Factory Horsepower Ratings (1 Viewer)

[house]

I just saw an episode of American Musclecars that investigated horsepower ratings of some vintage factory engines. Horsepower then was reported at the flywheel so this program used an engine dyno and factory ratings as a benchmark. The ground rules for the "competition" were that the engines had to have standard displacement, actual stock blocks, the same cfm carbs as came from the factory, cams that were blueprinted to factory specs, factory heads, and be as close to how they came from the factory as possible. The results were:

Chevrolet 409 rated at 409 HP 406 HP/430 FT LBS Torque
Ford 427 rated at 425 HP 637 HP/554 FT LBS
Pontiac 421 rated at 405 HP 488 HP/470 FT LBS
Hemi 426 rated at 425 HP 820 HP/689 FT LBS
Chev L88 427 rated at 425 HP 527 HP/461 FT LBS

All except the L88 had 2x4 carburation which had one 4 barrel. I was amazed that the Hemi and Ford had such high numbers but thought the L88 would produce more (although it did have one less carb). Anybody out there know how to estimate what those flywheel numbers would equate to at the rear wheels?

It was a pretty cool show. Lots of car footage. Catch the re-runs if you can.

 

[john]

As Dick Landy stated "Any good street Hemi will make 425 HP with a plug wire pulled".

 

[BlueStangGT]

...Anybody out there know how to estimate what those flywheel numbers would equate to at the rear wheels?

Subtract about 15% for a clutch car and about 20% for an auto.

 

[house]

Subtract about 15% for a clutch car and about 20% for an auto.

Wow! That would still leave the 427 Ford at around 540 HP at the rear wheels and the Hemi at 697 RWHP. Quite impressive, given the numbers that are thrown around today. Also, all these motors were for sale off the showroom floor.....with warranties. The guy doing the testing was quick to say, however, that he would never race any of these motors, since they were 40+ years old and very valuable. He suggested reproducing them from available over the counter/mail order parts so as not to destroy a legend.

 

[Harry Mannback]

Back in the day the factory used to under report HP to keep consumer insurance rates low and the feds off their backs.

Dan

 

[john]

Was the L-88 a production motor? I thought a true L-88 had no rating and was not offered in a production car, or maybe that was the LS-7?
I'm a Mopar guy and that Street Hemi number just seems out of line, even an A-990 Drag Hemi would have trouble making 820 out of the box. I would think 550 HP is more like it, the piece they tested may have been "massaged" a little.

 

[BlueStangGT]

Wow! That would still leave the 427 Ford at around 540 HP at the rear wheels and the Hemi at 697 RWHP. Quite impressive, given the numbers that are thrown around today. Also, all these motors were for sale off the showroom floor.....with warranties. The guy doing the testing was quick to say, however, that he would never race any of these motors, since they were 40+ years old and very valuable. He suggested reproducing them from available over the counter/mail order parts so as not to destroy a legend.

btw - Which 427 Ford were they testing, the SOHC or one of the pushrod motors?

 

[john]

btw - Which 427 Ford were they testing, the SOHC or one of the pushrod motors?

I'll bet that is the wedge, the SOHC made a lot more HP.

 

[house]

It was the wedge. They specifically stated that they were only using production engines. I thought the Hemi was high, too, but didn't they de-tune those that actually went in the street cars? These engines were blueprinted, which may explain the difference. Also, the L88 was a one year, I believe, production option. It came with a console plate that warned of engine damage that would result from using anything but the highest octane fuel.

 

[house]

I just read on an internet site that the 427 SOHC was dyno'ed at 635 HP with one 4 BBL and 820 with two. That would put it right there with the Hemi.

I guess they called them "musclecars" because they came with outrageous engines, crappy brakes, skinny tires, minimal creature comfort, and took muscles and a really big set of stones to drive one hard.

 

[john]

I just read on an internet site that the 427 SOHC was dyno'ed at 635 HP with one 4 BBL and 820 with two. That would put it right there with the Hemi.

I guess they called them "musclecars" because they came with outrageous engines, crappy brakes, skinny tires, minimal creature comfort, and took muscles and a really big set of stones to drive one hard.

What, no link?

Your right about the brakes and tires back then, they were bad.

 

[Gary H]

Somehow I dont believe them. Ever check out Pure Stock Muscle Car Drag Race™
Pure stock except for the gear ratio

Some of the ET's from 2005
http://www.geocities.com/psmcdr/2005-files/results.xls

 

["Dr. Dirt"]

Looks like my GM engines are at the bottom of the barrel?
I think I'll keep running them any way. You know, like the last decade + of Pro Stock Champions do.

 

[Johnny Mopar]

The GM engines that were successful in the past aren't that competitive these days. I'll take a Greg Anderson / Jason Line bullet over any other plant out there. No one has ever run quicker or faster than the Summit cars. Cagnazzi is a close second with the 'Jeep' engines of Roy Johnson next.

 

[BlueStangGT]

Looks like my GM engines are at the bottom of the barrel?
I think I'll keep running them any way. You know, like the last decade + of Pro Stock Champions do.

Only because the big Ford motor is "illegal".

 

["Dr. Dirt"]

BlueStang Okie Tom,
Were you never spanked as a child?

 

[stanman]

There are a whole lot of things that could be done within the guidelines noted for these motors that would have drastic impacts on inflating the horsepower that these motors made on the show.

For starters, the rotating assemblies on the original production motors weren't balanced very well, if at all.

Ignition, is another area where HP would be gained over original.

Next, you have to look at the carburetors. I'll bet if you tested A-B with an original production Holley or Quadrajet then bolted a new Holley or BG of the same CFM rating, the new carb would make gobs more power.

Valves and valve jobs... you can pick up 10-20 horsepower just in the valve job alone. And that doesn't include the flow characteristics of today's valves to the vintage pieces.

The dyno itself... there are "happy" dynos and dyno techniques that will skew the numbers.

There are a handful of other tricks that could be done to an original production motor that would increase the output but I think you guys get my point... that the recently tested numbers are probably bogus compared to what those motors would have produced on the dyno back in their day.

 

[afx421]

i saw that episode, all were pretty legit exept the hemi. WRINGER! LOL seriuosly 820 hp? come on. was it a s/s hemi? lol

 

[stanman]

The most legit way to determine original horsepower would be to go to the track test from Hot Rod magazine and other such publications. The 1/4 mile times and MPH's were well documented. Knowing the weight of the car and the track info, there are formulas that will give the true horsepower within a small margin of error.

 

[Johnny Mopar]

The most legit way to determine original horsepower would be to go to the track test from Hot Rod magazine and other such publications. The 1/4 mile times and MPH's were well documented. Knowing the weight of the car and the track info, there are formulas that will give the true horsepower within a small margin of error.

There are plenty of documented, untouched muscle cars out there. I'd suggest putting untouched cars on a rear wheel dyno and doing a couple quick pulls. This would eliminate any aftermarket modifications. They'll all be running original distributors, carbs and exhausts. I'd allow them fresh points, plugs, caps and wires. Otherwise they must be untouched motors.

If you need some Mopars I can supply you with every engine combination produced, in untouched condition.

Let's roll...