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Thread: Actual Horsepower Of '60s/'70s Muscle Cars

  1. #1
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    Actual Horsepower Of '60s/'70s Muscle Cars

    Most muscle car enthusiasts know that the horsepower ratings of the engines were deliberately set lower than what they actually made. Usually for insurance reasons and so the cars could run in a more favorable class in drag races.

    Noted auto journalist Roger Huntington wrote an article about what these engines actually put out; here is the list: (All are gross hp & torque figures.)

    Engine------------------Advertised----Rated----------True
    ------------------------HP @ RPM---- Torque@ RPM-- HP @ RPM

    Buick 455 Stage 1-------360@5000----510@2800------420@5400
    Camaro Z/28 302--------290@5800----290@4200------310@6200
    Chevelle 396 L-78-------375@5600----415@3600------400@5600
    Corvette 427 L-88-------430@5200----450@4400------480@6400
    Mopar 340-4 bbl---------275@5000----340@3200------320@5600
    Mopar 440-Magnum------375@4600----480@3200------410@5400
    Mopar 440 Six-Pack------390@4700----490@3200------430@5600
    Mopar 426 Street Hemi---425@5000----490@4000------470@6000
    Mustang Boss 302--------290@5800----290@4300------310@6200
    Ford 351-4 bbl Cleveland--300@5400----380@3400------340@5600
    Mustang Boss 351--------330@5400----370@4000------360@6000
    Mustang 428 Cobra-Jet---335@5200----440@3400------410@5600
    Mustang Boss 429--------375@5200----450@3400------420@5600
    Oldsmobile 455 W-30-----370@5300----500@3600------440@5600
    Oldsmobile 350 W-31-----325@5400----360@3600------350@5800
    Pontiac Ram Air 400------366@5100----445@3600------410@5600

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Notes:
    -The most underrated was probably the 428 Cobra Jet engine... its official rating of 335 hp was a joke, especially considering that the 390-4 bbl engine was also rated at 335 hp.

    -The second-most underrated was probaby either the Mopar 426-Hemi or the 340-4 bbl. The 340-Six Pack was not listed, but with an advertised hp of 290@5000 rpm and torque of 340@3200 rpm, I would guess about 335 hp @ 6000 rpm.

    -The actual power output of that 455 Olds W-30 is very impressive... 440 hp!
    '76 Cadillac Fleetwood Seventy-Five Limousine, '95 Lincoln Town Car.

  2. #2
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    Very interesting Fleet, thanks for sharing.
    Reginald *IB4R* says:
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    David says:
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    Quote Originally Posted by fisetdavid26 View Post
    Very interesting Fleet, thanks for sharing.
    Glad you like it.
    It makes for a better comparison when you know the actual horsepower. There were comments on some of the cars in the text of the article, which I'll post in a little while.
    '76 Cadillac Fleetwood Seventy-Five Limousine, '95 Lincoln Town Car.

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    I'd also be interesting to know the actual net power of those engines.
    Lack of charisma can be fatal.
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    Did the specs under-rate the torque too ?
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

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    Quote Originally Posted by Matra et Alpine View Post
    Did the specs under-rate the torque too ?
    Good question!
    No, according to Huntington, the torque ratings were not underrated, probably because insurance companies didn't go by torque ratings.
    '76 Cadillac Fleetwood Seventy-Five Limousine, '95 Lincoln Town Car.

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    Quote Originally Posted by Ferrer View Post
    I'd also be interesting to know the actual net power of those engines.
    I can look that up, too.
    Huntington wrote a book called "American Supercar," and he did list estimated net hp for most of the muscle car engines. I'll post them soon.
    '76 Cadillac Fleetwood Seventy-Five Limousine, '95 Lincoln Town Car.

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    Nice list, looks like the current crop of muscle cars isn't that far behind their ancestors. Even if they are officialy watered down stats. Another notable "underated" engine was the 454 LS6 un the Chevelle SS. Rated at 450 hp. When I was in high school it was said that it's real output was 500+ hp.

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    Quote Originally Posted by taz_rocks_miami View Post
    Nice list, looks like the current crop of muscle cars isn't that far behind their ancestors. Even if they are officialy watered down stats. Another notable "underated" engine was the 454 LS6 un the Chevelle SS. Rated at 450 hp. When I was in high school it was said that it's real output was 500+ hp.
    Yeah, I would not be surprised if the 454 LS6 put out more than its claimed hp.
    '76 Cadillac Fleetwood Seventy-Five Limousine, '95 Lincoln Town Car.

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    Quote Originally Posted by Ferrer View Post
    I'd also be interesting to know the actual net power of those engines.
    Here are some figures from the book I mentioned:

    Engine-----------------------Rated Hp--Est. Net Hp

    '64 Olds 330------------------ 310------ 240
    '66 Olds 400------------------ 360------ 320
    '68 Buick 400----------------- 345------ 290
    '68 Chevy 396 L-78----------- 375------ 360
    '69 Pontiac GTO 400---------- 370------ 340
    '67 Pontiac GTO 400 ram air--- 360------ 310
    '68 Olds 400------------------ 370------ 320
    '68 Chevy 427 L-72----------- 425------ 390
    '69 Dodge 440-6 Pack--------- 390------ 370

    '65 Mustang HP 289----------- 271------ 190
    '65 Barracuda 273------------- 235------ 190
    '67 Mustang 390--------------- 335------ 250
    '68 AMC AMX 390-------------- 315------ 290
    '67 Chevy Camaro 350--------- 295------ 230
    '68 Plymouth 'Cuda 340-------- 275------ 290
    '68 Ford Mustang 428---------- 335------ 320
    (Note that the net rating for the 340 is actually higher than the rated gross hp!)

    The Mopar Hemis gained hp as refinements were made. For instance the '68-'69 had a camshaft with more lift and duration compared to the '66-'67. The '70-'71 Hemis had hydraulic lifters while the '66-'69 still had solid lifters.

    '66 Mopar 426-Hemi----------- 425------- 330
    '67 Mopar 426-Hemi----------- 425------- 360
    '68 Mopar 426-Hemi----------- 425------- 390
    '69 Mopar 426-Hemi----------- 425------- 420

    --------------------------------------------
    Corvette engines:
    Base 350-cu-in--------------- 300------- 200
    350 L-46--------------------- 350------- 290
    427 L-36--------------------- 390------- 280
    427 L-71--------------------- 435------- 400
    '76 Cadillac Fleetwood Seventy-Five Limousine, '95 Lincoln Town Car.

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    Ive read a boss 429 stang would out perform a Hemi car in stock form. Is this true fleet?
    UCP biggest mustang lover

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    Quote Originally Posted by rev440 View Post
    Ive read a boss 429 stang would out perform a Hemi car in stock form. Is this true fleet?
    Not typically, unless the Mustang had really low gears like 4.30.
    This was mentioned in the same book by Roger Huntington...
    "It would be nice if I could say the new Boss 429 went and out beat Chrysler's nasty old Street Hemi hands down. It didn't quite work out that way. As I said, those Shotgun ports were just too big for the street. Even with all the detuning and choking down by Ford engineers, they could not quite get their act together. Big ports made the low end and mid-range weak. And just about the time the big ports started to work on the top end, the restrictive carburetion and camming took over. The street Boss 429 didn't perform really well anywhere in the speed range.

    It was an intersting lesson in standing-start acceleration curves. With the street Bosses' huge ports and the soft low-end and mid-range torque, the car spent too much time getting up to 70 or 80 mph where the flow in the ports was decent. At that point, there wasn't enough left of the 1/4 mile to turn good numbers. All else being equal, the Street Hemi could could up to 60 mph 1- to 1.5-seconds quicker. And to top it off, the street Boss 429 didn't have the carburetion and manifolding to haul on the top end. The single 735-cfm Holley and two-plane manifold were poorly matched to the size of the ports and valves underneath. Flow velocity was fine through the carb and manifold, but slowed at the big ports, hurting air/fuel mixture. Interesting engine"

    Roger did test a '69 Boss 429 Mustang with a four-speed manual and 3.91:1 rear axle ratio and got these times:
    0-30 mph-------------- 3.2 secs
    0-60 mph-------------- 7.1
    1/4 mile---------------- [email protected] mph
    Estimated net hp------- 370

    Compare with a Car Life test of a '69 Dodge Charger R/T with 426-Hemi, 4-speed manual and 3.54:1 gears:
    0-30 mph--------------- N.A.
    0-60 mph--------------- 5.7 secs
    1/4 mile----------------- 13.9@104 mph
    Estimated net hp-------- 420
    '76 Cadillac Fleetwood Seventy-Five Limousine, '95 Lincoln Town Car.

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    Quote Originally Posted by Fleet 500 View Post
    Here are some figures from the book I mentioned:

    Engine-----------------------Rated Hp--Est. Net Hp

    '64 Olds 330------------------ 310------ 240
    '66 Olds 400------------------ 360------ 320
    '68 Buick 400----------------- 345------ 290
    '68 Chevy 396 L-78----------- 375------ 360
    '69 Pontiac GTO 400---------- 370------ 340
    '67 Pontiac GTO 400 ram air--- 360------ 310
    '68 Olds 400------------------ 370------ 320
    '68 Chevy 427 L-72----------- 425------ 390
    '69 Dodge 440-6 Pack--------- 390------ 370

    '65 Mustang HP 289----------- 271------ 190
    '65 Barracuda 273------------- 235------ 190
    '67 Mustang 390--------------- 335------ 250
    '68 AMC AMX 390-------------- 315------ 290
    '67 Chevy Camaro 350--------- 295------ 230
    '68 Plymouth 'Cuda 340-------- 275------ 290
    '68 Ford Mustang 428---------- 335------ 320
    (Note that the net rating for the 340 is actually higher than the rated gross hp!)

    The Mopar Hemis gained hp as refinements were made. For instance the '68-'69 had a camshaft with more lift and duration compared to the '66-'67. The '70-'71 Hemis had hydraulic lifters while the '66-'69 still had solid lifters.

    '66 Mopar 426-Hemi----------- 425------- 330
    '67 Mopar 426-Hemi----------- 425------- 360
    '68 Mopar 426-Hemi----------- 425------- 390
    '69 Mopar 426-Hemi----------- 425------- 420

    --------------------------------------------
    Corvette engines:
    Base 350-cu-in--------------- 300------- 200
    350 L-46--------------------- 350------- 290
    427 L-36--------------------- 390------- 280
    427 L-71--------------------- 435------- 400
    Fleet, that's really interesting. Thanks for posting it.
    Lack of charisma can be fatal.
    Visca Catalunya!

  14. #14
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    Quote Originally Posted by Ferrer View Post
    Fleet, that's really interesting. Thanks for posting it.
    Albert, is that the first time you and Fleet quote each other without arguing?
    Reginald *IB4R* says:
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    David says:
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    Quote Originally Posted by fisetdavid26 View Post
    Albert, is that the first time you and Fleet quote each other without arguing?
    No there have been other rare occasions where this has happened too...

    I have to say some engines are quite disappointing, like the 289 Ford and the 350 Chevrolet.
    Last edited by Ferrer; 07-02-2007 at 12:02 AM.
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