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-   -   HEMI Torque Curve from dyno (http://www.jeepgarage.org/f108/hemi-torque-curve-from-dyno-21287.html)

Bmwister 04-04-2011 07:10 PM

HEMI Torque Curve from dyno
 
I stumbled across this today and thought forum members would find it helpful. Considering the numerous posts comparing the Pentastar and 5.7L hemi, I thought this dyno test of the current 5.7L Hemi clearly shows how fat the power band truly is. Even though the test was performed on a Charger RT, the graph is a valid representation of what we have in the WK2.
http://img231.imageshack.us/i/hemito...edynochar.jpg/http://img231.imageshack.us/i/hemito...vedynochar.jpghttp://img231.imageshack.us/f/hemito...edynochar.jpg/http://img231.imageshack.us/img231/7...vedynochar.jpg
Reference:
http://blogs.insideline.com/straight...harger-rt.html



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Walt 04-04-2011 07:30 PM

Re: HEMI Torque Curve from dyno
 
1 Attachment(s)
Quote:

Originally Posted by Bmwister (Post 389444)
I stumbled across this ... dyno test of the current 5.7L Hemi clearly shows how fat the power band truly is. Even though the test was performed on a Charger RT, the graph is a valid representation of what we have in the WK2...

Thank you.

Here's another one for the earlier HEMI's: (click to enlarge)

moosehead 04-04-2011 07:34 PM

Re: HEMI Torque Curve from dyno
 
Spun all 4 tires today accidentally while finally breaking free of rush hour gridlock. OK, maybe spun is a bit of an overstatement, but let's say the audible chirp surprised the crap outta me and maybe those around the 5k lb beast. Bring on the tuners. Thanks Bmwister.

Walt 04-04-2011 07:52 PM

Re: HEMI Torque Curve from dyno
 
Remember that the torque and HP curves must cross at 5,252 RPM.

HP = (torque x rpm) / 5252. Torque must be in ft-lbs.

MasterWK 04-04-2011 11:11 PM

Re: HEMI Torque Curve from dyno
 
I screech my tires everyday pulling out of school in my 5.7! left turns are the easiest if you're looking for sound! stomp the gas and jerk the wheel a little

77rednecktruck 04-05-2011 07:24 AM

Re: HEMI Torque Curve from dyno
 
Quote:

Originally Posted by Walt (Post 389472)
Remember that the torque and HP curves must cross at 5,252 RPM.

HP = (torque x rpm) / 5252. Torque must be in ft-lbs.

where did that come from??? :)

the1jake 04-05-2011 08:11 AM

Re: HEMI Torque Curve from dyno
 
That torque curve chart should be fairly accurate.

Don't forget to mention that the 2011 Dodge Charger R/T does the 1/4 mile in 13.7 seconds. (sorry, couldn't resist guys)


I can't find the Road & Track full spec for the Grand Cherokee, but this is for the Charger. (note: PDF file)
http://www.roadandtrack.com/var/ezfl...4a6f8f2a3c.pdf

ibleedoil 04-05-2011 09:10 AM

Re: HEMI Torque Curve from dyno
 
Does the charger have the same output of our Hemi's? I know the truck version has 30 more hp and has a different top end (heads/intake)

Edit: Never mind. just looked back and saw that max torque and hp match ours.

Bmwister 04-05-2011 11:06 AM

Re: HEMI Torque Curve from dyno
 
Quote:

Originally Posted by Walt (Post 389472)
Remember that the torque and HP curves must cross at 5,252 RPM.

HP = (torque x rpm) / 5252. Torque must be in ft-lbs.

Quote:

Originally Posted by 77rednecktruck (Post 389691)
where did that come from??? :)

You and I and other techies probably already know where the 5252 constant comes from, but for those who do not: http://www.howstuffworks.com/question622.htm


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edogg23 04-06-2011 06:32 PM

Re: HEMI Torque Curve from dyno
 
Quote:

Originally Posted by ibleedoil (Post 389730)
Does the charger have the same output of our Hemi's? I know the truck version has 30 more hp and has a different top end (heads/intake)

Edit: Never mind. just looked back and saw that max torque and hp match ours.

Manufacturer HP and TQ are at the crank, the dyno is at the wheels. So numbers on the dyno are usually about 15% lower than what it is making at the crank depending on the drivetrain loss.

Bmwister 04-06-2011 06:53 PM

Re: HEMI Torque Curve from dyno
 
Quote:

Originally Posted by edogg23 (Post 390982)
Manufacturer HP and TQ are at the crank, the dyno is at the wheels. So numbers on the dyno are usually about 15% lower than what it is making at the crank depending on the drivetrain loss.

That is an accepted guideline. I assumed people would ignore the actual posted numbers themselves; it is the posted curve that is the key point. The curve is an accurate indicator of the broad powerband. It is merely coincidence that the at-the-wheel reading in the IL test is almost identical to the published crank figures.

Different dynos will give different numbers especially if they didn't properly dial in the correction conditions. I doubt the manufacturer's published Hemi HP and torque numbers are at-the-wheel measurements otherwise they'd have to publish different numbers for 4WD and 2WD vehicles.

Walt 04-07-2011 09:45 PM

Re: HEMI Torque Curve from dyno
 
Quote:

Originally Posted by Bmwister (Post 389840)
You and I and other techies probably already know where the 5252 constant comes from, but for those who do not: http://www.howstuffworks.com/question622.htm --

Heh heh. It actually comes from my Thermodynamics text. That's why I like long-legged engines over screaming over-square toys.


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