[SLOSteve]

Hey guys, I've heard it said that the actual HP of a 289 4v is 225HP. Now that's Ford's crank HP right? Not the RWHP. Does anyone know or had their 289 4v dyno'ed and found out their RWHP? That should be more than 225, yes? Is manual RWHP more that auto? Any info. would be great !

[ajusaf]

you're up late. I'll be lookign around soon for a good dyno place here in Miami. I'm going to get a holley carb book at barnes and noble so I can tune it well. All I can tell you that I read online somewhere that stated our fastback is only 2600 lbs and I got it weight (for free) and mine came in at 3240lbs with a half tank full of gas and ofcourse a 351w engine.

[SLOSteve]

Originally Posted by ajusaf

you're up late. I'll be lookign around soon for a good dyno place here in Miami. I'm going to get a holley carb book at barnes and noble so I can tune it well. All I can tell you that I read online somewhere that stated our fastback is only 2600 lbs and I got it weight (for free) and mine came in at 3240lbs with a half tank full of gas and ofcourse a 351w engine.

Does just anyone do it or is there a specialty shop, like a racing shop that it needs to be taken to AJ ? So will the RWHP be different depending on body weight? I suppose it would?

[Veronica]

Hello. They used to check the HP of cars with the motor on an engine stand with no belt-driven accessories on it, each of which robbed it of a little HP. You also lose a little bit at the clutch or torque converter. The only Ford cars that the HP rating would be pretty close to the rear wheel HP reading would be the 271 HP high performance 289. ( K code) The only belt they had was for the alternator. No A/C. no power steering, no nothing. All of the 65s were 4-speed cars and nearly all of the 66-67 cars were 4 speed. Hope that helps.

[SLOSteve]

Originally Posted by Veronica

Hello. They used to check the HP of cars with the motor on an engine stand with no belt-driven accessories on it, each of which robbed it of a little HP. You also lose a little bit at the clutch or torque converter. The only Ford cars that the HP rating would be pretty close to the rear wheel HP reading would be the 271 HP high performance 289. ( K code) The only belt they had was for the alternator. No A/C. no power steering, no nothing. All of the 65s were 4-speed cars and nearly all of the 66-67 cars were 4 speed. Hope that helps.

Thanks Veronica, as always you're a tremendous help! The drags on the engine reducing HP makes a lot of sense. I'd also kinda like to find out what others are getting HP-wise with their A codes. Any takers?

[5.0 in a 66]

Veronica is right, on certain engines, they cheated big time. No accessories, cranked timing, premium fuel, heck they would leave off the waterpump belt and dyno it till it died in some cases.

I remember having seen a dyno sheet on a basically stock 289 4V that came out to 165-175rwhp (been way too long) and it was tuned very well.

I'm hoping for 290-300rwhp out of my fully built 5.0HO. We shall see.

[94' cobra 351]

Originally Posted by SLOSteve

Hey guys, I've heard it said that the actual HP of a 289 4v is 225HP. Now that's Ford's crank HP right? Not the RWHP. Does anyone know or had their 289 4v dyno'ed and found out their RWHP? That should be more than 225, yes? Is manual RWHP more that auto? Any info. would be great !

RWHP is ALWAYS lower than crank HP. Like the other person stated, you loose power through all the pulleys and accessories your engine must run, but also every part your engine has to turn takes away power. The drive shaft, clutch assembly, rear axle and gears, wheels etc. In theory you also loose power through noise and heat, but that is getting too technical.

[lonestar69stang]

You also lose some HP through your drivetrain (transmission, rear diff.) to due to friction. I was watching HP Tv the other day and Joe freed up almost 10 HP just by changing all his fluids tho full synthetic royal purple oils but it was on a newer model camaro but i would think it would give pretty much the same results for any car.

[not2brite]

RWHP as measured on today's chassis dyno's is a mathematical function of torque (HP and torque cross at 5200 rpm so the dyno computer plots things from there). Rule of thumb for drivetrain and accessory loss on naturally aspirated engines is 17% for manual trans and 25% loss for automatic trans on a chassis dyno. 225 hp at the flywheel would be 187 rwhp for a manual and 169 rwhp for an automatic. Vehicle weight and other items are not factored in.

[SLOSteve]

Originally Posted by not2brite

RWHP as measured on today's chassis dyno's is a mathematical function of torque (HP and torque cross at 5200 rpm so the dyno computer plots things from there). Rule of thumb for drivetrain and accessory loss on naturally aspirated engines is 17% for manual trans and 25% loss for automatic trans on a chassis dyno. 225 hp at the flywheel would be 187 rwhp for a manual and 169 rwhp for an automatic. Vehicle weight and other items are not factored in.

Not2brite.......that's exactly what I needed/wanted to know. Someone had told me that manuals didn't lose as much as auto's and I just wanted to get that clear. Thanks all of you guys (and gal ) for your help here.