Diesel Bombers - FAQ

easy guys, some people need to take a quick look at the rules here.... mainly the last 2 or 3...



now back on topic here, when loading a truck on the dyno does the load have to happen throughout the whole dyno run? when i dyno'd mine it was loaded and as soon as the pull started it unloaded ( something about the programing of it???) it was a Dynojet 224XLC, i didn't net the power i was looking for and i attributed it to this.

also i have always dyno'd vehicles in DRIVE, some people want to argue with me and say they you should put a diesel in OD to get correct numbers, please someone tell me if this is correct.

 

Everyone I have ever seen dyno an automatic always locks out OD. Just like with my 6spd we dyno it in 5th gear. We use 4th gear in a 5spd.

 

that is all i have ever seen but there is a local to me, he is a big name in the diesel world so i won't call him out directly but he told me that all his pulls he makes he makes in OverDrive. In my thinking doing that will change the numbers since the drivetrain won't be in the 1:1 ratio of Drive and will make the TQ read low and the HP to read high, he makes pulls on a dyno where they don't have the tach adapter to read RPM so they don't go by TQ numbers, just by HP and all his trucks are quoted to be high HP trucks.....

 

If getting sick and tired of retarded people acting 10 feet tall and bulletproof on the internet trying to start crap about topics they have little to no factual knowledge about, although by thinking they do making themselves even less intelligent, and saying something about it in reply, somehow crosses a line, then my apologies for being honest but I won't stop doing it.


K that being said, in a perfect world direct 1:1 drive is best on a dyno to measure without additional variables, although tire pressure, tire size, etc will affect the results as well, and since a tire changes its size as it rotates, well, you can see where this is going...

The true way to measure an engine's power on a load dyno is to begin the test at rated RPM and apply the load slowly and as the engine loads up and pulls down in the RPM range you will see the torque numbers rise significantly, until a point where the load overcomes the ability of the engine and it will die, QUICKLY.....

People who run diesel pickups on a DynoJet would gain a lot of understanding by watching a Superflow take a class 8 tractor with a Signature 600 and bring it to a dead stop.

The terms "peak torque RPM", "rated RPM", and "torque rise" are all examples of major selling points of a diesel engine's ability that are easily measured, explained, and witnessed during the correct operation of a load dyno......abilities that are lost on those who continue to struggle with the wide variance of dyno results using improper tools and equipment, with improper operation, to do the tests.

Ya know, those of us who have actually worked on big diesel engines for a living, and have dyno'd said engines and chassis during said mechanical work, get really, really tired of reading the loads & loads of disinformation spewed out there in the land like gospel........

I say that with utmost certainty and do not fear repercussions from it.

Cheers,

Dan

 

The standard measure is a heavy wheel Dynojet 248 model run in O/D. I am well aware of the plunger diameters and cam plate lobe height differences. The HO VP44 also operates at a higher pressure allowing the engine to produce greater hp in factory form with a smaller nozzle. I did not start this knock down drag out bickering contest, but I mean to set it straight.

 

Weston, why run in overdrive? not arguing but trying to further my knowledge. i have heard it is very hard on a tranny and inflates the numbers due to the gearing difference between drive and OD, i can see why you say to if it is because of the added load on the motor but does it change the numbers enough to make a difference?

 

You will get somewhat higher numbers in OD, from what I have been told. I would see about 8-10 more HP in my dyno tune (locks in OD no matter what) then my extream setting and od locked out... I think it had something to do with loading the motor more... Mustang dyno for all of my runs.

 

I'm sure you were speaking of David, he runs everything in O/D, so does Llyod Mills on his 248X model, I trust these numbers more than others. On a turbocharged engine, to simulate load similiar to what you see on the street, a heavy wheel used as inertia in O/D seems to be the most consistant. I talked to a friend whom dynoed 1 week apart without any changes, one 248H model and one 248X model, no load in O/D and the peak number was within 2hp. I have had a few parts dynoed @ Lloyd's, and will continue to do so because I believe the results. I could get larger numbers from a differnt method, but I want honest numbers.

 

no it is Darren, and he was using a non loaded Dynojet, an older one that i don't know of the model, it is an in ground deal no bigger than the 224 that i use in Tallahassee.

 

Mike was locking out O/D on David Dunbars Dyno @ Blowing Rock.