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440 Factory HP/Torque Numbers Accurate?
#1157702
01/15/12 12:22 PM
01/15/12 12:22 PM
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
bobs66440
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Just wondering, because it says that a stock late 60's Magnum 440 engine was around 375hp and 480lb/ft. The motor I'm building is .030 440, summit 6401 cam, 9.2:1 (low side, I know), Stealth heads, Eddy dual quad dual plane (1000cfm), Hedman 1-3/4 shortys. I typed that all into my desktop dyno and it estimates 423hp@5000rpm and 480lb/ft@4000. I would think that it would be better than stock but it's not much. Are my numbers low or are the factory numbers high? 
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Re: 440 Factory HP/Torque Numbers Accurate?
[Re: bobs66440]
#1157707
01/15/12 03:56 PM
01/15/12 03:56 PM
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Joined: Feb 2005
Posts: 4,318
Prospect, PA
BSB67
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Years and years ago, before I built my first high performance/stock exhaust manifold car, I researched historic magazine articles for 440 dragstrip performance data. There are fairly well established empirical formula that will convert weight w/ mph data to net actual flywheel hp. Going by memory, the number was like 270 hp. But, net actual flywheel is not what you get on a dyno session, it is gross standardized flywheel hp. Again, there is some general rules to go from net actual to gross standard, however, there are a lot of info needed on the specific variables to make that relationship accurate. However, my conclusion was that the factory 440 hp engines were probably in the 300 to 320 range, with the 6 pack engines being about 25 hp higher.
Super Stock mag. did a test on an A12 car. Rumor was that it had the heads off for a competion valve grind, maybe head milling, and a chassis dyno super tune. It was a 4 spd car, with someone like Landy or Sox behind the wheel, and the car went 111 mph. This calculated out to be an honest net actual flywheel hp of 390, probably 430 "gross standard" that everyone uses. This test was the only one that mattered to me at the time as it indicated the 440 potential.
Also, Chrysler estimated the factory 440 at 315hp in there drag strip dyno literature.
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Re: 440 Factory HP/Torque Numbers Accurate?
[Re: BSB67]
#1157708
01/15/12 04:58 PM
01/15/12 04:58 PM
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Joined: Jun 2008
Posts: 3,916
usa
lewtot184
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the direct connection/mopar performance engine manuals give an estimated horsepower for a 440 4bbl (this probably includes 8:1 and 10:1 engines) at 270-330hp. when you tell somebody their "375hp" engine only makes 300hp it usually creates a "heated discussion". my '69 r/t ran a best of 14.01@99mph with a truly stock (exhaust, gearing, carb, everything) 375hp 440. that ain't 375 horsepower. the engine manuals give an estimated 340-370hp for factory 6-paks, and i think thats pretty close for truly stock engines.
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Re: 440 Factory HP/Torque Numbers Accurate?
[Re: bobs66440]
#1157711
01/16/12 04:06 AM
01/16/12 04:06 AM
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Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar
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Quote:
Just wondering, because it says that a stock late 60's Magnum 440 engine was around 375hp and 480lb/ft.
The motor I'm building is .030 440, summit 6401 cam, 9.2:1 (low side, I know), Stealth heads, Eddy dual quad dual plane (1000cfm), Hedman 1-3/4 shortys.
I typed that all into my desktop dyno and it estimates [Email]423hp@5000rpm[/Email] and 480lb/ft@4000. I would think that it would be better than stock but it's not much.
Are my numbers low or are the factory numbers high?
I ran that combination in the DynoSim 5 software and it is showing 475 HP @ 5,600 RPM, and 489 ft/lbs @ 4,600? Torque curve looks really good, 381 ft/lbs @ 1,000. I had to guess at the intake and exhaust runner lengths, but changing them only makes small changes in the power curve.
Used OOB Stealth Flow numbers (261cfm @ 0.500".)
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Re: 440 Factory HP/Torque Numbers Accurate?
[Re: 451Mopar]
#1157712
01/16/12 09:37 AM
01/16/12 09:37 AM
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
bobs66440
OP
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OP
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Quote:
Quote:
Just wondering, because it says that a stock late 60's Magnum 440 engine was around 375hp and 480lb/ft.
The motor I'm building is .030 440, summit 6401 cam, 9.2:1 (low side, I know), Stealth heads, Eddy dual quad dual plane (1000cfm), Hedman 1-3/4 shortys.
I typed that all into my desktop dyno and it estimates [Email]423hp@5000rpm[/Email] and 480lb/ft@4000. I would think that it would be better than stock but it's not much.
Are my numbers low or are the factory numbers high?
I ran that combination in the DynoSim 5 software and it is showing 475 HP @ 5,600 RPM, and 489 ft/lbs @ 4,600? Torque curve looks really good, 381 ft/lbs @ 1,000. I had to guess at the intake and exhaust runner lengths, but changing them only makes small changes in the power curve.
Used OOB Stealth Flow numbers (261cfm @ 0.500".)
Hmm, interesting. It was my first shot at the dyno. I was fumbling through it and may not have gotten all the numbers right. I have the spec card for the cam but the program was asking for data that wasn't on there. I'm sure yours is accurate, it would make more sense. Can you capture a screen shot and post it? It would be interesting to see. Thanks!
Did you input all the cam info manually or do they have a model for that one?
Here are the head specs from their site. Does it match the OOB model?
Intake Port Flow (at peak ~600 lift): 290CFM @ 28" of water
Intake Port CC: 212CC*
Intake Valve Head Size: 2.14"
Exhaust Port Flow (at peak ~600 lift): 220CFM @ 28" of water
Exhaust Port CC: 72CC*
Exhaust Valve Head Size: 1.81"
Chamber Volume: 80CC*
Thanks! 
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Re: 440 Factory HP/Torque Numbers Accurate?
[Re: ademon]
#1157713
01/16/12 11:31 AM
01/16/12 11:31 AM
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Joined: Jun 2008
Posts: 3,916
usa
lewtot184
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Quote:
the 383 was very close to the true 335hp rating, but i think the 375 for the 440 was a bit high.
they actually were around 280-285hp. last nite i was thumbing thru an october '67 hot rod mag and there was a dyno test article on a 383. this might have been a 325hp engine but the best stock hp was around 278. the engine manuals have an estimated horsepower for 4bbl 383's at 260-280hp. all the big blocks were overated. the only engine that made the advertised numbers was the 340. hemi's were even a little short.
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Re: 440 Factory HP/Torque Numbers Accurate?
[Re: lewtot184]
#1157714
01/16/12 12:58 PM
01/16/12 12:58 PM
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Anonymous
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Anonymous
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Quote:
Quote:
the 383 was very close to the true 335hp rating, but i think the 375 for the 440 was a bit high.
they actually were around 280-285hp. last nite i was thumbing thru an october '67 hot rod mag and there was a dyno test article on a 383. this might have been a 325hp engine but the best stock hp was around 278. the engine manuals have an estimated horsepower for 4bbl 383's at 260-280hp. all the big blocks were overated. the only engine that made the advertised numbers was the 340. hemi's were even a little short.
Yeah, that was a 67 engine, so was the pre-Road Runner 383 4-barrel engine. Road Runner 383 had better intake, heads, cam and exhaust, so would have been stronger - how much I'm not sure.
But what this HRM dyno test does show is that when the 383 4-barrel was put in A bodies in 67, they didn't really lose 45 horsepower, they just got a more honest power rating. As 340's did from the git-go. Why? Darned if I know.
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Re: 440 Factory HP/Torque Numbers Accurate?
#1157715
01/16/12 02:06 PM
01/16/12 02:06 PM
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Joined: Jun 2008
Posts: 3,916
usa
lewtot184
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Quote:
Quote:
Quote:
the 383 was very close to the true 335hp rating, but i think the 375 for the 440 was a bit high.
they actually were around 280-285hp. last nite i was thumbing thru an october '67 hot rod mag and there was a dyno test article on a 383. this might have been a 325hp engine but the best stock hp was around 278. the engine manuals have an estimated horsepower for 4bbl 383's at 260-280hp. all the big blocks were overated. the only engine that made the advertised numbers was the 340. hemi's were even a little short.
Yeah, that was a 67 engine, so was the pre-Road Runner 383 4-barrel engine. Road Runner 383 had better intake, heads, cam and exhaust, so would have been stronger - how much I'm not sure.
But what this HRM dyno test does show is that when the 383 4-barrel was put in A bodies in 67, they didn't really lose 45 horsepower, they just got a more honest power rating. As 340's did from the git-go. Why? Darned if I know.
the test 383 in the mag was a 67 so it had 915 heads. when a set of 1.74 exhaust valve heads were installed it only gained 4hp. these engines were just grossly over rated. the 383-280hp rating in the a-bodies was probably accurate. i don't remember them running much, if any, better than a 275hp 340. i estimate my 68 383 road runner was about 285hp with a good factory tune-up. 14.20's@ 96-98mph was the best it would do in factory trim.
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Re: 440 Factory HP/Torque Numbers Accurate?
[Re: lewtot184]
#1157716
01/16/12 02:41 PM
01/16/12 02:41 PM
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
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IL, Aurora
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Quote:
Quote:
Quote:
Quote:
the 383 was very close to the true 335hp rating, but i think the 375 for the 440 was a bit high.
they actually were around 280-285hp. last nite i was thumbing thru an october '67 hot rod mag and there was a dyno test article on a 383. this might have been a 325hp engine but the best stock hp was around 278. the engine manuals have an estimated horsepower for 4bbl 383's at 260-280hp. all the big blocks were overated. the only engine that made the advertised numbers was the 340. hemi's were even a little short.
Yeah, that was a 67 engine, so was the pre-Road Runner 383 4-barrel engine. Road Runner 383 had better intake, heads, cam and exhaust, so would have been stronger - how much I'm not sure.
But what this HRM dyno test does show is that when the 383 4-barrel was put in A bodies in 67, they didn't really lose 45 horsepower, they just got a more honest power rating. As 340's did from the git-go. Why? Darned if I know.
the test 383 in the mag was a 67 so it had 915 heads. when a set of 1.74 exhaust valve heads were installed it only gained 4hp. these engines were just grossly over rated. the 383-280hp rating in the a-bodies was probably accurate. i don't remember them running much, if any, better than a 275hp 340. i estimate my 68 383 road runner was about 285hp with a good factory tune-up. 14.20's@ 96-98mph was the best it would do in factory trim.
the 67 383 had 516 heads that had poor ports compared to the 67 915 heads which only came in 440's the low performance 440's had the 1.60 exh valve and the hi po 440's had the 1.74 valve. Bolting on a set of 915's even with the small valve would be a boost in performance over a 516 head on a 383, the bigger exh valve on a stock 383 is not going to make a huge difference, i took off my 906 heads and bolted on a set of small valve 915's on my 383hp and it picked up a bunch!!
Last edited by ademon; 01/16/12 02:45 PM.
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Re: 440 Factory HP/Torque Numbers Accurate?
[Re: ademon]
#1157717
01/16/12 03:43 PM
01/16/12 03:43 PM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Mopar Muscle also did a 383 and a 340 built all stock and dynoed. The 383 was a 906 headed 10.0 comp using the 69 Roadrunner cam and it actually made 338 hp. The 340 made 274 with a very lean Original Carter carb. They changed the carb to a newer Eddy carb and it made 319 hp all stock.
One other thing to remember is that if most of the stock engines back then were actually at the advertised comp ratio they may have made more hp as just about all of them came thru lower then advertised. Most 10.0 440's were more like 9.0 as most were about 1 comp point low. Ron
Last edited by 383man; 01/16/12 03:45 PM.
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Re: 440 Factory HP/Torque Numbers Accurate?
[Re: 383man]
#1157718
01/16/12 03:58 PM
01/16/12 03:58 PM
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
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Quote:
Mopar Muscle also did a 383 and a 340 built all stock and dynoed. The 383 was a 906 headed 10.0 comp using the 69 Roadrunner cam and it actually made 338 hp. The 340 made 274 with a very lean Original Carter carb. They changed the carb to a newer Eddy carb and it made 319 hp all stock.
One other thing to remember is that if most of the stock engines back then were actually at the advertised comp ratio they may have made more hp as just about all of them came thru lower then advertised. Most 10.0 440's were more like 9.0 as most were about 1 comp point low. Ron
Also the 71 340 was probably just a bit (maybe 3 to 5 hp) stronger than the 70 and earlier do to the better intake and t-quad carb. only exception might be the earlier 340's with the manual trans cams.
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Re: 440 Factory HP/Torque Numbers Accurate?
[Re: ademon]
#1157720
01/16/12 05:58 PM
01/16/12 05:58 PM
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Joined: Jun 2008
Posts: 3,916
usa
lewtot184
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Quote:
Quote:
Quote:
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Quote:
the 383 was very close to the true 335hp rating, but i think the 375 for the 440 was a bit high.
they actually were around 280-285hp. last nite i was thumbing thru an october '67 hot rod mag and there was a dyno test article on a 383. this might have been a 325hp engine but the best stock hp was around 278. the engine manuals have an estimated horsepower for 4bbl 383's at 260-280hp. all the big blocks were overated. the only engine that made the advertised numbers was the 340. hemi's were even a little short.
Yeah, that was a 67 engine, so was the pre-Road Runner 383 4-barrel engine. Road Runner 383 had better intake, heads, cam and exhaust, so would have been stronger - how much I'm not sure.
But what this HRM dyno test does show is that when the 383 4-barrel was put in A bodies in 67, they didn't really lose 45 horsepower, they just got a more honest power rating. As 340's did from the git-go. Why? Darned if I know.
the test 383 in the mag was a 67 so it had 915 heads. when a set of 1.74 exhaust valve heads were installed it only gained 4hp. these engines were just grossly over rated. the 383-280hp rating in the a-bodies was probably accurate. i don't remember them running much, if any, better than a 275hp 340. i estimate my 68 383 road runner was about 285hp with a good factory tune-up. 14.20's@ 96-98mph was the best it would do in factory trim.
the 67 383 had 516 heads that had poor ports compared to the 67 915 heads which only came in 440's the low performance 440's had the 1.60 exh valve and the hi po 440's had the 1.74 valve. Bolting on a set of 915's even with the small valve would be a boost in performance over a 516 head on a 383, the bigger exh valve on a stock 383 is not going to make a huge difference, i took off my 906 heads and bolted on a set of small valve 915's on my 383hp and it picked up a bunch!!
the test article did a switch to "440 heads"; only gained 4hp. folks i just ain't a believer on factory or magazine horsepower numbers.
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Re: 440 Factory HP/Torque Numbers Accurate?
[Re: lewtot184]
#1157721
01/16/12 06:02 PM
01/16/12 06:02 PM
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Joined: Jan 2003
Posts: 75,082
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,082
U.S.S.A.
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Quote:
folks i just ain't a believer on factory or magazine horsepower numbers.
ding ding ding .... WINNER
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