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-   -   I'm taking my car to the dyno tomorrow (http://www.jeepgarage.org/f108/im-taking-my-car-to-the-dyno-tomorrow-33814.html)

andyh 01-09-2012 07:29 PM

I'm taking my car to the dyno tomorrow
 
1 Attachment(s)
What gear should I tell them to use?

bone stock, no mods.

Edit: Results are in

2011 Overland w/ 5.7 Hemi and 19,000 miles
89 octane gas
Temp was 65F
Close to sea level
.98 correction factor

288.72 horsepower
307.86 pound feet of torque

Nissan-SR20-Man 01-09-2012 09:48 PM

Re: I'm taking my car to the dyno tomorrow
 
Answer = depends...

if 2011 5.7L = 3th gear = 1:1 ratio
if 2012 5.7L = 4th gear = 1:1 ratio (2012 have 6 speed)
if 3.7L use fourth no matter which year

Edit = tow/haul mode offsets numbers numerically down one - you have to numerically go up one on the indicator - try with on and off for shits and giggles to see if the ecu offers more torque during, it also allows longer rev holding prior to upshift - this would be key to uncorking TQ at the ecu software level

2012 = http://www.wk2jeeps.com/2012/2012_wk...ifications.pdf
2011 = http://www.wk2jeeps.com/2011/2011_wk...tions_June.pdf
Scroll down for ratios

The goal is to use as close to 1:1 gear ratio in order to properly measure engine torque at the wheels.

warm it up first, get coolant and oil temp stable. get it rolling, though the gears, slap stick in manual 4 to limit 4th maximum, you will have to play with throttle vs rpm to find where is stays in fourth without downshifting when punching it. Then hold it down until rev cut, make it count. i would suggest making gradual initial pulls, not sure how your getting charged. Per pull or by the hour.

Torque is measured, HP is calculated from the measurement. Garbage data in = garbage data out

Since i helped you, help us here by posting up the details, year, miles on engine, etc... along with your dyno sheets. Numbers are numbers, we want graphs. interesting to see if you are close to nameplate / specs in the TQ and HP department.:thumbsup:

ColdCase 01-10-2012 07:04 AM

Re: I'm taking my car to the dyno tomorrow
 
Because you can't really select a gear with these transmissions (just the max gear) you will see most charts start at 3000 rpms or so. It is just difficult to manage gear selection under 3000 rpms. If your dyno operator is familiar with the Chrysler transmission he will know what to do.

The 2011 and 2012 gear ratios are identical, but the EVIC may indicate a bit differently on the down shift and up shift. The literature often simplyfies the descriptions, but technically there is no so called 4th; the operating modes are not named like that. There are things like direct, underdrives, a couple overdrives. So directly attributing a EVIC display to a transmission mode is not obvious and have been a source of confusion to many.

FlyinRyan 01-10-2012 07:29 AM

Re: I'm taking my car to the dyno tomorrow
 
Have fun getting it to not force a downshift.

Make sure they really secure the truck down to the dyno, You will probably have to start the dyno run at about 70mph. On my old WJ we started around 68 and ended around 120. Made the operators a little nervous.

andyh 01-10-2012 11:59 AM

Re: I'm taking my car to the dyno tomorrow
 
results added to first post

77rednecktruck 01-10-2012 12:58 PM

Re: I'm taking my car to the dyno tomorrow
 
288 HP and 307 ft.lbs. - that seems pretty low for the HEMI doesn't it?

robpp 01-10-2012 02:38 PM

Re: I'm taking my car to the dyno tomorrow
 
you have to figure about 20% drivetrain loss. so arent they sold as 360 - 20% = 288.

He is dead on.


Its 360 at the crank. the dyno is showing at the rear wheels.

JDrew 01-10-2012 02:57 PM

Re: I'm taking my car to the dyno tomorrow
 
Quote:

Originally Posted by robpp (Post 549788)
you have to figure about 20% drivetrain loss. so arent they sold as 360 - 20% = 288.

He is dead on.


Its 360 at the crank. the dyno is showing at the rear wheels.


Exactly right.

yocubed 01-10-2012 04:13 PM

Re: I'm taking my car to the dyno tomorrow
 
Yep assuming a 20% powertrain loss you'd expect from the 5.7L Hemi with 360 BHP/390 lbft torque at the flywheel to get roughly 288HP and 312lbft of torque.
So his numbers are dead on with typical powertrain losses which actually impresses me because I was expecting more lost power from the AWD setup (AWD cars usually see 25+% loss).
With a bone stock engine that tells me that Chrysler is either down playing their actual numbers or the JGC is very efficient at putting power to the ground.
I'm also really liking that very flat torque band, basically tells us the Hemi delivers torque throughout it's powerband

If only we could get a tuner out now I'd expect to see numbers in excess of 350 with relatively easy mods.

andyh 01-10-2012 06:02 PM

Re: I'm taking my car to the dyno tomorrow
 
Here is a video.




ooja3k 01-11-2012 12:01 AM

Re: I'm taking my car to the dyno tomorrow
 
I like how it lowered for Aero :-)

Lets see it now with the volant and corsa ;)

Nissan-SR20-Man 01-11-2012 07:07 AM

Re: I'm taking my car to the dyno tomorrow
 
Did anyone notice the AFR???

Was the AFR taken at the exhaust tip? Taken at both tips???

I run 11.5 - 12:1 at the downpipe (12" downstream of turbo) on a 300HP 4 cyl nissan. I run pig rich due to melting holes in pistons (and I'm on the third engine) Taken at the tip has other affects on the AFR. Forced induction needs the rich mixture to help keep the pistons cooler. I believe there is some real power gains from leaning it out. Let alone timing tweaks. I feel Jeep has really downgraded the hemi to smooth as the TQ curve indicates, I wonder what the dodge version of the hemi looks like in the trucks / cars.

I have no experience tuning big modern V8's. Only carb'd older V8's.

I would be interested in seeing some WK SRT guys that have modded and tuned to see what they say.


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