HOWTO install an Omega 2.4E engine into an Ascona

There are many things that one has to change in order to get the C24NE from the Opel Omega-A to fit into an Ascona or Manta. The engine in itself is the same, it has the same block as all the other CIH engines, it even looks the same it you don't count the valve cover, which in newer (2.2E, 2.4E) is made of Aluminium.

There are differences though:

The Oilpan

The oilpan has the deep section in the front, whereas the Ascona/Manta has it in the rear. This requires three changes, namely:

The oilpan has to be changed to an item from a 2.0 or other CIH engine from Ascona/Manta
The oil pickup-tube has to be changed to an item from a Ascona/Manta engine. You have to use the bracket for the tube from the 2.4 engine though, as the longer stroke in the 2.4E requires more room around the crank. Please wait for a picture that explains that a little bit more. Shortly you can bend the 2.4 bracket some 90 degrees near the fastening hole so that it will support the tube, but still go clear of the crank.
The dipstick has to be re-located where it is on a 2l engine. In my engine there was no hole where the stick should go, so I had to drill one. The I used the tube from an old 2l engine, and go it to fit quite nicely. Remember to plug the hole where the 2.4l's stick was!

The flywheel

That should do it concerning the bottom, but if you go upwards, you will soon notice that the flywheel is pretty much larger than e.g. the 2.0E item. So, you have to undo the flywheel as well and then install a flywheel from a 2l engine. At the same time I recommend that you renew your clutch-assembly. You could go for a slightly larger clutch, the Item I'm now using is 8.5" (I think). This will fit without serious re-machining of the flywheel, please let your local machinery re-grind the surface though.

Head and manifolds

The next problem I had was finding a suitable inlet manifold. The of both the 2.2E and the 2.4E engines have their inlet ports situated higher up on the head, and they are also somewhat larger (?). This requires a different inlet-manifold as the one from Omega is so tall, that it would protrude some 10cm through the bonnet (someone could like that).

The different options I had was either to do something to the Omega manifold, get a 2.2E manifold and use that (I got one), or as probably the best option to go with a manifold from a straight six 12v engine. The head on the six-zyl engines have the inlet ports vs. the exhaust ports in the same pattern, so the "only" thing one would have to do is to saw off two of the ports from the manifold, and weld it shut again. as things came out, it wasn't so easy after all (who would've guessed :).

As the engine I got was a -90 from Germany, it was equipped with the Motronic injection/engine management system. This incorporates a lamba-sensor and a fully managed ignition, among other things. The pressure tube for the injectors on the Motronic engine is of a totally different design than the older L(E)-Jetronic models. It is a casted, light-metal piece that has small "hatches" on the ends. The tube won't fit inside a 2.2E manifold, nor will it fit under the flange for the throttle-housing. So, using the 2.2E manifold was out of the question for me. Well, actually, it was from the moment I actually saw the 2.2 manifold. It is far more restricted with smaller ports than the 2.4 or six-zyl manifold. So, I went for a six-zyl manifold, and soon found a used part on the Internet (lovely, the net...) and started to do some serious measurements.

There are at least four ways to implement a six-zyl manifold for a 2.2 or 2.4 four-zyl engine:

Saw off the last two ports, and weld it shut. Use a throttle-housing from a six-zyl (larger, better).
Saw off the first two cylinders, and weld the flange back onto the manifold. This would give a little better flow for the first two cylinders as the ports wouldn't make a sharp bend right after the throttle-housing.
Saw off the last two ports, and weld it shut. Use the throttle flange from a 2.2 manifold or the Omega 2.4 manifold and use the standard throttle.
Saw off the first two ports, take the throttle-housing flange from a 2.2E manifold and have it welded onto the manifold. This way you can still use the standard throttle-housing, and you will be able to get the pressure tube to fit inside the "curves" of the manifold. This is the way I went. Also I had the brake-servo attachment moved a few cm upward/backwards. (Please wait for pictures).

Here's the modified straight-six manifold, please note the moved nipple for the idle adjuster. The nipple was right in the way for the pressure-regulator. (click image to enlarge)

The reason I went with alternative four are that the pressure tube, which I didn't want to replace, is so bulky that it wouldn't fit under the throttle flange, ruling out all aternatives which incorporated sawing off the last two ports. So, I was stuck with alternative two or four. I was hesitating with getting another, for me unknown throttle-housing, and to try and get that to work with the Motronic (This is probably not that difficult). Because my engine is not going to be fitted with a hotter cam-shaft (yeah, righ, we'll see about that }:) , I deemed a larger throttle housing unnecessary. If you would like to install a hotter camshaft, and otherwise tune the engine it would probably be wise to go for alternative two. In that alternative you don't have to get a third manifold, this as an extra bonus.

Exhaust Manifold

This was a lot more easier than the inlet manifold, because the exhaust manifold from the 2.0E will be bolt-on. The only thing you have to consider before lifting the whole thing into the front of your car is the lamba-sensor. There are at least two places where it can be installed:

Weld a nut onto your exhaust pipe, as close to the manifold as possible
Have a machinist drill a hole in your exhaust manifold. I will put up some pictures here, from where you can see how I had it done. The hole has to be threaded for the sensor. It's probably the same thread as a spark-plug so with some knowledge and skill you can probably do it yourself.

So, here's a picture of the exhaust manifold. I drilled the hole and had the hole threaded. The hole in this version is just into one of the two exhaust down-pipes, although the Omega manifold had the tip of the sensor between the holes so that it was able to "sniff" both down-pipes. This should work as well. (click image to enlarge)

The nice thing with having the sensor in the manifold is that stock exhaust pipes can be installed without modifications. This is a great plus at least for me.

Other things

Well, as of to date, 19 Oct 2000, I'm still not finished with the project. I am taking some pictures, and I'm also writing some more stuff about this, but this is about how long-gone I'm by now. Please stay tuned.