IF there's an insistence on 93, I agree. However, I must reassert that E-85 and high compression is the preferable option. For one, if you ever want to ditch the blower, the motor isn't useless. Granted, it's a long shot consideration. And E-85 presents other challenges, but I'd rather have a 12:1 motor on E and make 900, which is VERY VERY SAFE (and more consistent and testable than rolling the dice every tank with 93).
Because Ford has to satisfy a list of government agencies, regulators and laws as long as this forum. And marketing wise they have to cater to the center of the market, which is middle aged men who want to buy a jacket and be a part of a car club and hand the keys to someone else to change the oil and buy pump 93.
Good question. You are correct that if you increase boost to make up for power lost due to compression, the blower will be driven harder and discharge temp will be higher. A quick and dirty calculation yields a blower discharge temp of 190 deg F at 100 deg ambient and 10 psi. Increasing boost to 12 psi yields a discharge temp of 204 deg F, an increase of 14 deg.
There, I fixed it for ya'! ;)
An 11:1 or 11.5:1 on 15psi of boost can go anywhere in the country with the fuel on any corner. Add a little octane booster if you gonna get really low quality chocolate milk. Don’t go racing with you Chocolate milk and that’s it. Don’t make it sound like I can’t drive 500 miles to a family get together because a higher compression motor will fall apart cruising on the highway on 93.
Physics, thermodynamics, and kinematics have not changed.
You are absolutely correct that you can retard spark or change cam timing to reduce peak cylinder pressure (PMax) and move away from detonation. But by doing so at the same static CR, you are also reducing mean cylinder pressure (BMEP), which reduces torque and power output. The advantage of low compression is it can maintain high BMEP at a reduced PMax. I've posted it before, but I can show both thermodynamically/kinematically and in practice where this is true. And again, who wouldn't want more power at lower peak cylinder pressure that results in less chance of detonation and lower stress on parts?
Again, why would the 9.5/1 GT500 not become knock-limited on 93 until 17 psi and 900 rwhp, but the 12/1 GT350 when supercharged hits the knock limit at 150 hp less? The engines are identical in many ways, but not compression ratio. Funny that practice agrees with theory in this case. In fact, we can apply the same adjustments I posted earlier to this case to test them. I posted that every compression number is worth 3-5% power and every psi boost is 20-30 hp. So, assuming the starting point is the GT350 at 10 psi making 750 rwhp, we drop compression by 2.5 numbers, which lowers output by 10% to 675 rwhp. Add 20 hp for every psi and 675+140 = 815 rwhp. It turns out, my math was conservative and actual gains in practice are quite a bit higher.
Nice straw-man argument. So your solution is to set it up for E85, then put whatever is available in the tank and just remember not to get on the throttle if you happen to not have a can of octane booster. Sounds like a great plan...for you. That's not for everyone, though.
You keep posting examples but it's a false comparison. It doesn't elude to what those motors COULD make if ran with better fuel and higher compression. And your inquiry about safety again, is predicated UPON 93 as the fuel. My E-85 tune is safer than your 93 tune. Period. End of debate. I don't care WHAT you've done to the compression or spark or components, it's inherently safer because I can at least VERIFY the relative quality of the fuel going into the motor. And not for nothing, virtually every tuner would tell you they feel "safer" tuning a 12:1 compression motor (with more timing) on E-85 with boost than a lower compression motor on 93 and boost. Simply because despite compression, E-85 is more resistant to preignition.
You're obviously very sharp and knowledgeable but again, I think we're arguing two different things past each other. One of your initial assertions was "lower compression and higher boost is better" which I only PARTIALLY agree with and that's with the asterisk * (with less than optimal fuel). I don't agree that's a widely accepted or true statement when all fuel options are laid on the table. As I said, if THAT were true, then there'd be no need to pay 30% more for premium gasoline, you could just drop the compression by a couple more points and run 40 psi and according to you, be safer for it.