5th generation civic hatchback - improving aerodynamics

[gildo4realdo]

Thanks for the replies. I figured that was the case. I've tried teaching myself the techniques like you've discussed (low speeds, coasting to lights, etc.) but I'm also doing tank to tank averaging. I've thought about the scangauge but just haven't justified it yet, but definitely agree it's probably the best tool for learning techniques.

Metro, thanks for the link to your breakdown, I had seen it before but some of it never clicked. I think 8% increase with pulse & glide engine on is interesting. I'd like to get a scan gauge and repeat with my car. One thing is for sure though, I'll never do the engine off stuff. I understand it's all opinion and I'm not trying to stir up trouble but I think even with a competent driver, there's nothing safe about turning off power steering and brakes. We can agree to disagree here but I didn't realize that P&G works with engine on as well so I'll give that a shot. Also, I noticed you mentioned you pop the clutch when doing the P&G.... how often do you have to replace a clutch? (or next weakest mechanical link) I just flinch when I think about having to pop the clutch every 16 seconds. I figure using the starter is probably even worse. I'm just curious.

I figured there were some non-normal driving techniques going on here so I wanted to add to this thread so noobs like me don't come in here and think you automatically get 30%+ gains by just doing the mods alone and maybe just driving 65 instead of 70 on the interstate. (which is about all I do as far as driving style goes)

I've all but convinced myself to get the scangauge but I'm cheap. btw Larry, I am an engineer, but I have a hard time convincing myself to stay disciplined to these driving techniques so early in the morning... especially since I don't drink coffee. Anyways, happy hypermiling and I hope I helped add to this already extremely awesome thread which outlines what everyone needs to know about hypermiling.

[larryrose11]

gildo4realdo,
another engineer to the mix huh? Welcome!
Perhaps I shouldn't generalize. We are all wired differently. Hell, I KNOW Im a wierdo. I came to engineering as a shortcut to a job in the sciences. I graduated form HS with an emphasis on Art, mostly jewelery and metal work.

On clutches: I have yet to relace a clutch once I learned ho to drive a stick. I replaced 1 clutch on my firs car, when I was 17 and just leaning a stick. Since then, I haven't replaced a single one. Ive been doing this type of engine off. bump start for 6 years now. It takes practice to make it smooth, but so does everything right?

I don't have power steering, so there is no loss of function there.

I can get about 3 good stops with the stock vacuum reservoir. I probably will upgrade to a larger one soon. Again, If you drive conservatively, then the panic stop situations decrease dramatically.

Larryrose11

[Daox]

gildo4realdo,

I initially thought the same as you about all these things. One day a member of another forum invited me to a hybrid club meet and they offered driver training. With a little instruction I had at least made up my mind that it wasn't hard to do. After I filled up the tank there was no going back. The techniques work and done properly you will be a safer driver than most on the road.

However, with your Civic HX and its learn burn ability you are probably better suited to not do continuous pulse and glide. I would suggest accelerating up to speed at roughly 80% engine load (scangauge tells you this) or around 1/2 to 3/4 throttle is a good guess. Once you are up to speed, you basically want to keep your foot as still as possible on the throttle. What kicks your car out of lean burn mode is changing throttle position. So, hills will be your biggest obstacles.

If you are looking for the scangauge to estimage your mileage for you then you may be disappointed. It does not calculate properly for lean burn mode and will not show correct mileage when in lean burn. However, it is still a great tool for monitoring all the other sensors on the vehicle.

[MetroMPG]

Daox - good point on the leanburn + ScanGauge. The MPGuino does not have that problem - its design works fine with lean burn.

[instarx]

Just read this post from start to finish - very interesting and informative. Great writing AndrewJ. What I like most about Andrew's work is that all the mods look so professional and well done.

I don't want to hijack the thread from Andrew's work but you might be interested to hear a historical tidbit about disconnecting alternators. In the late 60's there was a factory option for Pontiac GTOs that allowed belt-driven accessories to be turned off from a switch in the dash. It used an electric clutch to disconnected everything belt-driven, including the fan. Of course it was for racing, but it is interesting how things can come full circle. Now, 40 years later AndrewJ is working hard to recreate what you could order for $100 in 1968 as a drag-racing option!

I think ironic is the proper word to describe this situation!

[MetroMPG]

That's a very neat tid-bit about the GTO.

[Vince-HX]

sorry about continuing to highjack

Originally Posted by Daox

However, with your Civic HX and its learn burn ability you are probably better suited to not do continuous pulse and glide. I would suggest accelerating up to speed at roughly 80% engine load (scangauge tells you this) or around 1/2 to 3/4 throttle is a good guess. Once you are up to speed, you basically want to keep your foot as still as possible on the throttle. What kicks your car out of lean burn mode is changing throttle position. So, hills will be your biggest obstacles.

I have found that in city pulse and glide is much more efficient than leanburn cruise. On the highway its vice versa. IMO trying to drive only in leanburn mode is pretty rough without the help of a capable wideband controller hooked up to another L2H2 sensor. The DWL technique will help quite a bit.

MPGuino

I got to get off my lazy butt and build one for my lean machine


I really want to delete my alternator also pretty soon. I would love another 10% to tack on

[Binger]

very interesting work...definatly gratifying results. The doubling in fuel economy probably will help to justify keeping the car with the wife whenever you need a major repair.

Looking forward to trying these things on my Mirage

[rcpmac]

Originally Posted by instarx

J there was a factory option for Pontiac GTOs that allowed belt-driven accessories to be turned off from a switch in the dash. It used an electric clutch to disconnected everything belt-driven, including the fan.

This would be the same as a pulley clutch on a typical automotive AC compressor. Shouldn't be hard to adapt one... or should it...?
In any event, does anyone have data on how much load is created when the alternator is spinning but with out electrical load?
And perhaps the easiest solution is putting a switch on the field windings.

[randomthot]

i realize this might drain more power than you want, but why not hook up a LED array from your gauge to list your mpg instantaneously while driving! I think that might be worth the electricity!

[AndrewJ]

Ok, looks like I gotta re-hijack my thread for a little bit

With my recent relocation so stiflingly hot Missouri, and a subsequent lack of internet access, hence by absence here, I started a little project to keep me busy.

Step 1: Strip everything off the back of the car and throw it in a pile on the garage floor.





Step 2: Get a bunch of 1" x 1/8" steel bar-stock from your local hardware store. (Aluminum would be better, but when you're using 30' of the stuff that could get really pricey.) Once you've got your bar-stock, get all creative with it.











Step 3:
Proceed to get out the arc-welder and stick everything together with really crappy welds.











Step 4:
Get a little piece of plywood to stick on the end to hold the new taillights and license plate and such.









Now all I have left to do really is get the sheet-metal, attach it, and then figure out some way of putting on a bit of plexiglass.

More pics to follow as progress and internet-access allow...

[AndrewJ]

Oh, and about the alternator use:
Yeah, I'm trying to put in my fuel-log the approximate percentage of time that the alternator is unbelted.

And about technique vs. mods:
My mods have definately helped out a lot, but as a percentage, technique is more important. Without doing any P&G or EOC (just watching the 'Guino) I was able to pull 63mpg passing through Wyoming at about 65mph. That could have been MUCH worse without watching the 'Guino.

I've let my wife drive a few times (I belive I noted that in my fuel log) and she (the non-hypermiler) got abysmal mileage, somewhere south of 50mpg.


And a note about cx/vx's and P&G:
P&G has never worked for me. Not once. It seems everyone has their theory as to why this is so, tall tranny ratios, Honda engine magic, etc...
All I know is that my car likes constant throttle at light loads, but not too light of a load. I discovered a month or so ago that my "target" speed for best MPG has been too low.
55mph just won't cut it. On the highway my mileage is best when my speed is between 60-65mph depending on the wind direction. Unless I'm driving into a strong headwind, 65mph is my new "target" speed. I'd have never known if not for the MPGuino.

[KJSatz]

One good place for window-age might be in the plywood stern. The license plate will cover some of it up, sure, but that should be an easy way to add visibility. Is it hard to make a window in sheet metal?

Out of curiosity, how do you plan on attaching the sheet metal to the steel frame? More welding? Rivets? Bolts?

It looks pretty BA.

[rcpmac]

How to really build a body panel.
Here are the steps. There is a link below with pics of a guy's project.

This panel would be constructed out of foam core panels and fiberglass/epoxy resin.

Build a mold-
consisting of plywood cross sections in the same plane as the plywood end piece that you currently have moving toward the hatch about every foot and ending with the shape that would provide contact to the body. Call them bulkheads.

Attach battens of flexible pine strips from bulkhead to bulkhead to rough out the shape. Gaps and spaces are fine.

This is your mold. It will need to be undersized because the next step is to-

Attach strips of foam to the mold. 1" thick is probably fine. Use a heat gun to bend it. Screw it to the mold if necessary to hold it. Glue / fill the foam to make a continuous form and fair it out with tools. Remove the screws.

Fiberglass the foam form using standard glassing techniques.
Dissemble the wood mold that is inside. Of course you were clever enough to allow for easy disassembly when you built it.

Smooth out the inside and glass the inside after embedding wiring and structural attaching flanges in the foam.

This will be strong light and look as professional as you want.

Here is a link to a guy building a boat using a similar technique but with a vacuum infusion system that takes some work to set up. Vacuum bagging on the other hand is similar and can yield excellent results- google it.

Scroll down to "2002" and check out pics. He used female moulds to form this hull.

http://www.fram.nl/

[Stuey]

AndrewJ,

I recently (Yesterday) used Lexan to make some covers for the lower grille on my car (Acura EL) and they're crystal clear for the most part. The stuff's pretty similar to plexiglass so I'm sure you can use the same technique as I did, just a heat gun and some work gloves will let you curve the edges if you want to smooth it out into the sheet metal. (the stuff gets really hot though, felt like my fingers were on fire most of the time even with the gloves on so try to find some thick gloves).

Hopefully it will stay fairly clear with sun exposure, etc...

I wouldnt suggest trying to curve the entire sheet though to make a curved window by hand... you'd be better off maybe shoving the thing in the oven at a low temp to uniformly warm it up, and have it rest on a curved surface that matches the curve you want.

This was my first time working with Lexan other that watching the guy at my local machine shop use some with a heat gun (that's where i got it) so I'm no expert on the stuff or whether the oven is a good idea. Anyone have any thoughts?

I agree with KJSatz, car looks pretty BA, can't wait to see how it turns out!

[landscaper52]

just saw your airdam...I just put a basic one on my Ford Ranger last weekend...seems to be improving gas mileage immensely...however, it took a few days of abuse from all the guys I work with who all drive trucks, and now consider me some kind of eco hippie freak...I don't give a dam!!! I'll post pics soon

[MetroMPG]

Welcome to the site, landscaper52. If you do get some pics, post them in a new thread. I'm sure there are others who would like to see what you've done.

[AndrewJ]

Well, the boattails been done for over a week now, guess it's time to get some pics posted up of the finished product.

It's pretty amazing how much the boattail has helped with coastdown times. I'll look down at the speedo after a good 10-15 seconds of coasting on level ground and I *might* have dropped 5mph (from 65 to 60) on a bad day.

Mileage seems to have been improved at least 10%. I'm now able to consistently hit 55mpg burning 87 octane E10 gasoline. I'm positive that I'd be reliably in the 75mpg range with "real" gasoline.


















I scavenged the key mechanism out of the hatches "tailgate" and with a little copious modification it made a serviceable lock for the new rear window.

[MetroMPG]

Andrew! Wow.

No wonder you've been so quiet lately - you've been a-fabricatin'.

Any tuft testing, hmm?

[SVOboy]

God among men!