How does GM measure horsepower?

[Renze]

I am betting the GM 327 CID engines from the mid sixties with 300 hp will run circles around the 350-400 hp rated cars and trucks of today. Ken Sweet

Doubt it. Todays gas engines can get a flat torque curve because of fuel injection and multi valve heads. Todays automatic transmissions have more efficient converters and less clutch drag. Todays manuals have 6 speeds instead of 3 or 4.

However, reliability and longevity might be another cup of tea...

 

[radioman]

The EPA also has a hand in the power delivery because emissions is THE major player in power design. The motor's first 20 seconds of warmup during the EPA test cycle defines the performance allowed, because that's when the engine is dirtiest. Fuel economy goals have to be met too. In fact, extra raw fuel must be dumped into the motor to heat the converter ASAP to get the emissions requirements met. That extra fuel is expensed as a fuel economy penalty for the powertrain rating printed on the sticker.

Let me see if I understood this- We are wasting more gas at startup just to lower pollution? IS this everytime you startup the car or is there a switch/sensor that knows how warm the converter is and dispense extra gas as needed?

 

[JIGBUILDER]

I campaigned a factory stock '65 Chevy II 327 with 365 hp 4 speed. The chevy IIs ET was in the low 13s so I doub't any of the new gen high hp smallblocks could touch it. The old 327 has nothing in commom with the new 327 engine. The 365 hp version was with a single carb. There was a 327 ci 375 hp mechanical fuel injection that was a sleeper IF the mechanical injection could be kept tuned. The 365 hp and the 375 hp had the great rumpity rump idle

The old 327 had several different HP versions from the lightweight chevy II up to the 4 door 4600 lb Impala and pickups.

Chevy was known for low hp advertising on their smallblocks by simply publishing the hp at 5800 rpm but the 327 (example) would run to 7k shift points easilly.

The old '69 350 ci with the 370 hp version was another strong chevy smallblock.

 

[PoorMansCat]

Back yeas ago... 60's era, engine hp was as athers have stated. a GROSS Measurement. This could include adding headers, different carburetion, timing, electric water pump, no fan, high octane fuel, etc... to get a big number. None of these modifications would ever get into the production automobile. The gross hp number was bascially what the block, heads, and internals COULD do with the right add-ons.
Now, as others have stated, the hp of an engine is rated as a NET hp rating. All components as it will be installed in the vehicle must be installed and/or accounted for during hp measurement..
CAFE.. thats another evil, gubbament Al Gore wannabe, bunch of infected piles of smoking horse dung!!!. Guess we will have to install filters on horses butts for Methane Emissions now!!!

 

[Nightrain1]

There is no replacement for cubic inches. An antiquated big block chevy with a single carb can produce a thousand plus hp. Start implementing computers, injection, etc and those numbers will go up even more.

 

[PoorMansCat]

Then by this thinking, all 327s would have the same hp ratings. I don't know where you got this info, but it's bogus. :thumbdown:

No its not.

How can one infer that all engines of the same displacement would be the same hp by what I said??
The gross hp ratings once used were highly questionable. Manufacturers would skew the numbers by changing exhaust, carburetion, ignition, etc.. to get more hp out of the engines. They would often run an electric H2O pump to reduce parasitic losses. Air cleaners would be removed, manifolds would be replaced with headers.
On a side note; as the 60's were coming to a close, some engine manufacturers actually started fudging #'s on the low side due to pressure from insurance agencies and the government.
None of these practices are used in the modern automotive industry.

 

[timswi]

My neighbor had a 351W in a early 70's Mustang. He did quite a bit of stuff to it to do 13sec 1/4 miles. His wife's 2005 Lincoln Aviator will beat it stock.

Chris

A stock Lincoln Aviator will do better than 13 in the 1/4 mile...Like to see the time slips on that.

I do agree that many of the performance cars out there will destroy my 70SS396 Chevelle..Just better engineering and much wider power bands. The Chevelle is still fun, even though my 2011 GMC 6.2 could probably beat it.

 

[Diamondpilot]

A stock Lincoln Aviator will do better than 13 in the 1/4 mile...Like to see the time slips on that.

I do agree that many of the performance cars out there will destroy my 70SS396 Chevelle..Just better engineering and much wider power bands. The Chevelle is still fun, even though my 2011 GMC 6.2 could probably beat it.

Thats what I am getting at. I did not mean it broke the 13 second mark but got to it. I did a poor job stating what I was going to say.

He spent $1000's of dollars to get his Mustang to break the 14 second mark. His wifes Aviator did 13.9 in the 1/4 and zero to 60 in 7.2 seconds. Pretty amazing for a 5,100# truck, about 2,000# heavier than the Mustang. Same thing with your current truck. It will run pretty good also. My 04 F-250 with $500 of mods will do 14.1 in the 1/4 mile at 7,600#. In the case of the Aviator AWD make a big difference and 300+ HP lus those 60's/70's muscle cars just ran out of gear. The new automatics are plain amazing.

Most new cars are in the 14/15 second mark from the factory and we though we were doing great back in the day getting a car to that point.

Chris

 

[JIGBUILDER]

No its not.

How can one infer that all engines of the same displacement would be the same hp by what I said??
The gross hp ratings once used were highly questionable. Manufacturers would skew the numbers by changing exhaust, carburetion, ignition, etc.. to get more hp out of the engines. They would often run an electric H2O pump to reduce parasitic losses. Air cleaners would be removed, manifolds would be replaced with headers.
On a side note; as the 60's were coming to a close, some engine manufacturers actually started fudging #'s on the low side due to pressure from insurance agencies and the government.
None of these practices are used in the modern automotive industry.

Correct.
The old 327 ci chevy in the years from '63 to '69 had about 10 different HP numbers. These engines went in the big four door chevy sedans/Corvette's/Chevelle /Camaro and down to the little Chevy II.
One example I refered to was in the 325 hp at 5600 rpm and the 350 hp at 5800 rpm with the same engine specs. Just playing with the numbers.
The 350 hp version was used in the Vettes a lot and the 325 version was used in the Chevelle in certain years.

Chevy had certain dealers that sold special high performance parts. Those guys that worked the counters were the ones you offered steak dinners/etc for the latest factory HI Per gimmick to make more power for those smallblock engines.

The higest HP engines usually came in plain jane version vehicles. Example the 2 or 4 door chevy sedans were the Custom or delray models. My chevy II didn't even come with a radio or any chrome. These cars were specifically for racing and came with no warranty.