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

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...

https://www.dissimilation.com/1.jpg

https://www.dissimilation.com/2.jpg

https://www.dissimilation.com/3.jpg

https://www.dissimilation.com/4.jpg

https://www.dissimilation.com/5.jpg

I sure do love the little guy.

: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.

Thanks! The paint is Earl Scheibs's work. The rebadging was also Earl Scheib's work :rolleyes: (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).

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...

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?

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.

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.

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.

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.

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 :p

Very nice car though :)

There are other ways to get 30lbs of weight out of the car. Take the soundproofing asphalt out. It is under the carpet and in the trunk. That was around 25lbs in my car. You can swap the seats for fiberglass racing seats and a 5pt harness. Each front seat and seatbelt assembly is about 40lbs. A racing seat and harness is probably 10lbs. There is other random stuff you can live without that can be removed if you want to go nuts.

I would also put an XFi cam in and advance the cam timing a few degrees, if you can live with taller gearing get an XFi or 4 cyl transmission for the 3.79 or 3.54 rear end ratio. If you put the taller gears in you really need the cam though, because it's power curve is lower in the rpm range so it works better with the taller gears. But even without swapping cam or gears you can advance your stock cam 5-10 degrees and it will improve your bottom end power and let you shift earlier and run much better at lower rpms and pick up a bit of mileage if you don't drive really fast.

Also you should sell me your extra convertible :) I have been looking for a convertible body to build into something strange.

I'm at work, so I'll reply to all your other great ideas and suggestions later today. Just wanted to answer the one about selling the parts convertible. I will be selling it, but only half. When harvest season is over, the other vert will be cut in half to make a matching trailer. The bisection will be right along the floor where the doors end at the back of the car. I had one guy who was very interested in making the remainder into a 3 wheel car, but I lost contact with him. The ECU, engine, trans and so on will be intact and included will be the exhaust system and gas tank. I would love to see the other car reincarnated into another cool vehicle. Keep in contact with me as I chronicle the build. I bought the parts car for only $375, so I'll be plenty reasonable on selling the remains.

I had an idea on the way to work... that cutting away the outer door skins from the donor car and using them to make a perfect fit wheel skirt would be just about the best sano look one could hope for. Simply putting some welded tabs within the wheel well to keep it from falling in and some fasteners on the inside at 10, 12 and 2 o'clock to hold them against the tabs. Perhaps narrower tires on the back end as well?

That is a nice looking geo :) .
If you don't want to alter the look of your car like I did, driving technique is a big help. Engine off coasting is a very effective technique. I was looking back thru my gas logs and noticed a good increase in mpgs after I installed my fuel injector kill switch. Of course it must be used to get the gains, but it made it much easier to coast with the engine off (as apposed to using the ignition key). Don't do it unless your comfortable with engine off coasting though.

Also good maintnence is key. Make sure your wheels spin freely and your tires are pumped up good. I've had several issues with brakes dragging and it really killed the coasting of the car.

edit: I forgot to mention that my geo doesn't get great milage at highway speeds so I take back roads. Keep your speed down if possible. I avoid going over 45 but I have a short run on the freeway where the minimum is 55. The gearing and aero drag really bring down the mpgs.

This car screams out for a tear drop roofline. Either just to the end of the trunk, or a bit further. Wherever you end it, make sure that it is going near parallel to the ground, and when it starts, it should follow the windscreen line and start curving immediately.

It's a very similar thing I was thinking of doing with a Ford Capri. But it has a better angle between hood and windscreen. Nice find!

There was a recall mod on my 1994 Geo Metro 5 door where they added a bleeder fitting into the MAP sensor which lowered the vacuum it would see from the engine and cause the engine to run richer - cost me about 5 mpg.

Don't be too sad. I do graphics work for a living and by those photos I'd guess the car was red. It looks like a orangey-red on sunny days, like the day those photos were taken.

I still have an extra can of freon to charge it, I just need to get it tested for leaks before I use my last precious can. As for the 30lbs, I'll start taking walks at night and loose 30lbs for the car. Should be fun to record my mileage and my weight and see how they correlate. If I run out of self modifications, maybe I'll be so hooked that I'll start cutting weight from the car. As far as weight goes, there's two steel beams that run below the car that were put there for extra strength and rigidity. I'm willing to bet those alone add at least 100lbs to the car. I'm going to be looking into if those can be replaced with lighter metal.

You guys are bringing me around on this. The present trans will only last so much longer, especially racking on 70 miles a day - then I'll start hunting for an XFI trans. I already did a part search and found some with ridiculously low miles on them. Unfortunately car-part.com doesn't recognize an XFI engine as unique, so you can't do a simple search for it. Is there another parts site you guys have found reliable for searching?

I hope you're joking. Volvo driver here, safety first.

I suppose you could engineer a lighter pair of beams out of titanium. If you can find the right engineering and metalworking skills for that. Or maybe high-strength aluminum??? But those little Geo's are pretty darn lightweight compared to other cars - I wouldn't go removing safety features!

Maybe remove other things like spare tire (replace with AAA membership and/or Fix-A-Flat can), rear seat, junk-in-trunk, a/c and power steering, etc. etc.

From your photos, the Earl S paint job looks pretty good. How does it look up close?

Not joking, it wouldn't be replaced with something lighter unless it was equally strong. Safety aside, without that support the car would warp and contort itself into oblivion. I plan on taking some photos of the underside with some measurements and email my friend who cuts and welds metal to have him inspect whether or not it could be improved upon. If he thought it was compelling enough, I'd take one beam off the donor car and take it to him and go from there.

As far as the spare tire goes, it weighs so very little. It's actually an under sized spare, which for a Metro is way way small. I'll weight it and see exactly how much I'd save. There's no rear seat or power steering, Suzuki already did that for me. :)

It looks pretty good, but as good as you should expect from a $250 paint job. It wasn't masked too well around the trim here and there, but as the owner - I'm the only one who would ever notice. None of the trim is far off enough to catch the attention of a casual glance, nor detectable from about 6 feet away. With only a single window on the car and body colored bumpers, they didn't have that much masking to mess up on. The paint itself is a good continuous coat, no drips or bubbles anywhere.

I got my Civic painted a little over a year ago, and they did a good job on that as well. In both cases I sanded down the black trim that was flaking and masked it and painted it black before getting it painted. Also in both cases, I wished I had done it the other way around. I had learned my lesson the first time, but the second time I was getting the convertible painted for the wedding and had it painted just about 3 days before. The reason being was that you can't wash a newly painted car for several weeks, so I just did it right before hand to have a clean car that day. I painted the trim beforehand obviously because covering a new paint job with masking tape isn't a wise choice.

I checked my door jam for the official curb weight and was surprised to find the little guy weighs in at 2290lbs. I knew it before, but it's one of those things where you know the car is about 600lbs+ over the weight of the hatchback and it seems so crazy that you just think you're exaggerating and have to check the facts to make sure. Considering the guy is lugging around 640lbs more car and a 360lb passenger, that's a half ton over the weight of an XFI. What if I were to change the stock trans to have a 5th gear ratio similar to an XFI instead? 95% of the driving will be done in 5th anyway.

All of you guys have made excellent suggestions, some a little more radical than I might be comfortable with - but I take them into consideration all the same (I have spent a bit of time day dreaming in traffic on how one would go about making a detachable tear drop roofline. I was wondering what some more basic suggestions would be such as the best wheels and tires, thermostat, intake system, etc.

A 5th gear swap would net you some gains if you get to 5th as quickly as possible. The only downside to this is that you may have to take 4th up a little higher so you don't bog 5th.