13:1 Compression Pistons in 340 Small Block

The last build I was in with compression in that neighborhood (14:1!) took two cans of 104-Plus to 20 gallons of premium fuel... I won't even go into all the complications and legalities involved with aviation fuel, but being it takes e 85 components to withstand long term exposure to that devils juice, your better off with the legal e85 plan.