Dyno runs, gear differences between Dynojet and Mustang?

[Gary - K7GLD]

More experienced diesel owners seem to recognize that our slower reving diesels give more accurate power readings on load type dynos - and some seem to feel that if a inertia type (Dynojet) is used, running in OD will spool the turbo better and give higher, more accurate readings.



That seems pretty well proven in past posted numbers - but will that likely also hold true when running on a Mustang (load-type) dyno?

 

[Greenleaf]

There is a local diesel performance/injection pump shop. They currently have to road test a vehicle with attatched gauges etc. I asked if he bid on the Inertia dyno that was up at auction to test trucks. He replied that inertia dynos are only good for one thing and it wasn't testing diesel trucks... ... ... LOL



I suppose that is his opinion. Some folk seem to like 'em.

 

[mattymac]

I like load dyno's because most inertia dyno's that I have seen with the higher HP trucks dont load the motor enough, they still give close readings in relation to the trucks HP but Ive seen some twin turboed trucks only make 30-40 lbs of boost on some inertia dynos when they run down the road at 50-60+?

 

[jwilliams3]

I think inertia dynos are better for our street trucks. Flame away!! :-laf

 

[DavidTD]

Gary, more experienced diesel owners?



Two identical trucks with identical HP.



Truck A makes same power on inertia as on a load cell.



Truck B makes less power on inertia, but matches truck A on load cell.



Truck A will hand Truck B his butt all day on the track (everything else being equal)

 

[DBF]

Gary, more experienced diesel owners?



Two identical trucks with identical HP.



Truck A makes same power on inertia as on a load cell.



Truck B makes less power on inertia, but matches truck A on load cell.



Truck A will hand Truck B his butt all day on the track (everything else being equal)

I didn't confirm this when I ran on your dyno at Suncoast Converters, but I take it your mobile dyno is a load type, right? That's quite a rig.



Tx, DBF

 

[DavidTD]

DBF, no my rig is a Dyno Jet 248 which is inertia.



Thanks.

 

[Greenleaf]

I hear that the inertia dyno will not asllow the engine to build boost as you would with pulling a load on the road or with use of a load dyno.



I have NOT put my truck on both a load and inertia unit so Icannot speak from personal experience. However it seems to be common that the inertia dyno will not allow the engine to build boost.



From what I understand, boost is directly related to HP developed. Unless one was to insert a potato into the tail ppe.



Just this weekend a fellow commented to me (at a dyno event) that the engine built only 15 psi boost on an inertia dyno and wanted to know how that is an accurate reading. I don't have the answer.

 

[SKargo]

On my dyno run a few months ago on a dynojet, I could only hit 30 psi of boost. Out in the parking lot I hit 34psi.

 

[DavidTD]

I hear that the inertia dyno will not asllow the engine to build boost as you would with pulling a load on the road or with use of a load dyno.



I have NOT put my truck on both a load and inertia unit so Icannot speak from personal experience. However it seems to be common that the inertia dyno will not allow the engine to build boost.



From what I understand, boost is directly related to HP developed. Unless one was to insert a potato into the tail ppe.



Just this weekend a fellow commented to me (at a dyno event) that the engine built only 15 psi boost on an inertia dyno and wanted to know how that is an accurate reading. I don't have the answer.

Why doesn't anyone ask if person A can make 60 psi on this dyno, what can't I?

 

[Greenleaf]

So that's pretty good comparison I would think,,,,,,,,,,,right? I'll have to have my truck on the inertia rollers and I can compare reality to inertia myself.



I'll bet the dyno operator has a lot to do with it (how he operates the truck). As well as the turbo/transmission. One guy may see realistic results with a particular set-up where another truck may not... . (???????)

 

[RustyJC]

Running in a higher gear on an inertial dyno will effectively increase the inertia of the rollers and make it easier to load the engine/spool the turbo. Running in 5th (2 pulls), I only made around 320/650; running in 6th (2 pulls), I made 347/762.



Rusty

 

[BILLVO]

Want true real hp torque #'s use load dyno. Want to brag about running on dyno with diesel go inertia if just having a sheat of paper with #'s on it is what you want. Load dyno takes into account all factors tires gears ratios cubic inches on and on and on..... Inertia dynos are very generic.

 

[Hohn]

There's no question that a Dynojet is more repeatable and consistent.


Inertial dynos are generic because HP is generic. All it is is how fast you can move a given load from point A to pt B. That's simple. HP doesn't care about your gear ratios or tire size.

The beauty of a DJ is the simplicity. It accounts for EVERYTHING, because all it measure is the outcome-- which is the product of all the factors that determine it.

Load dynos are inconsistent because no one has yet developed a braking mechanism that's super precise. The dual eddy current dynos are very close and very nice, and probably the best load dyno you can get.

On a Dynojet, the load is the inertia of the drums. This load NEVER changes-- even the slightest amount. That's why they are consistent.

A load dyno, however, relies on a comparatively inconsistent braking mechanism, which has more variability as heat is introduced.


If you use your truck for towing, then you want to measure TQ, and a load dyno is probably better for you.

If you can more about acceleration, then you want to measure HP and an intertial dyno is better for you.



In any case, an intertial dyno is still THE standard. Which dyno do NASCAR teams use? Dynojet! In the higher levels of motorsport, DynoJet is the standard.

This is because the Dynojet is consistent enough to tell the NASCAR engine builder if his new cam is giving him the 3hp he's hoping for.

The load dyno can't be trusted when precision matters... (note, precision is not accuracy). The Dj is PRECISE!!

 

[Hohn]

Why doesn't anyone ask if person A can make 60 psi on this dyno, what can't I?

NO joke.

What we need is a DJ248c with 10K # drums..... That would be ideal, imo. You could run in either 5th or 6th and get good number, plus it would simulate a small trailer or just a heavy truck...

jh

 

[RustyJC]

Justin,



Actually, most of our company's R&D and production test dynos are water-brake load-type dynos. The regulation of the water supply only imposes a variable, controllable load (i. e. , a relative torque between the rotating impellers and the casing-mounted stators) - the dyno casing has a load cell under one mounting foot to measure the torque load imposed on the casing, and this load (measured in pounds), combined with the known offset between the shaft centerline and the load cell (measured in feet) as well as engine speed, is what is used in the horsepower and torque calculations. The load cells are routinely calibrated and extremely accurate.



Rusty

 

[nps]

Justin,



Actually, most of our company's R&D and production test dynos are water-brake load-type dynos. The regulation of the water supply only imposes a variable, controllable load (i. e. , a relative torque between the rotating impellers and the casing-mounted stators) - the dyno casing has a load cell under one mounting foot to measure the torque load imposed on the casing, and this load (measured in pounds), combined with the known offset between the shaft centerline and the load cell (measured in feet) as well as engine speed, is what is used in the horsepower and torque calculations. The load cells are routinely calibrated and extremely accurate.



Rusty

Hey - dyno party at Rusty's shop this weekend! :-laf

 

[DavidTD]

NO joke.



What we need is a DJ248c with 10K # drums..... That would be ideal, imo. You could run in either 5th or 6th and get good number, plus it would simulate a small trailer or just a heavy truck...



jh

:--) I sure don't want to pull THAT one around. :-laf

 

[Hohn]

Justin,

Actually, most of our company's R&D and production test dynos are water-brake load-type dynos. The regulation of the water supply only imposes a variable, controllable load (i. e. , a relative torque between the rotating impellers and the casing-mounted stators) - the dyno casing has a load cell under one mounting foot to measure the torque load imposed on the casing, and this load (measured in pounds), combined with the known offset between the shaft centerline and the load cell (measured in feet) as well as engine speed, is what is used in the horsepower and torque calculations. The load cells are routinely calibrated and extremely accurate.

Rusty

Good to know. That's why I think a water brake dyno like the Superflow is so good.

My references to load dynos mostly pertain to the "brake shoe" dynos that just use large train brakes to apply load, and are grossly imprecise.

In the end, the operator makes more difference than anything else when dealing with a higher-end dynamometer. (Superflow, Dyno Dynamics, Dynojet)

jmo