Dyno number guesstimates wanted

[66FBCharger]

Now a days, it is fairly easy to find a larger car show/swap meet with a chassis dyno setup. Is there a percentage of approx. how much lower the HP and Torque numbers would be vs. the numbers obtained from running the same engine on an engine dyno?
How would the numbers from the engine dyno compare to the factory advertised numbers?
Hypothetically, if you could build a '70 440 Six Barrel as close to factory as possible with the advertised comp. ratio, cam timing, etc., what kind of HP and torque would you expect to see?

[metcoll]

around 250 hp & 310tq to the wheels on a dynojet through a torqueflite

[68charger440]

That seems very low... The 70 440 6 pack was advertised at 390 hp.  Take away 20% and you are still over 310 hp.  ...and the advertised torque was 490.

[Challenger340]

around 250 hp & 310tq to the wheels on a dynojet through a torqueflite

That does seem low ?

We restored a '70 440-6 pack W/minor upgrades... Engine Dyno'd at 435 hp and 504 ft/lbs
the owner later rear wheeled after install for sh*ts and giggles,
I'd have to conform...
but I believe he told me 33? hp or so ? I forget the Trq.

[68charger440]

That sounds more like it!  Those other numbers must have come from someone wearing a bowtie!

[heyoldguy]

I ran 928 HP on an SuperFlow engine dyno and 696 HP on a DynoJet through a 4-speed in a national dyno contest. You can't race dynos and you can't race flowbenches, everyone is different.

I ran on a chassis dyno and made 616 HP. Should have been more so I told the operator to load the dyno more..........656 HP. You can wind an engine to 7000 rpm in neutral and with no load it won't make any horsepower, but put it in gear, load it and the power comes.

[68charger440]

I have seen a few dyno sheets on 440 6 packs and while they can vary for sure, 250 hp is way off base, so i'm not buying unless something is seriously wrong with the build/tune or dyno/operator.

[RECHRGD]

I don't remember where I read this, but years ago some magazine stated that a bone stock 440 4 barrel (375hp) would put down around 265 to 280 at the wheels.  Given that, the six pack would be slightly higher.  My original build was slightly warmed up with headers and a Holley 750.  It put down only 270 or so.  Seems about right, as the slugs were down in the hole a bit.  My last chassis Dyno, after modifications, came in around 335rwhp.  So I'm, at least over 400 gross hp, I guess....

[Brass]

In theory, you can expect a loss of somewhere around 25% on a chassis dyno.  But it seems to me the real-world numbers can be all over the map.  The type of dyno, who is operating it, etc. all play a role in what the output reads.  Arguably, the best use of a chassis dyno is for tuning purposes.  Establish a baseline and go from there using the same dyno and the same tech.

[BSB67]

How would the numbers from the engine dyno compare to the factory advertised numbers?
Hypothetically, if you could build a '70 440 Six Barrel as close to factory as possible with the advertised comp. ratio, cam timing, etc., what kind of HP and torque would you expect to see?

These things are always fun to discuss.  So, here is my 2 cents, that is reasonably supported.  The factory 440 6 pac was factory rated at 390 hp, but was actually about 350 (from memory, these are Ma Mopar's numbers, not mine, but well supported but track testing results.  I can check when I get back home).  My personal observation of a hand full of 440 B Body automatic cars dyno'ed on both engine and chassis dynos is pretty close to 20% +/- about 2 % for drive train loss.  That would put the chassis hp numbers for a factory 440 6 pac around 280 hp.

[ws23rt]

These things are fun to discuss.
Even though torque and horsepower can be calculated-- measuring it tells the tale.
I do recall the at the wheel numbers for a 440 6bl. from many years ago as being around 260+ hp. It wasn't spoken of much then because it didn't sound good in bragging conversations.

[1974dodgecharger]

That seems very low... The 70 440 6 pack was advertised at 390 hp.  Take away 20% and you are still over 310 hp.  ...and the advertised torque was 490.

for manual sure 20% on a perfect build everything the whole driveline working  perfectly....autos lose even more on the car due to torque converter etc....they lose nearly 30 to 35%...I rebuilt my whole driveline and im NO expert by any means and have a loss of 25% or so.....mine is a manual.

Like I said before our cars are not MONSTERS as what people put them out to be...a lot of the modern tech V6 stuff beats our cars....we make up for things in the torque division which modern cars with same HP don't have.  People always think my car is something like 800HP I always tell the truth no just 500HP and they always respond with a  odd look, 'oh' 

[ws23rt]

That seems very low... The 70 440 6 pack was advertised at 390 hp.  Take away 20% and you are still over 310 hp.  ...and the advertised torque was 490.

for manual sure 20% on a perfect build everything the whole driveline working  perfectly....autos lose even more on the car due to torque converter etc....they lose nearly 30 to 35%...I rebuilt my whole driveline and im NO expert by any means and have a loss of 25% or so.....mine is a manual.

Like I said before our cars are not MONSTERS as what people put them out to be...a lot of the modern tech V6 stuff beats our cars....we make up for things in the torque division which modern cars with same HP don't have.  People always think my car is something like 800HP I always tell the truth no just 500HP and they always respond with a  odd look, 'oh'  

I'm glad you brought up torque.  This is what we feel when we drive but when we talk it's always hp.
The little cars feel like big ones because it takes less torque to kick them to speed.
Torque is what we feel. Horsepower is what burns up more fuel to keep the big ones at speed. Transmission gears and rear end gears are just torque multipliers.

I see no soon change in the way we speak about the measure of how our engines perform. We are stuck--- kinda/sorta like water boils at 212 deg. and not 100 deg.

[68charger440]

I guess I always bought into the line from back in the day where they used to say that the HP numbers were understated for insurance purposes.  I guess maybe that was just marketing bull.

[1974dodgecharger]

I guess I always bought into the line from back in the day where they used to say that the HP numbers were understated for insurance purposes.  I guess maybe that was just marketing bull.

some of it was true and most was not...same with the hellcat engine people say dodge downplayed it, but in the end its marketing for dodge and they are winning because of it...you think insurance companies care when dodge saids 707 vs 721hp...no matter how you slice its, its in the 700HP terrirority.

A original HEMI 426 probably put out best 450Hp stock form add some mods to it from customer 500HP add in drive train loss...and you have your number.

[68charger440]

I also had no idea the loss could go as high as 35%.  I was thinking even with an auto you wouldn't get above 30, but that was not from any experience, just hearsay.  Just goes to show that if a lie is told often enough it is accepted as truth.

[ws23rt]

35% loss does seem on the high side. With a high output engine that translates to a lot of energy/heat. --Trans. coolers were added to some cars but aside that???

[1974dodgecharger]

for some examples this is an auto 800HP, but puts down 500Hp to wheels....HP is only part of the story here folks your forgetting TORQUE!!!
https://youtu.be/h2NLbuZyv4E?list=PLaAWXLtSQ0fvawE6ofRI9fPqY0C4Hapwp


440 built by muscle motors a well known company 262HP to wheels and that folks is REALITY you can fudge the dyno a bit, carrese the motor a tad and lets say 300HP for street talk.
https://youtu.be/gn6QkfCBu7A?list=PLaAWXLtSQ0fs3QWJEI6bO4xOghBrPcSvE


I seen many others also like this on the dyno....YES the 727 is a great tranny, but it does not compare to modern trannys that are way more efficient.  They say the hellcat tranny manual is only 15% loss.....

My engine is 500HP/515TQ and on the dyno I put down 383HP/393TQ that was my best with a bad carb...when I mean bad it was BAD no rebuild would of saved it unless I got a new bottom plate among other things new bowls, etc..mind as well buy a new carb right  

why do you guys think people are scared of dynos....they don't want to know the reality of their, 'HP FEELINGS' driving  car...

In the end its just a number folks just get out there and enjoy your cars who cares if people make fun of you for low power ratings etc....

I get mocked of my car daily and don't give 2 craps for it......my car my choice  

have to throw mine in there with a leaky valve cover so a lot of smoke:
https://youtu.be/adApvKUbcUU

[c00nhunterjoe]

Like heyoldguy said, you can change the dyno to move the power. Give me 1/4 mile trap speed, air density and a calculator anyday before i would get on a dyno.

[BSB67]

Man, like I said, these things are fun to discuss, and did I mention entertaining.

If you have more that 25% drivetrain loss, you have a drive train problem or one of your the two dyno results is BS.

15% loss is quite common for even a 50 year old manual trannys, including the 833.  No special magic going on with the Hellcat. Well maybe there is, but it is offset buy the additional power robbers in that tranny.

For all you guys that want torque, I'd gladly trade you some of mine for some of your horse power.

Oh, and I did check what Ma Mopar claimed as actual 440 Six Pac power.......350 hp.

[Brass]

Deleted - off topic.

[BSB67]

Deleted - off topic.

Why?  I actually thought it was on topic and made a point. 

[SRT-440]

The 727 will murder output..it's killing my 6.1..I bet I'm losing 40-50hp to the wheels running a 727 with a 3000 stall. The first chance I get I'm dumping it for a modern trans..even if it's a *gasp* a 4L80E.

But, from what I've seen, 260-290 rwhp is what even warmed up 440's are laying down..start tweaking and add a little compression and it goes up fast.
Torque is what gives it the umph..mopars have lots of torque. 

Anyone, have any data on a stock 440 on a engine dyno?

[justcruisin]

I have a magazine around somewhere that dates back 20+ years, it covered a rebuilt on an untouched 440 magnum. They rebuilt it to factory specs which included leveling up the block and cc-ing the heads to the advertised spec which as we know was rated higher than delivered. From memory it turned out around 350HP (347HP) I think. They then added a bunch of bolt-ons with a 509 cam and it turned out 425HP. I will try to dig it out.

[c00nhunterjoe]

Once you deck the block and mill the heads, its no longer "rebuilt to stock" you have made it better.