Dcr

Thanks nm9, for the encouragement.
Yeah we knew about effective, but I never really got into it, what with raising a family and all, through the 80s, 90s, and the last child, my baby-boy, left in 2004. So in 1997 when I decided it was time, I had a lot of research to do, and you might remember the internet back then? Naww it was magazine articles for the most part, and nobody was talking. They were just delivering recipes and expecting us to blindly follow them.Well, I'm no follower.And, I got a thick head, but I did learn something in high-school, namely trig and algebra. But again, no one was publishing Dcr targets. So I had to back-engineer a lot of recipes to generate some data. In the end the numbers were all over the place and almost totally non-helpful. So I bought the Desk-top Dyno program and started generating my own data. I was not looking for absolute numbers, but rather,trends. And of course my library of hard copy books grew and grew. Some of that data actually made it into my head! I finally figured out that Dcr was a special key. I still didn't know how to use it though, cuz nobody was publishing targets. All this was going on during the time the body was in the bodyshop, and I was collecting new parts as money became available.
Eventually I resigned myself to the possibility that I was gonna have to entertain the idea that water injection might be mandatory, cuz by this time I had made up my mind to push the CR envelope.There was just no way I was gonna spend money that was so hard to come by on a lame 9.5 engine.No, I wanted 11 or better. And I was willing to create the target. So I picked what I had come to believe was a reasonable Dcr target,namely 8.5. And I had made up my mind that I wanted the 292/509. With a 70* ICA,that required an11.2Scr. Right on target.Unfortunately that was not possible with the parts I had; 65cc head,6.5 gasket 5cc eyebrows and 0 deck, for a total 76.5..This yielded a 10.83Scr/8.24Dcr @104ICA. I advanced it an extra 4, and this put the Dcr up to8.52. Since I was using the .029 gasket on a zero deck, I was done.
Well I had a hard time getting that past anybody. But I didn't care; what did they know? Had they spent months and months and months, doing the research? No they were stuck in old-school thinking, that 11.2 was beyond do-able. Perhaps I was more foolhardy than brave.
Well, much to my surprise, that stupid thing ran on 91non-oxyginated right out of the gate! A little tuning and 87E10 was easy. That was the beginning, in 1999.
Since then, I've learned a few other things about Dcr. It's not a fixed thing.It varies with rpm and other factors too.In my engine, it might start out at 8.5, but as cylinder filling improves through-out the rpm range, there will/may come a point where it becomes the Scr(10.7 in my case). With exceptional filling, it may even become greater. So even though the chart shows Scrs over 11.4, I have no idea if it's runable.
10.83/8.52 worked for me.(EDIT; 11.2/8.5 formerly posted,was in error.)
Your results may vary.
Turns out that 292cam is a bit of a pig on gas, but worse, it's not very streetable. The bottom end where I was spending most of my time was pretty soft. So the first guy that showed interest got that cam cheap.
My next cam was much smaller. The Hughes HE2330.This is a 270*cam, and has a 61*ICA and produced a Dcr of 8.62. This too ran on 87E10, with aluminum heads.And it was a tyre-fryer!
The last cam a Hughes HE3037. This is a 276*cam, in at 64*ICA came in at 8.75Dcr. But by this time the well-used .029 headgaskets gave up, and so I swapped to .039 Fellpros. This dropped the Dcr to 8.53, and I'm still on 87E10.
Long story short, I guess the target was conservative,as it has no problems at this 8.5 level.

For my next iteration, I think I will target a Dcr of 9.5 with the Eddies and and the .039 gaskets. Yeah I'm being brave. Problem is I've run out of adjustability. I guess pop-ups will be in my future.There will be other changes as well.....Then again maybe I'll just stick with what I know works.
EDIT I redid some of the math. Apparently, the highest I've run is 10.82/8.52 with the 292cam.And 10.54/8.62 with the HE2330. And the current is 10.66/8.53 with the HE3037. My bad.It was a long time ago.My apologies.So no pop-ups afterall :(