So i wanted to get a baseline ... (being very new to dyno) ... before i get a turbo and injectors ordered ... so i headed over to the closest place w/ a loaded dyno. I just wanted a baseline pass done ... just so i have a starting point .....

Was a learning experience ... and boy did i learn allot ! ... I can hit 1500 by 50MPH ... and didn't even get to finish the test, as i wasn't going to leave that needle pegged longer than a few seconds....

So my question ... *** are these torque numbers supposed to mean ?... He tried to explain that you can read torque numbers from a few different places on the dyno ... blah blah blah .. and he couldn't explain enough for me to understand. I just know that these just don't compare to what i've seen for normal dyno numbers.

http://lanbash.com/dyno.pdf

 

Figure out your RPMs at a given speed in the gear you dynoed it in. The dyno wasn't calibrated for your gearing/tire size, so the torque numbers are all screwy. Mine is the same way, although not to the same extent.

I don't know what tire size you have, but if you're running the stock 245/75R16's, your tires would be turning 660rev/mile. If you're running in drive (1:1 ratio), and your peak hp is 239hp at 85 mph, we'd multiply 660 rev/mile by 58 MPH. That gives us 56100 rev/hour Multipyl by your rear axle ratio. Say its 3.55. 56100 x 3.55 = 199155rev/hour of the driveshaft. Since the tranny is 1:1, your engine is doing the same. Divide by 60, and that gives us 3319 RPM. Then back to the old HPx5252/RPM and you get torque. Doing all this, I get 378ft.-lbs. If you are running something like 285/75R16s, and ran it in OD, your numbers would be closer to 590.

 

Wow ... i didn't realize it was that complicated.

Another problem i have with the dyno ... being new to the process ... he started WOT from 0 mph ... which obviously caused the pyro to bury very early ... i would have expected to kinda ease up to 1:1 lockup in OD (where the big power is made) and then start the test ... but what do i know.

I'm on 315's w/ 3.55's ... my slow brain will try to do the math ..

Shouldn't the dyno be able to account for tire size and gearing automatically ?

 

Find another dyno and operator. If he started from a dead stop and let the truck shift through the gears he is doing it all wrong. You'll never get accurate results that way. I have attached my last dyno run as an example of how it will look, although results will be different for every truck. Mine was done in 5th gear (1:1) with the pull starting around 1300 rpm to redline.

http://www.dynotuning.com/nor-cal-ch..._rpmactual.jpg

 

Autos are the hardest to dyno as you want them to pull in direct with as much throttle as possible without shifting down. Dumping the fuel to the engine doesn't tell you much. You have to operate the truck like you are coming to a hill, steadily going to WOT. Punching the throttle comes from testing gassers.

 

Now we'll see if they are willing to do something to fix my worthless results ...

The guy running it i was told wasn't their 'regular' guy ... but they shouldn't have put him in there if he didn't know what he was doing ...

But i digress ..... I'll have to give them a call and see if they'll fix the mistake and retest it.

Thanks for all the info !

 

So ... i went to another shop today ... and spent a few hours on the dyno ... (they really liked and were impressed w/ the truck) ... they had only dyno'd a handfull of diesels ... and were all fords and a stock 3rd gen auto.

So i took all of the good advice i got here (thanks for all the PM's) ... and pulled about 20 times in 3 hrs ....

I ran a good set in OD lockup, but most in D lockup w/ OD locked out. It is very tough to get a good pull w/o a mystery switch as the TQ really likes to UNLOCK w/ enough go pedal.

So i have the new graphs i'll post in a few, but needless to say these numbers were MUCH more realistic.

Best was 305/640 .... but the ones i'm taking that TQ never unlocked were 298/632. So it's time to order up a turbo, some injectors, some DV's, studs, exhaust, intake ... and then we'll see what she can put down!

So if anyone is in AZ looking for a GREAT shop, that really cares about it's customers, let me know. If you want a shop to avoid at ALL costs, look at my first dyno sheet. I wouldn't take my truck back there for an oil change.

Thanks again for all the great info!

Here's the sheet:

http://www.lanbash.com/newDyno.pdf

 

Nice numbers.

 

Much better...

 

Did you have Smarty SW running for that dyno?

Jim