Posted by Fastman (209.179.227.80) on May 13, 2001 at 17:00:42:
In Reply to: SAE gross hp vs SAE net hp posted by 74merc on May 13, 2001 at 13:19:10:
: 68 2v 289 is rated 195 gross hp. thats without the alternator, ps, etc, tuned to the max at the flywheel.
: in 72 the rating system was changed.
: with full accessories on and running, a 1974 Maverick/Comet 302 has 138 net hp at the rear of the tranny.
: take the 74 engine, run the same tune and setup and dyno it and it isn't that much weaker than the 289, although it has been neutered by Ford...
: to simplify, the pre-72s gave best case scenario horsepower, the post-72s gave worst case scenario.
: reality is somewhere in the middle.
The 289 with 150 "net" hp I am talking about was based on 65 Mustang RWHP dyno results. I had seen a mag test of a 289 2v in a bone stock 65 Mustang that put out 129 RWHP. I am unsure if it was an auto or manual trans. Now, by using the 25% loss through an auto= around 170 flywheel HP as a "net" result. Through a manual trans with 15% loss= 150 flywheel "net" HP. I would believe the 150 "net" more than I would the 170, that is why I used that number instead. But the car made 200 ft. lbs. of Torque to the wheels thus making flywheel numbers around 230 Net Torque on the high end or 220 on the low.
You are right in that "net" took over in 72, but I am just using modern day comparrisons of dyno results from owners cars.