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Originally posted by Quadman313
I was just saying that with CR ratios of 10.5:1 and 10 psi you are going to need to run 100 octane which is completly acceptable for a race car but not so much for a daily driver IMO.
Well, not exactly. I have had 10.5:1CR all motor for better than a year and ran the AFX/R ECU (which requires 93 octane) on a completely stock fuel system on 91 octane - the highest I can get that isn't leaded race gas. Never so much as a single knock. I'll be boosting this all motor set up (high compression, Crower 2, and a 9,000rpm redline) to hit a target horsepower number I'm not about to share here until it's actually done. But it will get done. As you said, the idea is not that it's impossible, just harder to get to. I won't be bolting up a snail, filling the tank and maxing out the MAP (mind you I have Megasquirt) right away. I plan on keeping the boost very low and making test runs, data logging these test runs, and then looking at the logs to determine just how much more I can go. Slow and steady wins the race. 
Originally posted by Quadman313
Also could you explane this again im juat a little confused mabye because its the morning but anyways, and I do understand that each turbo has a diffrent compressor flow maps and that it varies for each turbo. Thanks in advance. This is where turbo effciency comes into play. if you have a turbo that is highly efficient compressing at 35psi, a lower CR motor would be able to spend more time in the efficiency "island" of the map. A higher CR motor, which couldn't handle as much boost, might not be able to spend most of it's time that high up and be, what's the word, stalling out on you? You can make the same horsepower either way.
Okay, my wording there probably wasn't the best. All this turbo stuff is sort of new to me, being a died in the wool all motor guy for the better part of 2 years now. When you drop to 8.8:1 CR, you run higher boost to make the same power. Now, my numbers here are total bullshit only to illustrate a point, so don't take them as anything more than something to sort of paint a picture if you will. You have a turbo which, on your engine, is going to be the most efficient between 15-30psi. You have a high compression build and you might only be able to tune to that 15psi safely. This would still be possible, but you would be running closer to the surge line of the map (I've got a link about this at the bottom). You would be at risk for stalling the turbo and damaging it (wearing it out) from extended time in partial throttle, sub 15psi boosting. A lower compression build, on the other hand, would maybe be able to run up in the 20-25psi range - right in the middle of the efficiency island. Maybe you could think of the efficiency island as the "sweet spot" on the baseball bat that you want to hit the ball with after you just pointed out to left field. Granted, you have to transition though the surge line to get to the efficiency range, but the idea is to not spend a lot of time there. It's not good for the turbo.
Conversely, if you have smaller turbo that's efficient in the 10-20psi range, running the 10.5:1 CR mentioned above would be right there and, with proper tuning, would make similar power as the 8.8:1, only it would do so at 12-15psi. So you can see that, dropping CR and having to run 30psi to make power on a turbo only rated efficient to 25psi would be taxing the turbo and pushing you towards the choke limit. Once you start getting out the other side fo the efficiency island, you're going to be blowing in more and more heat. Heat is the killer. Heat is the cause of knock. Again, all these numbers are total bullshit, and I'm just making them up to explain this the way I see it. I don't have formulas or data with exact numbers to back any of this up, so I made numbers up to sort of put the puzzle together as I see it. I don't think anyone here can give you concrete numers for any of this stuff. You just have to sort of get the gist of it and build accordingly. It's all about the tuning and carefully considering your goals when building the engine.
www.turbobygarrett.com/turbobygarrett/kits/basics_techinfo.html
EDIT:
I'm still not happy with the way this all cme out, but it's time for a beer and I'll just say that I think the only three numbers that aren't bullshit when it comes to tuning your car are AFR, WHP, and price.
"By three methods we may learn wisdom:
First, by reflection, which is noblest;
Second, by imitation, which is easiest;
and third by experience, which is the bitterest." - Confucius
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, and yet, I'm waiting for my custom 10.5:1 Venolias to arrive, Terry. I figure the MSnS (and more than likely water injection come summer, here) will be more than capable of tuning the knock out of the juice. I'd sure hate to have to wait another 3 months for some 8.8:1 slugs this summer... 
