car Horsepower definition

[SFRT - Frenchy]

I was checking on the V8 302 rating of the 72 Grand Tomato and it reads 140HP. 140HP? I had 155HP on my stock 2.0I from my 88 Honda Prelude.

Then i remember someone talking about a change in the way horsepower was rated after the mid seventies till nowadays. Anyone cares to enlighten me?

[SaburoS]

Actually it was 72-73 when the change happened (IIRC).
Car manufacturers used to rate their engines using gross hp. Basically checking the rating while the engine was running without anything hooked up (alternator, powersteering pump, etc.) giving an unrealistic high rating.*
After 72 (IIRC) the hp ratings were measured with everything hooked up. That's when they started calling it net hp.

*Funny on the gross hp ratings. Supposedly, manufacturers would downgrade the max hp rating on their most powerful models as the insurance companies started to increase rates based on hp ratings.

[FUNKED1]

Frenchy that HP rating is for real.  The US government was the world leader in emissions regulations in the early 70's.  Unfortunately the US auto industry took almost 20 years to adapt.  So there was a whole generation of cars with huge V-8's and less than 150 hp, because Detroit couldn't figure out how to reduce emissions without reducing power.  It's the main reason why a lot of people from my generation have a disdain for American cars.

[J_A_B]

Ah the days of the 150 HP V-8 that got 14 miles per gallon....

Don't forget how butt ugly most of these cars were, too.

The late '70's and most of the '80's really sucked for Ameican cars.  Things didn't really start to get better again until around 1992 or so.   What Funked said is largely true--lingering bad impressions from this time period have hurt American automakers and ESPECIALLY the sales of larger cars.   My cousin flat out would not believe that my Roadmonster would out perform his Camaro RS....until I demonstrated it.

Vehicles like the new Chysler 300 show that the automakers might finally be "getting it".....that car has potential although it's overpriced.  MY Buick "got it" too but according to tradition GM discontinued it as soon as they perfected it.


In minor defense of those horrible engines, I'd point out that they still perform better in the low end power band than a typical 4-banger of equal max power does.  So they weren't totally horrible, just mostly horrible.  

My pevious car (the Cadillac) "only" had a 180 HP V-8 (this particular engine dated from the time when they began to improve them), but I could easily beat cars with 4's or 6's with an equal or slightly higher max power rating.

J_A_B

[midnight Target]

'72 cars should be pre-emission. I'm pretty sure Califonia emission standards kicked in in 1974. But the pot was good back then so I didn't care one way or the other.

[Roscoroo]

california emissions started back in '66 (thats the year of the nasty air pump)
'74 was when they started vac porting and egr
'76 was official year of the cat converter
'81 or '82 was anouther buckle down year and thats when most of the big v-8's went bye bye  


'73 was the year they switched from gross HP ratings to net (rear wheel hp ratings)

[beet1e]

Hmmm... interesting thread. I was living/working in the US in that 1979-82 period. Even in that brief time I saw some enormous changes in the cars. It was a sad time. The legendary muscle cars were no longer being made. Didn't Carter mandate that the largest permissible engine would be a 3.0L V6? Jaguar got fined $6m for not building a proportionate number of "fuel efficient" cars. As the PR guy explained at the time - "We build only luxury cars with relatively large engines. We don't build any 3-dr hatchbacks".

About that air pump/smog pump thing: What was it, what did it do and how did it work? I don't recall having one on anything other than an American car. We've only had CATs on the cars sold here since 1993.

[SFRT - Frenchy]

The 1973 455SD provided the last real muscle car, as far as I'm concerned. Looks like it was quite a story:

Well, it appears that Pontiac had to play games to get the Super Duty a smog legal status. Originally, a camshaft with .480" inches of lift was planned and indeed this engine seemingly passed the emissions tests, as the duration of the tests lasted 50 seconds. Pontiac developed an EGR system that would only be activated for 53 seconds of run time, enough of a cushion to allow for production variances. The EPA found out and decided this little variation wasn't quite in the spirit of the law so the approval was revoked and Pontiac set out to re-engineer the SD so it would be legal again. Carburetion changes were required, but the biggest "take-away" was a new camshaft, now limited to .410" of valve lift. Not quite what had been promised, losing 20 horsepower, but Pontiac could have easily given up on the whole project, and the Trans Am world would have been without one of the greatest supercars of all times. As a result of the recertification process, deliveres of the SD-455's were held until April of 1973.

On my 455 (non SD or HO), in 1973 HP is down to 250, you can see the HPs going down thru the years.

[Replicant]

Originally posted by beet1e
We've only had CATs on the cars sold here since 1993.

Actually it was 1992 that Cats be fitted as standard to all petrol cars.  They were available before hand though, I think the Rover 827 was the first to have it as standard in about 1989 I think?

With the introduction of Cats meant that all new cars ran on 95 RON unleaded fuel; some of the more perfomance cars could use 98 RON unleaded.

As for 'Gross HP', in the UK that was often called HP taken at the flywheel (i.e. nothing else attached).

[SFRT - Frenchy]

1970

Engines: 250 I6 155 bhp. 350 V8 255 bhp. 400 V8 265 bhp. 400 V8 330 bhp @ 4800rpm, 430 lb-ft @ 3000 rpm. 400 V8 (HO) 335 bhp @ 5000rpm, 430 lb-ft @ 3400 rpm. 400 V8 (Ram Air II) 345 bhp @ 5000 rpm, 430 lb-ft @ 3400 rpm. 400 V8 (Ram Air IV) 370 bhp @ 5500 rpm, 445 lb-ft @ 3900 rpm. 400 V8 (Ram Air V) 500bhp.

Performance: 400/370 (RA IV): 0-60 in 5.6 sec, 1/4 mile in 13.9 sec @ 102 mph.



1971

Engines: 400 V8 300 bhp @ 4800rpm, 400 lb-ft @ 3600 rpm. 455 V8 325 bhp @ 4400 rpm, 455 lb-ft @ 3200 rpm. 455 V8 (HO) 335 bhp @ 4800 rpm, 480 lb-ft @ 3600 rpm.

Performance: 455/335 (HO): 0-60 in 5.9 sec, 1/4 mile in 13.9 sec @ 103 mph.



1972

Engines: 400 V8 250 bhp @ 4400rpm, 325 lb-ft @ 3200 rpm. 455 V8 300 bhp @ 4000 rpm, 415 lb-ft @ 3200 rpm.

Performance: N/A



1973

Engines: 350 V8 150 bhp. 400 V8 230 bhp @ 4400rpm, 325 lb-ft @ 3200 rpm. 455 V8 250 bhp @ 4000 rpm, 370 lb-ft @ 2800 rpm. 455 (SD) V8 310 bhp @ 4000 rpm, 390 lb-ft @ 3600 rpm.

Performance: SD455/310: 1/4 mile in 13.5 seconds @ 104 mph



1974

Engines: 350 V8 155bhp. 400 V8 225 bhp @ 4000 rpm, 330 lb-ft @ 2800 rpm. 455 V8 250 bhp @ 4000 rpm, 380 lb-ft @ 2800 rpm. 455 (SD) V8 310 bhp @ 4000 rpm, 390 lb-ft @ 3600 rpm.

Performance: SD455/310: 1/4 mile in 13.5 seconds @ 104 mph



1975

Engines: 350 V8 155bhp. 400 V8 185 bhp, 310 lb-ft. 455 V8 200 bhp @ 3800 rpm, 330 lb-ft @ 2000 rpm. 455 (HO) V8 200 bhp.

Performance: 455/200: 1/4 mile in 16.1 seconds @ 89 mph



1976

Engines: 350 V8 155bhp. 400 V8 185 bhp, 310 lb-ft. 455 (HO) V8 200 bhp @ 3800 rpm, 330 lb-ft @ 2000 rpm.



1977

Engines: 231 V6 105 bhp. 301 V8 135 bhp. 305 V8 (California). 350 V8 (California). 350 V8 155bhp. 400 V8 185 bhp, 310 lb-ft. 403 V8.

Performance: 400/185: 1/4 mile in 16.02 sec. @ 89.64 mph.



1978

Engines: 231 V6 105 bhp. 301 V8 135 bhp. 305 V8 (California). 350 V8 (California). 350 V8 155bhp. 400 V8 185 bhp, 310 lb-ft. 403 V8.



1979

Engines: 231 V6 105 bhp. 301 V8 135 bhp. 305 V8 (California). 350 V8 (California). 350 V8 155bhp. 400 V8 185 bhp, 310 lb-ft. 403 V8.



1980-81

Engines: 301 Turbo V8 210 bhp.

Performance: 301/210: 1/4 mile in 17.02 sec @ 82.1 mph.

[beet1e]

Originally posted by Replicant
Actually it was 1992 that Cats be fitted as standard to all petrol cars.  They were available before hand though, I think the Rover 827 was the first to have it as standard in about 1989 I think?

With the introduction of Cats meant that all new cars ran on 95 RON unleaded fuel; some of the more perfomance cars could use 98 RON unleaded.

As for 'Gross HP', in the UK that was often called HP taken at the flywheel (i.e. nothing else attached).

1992 sounds about right. I was working for Honda back then, and I do believe that 2.7L engine in the Rover was a Honda engine, used in the Legend. The Jap engines were way ahead of anything else on sale in Europe in terms of emissions.

The years leading up to 92 were interesting. Remember R.U.L.E. ? Four categories of cars - those that could run on Unleaded, Leaded, Either - I don't remember what the R category was. I had a Toyota Celica 2.0GTi 16 which I bought in 1988. A great car - never had an ounce of trouble from it. It didn't have a CAT but ran on leaded or unleaded.

[Replicant]

Originally posted by beet1e
1992 sounds about right. I was working for Honda back then, and I do believe that 2.7L engine in the Rover was a Honda engine, used in the Legend. The Jap engines were way ahead of anything else on sale in Europe in terms of emissions.

The years leading up to 92 were interesting. Remember R.U.L.E. ? Four categories of cars - those that could run on Unleaded, Leaded, Either - I don't remember what the R category was. I had a Toyota Celica 2.0GTi 16 which I bought in 1988. A great car - never had an ounce of trouble from it. It didn't have a CAT but ran on leaded or unleaded.

Yeah, I worked at a Rover franchise as a mechanic then and half the Rover cars had Honda engines!  In 6 1/2 years I never saw one engine fail!  They were in Rovers 213, 825, 827, 620, 623, 216 (H to N reg)?

I can't remember R.U.L.E.?  I know I hated the environmental friendly customers who wanted their old cars converted to run on unleaded fuel.  Some needed completely new engine heads but also required the ignition retarding.  The amount of burnt out valves we had was unbelievable!  I don't think the cars were quite ready for unleaded fuel just then!

[beet1e]

Originally posted by Replicant
Yeah, I worked at a Rover franchise as a mechanic then and half the Rover cars had Honda engines!  In 6 1/2 years I never saw one engine fail!  They were in Rovers 213, 825, 827, 620, 623, 216 (H to N reg)?

I can't remember R.U.L.E.?  I know I hated the environmental friendly customers who wanted their old cars converted to run on unleaded fuel.  Some needed completely new engine heads but also required the ignition retarding.  The amount of burnt out valves we had was unbelievable!  I don't think the cars were quite ready for unleaded fuel just then!

I've just sold my 1972 air cooled Beetle - sold it on eBay - LOL. Anyway, when I bought it the owner said it could run on unleaded. But I only ever put LRP in it because of concerns that you mention here - valve seat hardness etc.

I worked at "Honda UK" which at that time was based in Chiswick. The engine plant was at Swindon - built on the site of the old South Marston airfield. When Honda and Rover were in that partnership, what had been built as the Rover 213/216 became the Honda Concerto. Not a bad little car. Rover built the cars, Honda built the engines. An amazing process by which aluminium ingots in a hopper were heated to molten metal and then poured into a cast. When the thing had cooled off and hardened, the crankshaft, camshaft/valve gear/cylinder head and electrics could be added. Then they'd add oil, connect it up and most of 'em would start at the first attempt. I heard the whole process took about 2 hours.

[lazs2]

yep... the environmentalists mandated laws that were unrealistic for the tech of the day 10-15 years too soon.  Sorta like Californias current "zero emmissions" law for a percentage of fleets.

To meet the law most mnufacturers basicly recirulated burnt fuel back into the engine and lowered compression and valve overlap and raised the working temp of the motor..  This worked... too a degree.   if everything was just right and in perfect condition... you got somewhat lower emissions but at thje cost of performance and economy... you cut emissions in half but you also cut efficiency in half and milage.. net gain was about zero on well tuned engines.

Catalytic converters were ok but were poisonous and hazardous waste was created.  

No real improvements in smog reduction and efficiency could be attained with large engines until computer tech and electronic fuel injection tech caught up in the mid 80's.

lazs

[Boroda]

Every educated person knows that one horse power is a power produced by a spheric horse, 1 meter in diameter, in vacuum. The ethalon of a horse in kept in a Board of Weights and Measures in Paris