Found this killer page from HOTROD the other day while browsing the internet. As i'm reading it I realize there was significant Oldsmobile related info, which I was happy to see. This caused me to immediately look for who wrote it. What a pleasant surprise it was to see it's our fellow member Diego ! Its for Muscle Car Review and its a real gem.

https://www.hotrod.com/articles/hors...r-1960s-1970s/

Mr Joe Padavano you have been saying this for a very long time.

When looking at the 1970 455, the numbers are all over the place. All the 442s were underrated with the actual gross rating being taken at a lower RPM... All the regular non muscle 455s were overrated...

For example the 1970 Toronado GT W34 factory rated at 400 HP @ 4800 RPM was actually 368 HP @ 4800 RPM GROSS


I will post spec charts in next post.

 

https://www.hotrod.com/articles/hors...r-1960s-1970s/

Diego, thank you so much for providing us with this information. Regardless of what happens with the magazines, I hope you will continue to contribute online.

 

So my take on these charts.

Only the as installed specs are 100% on the money and the engines actual peak net horsepower specs ?

Production HP @ Maximum Brake Torque essentially is the net HP tweaked. Timing advanced, plus whatever they list to go along with it. Headers, race fuel, ram air, etc ?

Gross HP is given at a specific but not necessarily peak RPM and is accurate although true peak may occur at slightly higher RPM on some engines ?

Advertised HP is just that, In the ballpark of reality but essentially whatever the company thought was in their best interests ?

 

As the article states hp ratings were in line with the weight of the car. 1hp per 10 pounds of car has almost all mfg's. toeing the line of the insurance rates at the time. If you research Pontiac's Ram Air IV engine rating of 370 in the GTO but only 345 in the Firebird it makes sense. I wasn't old enough to buy a new car in 1970, but I've heard some insurance companies would not insure Hemi's and other over the limit musclecars.

 

Horsepower to weight numbers were in fact a big factor that affected car sales greatly. A 25% to 50% surcharge on car insurance for "performance cars" was real. Not only did it affect new cars, insurance companies also encompassed previous years cars. Things like stripes and hood scoops were also things that would qualify a car as a "performance car". None of the car makers rated an engine higher than 425 HP, no matter what it was.......except the 435 HP tri power Corvette came along.

 

Thanks for posting about this great article!

One thing puzzled me. I think Diego meant Mean Best Timing. None of those engines made maximum torque at 5000 rpm.

 

and here's another view (Scientifically / LOL)

The True HP of the 10 Most Powerful Classic Era Muscle Cars

What The Most Powerful Muscle Car Engines REALLY Produce…!

Updated on October 26, 2019. In Cars

That said, we’re relying here on the excellent research of author and automotive historian Roger Huntington who researched these classic muscle engines to determine, scientifically rather than hearsay and rumor, as to whether these monster motors were underrated, and if so by how much. By taking samples from many different areas – dyno tests of exact rebuilds of classic motors, drag race results, 0-60 times, and other test results and developed an algorithm by which he could compare claims to reality. For all his hard work, we thank him (and if you’re interested in this stuff, check out his books).

Number Three: Oldsmobile 455 W-30
Who would have figured that out of the three B-O-P (Buick-Olsmobile-Pontiac) group that it would be mostly overlooked Oldsmobile who would have the most powerful engine of the group. While all three brands had 455 engines, there were literally completely different motors – no parts interchange except for some tiny parts and those were most likely by chance). At the time Olds told the public the 455 W-30 produced just 370 hp @ 5300 rpm, in reality the output at 5600 rpm was closer to 440 horsepower.

https://autowise.com/the-true-hp-of-...a-muscle-cars/

 

I had to look up MBT because I was not familiar with it myself. Definitely timing related.

Look at the auto W30, 54 net HP gain, with max timing advance, race fuel, and headers. OUTSTANDING !

If the charts I posted are what I think they are. We are looking at the holy grail of Oldsmobile engine specs. All the educated guessing is taken out of the equation at least for the given RPM. With that said Roger Huntington was a tremendous asset to the car community, even if he may have been optimistic with regards to the stick W30. Still underrated but not nearly as much as thought if you use the 1971 Oldsmobile spec breakdown.

For 1971 the W30 455 was rated 350 Gross and 300 Net HP @ 4700 RPM . About 15% less gong gross to net. So for 1970 322 Net HP would translate to 380 HP Gross @ 5200 RPM. What if Olds did rev the gross 1970 engine to 5600 RPM ?

(Hmmmm wandering now if the 68 and 69 Hurst Olds were not really underated at 390 HP and 380HP respectively... After all they didn't need to worry about Lbs to HP specs, etc, they were aftermarket ? )

 

Where did the '70 LS6 454 fall in this list? I can't believe it doesn't fall into this top-10 list, unless it was NOT under-rated and therefore not included.

Bottom line, HP numbers only indicate a given car's potential. It takes a skilled driver to wring the most out of that potential. Also, I think the 1/4 mile trap speed tells the HP story the best; it is much less subject to the effects of traction (lack of) like 0-60 or ETs.

 

I believe the LS6 was rated at 450 HP which defies Ralphs comment that nothing was rated above 425 HP. Hard to believe a Hemi was only rated at 425. Talk about underrated.

 

Engines were rated with readily available "pump gasoline" and no headers. Both the '68 and '69 H/O's were under rated, thats why the '68 H/O was factored to 400 HP by NHRA. I don't recall if the '69 H/O was factored upward by NHRA. Insurance companies did scrutinized HP/weight ratio's so they could charge significantly higher premiums' Ask me how I know....

Magazine articles sold cars.

I was unaware/didn't care what the LS6 was, I stand corrected. I did notice the tripower 435 HP Corvette, dual quad Ford's, Chryslers and AMC's. HAHAHAHAHHAHAHA everybody knew Chrysler was lyin about the 426 Hemi. Even Oldsmobile had their "engineering exercises" going on. I am sure Oldsmobile could have sold 500 455 Hemi's to get certified for racing organizations.

 

The L88 Corvette was probably one of the biggest lies. I think GM rated it at 430 HP which was 5 less than the tri-power version. It was a racing engine that required 103 octane and was probably underrated by at least 100 HP.