Reality Check: Actual RWHP old vs new

[JBrady]

Interesting article testing 8 hi-po Ford Mustangs.

http://www.mustangandfords.com/techarticles/5216_8_mustang_musclecars_dynojet/index.html

Not all the cars were in perfect factory tune but the difference in advertised HP vs actual dynojet HP is eye opening.

Consider that a stock GS400 typically makes
235rwhp @ 6000rpm / 245rwtq @ 4000rpm
Consider that my old 5.0 Ford V8 that I ported the heads made
249rwhp @ 4400rpm /314rwtq @ 3500rpm

Here are the test cars and results (they used 17% manual and 25% automatic drivetrain loss for flywheel calcs)

1965 289 High-Performance Automatic (289cid/4.7 lt)
Actual Rear Wheel: 141 hp/254 lb-ft
Estimated at Flywheel: 176 hp/318 lb-ft
Factory Rating: 271 hp/312 lb-ft

1965 Shelby GT350 Four-Speed (289cid/4.7 lt)
Actual Rear Wheel: 202 hp/237 lb-ft
Estimated at Flywheel: 236 hp/277 lb-ft
Factory Rating: 306 hp/329 lb-ft

1966 289 High-Performance Four-Speed (289cid/4.7 lt)
Actual Rear Wheel: 144 hp/238 lb-ft
Estimated at Flywheel: 168 hp/278 lb-ft
Factory Rating: 271 hp/312 lb-ft

1967 Shelby GT500 Four-Speed (428cid/7.0 lt)
Actual Rear Wheel: 240 hp/354 lb-ft
Estimated at Flywheel: 281 hp/415 lb- ft
Factory Rating: 355 hp/420 lb-ft

1968 GT500KR Automatic (428cid/7.0 lt)
Actual Rear Wheel: 275 hp/336 lb-ft
Estimated at Flywheel: 344 hp/420 lb- ft
Factory Rating: 335 hp/440 lb-ft

1969 Boss 429 Four-Speed (429cid/7.0 lt)
Actual Rear Wheel: 214 hp/324 lb-ft
Estimated at Flywheel: 250 hp/379 lb- ft
Factory Rating: 375 hp/450 lb-ft

1969 Mach 1 428 CJ Automatic (428cid/7.0 lt)
Actual Rear Wheel: 213 hp/266 lb-ft
Estimated at Flywheel: 266 hp/332 lb-ft
Factory Rating: 335 hp/440 lb-ft

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

 

[stevechumo]

Interesting...So if my car is dynoed at 260 rwhp, it should be factory rated at 350 hp range.

 

[jibbby]

It's ironic that you brought up the family of Ford Mustangs... I've been looking at a 1967 Mustang GT500 that has been restored... I drove it and it sure doesn't feel like it has 281 or 355hp for that matter...Feels more like 250hp if I had to guess.... I guess that is because it is 30 years old, heavy and worked over and used.. Compression isn't as good maybe, worn parts, etc..

I guess it is safe to assume as a car gets older even with proper maintenance I believe it gradually loses horsepower thru the years... Wear and tear on all moving parts and what not...

Oh, and new car manufactures that claim more horsepower then the cars actually have should be held accountable for their exaggerations.. People whom buy these cars new surely expect to get the power that is promised... That's a classic example of false advertising, no?


This is a few pic's of my neighbors restored 67 GT500... I am not much of a Ford guy but I do love this perticular Mustang... It looks alot better in person too.

 

[Jake Breyck]

Jibby how do you get that its a heavy car? it weighs less then your sc400.

also many car manufactures have been held accontable for false power clames, and took the cars back from the people who cared enough to give them back. but most people who buy a car today even a sports car just cruse to work and back in it and really just want somthing that looks fast, and cool and doent really care if it accually is.

 

[Tacoma_Kyle]

Kinda, I guess.

The problem, JBrady, is the examples dont state what RPM each reading is at. It could be the max's listed, but it doesnt specify.

I am thinkin the HP numbers may be at the max torque's RPM. Back then these larger engines generally had lower RPM peak torque numbers, which results in a lower max hp. The only thing that connects a torque to hp number in these auto engines is RPM and a equation.

HP = (t)(rpm) / 5250

t = torque in ft-lb.


I did some quick comparing of numbers, I think that is the case. The dyno'd numbers are probably at a constant RPM and at max torque, while the apparent MFG claims are the max's of both. Notice the torque numbers are reasonably close when compared the the terrible HP numbers.

So I am skeptical on the info provided. No sayin there hasnt been shitty numbers given in the past.

 

[XR8tt]

Would factory figures be done without alternator, power steering etc ??
Comparing rwhp to fwhp is not always directly comparable...
The Mustang 2000 Cobra DIDN'T have as advertised power figures and where recalled, the extrude honed inlet which gained advertised figures...
Its a little unfair to compare old engines. Especially old pushrods..
Dyno's are a tuneing tool .. Been way too many arguments even with latter model cars on dyno readings....

 

[stevechumo]

This is just a joke abbreviation about Ford that people use to say, so please don't get offended at me. Ford stands for Found On Road Dead due to their unreliable cars. :32:

 

[XR8tt]

Been to more than few local dyno days... Its just not Fords... All brands including the generals Gen lll.. Some rwkw are no more than older lower performance engines...

 

[XR8tt]

Here's numbers from recent dyno day .. G.M v Ford....
The XR6T is a turbo straight twin cam 6.....
RWKW to convert to h.p.. kw X 1.34 = h.p....


Scott- Ford ELGT- 144.6kw
David- Ford BA XR8- 210.5kw
Frank- VZ Commodore- 206.8kw
Joe- VZ R8 Clupsort- 231.2kw
Cou- HSV R8- 193.4kw
Justin- VY 11 SS Ute- 194.9kw
Dus- Holden VX- 249.1kw
Matthew- Holden VZ SS- 207.8kw
Ross- VY Maloo HSV- 278.3kw
Craig- SS- 252.8kw
Haken- BA MKZ GT- 280.1kw
Dennis- UT- 200.5kw
Darran- Holden Commodore- 231.7kw
Rob- VZ Clubsport- 224kw
Khaled- VY SS Ute- 233.3kw
Khodre- Holden VT- 254kw
George- Ford BA XR6- 139.9kw
Joshua- VR Commodore- 102.6kw
Jody- Ford XR6 VCT- 104.9kw
Damien- VY Commodore- 103.8kw
Peter- Ford Falcon XR6 Turbo- 301.2kw
Owen- Holden S Pac- 183.2kw
Ben- Ford XR6T- 238kw
Nicholas- Ford XR6- 304.9kw
Dave- XR6T BA 11- 330.4kw
Michael- Ford XR6T- 300.2kw
Peter- XR6- 206.5kw
Brain- Ford F6- 517.2kw
Dane- VT Commodore- 200.2kw
Jack- Holden Vl Calais- 236.6kw
Ziggy- GTS 01- 372.7kw
Graeme- Ford XR8- 406.4kw

*****************


N/A 6 = George Hartis BA XR6 139.9

N/A 8 = Hakan Gursel BA MK2 GT 280.1

Forced 6 = Brian Lord BA F6 Typhoon 517.2

Forced 8 = Greame Elliot EB XR8 twin Turbo 406.4

Overall = Brian Lord 517.2

 

[turboandrew]

Also consider that a lot of these cars were rumored to make even more than they were rated at. Lies on top of lies

We really have it good these days. You can get a Toyota truck that has 381 HP on 87 octane gas! And they just released a supercharger to get over 500! The 60's wish they had it this good... OK, gas prices suck today...

 

[Lextreme II]

You can get a Toyota truck that has 381 HP on 87 octane gas! And they just released a supercharger to get over 500! The 60's wish they had it this good... OK, gas prices suck today...

500 bhp will be one fun Tundra. That will make the Dodge V10 (Viper Engine) truck and the Ford Lightening (Supercharged 5.4L) truck cry.

 

[jibbby]

Jibby how do you get that its a heavy car? it weighs less then your sc400.

Well now Jake, I never said the SC400 was light in weight either...

Remember, this 67 GT500 comes equiped with 428ci iron block motor, cast iron heads, etc...and not the 289ci ....That alone should make the front end of that Mustang fairly heavy, no?

 

[XR8tt]

Umm? I'll take the 428 [427 is better] Mustang any day...
It would be appreciating in value..

 

[JBrady]

Kinda, I guess.

The problem, JBrady, is the examples dont state what RPM each reading is at. It could be the max's listed, but it doesnt specify.

I am thinkin the HP numbers may be at the max torque's RPM. Back then these larger engines generally had lower RPM peak torque numbers, which results in a lower max hp. The only thing that connects a torque to hp number in these auto engines is RPM and a equation.

HP = (t)(rpm) / 5250

t = torque in ft-lb.


I did some quick comparing of numbers, I think that is the case. The dyno'd numbers are probably at a constant RPM and at max torque, while the apparent MFG claims are the max's of both. Notice the torque numbers are reasonably close when compared the the terrible HP numbers.

Kyle, no, the HP given was the peak for the dynojets run through the RPM range. If you go to the link I provided you can get details on each car. Most had been stored so there was concern that a proper tune up would be needed for most of these cars. Overall while the torque calculations where reasonably close the HP at the wheels and subsequent calc for the flywheel were for the most part much lower than "advertised".

The bottom line is the old "Muscle Cars" where not as powerful than todays "Muscle Cars". A 405hp rated 2002 Corvette Z06 typically makes 350rwhp. The 505hp 2006 version more like 440rwhp. A bone stock 2003 S600 Mercedes dyno'd at 481rwhp and a 2006 SL65 540+rwhp. We are truly in the golden age of automotive performance. All the above numbers are STOCK. Modified there are more and more cars in the 600rwhp, 700rwhp, 800rwhp, 900rwhp, 1000rwhp and beyond.