I am currently flying KIAD-KMIA in this great a/c at Fl330 and M.74. All goes well. However, on climb to cruise I had a serious speed issue. With 90% fuel, I set climb to average 2000 fpm from ground level using FSNavigator. Above FL200, IAS decayed steadily even though VS was reduced automatically by FSNav as I gained altitude. Commanded climb speed was IAS 270 above 10,000' although the ship never got above IAS 263 at any point and speed decayed to IAS 230 by FL330 which was the cruise alt. N1 never exceeded 92% during climb. I was using AT+AP with FSNav so the SPD function was fully automated.I am surprised with this poor speed performance in climb even given the heavy fuel load. I would have expected that this a/c could easily handle the VS rate and maintain commanded climb IAS.Was I doing something wrong? Appreciate posts, thanks!JS

Go into the 737's aircraft config file and replace this line located in the TurbineEngineData with this value:static_thrust=22900.000000Climbs like the real bird now (at least as good as the many flights I've been on in the 737-200).

Whoa! Make the baby JT8D-9A fan into a massive affair, bigger than the 707-320C? OK, I shall try what you suggest.Thanks for posting.JS