how to help my matrix
 

What can I do to help my matrix get above 45MPG regularly? I can get around town 41-43 and on trips (steady state driving) I can break 45 some times. I feel that I am maxing out my driving options. I have a belly pan under the engine (past first axle).

I am thinking about mods that might help.
wheel well covers, what gain could I expect? how should I do them?
My matrix has a fairly flat back, would a tail or smaller mod help?

http://i835.photobucket.com/albums/z...r/GEDC0270.jpg
( Last winter, I took the hub caps off as they would not stay on)

I want any mod to be reversible, so attachments need to be hidden.

What are your ideas?

Start by inflating the tires to 45 PSI and blocking the upper grille, if you haven't already. That's an easy place to start.

They have been at 42-44 psi for over a year.
I had both a upper and lower grill block on over the winter, but as it warmed up I removed them so the fan would not run all the time. Should I still to the upper grill bock and let the fan run some?
http://i835.photobucket.com/albums/z...r/GEDC0284.jpg
Last winters set up.

Looks like there are a few things you can do, If you want a good list of ideas have a look at the garage section and see what mods others have done, the trip logs usually have some good info on what mod level cars are at and the MPG they got.

What will work best for you depends on what sort of trips you do. For example my normal commute involves short trips mostly so i concentrated on my cold idle which helped a lot. If you have lots of stop / starts due to lights look at weight reduction, if you are freeway driving mostly look at aeromods

either way a few MPG should not be too difficult with a few mods

Some ideas that i have tried that would work for you.
- side mirror delete, if you dont use them / if you can do head checks but check with your local laws
- mud flap delete, i think i can see a mud flap in one of those pics
- idle reduction both cold and warm idle (my car had seperate mechanisms for both) helps during P&G if you leave the car idleing rather than engine off, helps at lights, helps at start up
- power to manual steering, I have only just done this so im not yet sure if it is worth the annoyance of heavy handed steering
- weight reduction, what can you strip out of your boot that is just asthetic which nobody sees anyway. Can you take anything out of your engine bay, do you have AC you never use.

some other ideas i havn't tried
- look at plug up those round holes at for right/ left at the bottom of your front grill. Not sure exactly what they are for, if only one is for a air intake then block the other. See what you can do with them
- you can do more aero mods around your wheel wells although if you want your car to look normal this can be done but its difficult.
- engine block heater, heat up the engine with mains electricity before you leave in the morning. I have never tried this but plenty of threads on here about it and it might work well for you if your in snow areas
- you can do a full belly pan, will give you a bit extra but not much

Since you asked in your first post, Wheel well covers you can do with fiber glass which will give a good finished look but takes a bit of time. Otherwise you can do i out of coroplast and paint it the same colour as your car and try to make it so seam joins are hidden so it looks continuous as if there is no mod. I havn't done this yet, its on my to do list but there are plenty of threads about wheel well mods or others can suggest good ways to do this.
Yea a tail would work for you, someone in a thread mentioned anything more than a 12 degree change in angle will cause drag as air flow wont stay connected to the car. So you will have a large drag area behind your car. So a tail will help, very hard to make this look normal. You can also look at vortex generators which would go at the back on top of your car and intentionally disturb the air flow in a particular way so that it causes a smaller drag area. Plenty of threads on that one too.

Well good luck

thanks for the ideas!
comments, no mud flaps (icicle hanging down due to melted snow).
Mods it can look any way I want, I just do not want holes to patch if I take the mod off, so screws holding the bell pan on are on the under side where they will not be seen.

Weight reduction, I have done all that I am comfortable doing, I can remove some weight, but I have done some ABA testing (round trips to school and back on the same day, 90 miles each way) with 200+ pounds added and found that the weight makes very little difference (longer coast times offset by longer acceleration times).

Side mirror issue, I regularly have stuff in the back that blocks my view. I also feel that safety wins out over that mod.
The power steering to manual is an idea I might look into (I worked with steering systems for 18months). I wish my car had esteer (electric steering assist) where I worked they had data that showed a 1-2 mpg improvement from removing the power steering pump. The cost of an esteer system is the draw back, $300-600 added cost to make.

those round holes are where the fog lights would be if I had a non base model matrix. I been looking at them for some time as well, I can take out the plastic cover that you see in the picture, so I can mod them off the car.

I think a tail would be too big, but a Partial Kammback might work. I am looking for ideas on attachment that makes the hatch still workable. I think I could use the glass mounts for the lower part, but the upper has me stumped. Ideas please :)

I just might do the wheel well covers, I have both chloroplast and some galvanized sheet steel. which would be best? I can bend the sheet steel to make a lip to go into the wheel well (or at least several tabs). My issue with the wheel covers is that the back side of the car is inset from the tier (so my cover would need to stick out from the back side or have a bow out in order not to scrap the wheel. I can try to get some pics up tomorrow. Ideas?

on the Kammback, what is the best angle to use? base it off the level ground. Saand mentioned to keep it under 12 degrees transition from the roof to the Kammcack.

Other ideas?

...take a look at what Tango Charlie has done with his Pontiac Vibe (re-badged Matrix) for "workable" ideas as to how much & how well each mod has worked at improving his fuel economy.

good idea, but I am ahead of him in MPG

Here is the wheel currently:
http://i835.photobucket.com/albums/z...s/GEDC0135.jpg

My idea of a full wheel skirt:
http://i835.photobucket.com/albums/z...s/GEDC0143.jpg

the issue with a full one is that I would need to bow it out or else I need a 2-3" stand out on the back side:
http://i835.photobucket.com/albums/z...s/GEDC0139.jpg

Ideas please!

Here is how much I can cover by going strait across (magnets are on the edge of wheel well):
http://i835.photobucket.com/albums/z...s/GEDC0144.jpg

All ideas on how to build this would be helpful!

I can make a cardboard one first and I have chloroplast and galvanized steel as well.

bump for ideas

The point of wheels skirts is to keep airflow attached to the rear of the car. I'd go with as full of a skirt as you can.

Ok I did some work on it today, I made a brace for the bottom so that I can get the right shape.
http://i835.photobucket.com/albums/z...GEDC0144-1.jpg

Here is the bracket I will be using to hold the brace and skirt on.
http://i835.photobucket.com/albums/z...s/GEDC0156.jpg

question is how to do the top. I had two ideas:
http://i835.photobucket.com/albums/z...GEDC0150-1.jpg

Use a hinge so that I can fold it open (for tire rotation).
or

http://i835.photobucket.com/albums/z...s/GEDC0152.jpg
just a bracket

http://i835.photobucket.com/albums/z...s/GEDC0153.jpg

what would you do?

Back when I was driving my Vibe, it responded well to a change to synthetic oil and transmission fluid change to the tune of nearly 2mpg.

Never got around to changing the tires to LRR, but I consistently drove them @ 50 psi with no issue, I also gutted the rear end of the car by removing the back seats and leaving the spare snce it was always just me in the car.

I also resculpted the nose which helped me stay well above 40mpg throughout my time, but I never got around to lowering the vehicle or adding wheel shirts etc ...

Trikkonceptz, thanks for the advice! I run Amsoil in my trans and engine, I noticed smoother shifting and longer coasting. I run my ties at 44psi, any over that and the ride gets very bumpy and I did not see it helping past about 44psi.

here is what I got done before it started raining:

Cutting out the sheet metal:
http://i835.photobucket.com/albums/z...GEDC0136-1.jpg

cut piece before bending:
http://i835.photobucket.com/albums/z...GEDC0137-1.jpg

With brace on (right side is only on loosely):
http://i835.photobucket.com/albums/z...GEDC0138-1.jpg

On car (no top attachment):
http://i835.photobucket.com/albums/z...GEDC0139-1.jpg

http://i835.photobucket.com/albums/z...GEDC0140-1.jpg

How does this look?

How would you deal with the gap on the edges? It is due to my bending of the sheet steel not to the exact shape.

Update
 

I got the first one done (except for painting).

Open
http://i835.photobucket.com/albums/z...GEDC0141-1.jpg

http://i835.photobucket.com/albums/z...GEDC0142-1.jpg

closed:
http://i835.photobucket.com/albums/z...GEDC0144-2.jpg

http://i835.photobucket.com/albums/z...GEDC0146-1.jpg

http://i835.photobucket.com/albums/z...GEDC0147-1.jpg


After some adjusting to narrow the gap:
http://i835.photobucket.com/albums/z...s/GEDC0151.jpg

http://i835.photobucket.com/albums/z...GEDC0153-1.jpg

Off for priming:
http://i835.photobucket.com/albums/z...s/GEDC0155.jpg

I should have time to make the other one before the paint come in. My car color is special order at the auto parts store. I also need to get the car washed before I can epoxy on the right (front of car) side lower bracket. I my also add some epoxy to the hinge mount to give it more strength (epoxying the back side of the screws should make them fun to take off).

One note on what I did. I made a paper outline of the wheel well then added .5" to .75" to it before cutting. I then bent int the extra material to form a rounded edge so as not to rub the car. It also allowed for size tweaking. These tabs also should help keep air from getting under the skirt.

:thumbup: Looking forward to ABA results. Do you have a ScanGauge?

Cheers
KB

Looks much better after you closed the gap up. Nice job.

Yes I do (since last October and it has paid for it's self already)!

Doing the fine detail bending took some time but cut the gap in half! I made it with an extra 3/4" bent in so that I could play with it since I was not sure that my paper template was just right.

Daox, what is your ideal testing method?

ABA? If so, how sound I do it? for a whole tank at a time (right now my driving is not consistent at all)?

Coast down? There are some nice back county roads out my way that I could use for hours without seeing any other cars http://dotable.com/images/smilies/turtle.gif

Both?

I would think that to do this right I would need to test with both sides on so that the change is bigger (will stand out from the noise better). It will be a few days till I can make the #2 skirt.

Darin wrote a good article a while back on how to test.

http://ecomodder.com/forum/showthrea...ery-11445.html

That being said, I'd do a constant speed test and measure the difference in MPG on a scangauge/mpguino if you have either. If you don't, a coast down is all you can do.

With a scangauge, How to I reset it for each run?

I believe the "reset" option is in the "trip" menu.

EDIT:

FYI, I've tested wheel skirts on 3 vehicles, and the change ranged from very small (couple of percent) to undetectable at 55 mph. The faster your test speed, the more likely you'll be able to measure a difference.

thanks for the tips!
all the roads around here are 55mph but I could hop on the freeway for a 5 mile stretch and go back and forth.

how many runs should I plan for? I will add a few to make up for bad runs.

Update:
Both skirts are made and test fitted.
Both front side brackets got a second dose of epoxy and it is curing.
One is painted and clear coated the other one has it's first coat of clear coat on.
I am planning on doing a test drive to make sure they stay on later today.
I may also get to doing some ABA testing today.

How long should my steady state tests be (miles each way) in order to make a valid test?

update:
Both skirts are done!
http://i835.photobucket.com/albums/z...GEDC0144-3.jpg

On the car:
http://i835.photobucket.com/albums/z...GEDC0145-1.jpg

http://i835.photobucket.com/albums/z...GEDC0150-2.jpg

http://i835.photobucket.com/albums/z...GEDC0156-1.jpg

http://i835.photobucket.com/albums/z...s/GEDC0154.jpg

I also took it for a drive and they work (stay on and do not rub).

Testing data to come soon!

testing data
 

I ran two tests today, the first one was a 2 mile each way steady speed MPG test, the second was a coast down test from 55MPH.

My data is not what I had wanted but it is something. I think I still need to work on my testing methods.

I will post up my summaries here and do a second post with the raw data later.

Here is the graph for the steady speed test: (Each test data is vertical showing the range of results)
http://i835.photobucket.com/albums/z...8-11at1057.jpg

data chart:
http://i835.photobucket.com/albums/z...8-11at1056.jpg

Testing notes:
winds changed a lot during the 2.5 hours of testing. They started out a 8-12 mph out of the S,SE. Part way through (A2) they were calm. Then they went back to 5-10mph out of the S,SE. My road was East West.
Temp, 84 RH over 80%, it started sunny then got cloudy.

Speed was 55MPH using cruse (same set point throughout).
The road I used was not that flat, had several high and low points, also the road was well rounded or crowned.

I warmed up car by driving 15 miles before testing.
A= normal no skirt
B= with both wheel skirts on
1W= run 1 West
1E= run 1 East
Each way was 2 miles of testing.
Measurements done with scan gauge on current trip mode, hit rest at start and wrote down number at end of two miles.
Getting good data points going east was harder due to traffic coming that way more often in the afternoon.




And the coast down test:
http://i835.photobucket.com/albums/z...101149PM_2.jpg

Chart with raw data:
http://i835.photobucket.com/albums/z...102235PM_2.jpg

Testing Notes:
Start at 55mph by cruse, hit reset on scan gauge and clutch at same spot.
Star was still warm from other test (cooled off for an hour during dinner).
I warmed up the car for 4 miles first.
all are .9 + x car lengths, measured by my eye (and by where I stopped).
Since I started at the same spot the end spot is also a valid measure.

After looking at the steady state data for a while, I noticed that my with skirts data was about 1% lower than the base line. It is well within the Standard deviation of the data sets though, but I think that it is lower. I think I know why as well, the wind. I noticed that during the 3 hours of testing the wind went from not much at the start, to gustier on my B test. For the A2 set of runs the wind was almost none, only a few times did I see leaves move. For the B2 set it was back to windy (it rained 20 min after I stopped testing). Since I was looking for a change at the margins of the data I think that the wind (and time) invalidated the results.

Other ideas?

what should I change if I try the test over?

Thanks for posting your test results. It takes a lot of time to do right and can be frustrating if weather conditions don't cooperate. The coast down graph looks encouraging. What does the 7.25 number signify? Also, were you able to leave the car running and cruise on, but disengaged so you could just "resume" to get to the same speed for the A-B Scanguage test? I hope you can find a calm day to try another set of tests.

The 7.25 is the number of car lengths past .9 of a mile. It is aprox done by eye, but I used the same start point so can judge the difference in the ends.

Yes I did leave the car on and used the same cruse setting for each run. I hit resume before my start spot and gave it time to steady out, then put the clutch in at the end.

I think that today it is a lot calmer out, I might do some more runs. this time I will do it on a flatter road. I think I also will only do 1 mile each way to save time.

other hints?

...wind and terrain elevation changes (even slight changes) can affect one-way numbers. To reduce this, back-to-back, two-way tests are preferred (I did automotive-tank fuel economy tests on the GM and Chrysler XM-1 tanks at the USArmy's Yuma Proving Ground).

All my testing was both ways. start go 2 miles, wright down data, turn around and run 2 miles back to start. the elevation should have averaged out, but the wind was not steady, it was shifting, changing speeds and gusting.

here is my data file. it has all my raw data and charts.

Good testing is hard to do even when the weather (wind) does cooperate!

One suggestion: higher speeds will make any difference from aero mods stand out more (if there is any difference).

how can I test at a faster speed with out braking the speed limit of 55mph? The only place I can think of is on the freeway (70MPH) but to get no traffic I would have to run the test between 2am and 4 am.

other ideas?

PS did more BABA testing this morning still need to put the data into excel.

More data
 

Update:
I did a second set of steady state testing today.

Notes on testing:
Tested in this order B, A, B2, A2
warmed up car by driving 14 miles before testing (I think this was not enough)

Testing conditions:
Winds 5-8 N, NE
Temp, 78-84
RH: over 90%
speed was 55MPH using cruse
road was about as flat as I have around here.

A= normal no skirt
B= with both wheel skirts on
1S= run 1 South
1N= run 1 North
each way was 1 miles of testing
measurements with scan gauge

Here is the data:

http://i835.photobucket.com/albums/z...08-12at303.jpg

http://i835.photobucket.com/albums/z...08-12at303.jpg

Comments:
Wind was far more consistent today. it had some change to it but not a lot and it did about the same thing during each set of runs. I tossed of runs where there was lots of wind or no wind and still had more samples than yesterday.

The test mile was almost level, it had a hump at the start and end (intersection high spots). This made for less acceleration by the cruse control.

I might make up a graph without set B. I ran this set first and I think that the car was not fully warmed up by the 14 mile drive I did to warm it up. By the end of set B things seem to have fully warmed up as the next sets are similar to each other.

Summery: the data shows a slight benefit with the wheel covers on (.4 MPG or about 1%), This is still within the error rate for the test (standard deviation of between .6MPG & 1.1 MPG).

The benefit is even better if I toss out set B and only use the B2 data (.62 or 1.5%) with the same SD.


Those of you who have done testing like this, what do you think? valid results or not?
Attached is the data file with both today's and yesterdays tests.

That looks slick!! Get ready to roll into the World of Rubberneckers:rolleyes:

That's pretty much what I did. Well, almost. I started at 4:30am and it turned out that was too late (too much traffic).

what were the results of your testing? I only found MetroMPG results when I was looking at doing this. If you have good data, lets get both of our tests linked on the 65+ mods page! I think a moderator has to do it though:rolleyes:

My results are in my mod thread, post #40 and post #43. I got an 8% improvement in fc @ 100 km/h (62 mph), but this was for rear skirts, Kammback, removed roof rails and folded passenger mirror. I didn't have time to test each individually:( I've been hoping to test again this summer, but so far each weekend has been otherwise occupied. I want the second test done at a different site (less traffic) to compare to the first, and to compare once I get a bellypan, which can't be A-B-A-B tested easily.

I will have to look at how you did your kamaback, I need to see if it is worth doing on my car.

Here is my cost data for the wheel skirts:
materials:
braces $8.00 bought two used one, cost is for both
screws $0.50 used some I had, but bought some to refill stock, cost is for ones used
sheet steel 0 free, had it laying around
brackets 0 free, taken off junk stuff
hinges 0 free, taken off junk stuff
Primer $5.00 Used 95% of one can
paint $14.00 bought two 8 oz cans used 1.5
clear coat $5.00 used less than half of can
Total $32.50 (only what was used = $22)

Time:
design time 2
build first bracket 2
build first skirt 2
mount and tweak first skirt 1
paint first one 0.75 (not counting dry time)
build second brace 0.5
build second skirt 1
mount and tweak second skirt 0.5
paint second one 0.75 (not counting dry time)
Total 10.5 hours

Testing:
Time:
planning 0.5
first ABA test 3.5
coast down 1.5
second ABA 2.5
Total 8 hours

Costs for testing:
gas 7 gal
cost $19.00
miles 280


So in total I have about $50 invested in skirts and testing. I also have 18.5 hours invested in making and testing them.

Testing takes a lot longer then I had thought:turtle: But good data is nice to have (and share):thumbup:

Update: after 700+ miles on the car I have had no issues! No rubbing or loose parts!

With all my mods I have seen a 2-3 MPG gain (very conservative number).