Best FE Recipe for a 1990 Geo Metro Convertible...

[dissimilation]

Hey there, I posted last week a few questions about CRX HFs and went to buy one (cash in hand) only to find I'm too tall for them. Currently I have two main vehicles, a 93 Civic DX and a 90 Metro Convertible. The Civic is my daily driver and I get between 39-41mpg with it. I'm looking to give the Civic to my wife and use my Metro Vert as a daily driver. I drive 35 miles each way to work, all freeway and about 33 miles of that is smooth sailing (no stop and go). I used to drive a 91 Metro HB in college that I would continuously get around 52 with on mixed city/hwy driving. The convertible as you all know, is a different story. The extra weight added for rigidity lost from going topless and larger tires make it get a bit less than my old beloved college cruiser. My basic need is to get this thing over 40mpg to justify driving it instead of the civic.

You guys might say I'd be better off modding the civic, but I'm squeamish with messing with the car as it is completely stock, has run perfectly without anything but standard maintenance since new and has been pampered so much that it still had it's original brakes until around 85k miles. Also, my wife needs the room of a hatchback. The Metro on the other hand cost me $450 and is, well, a Geo Metro. My Dad and I replaced the engine in my old one over a weekend and replaced a friend's transmission in a day - I know these cars too well and have two parts cars to back it up. The $450 was due to it sold not running from the prior owner. It was completely straight, stock and had a good interior. It took me an afternoon to figure out that a $16 timing belt was the only thing keeping it from getting back on the road.

So here's what I have...

1990 Geo Metro
3 cyl
5 spd
A/C (not working, presumably needs to be recharged)
170,000 miles

What I have in parts...
A 91 Convertible parts car with a bad engine knock
A 94 3cyl motor with approx. 120,000 miles
A 91 Metro HB with all parts not needed for it's new life as an EV up for harvest (the 94 motor is currently in there)

Interesting fact: The place I work is building a solar roofed carport with a charging station. Perhaps an alternator-less conversion with day charging?


I'm experienced with keeping these things running, but I'm new to tuning them for MPG. Your suggestions would be greatly appreciated! Here are some pictures of the car from our wedding back in August...











I sure do love the little guy.

[atomicradish]

:swoons: I love it! Exterior paint looks great!

What kind of MPG are you currently getting? Honestly, I dont see how you're not already getting near 40 MPG or better. My Mitsubishi Galant has a DOHC engine, lots of horsepower (for a 'gas saver' car), and I drive on the interstate at speeds which no hardcore gas saver would ever do (70, 75 or more) and still easily pull 30 - 32 highway. Just drive it in 5th at a moderate speed; 60 - 65, and you should be driving pretty efficiently.

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Thanks! The paint is Earl Scheibs's work. The rebadging was also Earl Scheib's work (don't look too closely). It was a pretty bad faded red before the orange coat went on (about 3 days before the ring went on, we both had to look our best for the big day). It's a cool color that looks bright orange or bright red depending on how light reflects off it. I always loved orange and it was the only unique color on their "budget" palette of colors, so it was an easy choice.

I have actually not had a chance to calculate the MPG yet, as I only have driven the thing on surface streets for fun - which has got me somewhere around 33 as I recall. I'm guessing that's due to having the same power plant as a far lighter car and having to drag itself up from a start over and over on city driving. It has been a weekend fixer upper over the past year. I put in seats from the other convertible, fixed the convertible framing from donor parts as well, replaced the ragtop and a few other cosmetic things. I'm yet to give the old guy a tune up, so it's got some ways to go to operating at an optimum level. The shocks are way over due for replacement too, unless the convertible really does have that soft a ride (with the extra weight and cushy shocks, it reminds me of my 79 Caprice Classic back in High School).

[GasSavers_DaX]

I am SOOOOOOOOOOOOOOO jealous of your metro convertible! What kind of condition is the top in?

I'd get an XFi transmission for that thing and EOC all the time! You've already got the 3-cyl engine in there...

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Wow, I guess I finally found the right group to share my enthusiasm for the metro convertible with. My friends, family and coworkers either roll their eyes or think it's kinda cute, but both groups think I'm insane for driving it - let alone seeking one out and restoring it.

The top was in horrible condition when I got it. The plastic piece of the frame that met with windshield was cracked nearly in half and poorly mended with a fiberglass repair kit, one of the metal pieces to the frame was bent, and the original black vinyl top was torn faded and mended in the least attractive ways. With my parts car (whose top was in disarray as well), I was able to put together one perfect frame and ordered a new canvas (color and material) top. I'm really good at replacing those now, but next time I'll definitely inquire about how much it costs to have it done (not a fun job). So to answer your question, it's in great condition - minus me not having taken the time to sort through and find the best weather stripping from both vehicles to put back on there. Since I seldom drive it with the top up, and it hardly ever goes on the freeway - I just never got around to it.

Interesting idea with the XFI trans. I didn't realize it had a unique trans as well as camshaft. The XFI is new to me, and I thought I knew all there was to know about Metros. I've seen them many times and just thought that chevrolet was just getting too excited about decals in the early years - didn't realize it was anything more than a base model.

The transmission in the convertible is different than that of it's hatchback brethren. I don't know if an XFI trans could handle the weight over time. The stock "beefier" trans usually wears down on the second gear, which I was surprised to find on both the 90 and 91 verts I have - you needed a little practice on getting it to want to be in second gear. Also keep in mind, this driver adds 350lbs to the curb weight. I'm working on that "modification" right now. Though at 6'7" and my natural build, don't count on more than 100lbs being shaved off. Unlike a car, I can't remove my interior for added benefit (I already removed the appendix, so that's crossed off the list). So has anyone here done an XFI trans swap on a Geo vert before (or a hb?)? What do you think the real world difference in MPG would be?

[Improbcat]

The first two things that leap to mind for improving FE on this car are:

a)rip the a/c system out. Compressor, condenser, lines, swap in a heaterbox & controls from a non-ac car if one of your parts car has it. That'll shave a decent chunk of weight off, and any day warm enough for a/c you'd probably want to top down for anyway.

b)build a custom roof for it. Seriously. Use some sheet metal (or chloroplast for insane weight savings) over an aluminum frame. Design it to hook up to the stock droptop latches on the windshield frame, and strap to the trunklid somehow. You could then design it to have the optimal curve for best FE.
If you want to get really insane, combine this with a boattail to further reduce .Cd. If you design it well, it could drastically improve the .Cd of the car, and be fairly easily removable when you want to convert from MPG machine to fun convertible.

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Here in San Diego, I might appreciate keeping the A/C in. Besides the heat - there's also cold costal days where the A/C dehumidifies the inside of the windshield quickly. I'm not totally opposed to the idea though. The donor vert is non-AC equipped. What are the gains?

I'd say I've done enough roof work for the time being. Though a detachable hardtop would be be pretty sweet. I really love the look of the car, and don't want to make it different - but I know some fabricators and a friend with a water jet cutting machine that carbon fiber wheel skirts might be on the menu.

[Improbcat]

Ripping out the a/c has two gains, weight reduction of the parts being gone and the (very minor) gain of not spinning the clutch.

I mostly mentioned it because you said the system was non-functional anyway.

[GasSavers_DaX]

Personally I'd keep the AC - I have it in my Beater, and I'm still getting great mileage. All in all, you may save around 30 lbs taking all the AC components out, which isn't that much. The energy required to accelerate that 30 lbs isn't that great. You could loose the 30 lbs elsewhere and keep the creature comfort. As for the drag of spinning the clutch, it's almost nil when the AC is off. Keep that thing cherry!

As for the XFi transmission not being able to handle the extra weight of the car, I think you'll be pleasantly surprised. I've got a CRX HF transmission in my 4-door Sedan. The HF is in the 1700 lb range, while my sedan is over 2100 lbs! Sure, I drive like a grandma, but that's what gets the best mileage.

[trebuchet03]

This makes me sad..... You say it's painted orange... but I can only see red :/ It makes me sad because somewhat recently, I've discovered that I'm in denial of my color blindness

Very nice car though