living in brooklyn ny you pretty much throw gas mileage out the window especially with ac

 

my escort gt had th hot air valve it warmed up the car alot quicker and helped in winter driving when it got really cold and turbos are good but they need pressure from the exhaust where as a supercharger runs off your belt system and and lets more air in at a wider range of rpms

 

As an aspiring aerodynamicist myself, I have been somewhat struggling with why these Airtabs are being installed so far aft on all these vehicles. In aircraft, vortex generators are generally fairly close to the leading edge of the wing, to energize the boundary layer and keep the flow attached. But having this so far back, how does this still work? I am not doubting your results at all, I am quite impressed, I am just seeking a better understanding here.

 

I'm no serious engineer but I think the thinking is that somehow you break up the drag bubble right behind the car? Maybe by making the air flow stick to the side and rear hatch just a little better. ? Just a guess.

 

https://www.fitfreak.net/forums/gene...ios-chart.html

THIS ^ mod --- to lower the cars HIGH RPM...if it can be done?
too bad this guy doesnt post here anymore

 

RickXKU traded his Fit for a CRZ a while back.

Changing final drive ratio can be done without too much trouble. The real problem is finding the ratio you want, which may not exist, which means you may have to have gears made, which would pretty much completely blow the budget. I follow several fuel efficiency websites and I am not aware of anyone having done it on a Fit.

Another way to effectively change the final drive ratio is to put larger diameter tires (NOT wheels) on the car. That can have negative effects on handling, and would probably look like the very dickens too. But it's possible. Again I have not heard of anyone doing it for fuel efficiency.

Finally, although RichXKU might have thought the ratios to be bad for gas mileage at highway speeds, he might not actually be right. It may well be that the engineers at Honda chose the ratio to put the Fit in an efficient part of the power band at highway speeds.

Also, at speeds above 40MPH or so, wind resistance, or drag, overtakes mechanical friction as the major component the engine is fighting against. Drag increases with the square of speed so it goes up in a hurry. The Fit is definitely not aerodynamically optimal, so I suspect that this is much more of the reason behind why the Fit's mileage drops off at speed.

My next move will be low rolling resistance (LRR) tires. They've come a long way since my Fit was new so I'm hoping to find something with decent road manners as well as low RR.

 

Further to that we have experimented with a lower final drive ratio (numerical) and didn't get much from it. It wasn't as low as the auto but somewhere in between. Narrower tires, aka 165 and 175 section and those econ tires were a help. But so far nothing really has improved the mpg significantly. And the low rolling resistance tires were awful; it my opinion downright dangerous to corner carvers.
BTW LSD will not improve mpg and will certainly improve performancve (isn't better cornering and acceleration performance?)

 

For those of us experienced in reducing drag on Daytona and Talledega racers here's the scoop:

1. reducing the friction of air passing along trhe side of a vehicle is critical; the problem is thats not so valuable at less than 100 mph. AS good coat of airplane wax is a good choice anyway.
2. Anything you can do to prevent air from suddenly changing course, in particular by sucking up to the back end of a Fit or 18 wheeler will result in dramatic increases in mpg. Unfortunately , a 'Kamm' rear or tapered back end so used on high speed racers isn't very achievable on a Fit. (Incidently, thats why the back of your ZFit gets so dirty).
There are experiments being done on 18 whheelers rear dors to provide a tapered bacvk end so far the improvement appears to be 1-2 mpg which of course is invaluable on a 18 wheeler !
If you want to experiment try putting a trangular folded rear section on the back. Be sure to put bottoms an tops on the piece. Keep it lightweight too.
As an educated guess the taper should be from the door width to an edge about 3 feet behind almost same height as the door.
GOOD LUCK.. That might be worth 3 mpg as a guess and don't try it in crosswinds either. Nor use flexible sides either.

 

with my 15x7 rpf-1 enkei wheels with 195/55 tires i notice a slight increase of of mpg...

 

Those old Hondas were fucking Tin Cans... They weighed nothing with no safety at all and were Turds...

I love how people call that erra of cars Hondas Roots.... They were eco boxes like they are today.

Yes any mod to the engine will decrease MPG. Intakes are the biggest waste of money.

Headers and full exhaust maybe a slight bump in power but probably a loss in TQ which in these they need every ounce of TQ they can get. Would need a tune as well.

Best Mod for FE is a Scan Gauge or Ultra Gauge which is what I own.

 

A del Sol S gets an easy 40mpg highway but makes do without ABS, power steering, AC, side or curtain airbags, ACE, stability control, magic seats and about 200lbs more steel. Personally, I think it's a good tradeoff, all in. Not that I don't miss the dragonfly handling of the del Sol (the Fit is a bit minivanish by comparison, yet doesn't feel stable at speed). But overall, I like safety and comfort and I'm OK giving up 5 mpg.

I'll add also that if you want to burn less gas, there's something a lot easier than ANY of the modifications we're discussing. Drive less. Coordinate your shopping trips. Work from home two days a month. Face Time. Walk to town (I can; some people choose to live places where a car is required for travel).

But I know that's not the point. I do mods and track fuel efficiency too. It's the same people who would be chasing 5% more hp when gas was $0.99/gal back in 1999.

 

anyone think this mod would fit USDM fits?



other than the obvious opposing windshield wipers, is the relative shape of the cowl the same for JDM and USDM GE8? This looks like it could help reduce the drag created by the wipers...

 

Well, I am at Empty finally with 400 miles on one tank and will refill tomorrow to see how much goes in.. Im guessing 12.00 Gallons to the the top of the fuel neck. That only gets me 33.33 MPG.... I was hypermiling a lot with lots of coasting in neutral and shutting the engine off at long lights. I feel that my mileage is not as high as it should be. This is using an Ultra Gauge..

 

i would buy one of these in a heart beat, carbon = ok if need be, fiberglass = my choice

you'll be suprised!!!
i predict 402 divided into 10.7 = 37.5

 

The last two tanks of Gas I am able to put 12 gallons of gas in each time while driving with the low fuel light on for a little while.

So my math is 400/12= 33.33

Granted this was 95% all city driving with lots of hills and lights

 

Where can i buy this windshield?

 

Since the original post was a question about mods, not technique, here are my thoughts. Oh, and I am a Mechanical Engineer, so these mods aren't totally out of left field.

At freeway speeds your biggest enemy is aerodynamic drag. So get rid of your roof rack. Get rid of the spoiler on the Sport model. Get rid of your mud flaps. The underbody of the fit is pretty rough, underbody trays could help a lot, consider use of coroplast sheeting. The side view mirrors on the Fit are huge, remove and then for safety sake replace with something much smaller. Slab-side wheels like those that were sold with the Civic Hybrid when it was first introduced might help some. I like the windshield wiper cover from the last post. I also like the spoiler that comes with the eFit.

If you are willing to do big modifications, consider things like rear wheel skirts, and wheel spats/ wheel boat tails. Consider a boat tail or a kammback. Fill body gaps. Cover most of the openings in the front grill. I believe the base model front end is better than the sport.

Low rolling resistance tires are easy and should help.

In the city, weight is your enemy. Rotational weight is your enemy twice. The lightest wheel/tire combination you can find will help. Getting rid of excess weight in general will help. How crazy you want to go with this is up to you. I prefer a civilized interior to a stripped racecar.

On the drive train a higher 5th gear for the MT would help, or a higher final drive ratio. Don't over do it and end up lugging it all the time.

I would avoid mods to the engine. You are unlikely to do better than the very excellent Honda engineers. But here is one, if you live in a cold place, get an engine block heater. You will spend much less time warming up your engine which is when your economy is the worst.

Of course with racing the best improvements are in driving technique. Work on that first.

Have fun!

 

As a fellow engineer with 50 years of experience including aero mods for better speed (which also benefits mpg) let me add a couple of comments:
All those mentioned are good advice.
1. removing a roof rack is major improvemt
2. removing the spoiler helps but is really effective if you install a belly tray.
3. larger diameter but narrower tires are a big help.
4. no so much thosr low rolliong resist tires as they also reduce cornering power. The set we installed came off in a week, especially since the mpg improved only ststistically, not on the gass bill.
5. the boat tail is a known beter aero shape but almost imossible on a Fit. Besides it looks "bad".
6. The block heater does work in cold climates.
Lighter tires are better but never mind the wheels; they are useful mostly for racing. On the street even 9 lb wheels showed no mesureable difference. Tires do however.
7. If you want to fanatic tape all the seams around doors hood etc
after all that mu automatic gets 28-30 mpg all the time so I can't throw dirt on the exoected mpg of dome but the EPAtst certaily ays 28-30 mpg. If you want to freak out ov er mpg get a Toyota Priu C that gets 48 mpg but is a bit slower.

 

Short of removing side mirrors and a windshield, it costs enormous money in research and development to even slightly reduce air resistance.

Indeed, driving more conservatively and intelligently is the most effective way to increase effeciency.

 

Not all aero mods require an advanced degree in physics or engineering.

I am probably starting to sound like a recording in an infinite loop, but the Beatrush undertray I put on my car:

• did not cost enormous money
• did improve fuel economy
• did improve vehicle stability at highway speeds

There are also quite a few folks over on ecomodder.com who are seeing significant efficiency improvements through relatively inexpensive mods such as homemade underbody panels and front lips, pizza pan wheel covers, and the like.