Opel GT Forum banner
1 - 11 of 11 Posts

· Registered
19 Posts
Discussion Starter · #1 ·
I just bought a 1973 Opel GT and I was wondering what I could do to get a little more horsepower. Any information on cams lifters exhaust would be greatly appreciated. By the way I was wondering how fast a 1973 Opel Gt with a 1.9 4speed will go?

2,111 Posts
well for performance parts try posting a wanted add for performance parts on here or try OGTS (opelgtsource.com) and suselbeek (opelgtparts.com). and how fast does a GT go? not fast enough!!!!! slow gutless powerless vehicle if you ask me. according to road and track they will do 113 with a 1.9 and a 4 speed, it sounds underestimated to me though, as i've had mine up to 100 and only doing somewhere around 4500. some of the senior members on here will be able to give you tips on how to beff up that 1.9, or even engine swaps, which seem to be most prefered. wish you the best of luck with your new toy!!!

· Registered
521 Posts
published top speed is about 118-120 for the GT model. But most older examples with worn engines....don't expect to get that high.

First of all, you have a 73 spec motor which has slightly lower compression pistons and HP (thank the tree-hugging emission people for that one)

Here's a BRIEF "get-the-opel-up-to-date" minimum you should try if you want more power.

(Go see www.tgsi.com for a more in depth look)

1: If it has the Solex carb on it toss it out and put on a 32/36 Weber. (consider a 38 DGAS also, if your really bold and port match the intake manifold)

2: Crane XR700 electronic ignition.

3: Increase cylinder compression/ High compression pistons(shave cylinder head)

4: "sportier" camshaft

It's starts to get much more expensive after this....
BTW: headers/exhaust system probably won't make much difference at this point. I wouldn't go there yet....the motor has to be built up a bit more for these to become effective. At a minimum I'd do #1 and #2.

· Moderator
184 Posts
Funny I just posted a link to that article on a reply to a Classic Opels reply:

http://f2.grp.yahoofs.com/v1/cOLXPh...chnical Information/OANA Tech Tips/intake.pdf

I've got a '73 with the low compression engine. The Weber is a must, toss in a K&N air filter with a snorkle cold air intake. I read getting more effective gas/air into the engine and exaust out was the key to getting the most out of a STOCK engine. Breathe in, breathe out, so I've heard.

Granted head/cam/valve/piston mods will get great results, but that's digging into the engine. I was afraid once I got there the project would take on a life of it's own, like some many of my project do. I wanted a car to drive this summer so I was looking more for "bolt-on mods".

I did the intake porting and carb base mount matching as recommended in RallyBob's article, and rejetted the Weber. Easier in. I then found and installed a Sprint exhaust manifold. Easier out. I was amazed at what these two mods did. I still need to get the custom 2" exhaust installed to finish off the easier out part.

One day, no doubt I'll be digging into the engine, which will turn into an entire rebuild. For now I think I've gotten the biggest (and quickest) bang for the buck horsepower increase.

· Premium Member
1,796 Posts
pitch the points

Even bigger reliability and performance gains can be found with new ignition items before the carb stuff. I recommend doing a search here for "ignition" and deciding between the $55 points eliminator and the $200 dual coil model that RallyBob did a write-up on. I lean towards the latter, but your wallet may force the former.

Even with the Solex the ignition upgrades will make a world of difference, and no matter what you do with the intake or exhaust they will still help.

· Registered
48 Posts
I have just built up my Manta 72 1900S. I built up the engine with lots of new upgrades and my motor now pumps out about 150hp and revs to 7000 rpm. What I did is as follows:

From the stock 1900S (hi-comp) engine, I bored it out to 95mm and fitted 2.0 liter flat top pistons. I cleaned up the 1900S head combustion chamber and shaved the head to achieve a 10:1 compression ratio. I fitted bigger 2.0 valves and in the process, had a 3-angle valve job and had the head ported. I installed an Opel GT/E Camshaft with matching solid lifters and this is fed by 2 X 40DCOE Weber carburators (32mm venturis) with 2 inch velocity stacks. Exhaust is through a 4-2-1 header and a 2 inch exhaust system all the way.

Ignition upgrades include a Petronix Ignitor, Mallory Hyfire VI ignition system, Mallory Promaster Coil, Mallory 8mm ignition wires and Champion L87YC spark plugs. For the increased cooling requirement, I fitted a larger radiator (3 rows) and a DERALE oil cooler.

The flywheel was lightened and I fitted a 2.0 liter clutch. The gearbox has been replaced with a ZF 5-speed (5th gear still 1:1) gearbox (dog leg 1st gear). And I replaced the rearend with a 3.67 gearset (from an Ascona B 1.9N). I am currently looking around for a POSI unit but this is very pricey......

Total cost for the motor build up was approximately $1300. Being freindly with a machine shop was a big help for me. I was able to get a lot of parts from ebay in Germany and this saved me TONS of money. My advice to you is to do this, and find someone you know who can store some parts for you so you can collect a big number of parts before shipment. A 36" X 36" box sea freight from Germany cost only $60.

Have fun!
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.