Load bearing dyno numbers vs. inertia drum dyno numbers

[AED F250]

I was just wondering if anyone could tell me how much difference there is in power from load bearing dyno numbers vs. inertia drum dyno numbers. One would think that the load bearing dyno would help the truck build up boost for the pull, which will equal more power. I was just wondering if this is the case??????

[F250stroker08]

idk but when i was out at Sheid Diesel Extravaganza they had both and it seemed like there were more trucks making bigger power on dunbars drum dyno than on scheids load bearing dyno

[Dave]

Load dynos generally show higher power readings when operated properly.

The reason Dunbars Dyno was showing better results than Scheids is Dunbar knows what he's doing when running it.

[po-po 5.0]

You can make a dyno read whatever you like. So "knows what he's doing" isn't necessarily what it sounds like. "Knows how to fudge numbers" might be a better choice of words....

[AED F250]

I own an inertia drum dyno that I use for tuning cars here are my shop. I know its not the ideal setup for tuning anything with a large, slow spooling turbo. With these trucks where the entire pull only takes 3 seconds there really isn't enough time to reach full boost. I have been seeing 35ish psi at the end of the pull.

So basically what I'm asking is are the load bearing dynos producing more power due to loading down the truck to make more boost?? Not is the guy operating the dyno fudging numbers.

[Dave]

Originally Posted by AED F250

I own an inertia drum dyno that I use for tuning cars here are my shop. I know its not the ideal setup for tuning anything with a large, slow spooling turbo. With these trucks where the entire pull only takes 3 seconds there really isn't enough time to reach full boost. I have been seeing 35ish psi at the end of the pull.

So basically what I'm asking is are the load bearing dynos producing more power due to loading down the truck to make more boost?? Not is the guy operating the dyno fudging numbers.

The answer is yes. However you can simulate that a little by riding the brake on the truck a little in the beginning of the run

[AED F250]

Originally Posted by Dave

The answer is yes. However you can simulate that a little by riding the brake on the truck a little in the beginning of the run

Yeah I have tried that a couple of times, but I believe that when you touch the brake it unlocks the converter which makes the numbers lower and not accurate. I could be wrong.

[Dave]

Originally Posted by AED F250

Yeah I have tried that a couple of times, but I believe that when you touch the brake it unlocks the converter which makes the numbers lower and not accurate. I could be wrong.

Thats why you only do it initially. You dont ride the brake the entire time. Just long enough to get it to start to spool

[AED F250]

I'll give that a shot next time I strap the truck on the roller. Thanks.

[08stroker250]

Originally Posted by po-po 5.0

You can make a dyno read whatever you like. So "knows what he's doing" isn't necessarily what it sounds like. "Knows how to fudge numbers" might be a better choice of words....

Dunbar uses a 1.02 correction factor, which on my dyno run was a 10.01 difference in uncorrected. He showed me the computer and pulled up my results. My 1.02 correction factor numbers were 560/1110 and my uncorrected number was 549.98/109X. Then he showed me standard correction, which is what a lot of dyno operators use. That was 571/1133. I guess it just depends on the operator and what correction factor they use and what load they use....