Look into piston coating,cylinder head chamber and valve coatings, wide lsa cams to reduce cylinder pressure. Fuel injection setups that retard the timing if need be when it starts to detonate. $$$$$$ is it going to be worth it on a street car probably not.

Ive ran 12:1 on pump gas without any issues.... But pump gas varies from state to state, your camshaft will play a large roll in bleeding off some of the cylinder pressure... I usually use pumping compression for a good indication for pump gas. Ive seen multiple engines make a 1000 hp on pump gas naturally aspirated. Both were close to 600 inches.

For what it's worth, my advice.....keep the compression on the low side. You will never hear the detonation before it breaks stuff. You also may not be able to always access the fuel your motor needs to stay happy. On a big stroker it will make WAY more power than you can safely use on the street, you'll never notice the difference in a point or two in compression.
My old truck tries to kill me on a regular basis just gently rolling into the throttle.

my engine responded well with a raise in compression from 11.25 up to 12.5:1. almost 4 tenths and 4 mph. I did also have a electric water pump and new shocks on the front. I'm guessing the compression increase alone was worth 2 tenths. Compression makes your heads flow/work better. old slip was 10.40@130 and new slip 10.06@134. Compression does make a difference, you just need the fuel to match.

I have a customer with a Pettis 572 w/11.7 compression races on 94 pump and makes close to 1000hp based on it's 8.84 et at 151 mph at 3450 lbs with a pretty big 800 lift cam. so the RIGHT combo of parts can obviously work and his plugs look great so far......

Some of the big hitters on Drag Week run 15:1 compression, but they run race gas on the street all week. Curt Johnson is a prime example of this, and his 632 CI engine with LOTS of compression, runs race gas all week. He told us if he tries to run any type of pump gas through it, it will wash the rings out right away. He changes oil every day as well.

Wow, I can't imagine what it costs him to do Drag Week! That's ridiculous.

LOTS!!! We figured it out, to around 3K for fuel alone. But he has won his class 7, or 8 times. He has the formula figured out. He one year built a Pump gas engine, to minimize maintenance. Won his class yet again. He got bored, and the next year he had a 15:1+ engine again. He told me they put a 3-4K chip on the high side of the MSD for street driving. Didn't leave any room for goofing off, and was easier on the valvetrain. If anyone ever gets a chance to talk with Curt, do it. You will not be disappointed.

x2. Modern stuff does more than just retard timing to keep the engine from pinging, most of the engines that have high cylinder pressures (either high comp NA stuff or boosted applications) will limit engine load to keep them out of detonation. I don't know of any mass produced OEM car engine that is much past 12:1 NA. On a high output motor it isn't worth the risk.

my hemi was 12.2 to 1 comp ran on pumpgas always 93 octane at 30 degrees of timming it ran 9.60s at 140+ mph i eaven sprayed it into the 8s on pumpgas and 22 degrees of timming

How True! Unless you have an unlimited supply of 'good' fuel to ALWAYS use you are playing with dynamite. You will never hear it detonate, the damage can occur in a blink of an eye. A big inch street motor with a sane compression ratio will make way more torque than you can stick to the ground. My 605 makes 750+ ftlbs at 3500 rpm.

Can Hemi's get away with more compression than a Wedge?

Compression will make a big difference in power and torque, at the track and in the street.
I live in Michigan so have only driven my cars in the summer, but, if given the chance, i much prefer running race gas. Its easy to get, consistent compared to pump swill with who knows what in it.iItsvnever hard to access
I drive a few hundreds of miles on the street every summer, typically not thousands of miles, so at 7 bucks a gallon the cost to run race gas isn't that big of deal.i figure if i cant afford to put fuel in it, i am probably involved in a hobby i cant afford.
I have had several engines where i raised compression and saw it immediately at the track.
My project over the winter here will yet again. Going from a 360 to a 418, Changing nothing other than the cubes and compression, little bit of head work. Heads will be way to small for 418 inches. But going from 10 to 1 to 12.5 to 1 compression. I am expecting big gains for primarily that reason. Figure the compression alone is probably 40-45 horsepower. Same cam, headers, carb, etc, etc

I would love to find out if I kept my high compression, would 93 octane and any of those additives work?

That's my understanding

605 Hemi, 11:1, no signs of detonation on the plugs or audible pinging on 92 octane and 32 degrees of timing.

IMG_8495 by Greg Ault, on Flickr

Yes...Typically 12:1 is no issue on pump gas....I am at 11.6:1 on my big Hemi...No issues with that.

Dead on.

I've driven high compression motors on the street using not enough octane, with the plan being to stay out of the throttle. The question is do you have enough a self-discipline when an impromptu challenge arises? I don't.
It's like being alone in a motel room with a lingerie clad super model and agreeing not to look at her.

What is your piston comp height? I have ta buy some pistons for my 572 Hemi (7.1 rod)

Well I said earlier 12:1 Hemi on pump gas is no issue, save one, ever driven a +800hp on the street? And if there was a super model in the hotel room with me, in lingerie, I was only looking to make sure it was all female..I am on a budget after spending all that money on a Hemi...