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Bob,

How would your modified 1.9 intake (the racing one you wrote on article about years ago) with the wedge under the bowl and all cleaned up work on a 2.4 head/2.5 engine setup. I was considering using the new Holley Sniper EFI carb setup which claims to flow enough for 350 hp. It is all self tuning and looks like a really nice deal.
It would work. But you'd lose most of the benefit of the 2.4 head, it chokes it down that much.

Which is why for most applications a modded 1.9 is better. Smaller ports for more torque, as-good or better airflow (when modded), and works better with low lift cams. 2.4 and 2.2 heads don't start to shine until .525" lift.
 

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2.4 is a little bit different. However it exhibits the same high exhaust flow ratio of a 1.9 head. Just more of both. It flows 110 cfm intake/93 cfm exhaust.

I'd limit the work to the bowls then. No reason enlarging the ports on most street applications unless going to bigger valves and healthy cam.

Stock Opel 2.4 EFI (Motronic) is arguably the best used on any CIH engine. But there are two distinct issues. You still have to be careful if changing cam specs...low overlap only! The heads do like high lift, and wide LSA works well on bigger CIH engines.

The bigger issue is that the OEM EFI 2.4 intake in no way fits under a GT hood. Even the cut down 3.0 liter 6-cylinder intakes are a tight fit, and while they flow better than a 1.9 intake, you are leaving a lot on the table. I've flow tested a 2.4 head with cut down 3.0 intake and it choked it down a lot compared to modest 45 DCOE's with 36 mm venturis. There's a reason all the rally guys use 48 or 50 DCOE carbs on 2.4's....they need it!
The early Moe's was a pita to work with.
Add a resistor hear and there.

Thank goodness for the later Moe's that is more advanced aka software driven.
 

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Bob, what new cams are out there that have 0.525" of lift? For the 2.4 CIH.
Well, if you procure a new blank just about any cam grinder in the US can make what you want. High lift and long duration. High lift and medium duration. High lift and modest duration. Lots of options because Chevy uses the same diameter .842" liftsrs, and that determines the rate of valve acceleration possible.

Otherwise ya gotta go to Europe. Some of the top German tuners, pretty much all the Swedish and Finnish tuners, and Cat Cams make some high lift cams.

But they might be considered pretty hairy for street use.
 

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Pedal Smasher
1973 Opel GT
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Is anyone making a roller lifter set for the CIH? Or anyone have a roller lifters and roller cam set they would sell?
 

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Opeler
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I have a 2.4 with a Enem X5 (pretty wild hydro cam) ported 2,4 head, shortened 3.0 intake, tuned headers and haltech efi. Dynoed in a rototest hub dyno to ~170hp.
I would say that the engine is very much streetable.
But then again efi works wonders for the low end.
 

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Opeler
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659 Posts
I have a 2.4 with a Enem X5 (pretty wild hydro cam) ported 2,4 head, shortened 3.0 intake, tuned headers and haltech efi. Dynoed in a rototest hub dyno to ~170hp.
I would say that the engine is very much streetable.
But then again efi works wonders for the low end.
Nice! Is that in a GT and any issues fitting under the hood?
 

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Can Opeler
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Why?

I guess I'm getting too old. I have an Opel 2.4 engine and a 5 speed Getrag transmission in my GT. The part I can't figure out is the need for more power, and going to an engine that is a pain in the a$$ to fit in a GT. I have never found the top end on the GT because I was already 20 miles an hour over the speed limit. I guess as you get older, you take the path of least resistance. I don't condemn any modifications or engine swaps, but I have seen so many go to the junk yard because they got overwhelming. I repeat, getting old guides you along the path of least resistance. Like my friend says "growing old ain't for sissies".

Bob
 

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If you must swap, the only swap that makes sense to me is the 6 cylinder CIH. Seems that only the radiator support must be changed to fit it in. What seems to require more surgery is just about every transmission swap needs sheet metal work and adds a ton (ok a bunch) of weight.
 

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Pedal Smasher
1973 Opel GT
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If you must swap, the only swap that makes sense to me is the 6 cylinder CIH. Seems that only the radiator support must be changed to fit it in. What seems to require more surgery is just about every transmission swap needs sheet metal work and adds a ton (ok a bunch) of weight.
The Getrag 240 is about the easiest transmission swap you can do. Was designed for the CIH, and only the trans support needs to be redone. You can buy kits that will solve this problem for you. The Europeans have the best shifter solution for the Getrag.
 

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The Getrag 240 is about the easiest transmission swap you can do. Was designed for the CIH, and only the trans support needs to be redone. You can buy kits that will solve this problem for you. The Europeans have the best shifter solution for the Getrag.
I thought there was a thread here that they were becoming unobtainium.
 

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Tazdbs 71 Opel GT
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186 Posts
Which 6 cyl CIH engine?

What / Which 6 cylinder CIH engine will mate with the getrag 5 / 6 speed trans and drop and fit into the Opel GT?

I blew the rings out of my 2.0 Opel engine and 4 speed racing autocross and need to upgrade / repair it. Definitely need a 5 speed trans for sure.

I'm looking at the Miata engine and 5 speed swap but so far I haven't found one that is completed so a little hesitant.

Thanks,
Dick
 

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Pedal Smasher
1973 Opel GT
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Dick, you can put a straight 6 CIH into a GT but you'll have to relocate the radiator. Someone on FB just did this. The engine sits in the same spot, so no room for the radiator. If you really want 6 cylinders, I'd say you'll need to drop a V6 in. We have some members who have done this. It takes a lot of work though.

If you don't care about looking like a regular GT, why not rebuild the 2.0 as a turbocharged engine? I'm sure Rally Bob could help you figure it all out, he's doing a turbo CIH that has been put on hold while he builds his new mega shop. Then you could pick up a Getrag 240 or a Tremec. The Tremec will be a cheaper option. This will be an easier to implement plan than a 6 cylinder engine.
 
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