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In the 60,s the Hemi was rated at 425 Horsepower How many horsepower did it really have?
426 Hemi
- Thread starter jerseyguy357
- Start date
About 350 at the crank once you add an exhaust system, alternator, power steering, air cleaner, cooling fan, and water pump.
There are guys on YouTube that have dyo'd them. Iirc about 475 hp actual output according to the video I saw
Not in showroom form it’s not nonsense. Look at 1/4mi ETs and mph and do the calculations. See the times below from when the cars were new. For reference, my brother’s ’98 TA 6spd with only Nitto Drag Radials went 12.87@109, and my ‘09 G8 GT went 13.07@107 with only a Diablo Predator tune. Both of those cars were rated 350-360 SAE HP and easily weighed more than the 70’s Dodges. The day my G8 recorded that time it weighed 4179lbs on a certified scale with me and the baby seat in the back
For reference, documentation at the time put the 70 Charger R/T Hemi at 3610lbs curb weight. If anything from those numbers, 375HP stock was pretty typical for those things! Calculator says about 383HP for the fastest Dodge at 107mph…
And if you think a 6.3 0-60 paired with a 13.10@107 1/4 isn’t fishy as heck, I’ve got some oceanfront property in Kansas I’d like to show you.
From 0-60Times: 1968 Dodge Charger R/T 426 Hemi: 0-60 in 4.8 sec. Quarter mile ET 13.5 sec.
This is colaborated by a 1968 Car and Driver article that added that the trap speed was 105 mph and that the car weighed 4035 lbs.
The Wallace Racing ET Calculater back calculates 325 HP using the 13.5 ET. Using the trap speed of 105 mph the same calculation comes up with 384 HP. Of course the car had banana skin tires so would had a better ET and corresponding HP rating if it hooked up better. You can search the Car and Driver article. I don’t want to be dinged for copyright infraction.
This is colaborated by a 1968 Car and Driver article that added that the trap speed was 105 mph and that the car weighed 4035 lbs.
The Wallace Racing ET Calculater back calculates 325 HP using the 13.5 ET. Using the trap speed of 105 mph the same calculation comes up with 384 HP. Of course the car had banana skin tires so would had a better ET and corresponding HP rating if it hooked up better. You can search the Car and Driver article. I don’t want to be dinged for copyright infraction.
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The best my 1970 Chevy Nova SS ever turned was a 14.03 @ 103 MPH, (with the back seat and spare tire removed). And it was the 396/375 HP version, with the solid lifter cam, and a 4-Speed. It came from a factory with a 3:55 Positraction rear axle.
The only change I made was installing a Holly 850 double pumper, with mechanical secondaries. I believe it came with a Holly 780 and vacuum secondaries.
The 426 HEMI was rated at 425 HP, but in a Dodge Charger it was substantially heavier. So those posted times and speeds are pretty close.
The bottom line is that while these 60's big cubic inch muscle car engines were, and continue to be very popular, they pretty much sucked as far as power to cubic inch ratio.
Especially when compared to today's modern V-8's with fuel injection, computerized ignition, and lead free fuel. My Jeep Grand Cherokee with it's 360 HP, 5.7 HEMI and ZF 8-speed automatic, would have given my old Nova a good run for its money..... And in a much heavier vehicle. (Right around 4,700 pounds).
And when compared to the modern era high performance cars like the Dodge Demon, and this new 1,200+ HP Corvette they're going to be introducing, the older high performance V-8's are pretty much a bad joke in comparison. Several of these new high performance cars turn quarter mile times off the showroom floor, faster than the Pro Stockers turned back in the early 70's. (Mid to High 9's).
The only change I made was installing a Holly 850 double pumper, with mechanical secondaries. I believe it came with a Holly 780 and vacuum secondaries.
The 426 HEMI was rated at 425 HP, but in a Dodge Charger it was substantially heavier. So those posted times and speeds are pretty close.
The bottom line is that while these 60's big cubic inch muscle car engines were, and continue to be very popular, they pretty much sucked as far as power to cubic inch ratio.
Especially when compared to today's modern V-8's with fuel injection, computerized ignition, and lead free fuel. My Jeep Grand Cherokee with it's 360 HP, 5.7 HEMI and ZF 8-speed automatic, would have given my old Nova a good run for its money..... And in a much heavier vehicle. (Right around 4,700 pounds).
And when compared to the modern era high performance cars like the Dodge Demon, and this new 1,200+ HP Corvette they're going to be introducing, the older high performance V-8's are pretty much a bad joke in comparison. Several of these new high performance cars turn quarter mile times off the showroom floor, faster than the Pro Stockers turned back in the early 70's. (Mid to High 9's).
A couple guys I knew back then had 426 HEMI's, and they idled like a coffee can full of rocks. Especially when cold, and after a few hundred miles of city stop and go driving.
And the first thing they did, was take off those giant, black krinkle painted valve covers, and replace them with polished chrome one's. On a sunny day a woman could put her makeup on by just looking at them.
And the first thing they did, was take off those giant, black krinkle painted valve covers, and replace them with polished chrome one's. On a sunny day a woman could put her makeup on by just looking at them.
I remember when Bobby Isaac ran a 426 HEMI Charger Daytona at Talladega in 1970. He had several race laps over 200 MPH. And this was in a stock chassis.
I think Buddy Baker ran a similar car, (426 HEMI Charger Daytona), and had a practice lap over 200 MPH as well. Not long after NASCAR banned the high wings.
OVERKILL
$100 Site Donor 2021
Yeah, ET isn't a great predictor of power because it's so dependent on traction, but MPH is the tell, as MPH doesn't care about traction assuming you hook-up at some point.
Those sound like a reasonable range of numbers (in SAE NET) for a ~4,000lb car trapping 105.
A stock E39 M5 (395HP SAE NET) traps somewhere between 107 and 109 and is approximately the same weight.
My dad had Hemi's before I was born. He said when driving in the rain the spark plug tubes would fill with rain water and short out cylinders.
OVERKILL
$100 Site Donor 2021
Undressed engine dyno tests will always show higher numbers than SAE NET due to the lack of most accessories, intake plumbing, mufflers...etc. The stock 302HO heads, which were hot garbage, produced 306HP with a mild cam and intake on an engine dyno:
This was an engine that was rated for 225HP SAE NET.
I'll see if I can dig up a "more stock" example, I know one of the magazines ran one that was bone stock for a comparo and, not surprisingly, it made a lot more than 225HP on an engine dyno.
OVERKILL
$100 Site Donor 2021
Another video, here, right out of the junkyard, a stock 225HP 302HO with "worse than stock" manifolds on it and 35 year old valve springs made 251HP. Refresh the valve springs, put in a mild cam and intake/carb on it and it made 302HP.
and to think they were working on the A925 Hemi.....A DOHC Hemi....But NASCAR killed it by new engine rules....
OVERKILL
$100 Site Donor 2021
Yeah, they were not a great street engine for a myriad of reasons. Ford had similar issues with the 427 SOHC and the BOSS 429, which is why the "street" version of the BOSS 429 got quench areas added to the sides of the chambers to improve low speed drivability. As Chrysler found out, a hemispherical chamber is great when you have good airflow through the chamber (swirl effect) but is awful at low engine speeds.
Even the 392/6.4L, which benefits from modern chamber design and dual ignition still gives some "old hotrod" vibes on a cold start and they stumble and shake a bit for the first few seconds before cleaning up.
SammyChevelleTypeS3
$50 site donor 2023
Yes indeed, Dodge / Plymouth have been well known to fudge the Hp numbers as far back as the late 60s. Ford and GM pulled the same thing many times too.
SammyChevelleTypeS3
$50 site donor 2023
Dodge/Plymouth were certainly not the only auto maker to play around with Hp numbers for various reasons.
Dodge really told some fibs when it came to the listed Horses on the famous & wildly popular LA 340cui engine. Many folks at one time thought the "LA" had something to do with LA California. (I did too for the longest 
) I always had assumed it meant it either had originated or was produced in some California Mopar manufacturing facility. The nickname actually has something to do with the auto maker doing things in engineering/manufacturing it to lighten the engine weight.
One example was the 1970 LA 340cui engines that they famously listed as 270hp for Uncle Sam and the Insurance industry. It has been reported by many engine builders, dyno shops, long time Mopar employees, drag strips and race teams that an original factory prepped LA 340cui in 1970 put out near 340hp. In the Mopar world there are many other instances where the manufacturer had the Hp in sales literature always listed lower than real world ratings. FORD and of course GM did the same thing. Just not as famously well known as Dodge and Plymouth.
Dodge really told some fibs when it came to the listed Horses on the famous & wildly popular LA 340cui engine. Many folks at one time thought the "LA" had something to do with LA California.
(I did too for the longest ) I always had assumed it meant it either had originated or was produced in some California Mopar manufacturing facility. The nickname actually has something to do with the auto maker doing things in engineering/manufacturing it to lighten the engine weight.One example was the 1970 LA 340cui engines that they famously listed as 270hp for Uncle Sam and the Insurance industry. It has been reported by many engine builders, dyno shops, long time Mopar employees, drag strips and race teams that an original factory prepped LA 340cui in 1970 put out near 340hp. In the Mopar world there are many other instances where the manufacturer had the Hp in sales literature always listed lower than real world ratings. FORD and of course GM did the same thing. Just not as famously well known as Dodge and Plymouth.
