Is there any way to convert the old horsepower ratings into the newer ones? This is to help shut up someone I know who tried to talk down my future '66 Hi-Po because "with the new ratings, you've probably got MUCH less than 271." Just really pissed me off. Anyone who can help me convert the old numbers to newer ones would be appreciated.

 

He's right:

1966 289 Hi-Po 4-Speed
Factory Rating: 271 hp/312 lb-ft
Actual Rear Wheel: 144 hp/238 lb-ft
Estimated at Flywheel: 168 hp/278 lb-ft

It's got less at the rear wheels than the current V-6.

But you're not alone. Here are some other dyno results:

1965 289 Hi-Po Automatic:
Factory Rating: 271 hp/312 lb-ft
Actual Rear Wheel: 141 hp/254 lb-ft
Estimated at Flywheel: 176 hp/318 lb-ft

1965 Shelby G.T. 350:
Factory Rating: 306 hp/329 lb-ft
Actual Rear Wheel: 202 hp/237 lb-ft
Estimated at Flywheel: 236 hp/277 lb-ft

1967 Shelby GT500 4-Speed:
Factory Rating: 355 hp/420 lb-ft
Actual Rear Wheel: 240 hp/354 lb-ft
Estimated at Flywheel: 281 hp/415 lb- ft

1968 Shelby GT500 KR Automatic:
Factory Rating: 335 hp/440 lb-ft
Actual Rear Wheel: 275 hp/336 lb-ft
Estimated at Flywheel: 344 hp/420 lb- ft

1969 Boss 429 4-Speed:
Factory Rating: 375 hp/450 lb-ft
Actual Rear Wheel: 214 hp/324 lb-ft
Estimated at Flywheel: 250 hp/379 lb- ft

1969 Mach 1 428 CJ Automatic:
Factory Rating: 335 hp/440 lb-ft
Actual Rear Wheel: 213 hp/266 lb-ft
Estimated at Flywheel: 266 hp/332 lb-ft

1970 Boss 302 4-Speed:
Factory Rating: 290 hp/290 lb-ft
Actual Rear Wheel: 179 hp/209 lb-ft
Estimated at Flywheel: 209 hp/245 lb-ft

 

I would venture a guess that MOST hipo mustangs have rebuilt engines, so don't get a hipo that's built to original specs. And remember how light a 66 mustang is - my fastback is under 3000 pounds. With a mildly built motor, the little car is really very quick. Even if you are looking for originality, externally a hot motor can look like the original while running much better.

 

I knew someone would bring those numbers up. It was noted that the only one that was in real proper and completely working order was the GT500KR. This is a rebuilt engine and all the parts are new and working optimally. I know when I hit that gas, it wasn't any 141hp. I mean, it's got an aftermarket carburetor and completely modded exhaust, but all that can't make up for acceleration than was greater than in my old 2003 GT.

 

do NOT be disheartened by those numbers at all. One of the biggest and most important numbers in the classic cars is not HP, but TORQUE. The HP number is low because the motors were Torque built. They have a TON of torque. That's great too because Torque is much harder to get than HP. So you basically want to add mods that will give you HP (like a carburetor). Then you have the best of both worlds.

The 302 I put in my 66 is actually a lincoln motor. They were built for nothing BUT torque, and that was in the early 70's. I just added a TON of HP mods, and recently picked up a 9" rear end with 310 gears. Hopefully that mated with my C4 3 speed will really lay the rubber down.

If you want to hear sad, I have a buddy that has a 70 mach1. He put a 460 in it and really tricked the motor out. He had less than 200 Dynoed HP, but his Torque was unmeasureable. He barked the tires ON THE DYNO at 70 MPH. Tell me that isn't power? It's all Torque. Don't be disheartened!

If you ever need some advice on your resto, post a line on here and I'll try and help you out. I've done just about everything there is to do on my 66 coupe, and I'll be glad to lend some help. Congrats on your aquisition. POST PICS!

 

Eh, still, kids these days don't care about torque. They all just want horsepower, while I pay attention more to the torque numbers.

"Horsepower sells cars, torque wins races."

-- Caroll Shelby~

 

harleys are all about torque..

 

Eww, give me a crotch rocket any day.