First Time on Dyno!

[Evoking]

Had my 68 dyno tuned a couple days ago!  385hp and 407 lb-ft which equates to approx 550hp at the crank.  I was hoping for a nice round 600 crank hp but this is not too shabby.

[INTMD8]

Seems like it had more in it as it had not peaked yet 

Not sure about 30% drivetrain loss however.

[c00nhunterjoe]

Not to bust the bubble but 385 at the wheels is not 550 at the crank. Best to hit the 1/4 mile for a mph reading to give you an accurate hp number. I was never a fan of dynos for anything other then tuning or inflating chests.

[alfaitalia]

These numbers are from an article in Car Craft Magazine.

Powerglide_____18 hp
TH-350________36 hp
TH-400________44 hp
Ford_C-6______55-60 hp
Ford_C-4______28 hp
Ford_FMX______25 hp
Chrysler_A904__25 hp
Chrysler_727___45 hp

This is how much power it took to drive a on a tranny dyno...727 was second worst!  It's not a linear thing though so the more power you put through it the more power that will be lost. The figures quoted are to spin just the tranny.....so you would need a formula to work out how much your particular engine will sacrifice to the drive line. Add that to about 6 to 8% lost at the rear diff and it soon adds up.

[cdr]

on a Dyno jet is is about a 13% loss, so 445 hp @ crank

[INTMD8]

As alfaitalia mentioned, it's not a fixed percentage.

It's more like a fixed amount plus a percentage which varies by car/driveline.

[Mike DC]

 
727s cost a lot of HP and they also don't break.  It's not a coincidence. 

[cdr]

As alfaitalia mentioned, it's not a fixed percentage.

It's more like a fixed amount plus a percentage which varies by car/driveline.

it's all a guess , take it to the track as Joe said.

[c00nhunterjoe]

And dont forget to get the weather data for your runs when you do go. D/a, humidity, vapor pressure and temp will be most important.

[cdr]

And dont forget to get the weather data for your runs when you do go. D/a, humidity, vapor pressure and temp will be most important.

And to ad to that,, race weight , that is with driver.

[INTMD8]

Wouldn't say it's all a guess.  You can gain a lot of useful information tuning on the dyno but absolutely bring it to the track

To add to the density altitude note, dragtimes.com is an easy way to check.

[alfaitalia]

Even those useful posts and good advice won't tell you the power at the crank...just the tyres. If one car produces 30 brake more than another but loses 30 horse more through the drive line (unlikely I know but just as an example) then, all other factors being equal they will turn in the same times. So the track won't tell you how powerful that car is....just how much it put down. Which arguably is the only figure that counts I guess!....but the op wants to know the power at the crank...track won't help much with that.

[Evoking]

Even those useful posts and good advice won't tell you the power at the crank...just the tyres. If one car produces 30 brake more than another but loses 30 horse more through the drive line (unlikely I know but just as an example) then, all other factors being equal they will turn in the same times. So the track won't tell you how powerful that car is....just how much it put down. Which arguably is the only figure that counts I guess!....but the op wants to know the power at the crank...track won't help much with that.

I wasn't particularly looking to know power at crank. I had it tuned to smooth out the drivability. Knowing the output was a bonus. This is a cruise in between my much more focused weapons ;-). That said, the shop that did it is Superior Automotive of Orange County. They've been building and tuning engines for like 50 years - literally.  From the Bullit 68 Charger to Eleanor from Gone in 60, Fast & Furious cars and even Jay's personal collection. They engine dyno there as well!  When I reference 30% loss it's not off the top of my head - it's their real world experience with 727's and similar HP.  Had I got this e fine from them we would all know for sure!  I'm thinking it might not be worth pulling it out to confirm haha!

[INTMD8]

If it truly is 30%, let me know where they get their torque converters so I can make sure to never buy one  

Still curious why they didn't pull it any higher, (unless it lost valve control?)

But yeah, definitely not worth pulling the engine to find out for sure!

Enjoy it, more than enough power to have fun  

[Todd Wilson]

 
727s cost a lot of HP and they also don't break.  It's not a coincidence. 

Is that why the SS Hemi guys use the 904 adaptor and run 904's??

Todd

[Evoking]

If it truly is 30%, let me know where they get their torque converters so I can make sure to never buy one  

Still curious why they didn't pull it any higher, (unless it lost valve control?)

But yeah, definitely not worth pulling the engine to find out for sure!

Enjoy it, more than enough power to have fun  

Are you suggesting they should have gone higher than 5500 rpm?  At what RPM range do you guys think peak hp arrives on a stroked 440?

[hemi-hampton]

Look's like Horsepower was still Climbing at 5,500 rpm's & not dropped off yet while Torque dropped off at around 4,000 rpm's. I'd bee be curious to know where the Horsepower peaks & drops off. LEON.

[INTMD8]

Are you suggesting they should have gone higher than 5500 rpm?  At what RPM range do you guys think peak hp arrives on a stroked 440?

Peak hp would arrive at a different rpm for every engine depending on the combination. (being a stroked 440 one of many variables).

But yes, it looks like the run was chopped before it reached peak hp.  Just make sure your driveshaft is within range of critical speed if you turn it higher next time.

[c00nhunterjoe]

385 to the wheels factoring 30% loss is not 550... check your math.

Ss guys run 904 guts in a 727 case... but yes, for the rotational hp loss. Thus one of the many reasons a 590 hp 4000 race weight b body can go 10.15s in the 1/4.

[70 sublime]

385 to the wheels factoring 30% loss is not 550... check your math.

Ss guys run 904 guts in a 727 case... but yes, for the rotational hp loss. Thus one of the many reasons a 590 hp 4000 race weight b body can go 10.15s in the 1/4.

550 times .7 (100% - 30%) is 385

[RECHRGD]

How about 385x1.3=500......

[70 sublime]

How about 385x1.3=500......

He lost 30 % of original HP
Not gain 30 % of rear wheel HP

[c00nhunterjoe]

Indeed. Major brain fart.

[Challenger340]

Wheel Dyno's can be an excellent Tuning tool.
That said,
it would appear from most threads I've seen on this Site, that every time someone/anyone goes to a Chassis/wheel Dyno and posts the results ? The ensuing conversation then gets fixated on trying to then back-calculate Engine Flywheel Horsepower / Trq ?..... from the Chassis/Wheel numbers recorded.

Why is that ?
You will never know actual Engine/Flywheel HP/Trq because you were NOT measuring Engine/Flywheel power ?

If it makes 385 hp at the wheels and it runs great, be happy 

[c00nhunterjoe]

Well said. Thats why i suggested taking it to the track for some mph data. That is where it counts, not strapped to a roller.