390 estimated hp
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From: Wichita, Kansas
390 estimated hp
So I have a truck 390 (yes a true 390, not 360) and I had a question on estimated horsepower. So I understand there was a change from gross to net horsepower in 1972. I looked at my old Motor truck repair manual (dated 77) at the horsepower ratings for each year. In 1972 the 2 barrel 390 is rated at 201 @ 4400 & 316 @ 2600. I thought the 390's got a smog pump & other emissions crap in 73 resulting in the 2 barrel being rated at 161 @ 3600 and 299 @ 2000. The four barrel is listed as 206 @ 4600 & 320 @ 2800. So my 390 has none of the emissions crap on it, has a fresh tune up, and has had the cam put back straight up. I put the hotter accel coil on and 8mm wires, and double plat plugs. The manifolds are gone, and in place are headers and a true dual exhuast. I have been estimating my horses right around 275-280 due to the lack of emmisions crap, and the headers. How far off would I be? I know you guys have a lot more experience on FE's, so I would like your guys honest opinions
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So you had a net HP of 206 to start with. You removed what, just a smog pump? Add 5 HP. Cam timing, was it retarded? Seems there was some discussion as to whether the FE had retarded cam timing or not. Add 10 HP just for argument. Headers: Add 30 HP. So I'd say 250 or so.
Note with a truck motor, you still have the pistons sitting about .100 down the hole with resulting low 8 or high 7s compression.
332-428 Ford FE Engine Forum: 390 horsepower estimation?
332-428 Ford FE Engine Forum: Mighty 390 Dyno Test Results
Easy way to increase HP on stock truck 390 before install - Ford Muscle Forums : Ford Muscle Cars Tech Forum
Note the mean things said about the truck cam in that one.
Ford and everyone else lowered compression due to smog regs, but it was already standard practice to use low compression in pickup and all light and medium and heavy duty gas truck engines. Hours at WOT with full loads will cook a older higher compression motor in short order
Note with a truck motor, you still have the pistons sitting about .100 down the hole with resulting low 8 or high 7s compression.
332-428 Ford FE Engine Forum: 390 horsepower estimation?
332-428 Ford FE Engine Forum: Mighty 390 Dyno Test Results
Easy way to increase HP on stock truck 390 before install - Ford Muscle Forums : Ford Muscle Cars Tech Forum
Note the mean things said about the truck cam in that one.
Ford and everyone else lowered compression due to smog regs, but it was already standard practice to use low compression in pickup and all light and medium and heavy duty gas truck engines. Hours at WOT with full loads will cook a older higher compression motor in short order
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From: Wichita, Kansas
The only reason I was having a hard time with this is the 40 horse drop between 72 and 73 on the 2 bbl 390. I believe (could be wrong) that 72 is when the d2 - (yadayada) heads were used and the crappy truck camshaft was installed. Also both the 72 and 73 had 8.2 compression and were measured with net horsepower numbers.
I dont mean to beat a dead horse, I'm just seriously confused on how ford rated their engines.
I dont mean to beat a dead horse, I'm just seriously confused on how ford rated their engines.
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Not sure about the cam change if any, or the other hows and whys of the ratings. Looks more like they changed to the net numbers for '73 vs. '72. Data/warranty plates on pickups and mediums always listed a pretty low net HP number going way back before the change from gross to net.
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I always thought that the change to net hit the 72 model year. The 71 2 bbl 390 had 8.8 compression and was listed as 255 hp (I am not sitting at the book atm so I cant give the torque numbers). And I thought there was a new smog package introduced starting the 73 model year. My logic behind it was the 72 390 was rated 40 hp higher on a seemingly identical motor than the 73. So assuming all of the new emissions crap was removed, the 2 bbls numbers would be the same at 201. The 4 bbl was listed 40 hp above the 2 bbl was, so I added that to the total, and allowed myself 30 between the headers and more modern components. So basicly it came up to (in my head anywho)
206 (starting point)
+40 (removal of emissions based on 2 bbl figures)
+30 (modest bolt ons)
=276
206 (starting point)
+40 (removal of emissions based on 2 bbl figures)
+30 (modest bolt ons)
=276
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