Kammback assistance, Civic hatch - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum

aerohead · 03-12-2012, 06:05 PM

Quote:

Originally Posted by greasemonkee

The status quo around here seems to be a boat tail or nothing. The implications arising from such an extreme mod are a severe shift in the CG which I am not willing to tolerate as I drive through a LOT of tight turns daily on a strict schedule, aside from the fact that I often enjoy a spirited drive.

I've found that this abs plastic is quite easy to work with and have come to this. Hopefully I'll notice the results. Will post when a solid number is evident. Thanks guys

The tail on my CRX weighed about 30-lbs ( with a lot of body filler ).
With front engine/front-wheel-drive,CIVICs are perfect candidates for boat-tailing because of their CG.And the tail moves the CP rearward which is exactly what you want.
I've probably got over 100,000 miles with my tail and never a raised hair even entering curves near the limit of adhesion.These cars have beautiful understeer,just turn the wheel a little more and keep the throttle on.They keep up with Ferrari's just fine.
And without a boat tail you haven't a prayer for low drag.It's scientifically impossible!

greasemonkee · 03-16-2012, 02:25 PM

When fuel clears $6/gallon I'll consider the boat tail. At this point another 10 mpg gain would net about $900 savings a year minus the cost of materials - then the time involved in making a tail with a robust cargo area, which I don't want to think about right now. However, if fuel keeps climbing you can count on a boattail thread coming up.

The results - it did pickup about 2 mpg, bringing the average up to 51-52mpg at 15% city and a lot of mountains that require a lot of braking. It is possible to stay in leanburn a lot longer now, and coasting speeds have increased by 4 mph in some areas.

The extreme elevation swings are killing the economy, but at least the majority of my driving is over 2500'.

Wheel covers are next - hopefully the materials will be cheap on this one, thanks for the help guys

WD40 · 03-16-2012, 03:52 PM

Awesome job .. thats exactly the same as I have planned to make.
Have you noticed if the back window stays any cleaner now?

greasemonkee · 03-19-2012, 11:36 PM

Not much gets on the rear window now, but a very fine layer of lighter particles, and only enough rain water to make a mess. I checked the mileage on the hwy only (although I did travel through several cities on my route), but stayed under 70 mph and the mileage yielded 54.7 mpg. I'm sure it will clear 55 mpg by slowing down another 5 mph.

And for the record, I am running 195-50-15 ultra performance tires.

Sven7 · 03-20-2012, 01:29 PM

Just wondering... on long declines do you engine brake with dfco or use friction brakes? 50mpg is pretty good with mountains.

greasemonkee · 03-20-2012, 10:03 PM

It will do 55mpg by slowing down a couple mph I'm certain, in its current configuration.

If I have to use the brakes a lot I'll keep it in 5th and ride the fuel cut, even still, sometimes have to use the brakes. Sometimes I put it in neutral with a hair of throttle so it will idle in leanburn, and if it'll coast more than a mile I'll usually shut it off. That ecu won't let leanburn kick back in until about 15 seconds after startup

Edit - as of April the warmer temps (approx 75 degree average) have increased economyy to 56.2

aerohead · 03-21-2012, 05:11 PM

Quote:

Originally Posted by greasemonkee

It will do 55mpg by slowing down a couple mph I'm certain, in its current configuration.

If I have to use the brakes a lot I'll keep it in 5th and ride the fuel cut, even still, sometimes have to use the brakes. Sometimes I put it in neutral with a hair of throttle so it will idle in leanburn, and if it'll coast more than a mile I'll usually shut it off. That ecu won't let leanburn kick back in until about 15 seconds after startup.

I hope you've removed the steering lock mechanism.