Originally Posted by EdKiefer
I didn't know they made 1.1L GT , never say one .
On the gear ratios are you sure on that because I kind of remember the GT shared same rear gearing as standard Manta , which was 3.44 , the Manta ralley had 3.67 at least in the yrs of like 1970-1975 .
I always liked the 1.9L, its very strong engine with the way they engineered the head .
I later added a turbo to mine with upgraded 5 speed because stock 4 speed could not handle extra TQ (went through 3 trannies in one week an gave up on OEM one ).
Yes the 1.1L is pretty rare, only 3500 were made out of 103,400 total GT's produced, and not all that were produced came to the US. I've only seen a few of them in the 15 years I've been into Opels. I've restored several 1.9L's. I had one I bored to 2.0L with a hotter cam and higher compression plus the Getrag 5-speed. It was a blast to drive, wish I hadn't of sold it!
Anyway I'm piecing together a 1.1L. And I will swap it into my current GT that is 1.9L. I managed to find a guy selling the entire drive train minus the radiator and complete set of carbs. Actually two complete drive trains. Although one is disassembled and the block is locked up.
About the rear end. The 1.1L has a completely different rear end/axle than the 1.9L Manta or GT. Everything about it is smaller and lighter. Except for the gear ratio it is the same rear end used in the 1.1L Kadett. The 1.1L GT had a 4.11 rear ratio and the Kadett had a 3.89 rear ratio. The reason being is that they wanted the GT to have more pep, being that it was a sports car and the Kadett was more of a standard compact. But if you use it in a GT it will essentially be like an OD ratio.
Luckily I managed to find and obtain both a 1.1L GT and a Kadett rear end. If you really want FE in your car I would suggest sourcing the 1.1L motor. While there weren't many GT's that came in the 1.1L trim there were plenty of Kadetts and Wagons that came with the 1.1L so they're still around and will bolt right into the GT.
By the way here is a list of differences between the 1.1L and 1.9L GT that help it reduce weight (that I can remember):
Smaller 1.1L Motor (You can literally pick up the long block and handle it by yourself, it's like a toy)
Smaller 4-speed transmission
Smaller diameter drive shaft
Thinner engine cross member
Smaller diameter rear axle (with different ratios)
Smaller front brake rotors and calipers
Smaller rear drums
Half Sized Radiator
Dual down draft carb so it has a different
Dual intake air filter snorkel (for the carbs)
Front Suspension leaf spring had 2 layers vs 3
I actually haven't sourced the front leaf spring yet. It serves two purposes, it is lighter and it allows the front end to sit at the proper height. Because the engine is so much lighter in the 1.1L if you were to use the 1.9L front leaf spring the front end would sit up a few inches higher.
In addition to the fiberglass belly pan and hood available you could use the earlier crashbar-less doors to save some weight too, but I think I'm going to go with safety......