New Project 69' Opel GT 1.1L

opelgt73 · 04-25-2008, 09:44 AM

Greetings, I am new to this message board but have already found tons of useful information!

Anyway my project is a 1969 Opel GT. For those of you that don't know the US model GT came in two engine sizes 1.9L and 1.1L. The 1.1L can regularly get 50-55mpg and the 1.9L was about half that. The 1.1L is significantly lighter, everything from the radiator to the motor to the rear axle is smaller and lighter.

My goal is to break 65Mpg in mixed driving. There are several things I am going to modify that I believe will get me to that number. The first is the rear axle ratio. I am changing the 4.11 rear axle with a 3.89 from another model Opel, I have considered adapting a 5 speed manual (currently 4sp man) but I think the new rear end will give me the proper OD ratio. I am building a programmable FI system, the stock engine has two hard to adjust carburetors. I will also have a custom fabed exhaust system. I have not done a cost benefit of raising the compression but I may raise the compression. Beyond that the only engine modification I may experiment with is different cam ratios, but because I would have to have these custom made as there are none readily available, this is last on my list.

I also plan to do as much weight reduction as possible. Replace the metal hood and belly pan with fiberglass. Replace the steel wheels with light weight aluminum. Replace the steel radiator with modern aluminum. I don't know how heavy the stock seats are but I am guessing I can find lighter modern seats. Remove any unnessicary interior pieces.

I don't have the shell of the car yet but I do have the complete drive train. This weekend I am going to be tearing down the engine to rebuild it. If anyone is interested I will upload some pictures of my progress.

maxxgraphix · 04-26-2008, 06:11 AM

Neat little cars. However parts are very expensive and hard to find. I had a 73 GT with the 1.9L. Something was always wrong. Good luck.

Quote:

Originally Posted by opelgt73

Greetings, I am new to this message board but have already found tons of useful information!

Anyway my project is a 1969 Opel GT. For those of you that don't know the US model GT came in two engine sizes 1.9L and 1.1L. The 1.1L can regularly get 50-55mpg and the 1.9L was about half that. The 1.1L is significantly lighter, everything from the radiator to the motor to the rear axle is smaller and lighter.

My goal is to break 65Mpg in mixed driving. There are several things I am going to modify that I believe will get me to that number. The first is the rear axle ratio. I am changing the 4.11 rear axle with a 3.89 from another model Opel, I have considered adapting a 5 speed manual (currently 4sp man) but I think the new rear end will give me the proper OD ratio. I am building a programmable FI system, the stock engine has two hard to adjust carburetors. I will also have a custom fabed exhaust system. I have not done a cost benefit of raising the compression but I may raise the compression. Beyond that the only engine modification I may experiment with is different cam ratios, but because I would have to have these custom made as there are none readily available, this is last on my list.

I also plan to do as much weight reduction as possible. Replace the metal hood and belly pan with fiberglass. Replace the steel wheels with light weight aluminum. Replace the steel radiator with modern aluminum. I don't know how heavy the stock seats are but I am guessing I can find lighter modern seats. Remove any unnessicary interior pieces.

I don't have the shell of the car yet but I do have the complete drive train. This weekend I am going to be tearing down the engine to rebuild it. If anyone is interested I will upload some pictures of my progress.

mustngr · 04-26-2008, 10:36 AM

Great project, although personally I'd ditch the 1.1 in favor of the 1.0 Suzuki/Geo Metro motor coupled to a Samurai transmission. I'm currently installing this combo in my '78 Triumph Spitfire, along with as many of the (much lighter) Suzuki/Geo components as possible (brake master cylinder, radiator, etc.). My goal is a sub-1300 lb car and 60+ mpg.

This combo weighs 200 pounds even, offers fuel injection, durability, compactness, cheap and available parts and proven fuel thrift, for about he same horsepower as my smogged-out, nearly 500 pound Triumph motor/ trans. Assuming you have the skills this is about as simple as an engine swap gets, leaving an acre of open real estate, even under the Opel hood.

I envy you. Been looking for straight GT at a good price for years. They're quite possibly the best start in terms of aero and weight ever built. I wouldn't change a thing, (except everything forward of the firewall). Even the popup headlights wouldn't offer that much of a mileage penalty if you're already getting 60+.

Just my .02.

Mentalic · 04-27-2008, 06:54 AM

Quote:

Originally Posted by theclencher

I don't see how good fe is possible with a 69' car!

Only drive it down hill!

I had an Opel station wagon when I was 15, got about 14mpg hauling drum kit back and forth to school. Parts were easy to get then, the junk yards were full of Opel's!

VetteOwner · 04-27-2008, 09:35 AM

theres a junkyard by me that still has one. ive seen on drving around. neat little cars but id imagine parts are super expensive...

pic of said junkyard car

lunarhighway · 04-27-2008, 01:15 PM

the opel gt is actually based on the opel kadett C.. wich was soled in the us as the chevett or the isusu gemini. i don't know how much different these cars where but i emagine there's quite some similar parts in all.

i totally love the looks of the GT despite the fact it looks more aerodynamic than it actually is... fairly high Cd, but it's minimal frontal area and light weight should still give it an edge over bigger but more aerodynamic cars... and perhaps some small aero tweaks can help a lot in the aero department.

opelgt73 · 04-28-2008, 12:35 PM

Quote:

Originally Posted by maxxgraphix

Neat little cars. However parts are very expensive and hard to find. I had a 73 GT with the 1.9L. Something was always wrong. Good luck.

See I've found them to be quite the opposite. Of all the cars I have had and worked on the GT has been the cheapest to buy parts for. I'll see how it compares to a Civic. I just picked up a 91 CRX HF and will be restoring it shortly.

You can get anything for the 1.9L motor but the 1.1L motor that I have is a bit harder to find parts for. I have sourced just about everything but NOS pistons for it, which sucks because those are pretty important!