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I have a question regarding Horsepower

My 2005 Mustang GT is advertised at 300hp

How would I be able to compare a 1966 Mustang with 289 engine to my 2005 GT. Basically if comparing horsepower side by side what is the horsepower for each of the following

Listed below are the specs for 1966 289 engines in (Gross Horsepower)


1966 289 cid (two barrel) C-Code is 200hp, was i the equivalent of net horse power for it.

1966 289 cid (four barrel) C-Code is 225hp

1966 289 cid HI-PO (four barrel) C-Code is 271hp


could some one give me estimate figures,


Base on my calculation these are the result I got,,

200hp would equal 140hp approx.

225hp would equal 160hp approx.

271hp would equal 190hp approx.


Please correct me if I'm way off.
 

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I'm not sure what you mean by Gross or Net, but i'm assuming you're talking about Flywheel horsepower and Rear Wheel horsepower. Flywheel horsepower is the number they advertise at the dealer (ie 300hp on the 2005+ mustang GT)

That would mean that the 3 289 motors you mentioned have 200, 225 and 271 flywheel horsepower.

There is a small drive-train loss that is calculated in when figuring out rear wheel horsepower. Generally speaking there is a 12% loss in manual transmission vehicles and a 15% loss in automatics.

So your 289 numbers for an automatic would be 170 (of 200), 191 (of 225) and 230 (of 271).

And your manual numbers would be 176 (of 200), 198 (of 225) and 238 (of 271).

And your 2005 GT with an automatic should put down roughly 255. Remember that these numbers are just a guideline and most 2005+ GT's pull 265-270 rwhp stock.

:D
 

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You can't calculate vintage numbers into modern numbers because they were measured different and the loss from accessories can't be easily quantified or normalized from car line to car line and because the manu tended to fudge heavily 'back in the day'.

The best comparison you would be able to make is to find a car that is claimed to be restored to all stock and strap it to a chassis dyno and then strap yours to the same chassis dyno the same day and you will able to make a direct comparison of usable horsepower. (Or you could simply research other people who have dyno run their cars...just try to find people who use the same type aka dyno jet or a mustang dyno and you can some rough numbers for a comparison)

For black pony SAE net vs. gross is not a discussion of flywheel versus rear wheel. It is a discussion of rating a motors horsepower at the flywheel using 2 different approached, one with the motor sans things like accessories, water pumps, manifolds and the other is a measurement with all the accessories the motor would have attached to it hooked up.
 
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