Let's Talk Dyno Results

[RedTruck]

I figured I would try to start a new thread with only dyno results, and questions and comments about said engine.

I'll start off by posting the dyno sheet that came with my rebuild. I purchased a long block 6.9 through a local Navistar dealer. At the time I purchased this engine, Navistar was having Franklin Power Products rebuild the 6.9 and 7.3 engines. This should give a good example of a stock engine.

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I believe if I did my math correctly (someone here posted Torque x RPM / 5220 = HP) it comes out right around 155 HP.

Paul

 

[jperecko]

Safe to assume that this was taken at the crank, not on a chassis dyno?

 

[RedTruck]

At the crank it was taken, yes.

 

[jperecko]

Just good to make note... 'cause people comparing will likely be doing so with chassis dynos, having drivetrain loss. Thanks for the good benchmark.

 

[david85]

I'm confused. Aren't these engines supposed to put out over 300 ft/lbs of torque by 1400 RPM? Torque on this chart peaks at the highest RPM

 

[jperecko]

I'm confused. Aren't these engines supposed to put out over 300 ft/lbs of torque by 1400 RPM? Torque on this chart peaks at the highest RPM

turbo'd maybe

 

[david85]

Specs for N/A 6.9s are

315 Ft/lbs of torque @ 1400 RPM

170 Hp @ 3300 RPM

Factory turbocharged 7.3 IDIs had

388 Ft/lbs @ 1400

190 Hp @ 3000 RPM

Aftermarket turbocharged IDIs that are well tuned can produce (conservatively)

450 Ft/lbs of torque

250Hp


Factory 6.9 specs shown here:
http://www.oramagazine.com/archive/nov_2003/departments/nov01_oldiron_01.asp

 

[RedTruck]

David,

I'll call them and see if they can explain how this curve was achieved.

Paul

 

[Agnem]

Yea it doesn't look right. I doubt the validity of it, but we need to understand how they tested it.

 

[RedTruck]

Here's what I found out...

When they test the engine they aren't interested in producing an accurate dyno curve. They are only interested in horsepower at governed RPM, which they must calculate from this chart. They don't load the engine down enough during the run-up to produce an accurate torque curve over the entire RPM range. They care about the torque at governed RPM, oil pressure, and temp. That being said the HP calculated from the torque value at max rpm would be accurate, but since this is a long block they probably just eyeball the timing.

Can I get a do over on this thread? Sorry fellas.

Paul

 

[RLDSL]

aside from most likely not being timed, that is a fresh engine that has not had time to even seat the rings yet. Hardly a prime example for testing.
I imagine that they have their own internal specs that they are shooting for when one comes off the line for pass /fail

 

[david85]

Aww well. Would have been nice to see some better results but I guess we'll have to wait a little longer.

 

[motrack]

Just wondering how long its been since you brought that reman engine? Franklin Power Products was located in Franklin Indiana and closed its doors going on 2 yrs now.

They paid good money for rebuildable cores until they closed.

 

[RedTruck]

I bought it during the winter of 2000. It's been a great engine thus far.

Paul