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Old 04-15-2012, 09:56 PM   #3 (permalink)
turbothrush
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Join Date: Nov 2008
Location: Canada
Posts: 133

2 x wrecked vx - '92 Honda Civic Vx
Team Honda
90 day: 62 mpg (US)
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Quote:
Originally Posted by steffen707 View Post
I swapped a vx motor into my 96 civic hatch. I bought the vx donor car without a title. I liked the idea of 2 airbags, A/C, and the 96 hatch looks cool.

I've been slightly unhappy with highway performance. I can only go about 55-60mph to maintain lean burn with slight grade changes. At 65mph it really doesn't like to to stay in lean burn. I find that I either have to kinda pulse above 70 and then go in lean burn and slowly lose speed over a few miles, or must slow down to just maintain the lean burn. Well not only is that annoying, but I don't like driving 5-15mph slower than the rest of the traffic. I want to be able to maintain 65mph and stay in lean burn.

Today I stumbled upon this calculator
Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com
and this list of aero numbers Vehicle Coefficient of Drag List - EcoModder

I had no idea my car had a .762 CDA, the original 92-95 hatch the swap came from is 6.36, a crx is 5.57 and insight is 5.0, prius is 5.83. My hatch is as bad as my fiance's 03 Toyota Camry for CD.

Things to note, a crx is more aerodynamic than a prius, pretty cool. I plugged in the CD and A figures found on the 2nd link into the calculator and kept weight at 2400lbs, and same efficiencies ect. I just wanted to see the difference between the aero.


Well at 60mph the results are:
96 hatch = 38.70mpg
92-95 hatch = 46.56mpg
crx = 50.13mpg
insight = 54.23

I know my car can get about 50mpg at 60mph, so that means I should see a considerable boost if I swapped the vx back into a 92-95 hatch or crx chassis. I know i'm 12mpg over and that won't directly correlate to 62mpg in the crx, but it should be quite a bit more than 50.

Most importantly I want to stay in lean burn at 65mph. Any stock vx owners out there, that don't do pulse and glide and don't have huge aero mods done and can tell me if they have problems staying in lean burn at 65mph?
If your talking 65 mph with a flat road and light wind and summer temps than yes I get leanburn at 65 mph. I don't drive at 70 mph but I would doubt it .Not without a strong tailwind

If your talking 65 mph going up a grade and adding throttle to maintain speed than no leanburn. I get leanburn down till I go below 41 mpg ( 5th gear ) on the instant mpg.

I can tell you that my vx will get 57-58 mpg at a true 60 mph as I have hundreds of miles on a dead flat road with my mpguino. If I see 60 mpg than I have a tailwind and if I see 55 mpg I have a headwind. It really is as simple as that on a flat road . I really wish more people would give speed and wind when they talk highway mpg because as you know it makes a huge difference.
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