No they shouldn't be able to torture anyone suspected of terrorism. Some people may not be terrorists in the first place when they get tortured and may end up being accused of things they did not do. After a while of torturing any normal person would commit to the crime whether they did it or not.
It states in the 8th amendment "excessive bail shall not be required, nor excessive fines imposed, nor cruel or unusual punishments inflicted." This makes the act of torturing unlawful anyways.