3500-4000 RPM @ 70mph, whereas the HF is only at 1800-2000.

I'm not saying that changing gears won't improve your efficiency, I'm just saying that straying too far from your max torque will.

The Si could benefit from taller gears, it's a sports car... put efficiency car gears in it, and obviously enough, it gets better... the HF was a complete redesign.

All I'm asking is that people think before saying "use longer gears" b/c it's not always the case.

11-20-2008, 02:45 PM	#4 (permalink)
Christ Moderate your Moderation. Join Date: Nov 2008 Location: Troy, Pa. Posts: 8,919 Pasta - '96 Volkswagen Passat TDi 90 day: 45.22 mpg (US) Thanks: 1,369 Thanked 430 Times in 353 Posts	Stop for a minute and think about the ratios you're going to/from... If you had changed your Si to a HF tranny, you'd have been dogging from day one. The HF has more than 2x the gearing of a Si. Hence the reason your Si was at 3500-4000 RPM @ 70mph, whereas the HF is only at 1800-2000. I'm not saying that changing gears won't improve your efficiency, I'm just saying that straying too far from your max torque will. The Si could benefit from taller gears, it's a sports car... put efficiency car gears in it, and obviously enough, it gets better... the HF was a complete redesign. All I'm asking is that people think before saying "use longer gears" b/c it's not always the case. __________________ "¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"