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

[nota]

Anyone who thinks the 60s "musclecar" engines made a lot of power by today's standards is on drugs.

Oh, and here's one for the Ford fans. It contains the results of EIGHT vintage Mustang chassis dyno tests. The 428 Cobra Jet farted it's way to a whole 240 HP a the wheels. My bone stock, 3.5 liter V6 Acura TL Type S will put down more!

Thank you for your very informative & interesting post

I don't pretend to be any kind of expert. But my memory is still reasonably sharp as regards Ford Clevelands and the reported figures they produced 'back in the day' as opposed to historical revisionism, eg:

Ford Cleveland 351-4 bbl
"This one was marketed as a 'peppy, responsive' passenger car engine for the mass market. But actually it was a thinly desguised high-performance V-8 for the youth market. The advertised rating of 300 hp was very conservative. With 11-to1 compression, huge ports and valves, long camming and 650 cfm carburetion, the 351-4 bbl Cleveland would dyno 340 hp at 5600 rpm very easily. Note also that the optional Boss 351 version, with better camming and manifolding was good for another 20 hp at 6000 rpm. Healthy engines for 351 cubes."

Fwiw in 1971 a healthy 351C 4V Cleveland (aka 4-bbl) used to push a tad over 190 rwhp out the back end of an XY GT Falcon. How that translates into fwhp I don't know, but a race-prepared XY GT (owned by Jack Brabham no less, see pic) made 295 fwhp according to its specialist builder, and obviously a premier example. This is is a not inconsiderable 45hp less than the "340hp very easily" claimed above for your typical 351 4V Clevos - despite XY GT 351 engines being of identical specs (hi comp, closed chamber, big port) USA motors and yes at that time fully imported

Reputedly a carefully race-prepared Falcon GT-HO Phase Three (Clevo w/ Holley 780, upspec cam and OE extractors etc) made around 350 fwhp in Series Production trim - which is only 10hp more than this 340hp claim, for stock 351C 4Vs, in production trim with the Autolite 4300 carby!

I also recall 1971 quotage from a senior Ford-AU Executive in a drive-test of his personal XY GT-HO company car which did a genuine 160 mph on the Ford-Oz speed bowl through being modified by the factory race-team into 'Phase Three Plus' specs, that "she pulled 232 (rw)hp on the company dyno"

Another intriguing quote, this one from Allan Moffat's engine builder. Moffat was Ford AU's factory driver and #1 Cleveland racer through most of the 1970s, following his previous employ as contracted test driver & racer to the famous Kar Kraft USA. There would be few others who can claim to have been GIVEN a brand new Kar Kraft-built 1969 TransAm Mustang!
(Anyway it concerns Moffat's 1973 Bathurst winning Falcon which was flown over to the USA for rebuilding into his '74 Bathurst car by Kar Kraft, who farmed out the engine build to Kings Engine Services of Ferndale Michigan. The CAMS reference is to the Confederation Of Australian Motorsport, our governing body)

At about this time [1974] we also had an interesting development with King's Engine Services. The yanks had bragged on and on about the 351 Cleveland seeing 500hp with the stock intake manifold and an 850cfm square bore double pumper Holley carb. In Australia we could never squeeze out more than 400hp, and that was with twin 48mm DCOE Weber carbies.

Allan commissioned these guys to build an engine which we would compare with our home grown engine on the same dyno on the same day. Well, they screwed together their best killer engine, which did not meet CAMS [production] regulations due to bore size, head porting and manifold choice, and sure enough it made 500hp. They then fitted ours, which was CAMS legal, and it made 504hp!

[henk4]

Thanks for this very nice post..It partly explains why the Mercedes 6.3 was so popular despite having only 250 DIN PS

[harddrivin1le]

As can be seen in the various links I posted above, the old American SAE Gross HP ratings were nothing more than advertising hype dreamed up by the marketing department in the hopes of selling more cars. That advertising, combined with the results of MODIFIED engines/cars from that era has created myth and legend that has no actual basis in fact.

The suggestion that engines from that period were "under-rated for insurance purposes" is also baseless. In truth, virtually all of them were OVER-rated - mostly by a lot.

Today's "pure stock" amateur drag racing events only serve to further confuse the matter, since "stock" in those cases refers to the NHRA's version of "stock" (which permits overbores, 3 angle valve jobs, milled/decked heads and block, cheater cams, forged internals, upgraded valvetrain components and a host of other mods (including modern, custom-made exhaust systems, shift kits, locked differentials, huge gears, "loose" suspensions, etc.)

Making matters even worse is the fact that the magazines of the day were handed specially prepared test cars that weren't REALLY stock. They were often partially blue-printed, optimally tuned and, in some cases, fitted with completely different engines (e.g. CAR AND DRIVER 1964 "389" GTO, which was actually fitted with a modified 421 per the admission of Pontiacs PR man - 35 years after the fact.) Ferrari GTO

It wasn't uncommon for some magazines to install slicks, remove accessory drive belts and air cleaners, further "tune" the cars and even employ the services of professional drag racers (e.g. Ronny Sox) in order to get the best results. Everybody likes good numbers, so good numbers sold magazines. Such trickery produced the results that are generally quoted today when people attempt to cite the performance of the "muscle cars." The various "fastest musclecar" links floating around on the net are packed with them.

The '69 427 ZL1 Chevy was THE hottest production engine of that era (if you can call 69 engines "production.") They made 376 SAE NET HP - the way today's engines are measured. I have a second ZL1 dyno test (performed with a different engine) that yielded virtually identical results.

A select few engines came close to the ZL1 in terms of actual, "as installed" output, but none exceeded it. Among those engines were the '68 - '71 426 street hemis (the '66 - '67 engines were pigs), the '70 Buick Stage 1 and the "Super Duty" 421 Pontiacs (which, in truth, were too radical for the street).

The more common "muscle cars" typically made a LOT less horsepower. 200 RWHP on a chassis dyno was a big deal back then.

Most of these engines will make a lot more power if properly modified. However, the same can be said for newer engines. 4 cylinder Subarus run in the twelves with bone stock internals and very minor external mods (increased boost, exhaust and intakes), for example.

[kingofthering]

I'd like to take this time to mention that the old HP ratings were basically done using high octane fuel with all the power-sucking crap taken off. Not to mention that certain "additional parts" could be added, IIRC.

[harddrivin1le]

I'd like to take this time to mention that the old HP ratings were basically done using high octane fuel with all the power-sucking crap taken off. Not to mention that certain "additional parts" could be added, IIRC.

The things you mentioned (and many more) are covered here. Pay particular attention to Mr. Csere's editorial on the subject:

http://www.ultimatecarpage.com/forum...9-post119.html

Generally speaking, the advertised horsepower (and hence, torque) figures of that era had no basis in fact and were essentially chosen at will by the marketing/advertising departments. Not ONE "muscle car" engine was "under-rated" and virtually all of them were significantly OVER-rated - in some cases by as much as 150 HP (relative to how the same engine would be rated under today's SAE NET method).

[kingofthering]

Yeah, that's where I originally read it. Either that or Motor Trend.

[Fleet 500]

Generally speaking, the advertised horsepower (and hence, torque) figures of that era had no basis in fact and were essentially chosen at will by the marketing/advertising departments. Not ONE "muscle car" engine was "under-rated" and virtually all of them were significantly OVER-rated -

I can name ONE... the Mopar 426-Hemi. It's 425 hp (gross) rating was well below what it actually put out.
All of the '60s muscle car/drag racing fans know it.

The 428 Ford Cobra Jet engine was rated at 335 hp, exactly the same rating as the 390- V-8. Tell me that wasn't underrated!

[Fleet 500]

Anyone who thinks the 60s "musclecar" engines made a lot of power by today's standards is on drugs.

If they didn't make a lot of power by today's standards, then how did the Mopar Hemis go 140-160 mph (depending on what car it was in and gearing)?
You left out the page from that book you posted Hemi info that said this: "A well-tuned Street Hemi wtih 3.23 final drive could approach a top speed of 150 mph. This required about 6,000 rpm with stock tires. There was ample horsepower available to do it- if a tire didn't disintegrate first. Aerodynamic design was relatively non-existent by today's standards, so if it went 150 mph, it did it on brute horsepower alone. Fantastic engine."
(Page 93, American Supercar, by Roger Huntington)

I will tell you under no uncertain terms that I am a legitimate expert on this topic and have been published in several national magazines. The old cylinder heads and combustion chambers were JUNK by modern standards. The cams back then were generally lousy as well and most of them weren't really "hot" grinds to begin with. The ACTUAL compression ratios from that era were GROSSLY over-stated. Few topped 10:1 and the absolute greatest ACTUAL mechanical compression ratio was 10.6:1 (ZL1 and L-88 427 Chevy, both of which required 103 octane racing fuel and came with a tag on the center console stating that).

The highest factory compression ratio I've seen is 13.5:1 for the early '60s Mopar Max Wedge. I don't know what the mechanical compression ratio is, but I can check with a few engine rebuilders.

[Fleet 500]

Making matters even worse is the fact that the magazines of the day were handed specially prepared test cars that weren't REALLY stock. They were often partially blue-printed, optimally tuned and, in some cases, fitted with completely different engines (e.g. CAR AND DRIVER 1964 "389" GTO, which was actually fitted with a modified 421 per the admission of Pontiacs PR man - 35 years after the fact.) Ferrari GTO

True regarding Car & Driver, but other magazines like Car Life, Road Test and Motor Trend tested unmodified cars. And the relatively rare times they were modified, they let the reader know in the text.
For instance, Car Life tested a '69 383 Road Runner which was modified. The author of the article not only mentioned the modifications (aftermarket induction, headers and slicks) but the price ($450).

[harddrivin1le]

If they didn't make a lot of power by today's standards, then how did the Mopar Hemis go 140-160 mph (depending on what car it was in and gearing)?
You left out the page from that book you posted Hemi info that said this: "A well-tuned Street Hemi wtih 3.23 final drive could approach a top speed of 150 mph. This required about 6,000 rpm with stock tires. There was ample horsepower available to do it- if a tire didn't disintegrate first. Aerodynamic design was relatively non-existent by today's standards, so if it went 150 mph, it did it on brute horsepower alone. Fantastic engine."
(Page 93, American Supercar, by Roger Huntington)



The highest factory compression ratio I've seen is 13.5:1 for the early '60s Mopar Max Wedge. I don't know what the mechanical compression ratio is, but I can check with a few engine rebuilders.

That was the ADVERTISED Compression Ratio for the "R" version of the wedge. The "R" stood for race, required racing fuel and wasn't sold to the general public for street use. I don't know if that particualr figure was for the 413, the 426 or both.

A few 427 Ford engines, the 426 Chrysler Race Hemis, the Chevy ZL1s and L88s were similarly limited in application and availability. They weren't street engines. They are the equivalent of a C6R Corvette racing engine. How many of those are on the streets?

426 Street Hemis produce roughly 365 SAE NET HP - with a sharp tune. That's for the '68 - '71 engines; the earlier versions made significantly less due mainly to their milder cam grind.

I have Huntington's book. Patrick Hale's estimated SAE NET figures are more accurate, since Hale's formulas were computer-derived and Hale's math and computer backgrounds are more substantial. Hales' trap speed formula (used in the Moroso Power Calculator) remains an excellent formula to ESTIMATE peak engine flywheel HP.

I have dozens of vintage 426 street hemi road tests; not one produced a top speed of 150 MPH.

I suppose it's POSSIBLE, but only within the realm of peak HP being limited to ~ 365 SAE NET.

Here is a chassis dyno test of a low mileage, vintage 426 street hemi car (fitted with the later cam, which WAS hotter - depsite what the owner claims):

Hemi Vs. Viper!

315 RWHP. That lines up very well with other data I've seen.



It also lines up pretty well with Chrysler's SAE NET HP rating for the 1971 426 street hemi (the only year they published net figures). The numbers? 350 SAE NET HP.

SOURCE: 1971 Plymouth "Rapid Transit System" dealer brochure:



That's reality, man. 350 SAE NET HP for a 426 Street Hemi and 330 for the "mighty" 440 6 pack.

[harddrivin1le]

Check out this interesting article. It explains how "Super Stock" magazine got a "stock" 440 6 pack to run high twelves...The author was there for the original test (with Ronnie Sox) and came clean about it all ~ 25 year later in this article.

You'll see the absolute best result posted all over the internet on the various "fastest musclecar" lists. None of them bother to mention that the test car was a factory prepped "ringer" that was driven by a professional drag racer.

Lies like that are the basis for the "musclecar" myth.

'69-1/2 REGISTRY - SUPER BEE PROMO AD

[-What-]

Anyone who thinks the 60s "musclecar" engines made a lot of power by today's standards is on drugs.

Oh no no no, I've already served them that cup of reality. Ya see, I speak the truth 'round this bitch but they don't wanna here non of that. So from now on, if you wanna fit in...see all those facts and common sense statements you brought to the table? Ball that shit up and burn it. Blank your mind of that because that's not what flies around here.

Because here, if you ain't rockin' at least 1000 posts you don't have the credentials to support your statements.

Because here, 400hp in 1960= 640hp in 2007. Yeah, all these acceleration and top speed records being SMASHED today and they believe 60's power was king. 2007 transmissions are thhhhheeeeeeeeee sh*t! Right?

Because here, "it is" = "its" and "it's" does not equal "it is".

Because here, "false" = "true as hell", and "truth" = "STFU".

Because here, THEY ARE NOT ME.


I solved this puzzle 7/13/2007.

[harddrivin1le]

Oh no no no, I've already served them that cup of reality. Ya see, I speak the truth 'round this bitch but they don't wanna here non of that. So from now on, if you wanna fit in...see all those facts and common sense statements you brought to the table? Ball that shit up and burn it. Blank your mind of that because that's not what flies around here. All they want to read here is foolish un-truths posted by 1000+ posts people. They wanna believe.

Because here, 400hp in 1960= 640hp in 2007. Yeah, all these acceleration and top speed records being SMASHED today and they believe 60's power was king. 2007 transmissions are thhhhheeeeeeeeee sh*t! Right?

Because here, "it is" = "its" and "it's" does not equal "it is".

Because here, "false" = "true as hell", and "truth" = "STFU".

Because here, THEY ARE NOT ME.


I solved this puzzle 7/13/2007.

I solved it 25 years ago...

But I think ACTUAL ARTICLES say a lot more than undocumented claims.

Don't you? Check back a few posts and see the ones I've posted... ;-)

[-What-]

I solved it 25 years ago...

But I think ACTUAL ARTICLES say a lot more than undocumented claims.

Don't you? Check back a few posts and see the ones I've posted... ;-)

Don't....do that.

Don't get smartass with me. You can twist, bend, and contort yourself in an attempt to out-manuever whatever I've got to say, but don't....do that.


I'm not afraid of steppin' out of the neutral zone. I got "it" in me. You don't...but then again...who are you?





YOU'RE NOT ME

[harddrivin1le]

Don't....do that.

Don't get smartass with me. You can twist, bend, and contort yourself in an attempt to out-manuever whatever I've got to say, but don't....do that.


I'm not afraid of steppin' out of the neutral zone. I got "it" in me. You don't...but then again...who are you?


YOU'RE NOT ME

I'm not going to respond to anymore of your posts. You clearly have some "issues" that extend way beyond the context of this forum.

I posted several good links and scans that are relevant to the subject topic and that I thought would be of interest to the people who are involved with it. Much of that information is difficult to some by and is therefore of real interest to some people.