Modding a cavalier
 

I recently bought a 2002 cavalier with the 2.2 ohv motor and an auto trans, unfortunately the only cav I could find with a manual trans was in need of a new clutch and the owner wouldn't budge on price.
Epa highway mpg is 33 and my last couple tanks have been coming in just under 30. The car was reasonably well cared for but it's got nearly 160,000 miles on it. I ordered a new upstream oxygen sensor the other day since it looked like the original sensor was still in there and I couldn't find anything obvious that would be hurting mpg. And just to note I do drive gingerly and use some hypermiling techniques. The car is bone stock and I got it as a cheapo commuter to get me through my last year of college cheaply
I've been considering some aero mods and wanted to get some ideas/suggestions on where to start. The stock bumper cover has a lot of 'vents' on it so I was thinking of starting by blocking those off temporarily with tape until the weather gets warmer and I can fashion something out of fiberglass. I'm probably also going to get rid of the antenna since I don't use the radio anyway. I've been thinking about rear wheel skirts as well. I don't have the space or desire to do anything too radical like a boat tail or anything but I do want to do some modest things to squeeze a few extra mpg out of it. The next oil change is going to be with the lowest weight synthetic I can get away with.
What are your opinions? Would those aero mods amount to much? If making wheel skirts and a new bumper won't do a whole ton then I'd rather save the time and money and stick to using cheaper materials like cardboard and tape.

Is this a two door or four door ?

The main thing I see that stands out to me is the rounded trunk/boot.

An easy fix for that is to simply add a trip strip where the airflow would begin to tumble.

Your biggest gains will most likely come from adding a Kamm-back, and perhaps other mods like wheel gap fillers/smooth wheel covers, and a front spoiler or undertray cover.

Personally, I would do a Kamm-back before i did the wheel skirts.

Regarding the bumper holes, yes that would help some, but most likely not enough to show. It's easy to do, and would help - just not that much.

http://ecomodder.com/forum/showthrea...tml#post461814

http://ecomodder.com/forum/attachmen...1&d=1419976139

Here you can see the 'trip strip' at the edges of the bumper. If you follow the link i have above, there are some great tips.

It's the 4 door. The girlfriend was adamant that I not get a 2 door since we have larger dogs that go places with us. A kammback is a little more than I wad looking to do but adding a trip strip would be easy enough. What I'm really looking for is enough little stuff that on their own wouldn't do much but together would at least do some good.

That trip strip doesn't look too tough. I'm not too worried about hacking the car up too much since I got it pretty cheap. Also want to get a scanguage with my tax return.

Get an ultragauge, your using EOC or have lean burn so it's a little bit of a waste of money to get something as fancy as a scangauge. Ultragauge is 1/2 the price, does what the SG does, just not as clean as SG.

Thanks for the tip. Once I get my refund I'll look into it. I had a vacuum gauge in my old s10 and it was pretty useful. The car I rented after a tree fell on that truck had an instant and trip econ feature on it. Needless to say the weekend I had that car it was a fun game to play on my commute.

I should add I rented it with about 2 gallons in the tank and they said I could bring it back empty. I made those 2 gallons last for 4 days and a little over 100 miles, it was a brand new Ford fiesta

The Save the Flea project is an interesting read, as well as the 15 mods for 15% improvement.

The mods on Metro's Civic are pretty discreet and offer quite a bit of improvement over bone stock.

There are some other pretty simple mods that you can do that will help. From what I understand, an air dam and side skirts are some of the best aeromods since they basically don't allow air to get under the car.

Welcome to the site.

With my 97 Sunfire. The main trick was to get that torque converter locked up as soon as possible. After that torque converter locked, the mpg just kept going up.

If you don't already, I'd definitely get yourself a scangauge, ultragauge, or a bluetooth OBDII adapter and torque for your smartphone. Instrumentation is key to getting good mileage.

Don't know if your 02 has the 'Ecotec' engine or not. If it does get the updated timing chain oiler ASAP! The early Ecotec's have pretty marginal chain oiling (hole was too small) and by 160k you're WELL into the 'danger zone' of a catastrophic failure (valves crash into pistons). Realistically, a full timing set would be a wise investment.
Just a heads-up. :thumbup:

No ecotec, it's got the last of the old ohv motors. It's the same motor I had in my old s10 so I've got some familiarity with it's quirks. I'm going to look into doing some aero mods like a better air dam and changing the rear a little bit so air separates a little more clean. Probably just get some lawn edging to keep it cheap. Maybe blend it with some bondo and cover it with paint so it looks like it belongs there. Just waiting for my 1098-t from my school so I can get my tax return and buy an ultragauge! I've got a couple days off so after I get my homework done ill do some tinkering and post some pics of where I end up.

Cool.
I knew they started using the Ecotec somewhere in that time frame. I was unsure when the Cavalier got it. :thumbup:

Of all the Cavaliers I looked at it seemed to be pretty mixed on which ones had the ecotec for the 2002 model year. The must have made the switch mid year I guess.

Filled up my tank today only to calculate an abysmal 26.2 mpg...
That's with pretty mixed city/highway driving. I did a couple small 'mods' today though: I removed the antenna and just used plain ol' clear packing tape to close off the vents on the bumper, and filled the tires to max sidewall(44psi). Also picked up some convex mirrors to mount inside. I did some reading on Oregon's rear view mirror laws and it's quite vague, only specifying that a vehicle must have an unobstructed view of at least 200' behind the vehicle. No mention of side mirrors so those will be coming off soon. Washington state on the other hand requires at least the drivers side mirror, and I do have family I see semi-frequently in Washington so I'll need to consider that.
Also poured in some Techron to give the valves and combustion chamber a repeat cleaning, I did this shortly after I bought it. The PEA in it does a pretty good job at cleaning things up. Now I just need to wait to get the oxygen sensor I ordered in the mail and hopefully that'll improve things a wee bit!
While I was at the hardware store getting some unrelated stuff I had a look at lawn edging to make an airflow trip strip and the selection was paltry at best. It's a local mom n' pop hardware store and I prefer to give them my business but I may have to check out the home depot to see if they have anything better suited.
While not specifically aero related, I did a spark plug check & regap after I bought the car and noticed they weren't oem plugs; the S10 I had with the same motor was believe it or not fairly picky about what plugs it had so I may see if I can pick up some oem variety plugs and use those.

Have you been able to figure out under what circumstances your torque converter locks up?

Not quite. This is the first auto trans I've owned. I've given it a little gas while cruising at light load and the rpm hasn't climbed independently of the vehicle speed so I know it at least locks probably around 45mph or so. If I give it too much it downshifts and of course is no longer locked. I'll try some more at different speeds and engine loads though. I've always tried that on the freeway going ~50mph though.
God I hate automatics.

I deleted the passenger side mirror today and also removed the splash guards from behind the front wheels. I may end up repurposing them into spats and/or mounting points for wheel skirts with some minor modifications. So far for this tank I'm at 320 miles with 1/4 tank remaining, this is usually when I have to fill it so when that time comes I'm hoping for a decent improvement! I know just going off the gauge isn't too accurate but I'm hopeful. I just downloaded dashcommand for android and I'll be ordering a Bluetooth obd dongle to get some instrumentation here soon. Next up is an improved front air dam and some side skirts made from lawn edging. Would metal edging or plastic be a better choice? The flexibility of plastic would be nice for pulling out of driveways so I don't break anything when I scrape but I'm not sure if that flexibility would be a good thing on the highway.

A couple people around here use the composite plastic, which isn't as flexible as regular plastic so it doesn't flop around on the highway but is flexible enough to get out of driveways. Side skirts are a little difficult with lawn edging because it always wants to curl up while you want your skirts to be straight.

The thing about auto transmissions with TC is that you need to be up to speed before it will allow it to lock up. In the automatic, 5th gear is cruising gear, not an accelerating gear, so of course it will downshift when you lay down the gas, but once you are up to the desired speed and the TC locks up, you will get pretty amazing gas mileage. So if you want to get the TC to work with you, you need to have a lighter load once you are up to speed, or else it won't work.

Remember, 80% load for accelerating, <20% for cruising. In my Civic, 80% would be about 3k RPMs while accelerating or 3.0 Gph. Anything past that would be out of the max torque powerband and slower than that would be too slow to get up to speed before the next light. Your car will be a little bit different since it is a little older and a completely different brand, try to look up the BSFC chart for your car to see where and how to accelerate.

Hope this helps! :)

Thanks for the tip! I've been able to figure out how to coax the TC into lockup on certain roads I frequently take. Also have a gnarly hill on I-5 I take on my way home and have been able to keep it locked up in high gear by driving with load... tricky to do without proper instrumentation! Last night I built up a little speed before the hill and gently feathered the throttle to keep it from downshifting. I ended up bleeding off about 10mph when I reached the top and was able to coast all the way down to my exit where there's a very unfortunately placed stop sign to kill all the momentum I had :(

The more mods you throw at it the easier it'll go into, and stay locked up. When I dropped my p/s pump, the only change I could notice from driving was the TC seemed to be more willing to stay locked.

Just figured out the ecu's dfco parameters so i can take advantage of that in certain situations. Above 1800 rpm with 1% or less throttle for 8 seconds triggers dfco. If only it started instantly...