Originally Posted by
tdracer
The maximum thrust of the engine is limited on the 737 by the ability to counteract the thrust induced pitch-up moment - hence the max thrust on the 737-8 is not a whole lot different than the max thrust on the 737-800. It might appear higher if you only look at the Sea Level Static rating, but big turbofan thrust lapses (decreases) with forward speed - the higher the bypass ration, the greater the lapse with forward speed. So, while the SLS thrust might be higher for the MAX, the thrust at ~120 knots will be pretty similar to the equivalent NG.
BTW, this is nothing new - limiting the max thrust goes back to the 737-3/4/500 'classic' - the only difference being on the 'classic' the -300 and -500 had throttle blockers to prevent more thrust than the tail could handle, on the NG and MAX it's done with a rating plug.
The 737NG is rarely thrust limited, so there's not a compelling reason to provide much additional thrust in the MAX. The new LEAP engines were added primarily for increased fuel efficiency and not increased thrust.