Actual HP numbers from vintage Mopar engines.

[Dibbons]

(Times are from MSP tests.)

I don't know what is meant by "MSP test"?

 

[Dibbons]

Dodge St. Regis patrol vehicle per Allpar:

 

[Don Frelier]

I had both an 1984 Gran Fury and an 1985 Dodge Diplomat both with 318-2bbls.
I was having trouble with the 85 turned out to be a plugging fuel sending unit sock. (Which you will not find in the FSM by the way)
But in the process I stuck in a vacuum advance distributor and an old mopar electronic ignition ECU.
It went from being OK on power to spinning the tires much more lively.

 

[33 IMP]

I don't know what is meant by "MSP test"?

Michigan State Police.

 

[BSB67]

Roger Huntington was a famous auto writer/tester from the sixties and seventies who did testing on the muscle cars of the day, using a fifth wheel I believe. He was sure many of the muscle cars of the day were under rated by rating their horsepower at a lower rpm than actual peak. His list of top 10 underrated were all bigblocks but he did have a number for 340 4bbl.
340 factory 275 @5000
Real 320 @ 5600
Unfortunately he didn't test the 340 sixpack.
Below are excerpts from his top ten list, rated first, then his calculated. ( the whole list is posted on fabo under the title " real horsepower of muscle cars" from 2010)
#8 440 magnum 375 @4600, 410 @5400
#4 440 6 pack 390 @ 4700, 430 @5600
#2 hemi 425 @5000, 470 @6000.
Number one was the L88/ZL1 (big surprise) and the list included just about every hipo big block from the big three.
To me, the most comical was the 390/428 cj from ford. The 390 was a complete dog, rated at 335hp, ruined by 396 chevelles, and destroyed by roadrunners. But the 428cj was rated at the exact same 335hp, and was very competitive with any but the very top tier of muscle car.

That's interesting. Magazine track test results from back in the day show the opposite.

 

[Hubbarocks]

 

[oldbee]

That's interesting. Magazine track test results from back in the day show the opposite.

Trying to lower car insurance rates! Quid pro quo.

 

[69SportSatellite]

It made 338HP
But only 394 Torque?
Down from claimed 420ft lbs, I wonder why?

Given the importance of torque in a street driven car, I too wonder why these factory-spec rebuilds are always a bit low - marketing I guess.

So what is the best way to maintain or improve on the factory HP of a 383 4V yet still add low-end torque -- using the stock HP manifolds?

Cam and head selection I can see...would a roller cam be better for this - any benefit to EFI?

So many articles are written about how to get lots of HP out of our motors, but for many of us, low-end torque and driveability would be great. Maybe just make a 438 out of a 383?

 

[Bad B-rad]

So with the hot rod mag test dyno tests, the Roger Huntington tests, and the Steve Magnante 340 tests data
We know the 383 RR/Magnum is rated correct at 335HP
The Hemi is rated correct for RPM, but UNDER RATED and can produce 465-500hp @6,000
The 340HP4bbl is under rated and makes 320HP
The 340 6Bbl 356HP@5,500 and 382tq@4000rpm
The 440 Magnum is VERY close to rated HP, coming in at 360HP(but with headers and a larger carb it makes 420HP)
Info sourced from
440:
https://www.hotrod.com/articles/mop...et,four barrels at a more conservative 330 hp.


383:
https://www.hotrod.com/articles/mopp-0209-383-engine-restore/

340-4bbl/340-6bbl
https://www.hotrod.com/articles/bad-mopars-340-beat-ford-chevy-shocking-new-data/

 

[Bad B-rad]

69SportSatellite,
If looking to add torque,
I would say a set of nice (hooker super comps) Headers ALWAYS adds torque, toss in a "H" or "X" pipe balance tube and some flowmasters, and that will almost always add 15-25 ft lbs.(on big block Mopar, vs factory manifolds)
A lot of guys go big(too big) on the camshaft to gain HP up high, but give up the torque down low.
I would think the the Magnum/Roadrunner cam, or a modern version of that along with a nice DUEL Plane intake. The edelbrock performer RPM, is VERY HARD to beat, it makes nice torque AND HP, as it is a high rise duel plane.

The EFI is so efficient, again hard to beat, as it is reading O2 sensors and constantly adjusting to the perfect AFR.
But you can do just fine with a carb, as long as tuned correctly.

 

[Nate S]

Actually, I don't think so. I think this, like other formula that I know more about, are net-actual flywheel hp (verses gross-corrected flywheel hp from an engine dyno). Net actual can look a lot like RWHP, depending on several factors.

I think you’re right. It’s net actual flywheel that goes on the spec sheet these days. The method uses actual RWHP of course but the calc gives the other.

 

[Kern Dog]

But why would anyone OVERRATE?

I see it as a marketing ploy. I've noticed that Ma Mopar usually ended their ratings in a 0 or a 5 most of the time: 230, 235, 275, 290, 300, 330, 335, 350, 375, 390, 425.
Ford didn't. Their engines often had a variety of HP numbers.
Also......
I want to congratulate the OP.
You have only been here a short time but you have been a great contributor to this forum. I like your style and your enthusiasm.

 

[coronet68mx]

What is interesting is the 318 and 340, in chart #1 318 goes from 230 to 150, 340 is 275 to 250.
But on clayton chassis dyno, the 318 is 85RWHP, and the 340 is ONLY 90RWHP??
Once again that magical 5hp number pops up, LOL.


Could exhaust manifolds, strangle the 318 that much vs the 340?

The Mexican version of the 318 according to the bill of my car is 270 hp, as far as I know they use here 340 cilynder heads, forge crankshaft, and a four barrel carburetor, only for reference of course.

 

[BSB67]

So with the hot rod mag test dyno tests, the Roger Huntington tests, and the Steve Magnante 340 tests data
We know the 383 RR/Magnum is rated correct at 335HP
The Hemi is rated correct for RPM, but UNDER RATED and can produce 465-500hp @6,000
The 340HP4bbl is under rated and makes 320HP
The 340 6Bbl 356HP@5,500 and 382tq@4000rpm
The 440 Magnum is VERY close to rated HP, coming in at 360HP(but with headers and a larger carb it makes 420HP)
Info sourced from
440:
https://www.hotrod.com/articles/mopp-0104-buildup-1969-440-magnum-engine/#:~:text=Further in the Chrysler performance literature, the "Bracket,four barrels at a more conservative 330 hp.


383:
https://www.hotrod.com/articles/mopp-0209-383-engine-restore/

340-4bbl/340-6bbl
https://www.hotrod.com/articles/bad-mopars-340-beat-ford-chevy-shocking-new-data/

You're certainly entitled to choose to believe what you like. There are well established relationships between car weight and trap speed mph. The HP numbers stated simply don't line up with the cars weight and trap speed. Long ago I dug up probably 15 historic track tests and compiled the data in a spread sheet. The HP numbers from that were way lower than advertised.

Also, it looks like you're not interested in what Chrysler said the real HP numbers were from their engines from the factory. It's in their Chassis or Engine manual.

500 HP hemi don't run 105 mph in the 1/4 mi. and a 370 HP 440 don't run 98 mph.

 

[Bad B-rad]

You're certainly entitled to choose to believe what you like. There are well established relationships between car weight and trap speed mph. The HP numbers stated simply don't line up with the cars weight and trap speed. Long ago I dug up probably 15 historic track tests and compiled the data in a spread sheet. The HP numbers from that were way lower than advertised.

Also, it looks like you're not interested in what Chrysler said the real HP numbers were from their engines from the factory. It's in their Chassis or Engine manual.

500 HP hemi don't run 105 mph in the 1/4 mi. and a 370 HP 440 don't run 98 mph.

They were running those tests on bias ply tires, put on a set of radials bet times improve.

 

[Bad B-rad]

Spinning ain't winning.

I have time slips and photos to prove my 66 Charger with a stock 67 383 2bbl, with a 4bbl intake and carb runs 14.2 @99mph.
Thats the 290HP 1967 383, stock 67 heads, stock 67 cam, I bolted on a 4bbl intake, stock 1967 2bbl converter and 727, and 3.23 rear.
So how can I run same speed 98mph as a 440, with the 383?

I posted links to actual dyno tests, to back up the conclusions I have found.

EDIT383 also had electronic ignition with the "chrome" mopar box, instead of points.)
1967 Charger 426 HEMI auto 3.23 1/4 mile:14.2 @ 96mph.
How can my 2bbl 383 put down same ET, and MORE MPH??? and the calculator be correct?

 

[Bad B-rad]

I also used info in Mopar chassis and engine manuals, and in some cases it is a touch different then actual factory rated HP. That is why its hard to know WHAT to believe

 

[Bad B-rad]

AND yes I even (used) to rock a few gen1 Neons, LOL.
I would enjoy a 2door 5 speed Neon again, fun cars, that get GREAT MPG!!!!
I know they are kind of girly, but mine were PH BALLENCED for a MAN!!!

 

[BSB67]

They were running those tests on bias ply tires, put on a set of radials bet times improve.

Who said anything about times?

Tires and spinning have nothing to do with trap speed. That is why mph used, not et.

 

[Bad B-rad]

The HP calculator is just a tool, it is not 100% accurate, tons of variables,
look below:
SUPER STOCK MAGAZINE 6/69
1969 ROAD RUNNER 440 SIX PACK
ENGINE: 390 HORSEPOWER 440 SIX-PACK
AS TESTED : 4 SPEED TRANSMISSION AND 4.10 REAR
1/4 : 12.91 @ 111.8

CAR CRAFT 11/69
1970 HEMI 'CUDA
ENGINE : 425 HP 426 HEMI 2x4 BARREL
AS TESTED : 4 SPEED TRANSMISSION AND 3.54 REAR
1/4 : 13.10 @ 107

Now by those numbers the 440 Bee must have more HP then the 426 Hemi?
The Cuda is lighter, then the Bee correct?
So how can a lighter car with more power be slower?
Well easy, the out side temp, the rear end gear, the altitude, way to many variables, to get a 100% accurate data to make the HP calculator correct, can it get you close, yeah.
(all on bias ply, and some maybe ringers,LOL)

SUPER STOCK MAGAZINE 12/69
1970 ROAD RUNNER 426 HEMI
ENGINE: 426 HEMII 2x4bbl
TORQUEFLIGHT TRANSMISSION AND 4.10 REAR
1/4: 13.34 @ 107.5MPH

HOT ROD MAGAZINE 2/69
1969 CHARGER 500
ENGINE / 425 HORSEPOWER 426 HEMI 2x4 BARREL
AS TESTED / 4 SPEED TRANSMISSION AND 4.10 REAR
1/4: 13.48 @ 109MPH