Opel CIH stuff
Posted by Ascona73
Bob Legere Ultra Moderator Location: Spofford, NH Join Date: 03/07/2007 Age: Possibly Wise Posts: 308 Rally Car: 1971 Opel Ascona |
Okay, some things about the 2.2 head versus the stuff you've probably seen. 1.9 heads have great exhaust flow, but trouble getting intakes flowing well. They flow 89 cfm @ 10" on the intake ports 'as cast'. 2.0 heads have balanced flow (intake to exhaust ratio),. They're better than a 1.9 in stock form by a little...about 92 cfm intake flow with stock valves. They can be pretty easily upgraded to 120 cfm on the intake ports with big valves and common sense, nothing trick. 2.2 heads with the raised intake ports and bigger factory valves flow 122 cfm in stock form. Exhaust is weak at 77 cfm (just 63% of the intake). With some big Chevy valves, I've gotten 145-148 cfm out of them. Solidly in the 16-valve flow territory. Exhaust side needs a lot of work in the right areas. Port size is actually ok, but they are narrow near the valve guides and need widening there more than anything. The silicone molds I sent Dave should show this. With a bigger Chevy valve I can hit 105-112 cfm there. So it's a tad exhaust flow deficient still, but not much. I like to use split profile cams on the 2.2 head with more exhaust lift and about 6 degrees more exhaust duration. Wakes them up nicely. Now, the one area the 2.2 heads are really different: They like lift. The 1.9 heads and 2.0 heads don't respond well to very high lift. In fact a poorly-ported 1.9 intake port makes less power above .475" lift. At .475" lift, the 2.2 head is just starting out. I wouldn't bother with less than .550" lift on a 2.2. Reason being, I can get the 1.9 head to outflow a 2.2 head below .450" lift at all increments. So it makes more power and more torque with a low lift cam. BUT, if you get the flow from the 2.2 head, and put in the right cam...woooheeeee! The German tuners are still conservative for the most part...rarely more than .520" lift on anything. The Swedes are making these things really hum, and figured out what I did 20 years ago...Big lift on the raised port heads! Some of them are over .650" lift in rally engines, and they make the numbers...270+ hp from a 2.4 liter CIH reliably. Here's a 2.2 intake port reworked with 'small valves'. They're only 1.86" intakes. But the guy is running a stroked 1.9 with a 2.2 crank. 2130 cc's. 181 hp to the wheels. 
Exhaust ports for same: 
Overview of the head: 
For the bigger bore engines (97 mm), I step up to 1.94" intakes and 1.625" exhaust valves. 
Widened a lot on the hot side, around the guides:  Opel is a 4-letter word... http://www.flickr.com/photos/10498579@N07/sets/ Edited 1 time(s). Last edit at 08/04/2016 03:38PM by Ascona73. |
Bob Legere Ultra Moderator Location: Spofford, NH Join Date: 03/07/2007 Age: Possibly Wise Posts: 308 Rally Car: 1971 Opel Ascona |
Anyway, on to the roller rockers. Yes, there's always a market for them. People ask me if I have them all the time. Here and overseas. There is a German copy of my old rockers that is triple the price I used to sell them for. And people buy them!
The key is getting the geometry right. Chevy rockers have a low fulcrum. Opels are essentially in-line. 
My old design uses a flanged roller to locate laterally on the valve stem. And I modified hydraulic lifters with a press-in tool steel insert that had a flat top for the other roller to ride on. Later copies of my design used a custom lash cap over the top of the stock solid lifters. Seems to work fine and saves money. Opel is a 4-letter word... http://www.flickr.com/photos/10498579@N07/sets/ Edited 1 time(s). Last edit at 08/04/2016 03:37PM by Ascona73. |
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