Real HP numbers

[Bad B-rad]

I just got done reading some old threads and one shocked me. I was not around when our cars were new, but have always read that the 426 Hemi and 340 for sure were putting out more real world horse power then the factory rating, due mostly to insurance. Well REB  said that the speed channel did a engine dyno test and rebuilt the engines to stock specs and got 820hp and 760tq from the 426 Hemi. That can't be true. Was that the RACE Hemi that they rebuilt and tested?
If the stock ratting of 425hp and 490 torque is wrong what is real number on the 426 street hemi,and the  LA 340?
Also on the same thread it said that car and driver 1/4 tests had the 440 six pack(in the 69  Roadrunner 12.91@111mph) beating the 426 Hemi (13.4@107mph 1970 Roadrunner)in the 1/4 mile.  Is this also true, and was that because the 69 RR was stick vs the 70RR Hemi's auto? Both had 4.10 rears.

[alfaitalia]

Experts will be along in a moment but I well say that a laughed out loud at the 820 horse power.......if it was anything like true those quarters would be way faster.

[Bad B-rad]

That's exactly what I said!!!!If it was a true 820 then its 1/4 mile would be lower.(unless it is smoking the skinny tires the whole 1320!!!!)

[crj1968]

820...no way.

I always remember reading  the 426 was around 470hp, and a 340 close to 300hp


...and the slant six pushes something like 1200

[Bad B-rad]

Is that Hp number for slant six net or gross readings?

In that same thread is says the 4bbl 383 is really putting out 280hp.
So numbers are all over the place. What to believe?

[Dino]

I don't believe any numbers until I can see proof. But whatever the numbers, they are sure fun engines to have at your disposal!

I always heard the 440 was quicker in the 1/4 but the 426 would soon catch up and leave the 440 behind in top end given a bit more room to travel.

[Bad B-rad]

I always heard the 440 was quicker in the 1/4 but the 426 would soon catch up and leave the 440 behind in top end given a bit more room to travel








I have had a ton of fun in my 383's over the years.

And I have also been told that by friends of mine that had both engines in cars in the 70's and early 80's. But they always said it was on the street the 440 was better it was the track were the Hemi was able to shine.
I would just be very interested to read or watch the results of the engines built to factory specs  putting out the real life numbers.
I would also like to see a comparison of 383/440/426 Hemi vs 5.7/6.1/6.4 Hemi in 1/4 mile with everything being equal. Same car, same weight, same transmission, same tires and so on.  The older cars no mater what the engines were putting out were at a disadvantage in power loss through the drivetrain and the tires vs modern MOPAR.

[crj1968]

The GLHS Omni pretty much kills them all in the 1/4 mile.

[Bad B-rad]

The GLHS Omni pretty much kills them all in the 1/4 mile.


A stock GLH Omni? beats a new 6.4 SRT8 in the 1/4?


I always wanted to turn a rampage into a drag car. Turn it into RWD and put a v10 in the bed of it for power.
Maybe an Omni should be the test body for slapping all the engines in to have a 1/4 mile shoot out.

[John_Kunkel]

The published numbers back then were probably correct for the rpm they rated them at. IOW, suppose the Hemi did have 425 HP at 5000 rpm but had a higher HP above 5000 rpm.

[Kern Dog]

The Mopar Performance 426 crate hemi was rated at 465HP. This was a crate engine built to stock 426 specs with slightly less compression.

[Bad B-rad]

The published numbers back then were probably correct for the rpm they rated them at. IOW, suppose the Hemi did have 425 HP at 5000 rpm but had a higher HP above 5000 rpm.

Ok so your saying that for the 426 Hemi they may say 425hp@4500rpm and 490tq@3900rpm,BUT those are NOT peak numbers as you would normally expect.
That yeah it was 425@4500rpm but it was still climbing and may be 500hp@5400rpm and 520hp@6000rpm and so on. And for what ever reason, insurance,or what not they just picked 425hp.

Does any one know of dyno tests done on dead on stock spec engines engines?

I am mainly wanting to see 426 Hemi, the 440,Magnum and 6bbl,383 Magnum and the 3406bbl. The 426Hemi and 340 six pack,are the two that I read about the most,that have the reputation for being under rated  by the factory.


The Mopar Performance 426 crate hemi was rated at 465HP. This was a crate engine built to stock 426 specs with slightly less compression.

I thought the heads,intake(one 4bbl carb vs 2X4bbls)and exhaust manifolds were different.(org cast iron manifolds vs the crate used headers)
Now I don't know any of that for a fact, I thought I read it once,as they were explaining the things that were not the same.
But even the crate engine isn't  820hp!

[500Jon]

Hi Folks,

I can believe quite easily that a trick 340 would make 400 horses back the the day!
Everyone has got a 400 horse 318's now, if you believe all the magazine articles...

800 horses for a 60's 426 hemi is a tall order indeed!
Think the guys running the Wingcars were working on 600hp in 1970.
If 800hp was 'on tap' then the Aerocars would never have been built.
The 69 C500 would have trounced the opposition with that much HP.

800hp smallblocks are very common in Nascar now, its 50 years on, you would expect that!

[c00nhunterjoe]

The race hemi was not what you bought at the dealer. I can see 700- 800 hp in the nascar engines, as they were nowhere near stock engines. The nhra stock and superstock classes today are over those numbers. The wedge motors cant touch them.

[odcics2]

A Nascar spec engine with 12.5 to 1 compression, a Racer Brown STX-24 cam with a 950 Dominator would put out an HONEST 575 HP.  That's what it took to get Baker over 200 in the #88 Daytona. This info is per Larry Rathgeb.

[Bad B-rad]

I understand getting those numbers on "worked or hot rod engines"I was curious about the numbers the engine put out as the car was delivered. You know bone stock, from the dealer to the dyno. I just read an article and they rebuilt a 383 to factory specs for a 383 Magnum the only difference being their test engine had 9.2to 1 compression vs factory 10 to 1. It had the stock cast iron intake and HP exhaust manifolds and stock carb. It churned out 335.2 hp, they tuned the stock carb a bit and tweeked the timing and got 338hp@5000rpm and 392torque at 3600rpm. So basically it is right as advertised.
The two Mopar engines I always read about having underrated HP numbers from the factory are the 426 Hemi and 340 Wedge, so those were the ones I was wondering about.

The article in which they rebuilt the 383 was from Hot Rod mag, Sept 1, 2002 some one here gave me the link.

[crj1968]

https://www.youtube.com/watch?v=k6Utw4E3jGM

[Bad B-rad]

Wow that was cool, there is also one video called  1970 stock 426 Hemi dyno. And I think the video says Mikes 1970 stock Hemi. That one is good. It was 452@5500rpm and 490torque@4000rpm. That's very close to factory rating!!!! What surprised the hell out of me was the torque that this thing was putting down the dyno results start at 3300rpm and its putting out 465ft lbs of torque. and it is hit's peak at 4K and even when it starts to come down it never "falls off" it comes down slow. So basically from 3300rpm till 5600rpm (what the dyno rpm has listed)it is pumping out over 420 ft lbs of torque. That's just awesome.

I guess the number Chrysler put out was right on the money about the 426 Hemi. People must have just been so impressed with the "Torque curve" and how fast this engine moved a car down the road, they the couldn't believe that it was "ONLY" putting out 425HP. So they assumed that the factory was lying.
That's just my 


Now we just got to find the 340, and maybe the 440 Magnum or six pack.
The 426Hemi's torque just shocked me, not its peak number, but how it steadily just churns out over 425ft lbs, that's crazy. I would love to see off idle to the 3300rpm,what the dyno didn't show. just to see when that power starts.

[c00nhunterjoe]

There was a nascar article years back where theg interviewed a chrysler nascar engineer. I recall something  to the tune of they tuned the cars to make the hp they needed for a race. Anywhere from 575 to over 600 depending on the day. There was plenty of potential left in them. The drag race guys will show you what a stock hemi is capable of.... just do some youtube searches.

All of the factory numbers in the 60s were "tweaked". As john said, they would choose what rpm to publish their hp numbers to and also rate their dyno numbers without any accessories like power steering pumps alternators and water pumps.

[odcics2]

....and last for 500 miles!

By 1970 the circle track race hemi was pretty much fully developed to get the most HP and last 500 miles doing it.
Most teams used a qualifying engine that was "tuned up" a bit more!   

[Mike DC]

    
Just to mention if you don't already know it -

The car magazine road tests back in the day were even less reliable than OEM engine horsepower numbers.  From the methods of recording the timing, to the driver skills, to the consistency & condition of the cars they were given . . . it's ALL too far off-the-map to be relevant by modern standards.  And the 1960s tires alone will slow down the takeoffs.  You could probably do better with cheapo tires from Walmart now.

[tan top]

 https://www.youtube.com/watch?v=8JfkpyzlGxw

[Bad B-rad]

https://www.youtube.com/watch?v=8JfkpyzlGxw

THANK YOU!!!!!!!!! That was the BEST CAR PORN I have seen in a long time.
6100-6200rpm with duel points,wow and no one would run that now they would be doing electronic ing. That was great, I need a cigarette!(and I don't smoke)

[c00nhunterjoe]

https://youtu.be/4TKfV9Bflt0

The race hemi was much more potent then the nascar hemi.

[odcics2]

Apples to oranges.  A 1/4 mile ain't much of a test!   Try 500 miles wide open!   
Same basic 426 engines, just tuned for different applications. 

I think the OP should buy a 340, build it stock and put it on a dyno.