Why 2011 Mustang 5.0 Auto Torque so low? - Ford Mustang Forum
 
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post #1 of 13 (permalink) Old 06-07-2010 Thread Starter
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Why 2011 Mustang 5.0 Auto Torque so low?

Hey guys, I was reading where SCT was dynoing their 2011 Mustang GT 5.0 Auto and it only produced 326.23 pd ft of TQ and the HP seemed about right, 360.71. Anyway I knew auto trannies could pull some more parasitic loss than a manual but this much? I thought the car had 390pd ft how much would this equal out to be at the fly wheel? Anyway good news is with the SCT Canned tune they gained an extra 28HP and 34 pd ft of TQ! Any thoughts on why it is so low?

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post #2 of 13 (permalink) Old 06-07-2010
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mabey it was the gear ratio tested on the car. it might have been lower. like 3.15 vs 3.73 on the manual


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post #3 of 13 (permalink) Old 06-07-2010 Thread Starter
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That is what I also thought 2011gt310, but I thought there was a guy on here that ran like 12.7 @115 and I was thinking if TQ was down that low I don't think he is going to be running that fast especially when some of the 3:73 ratio guys haven't been going that fast! I know someone with 3:73 stock GT probably has but sure as heck haven't been the crappy magazine drivers!
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post #4 of 13 (permalink) Old 06-07-2010
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Quote:
Originally Posted by 2011gt310 View Post
mabey it was the gear ratio tested on the car. it might have been lower. like 3.15 vs 3.73 on the manual
rear gears do not change the power reading on a dyno, because of the way they calculate the power
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post #5 of 13 (permalink) Old 06-07-2010
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Some believe there is a 20% parasitic loss with an auto trans. If that's true, then 326 ft/lbs at the wheels divided by .8 gives you 407 ft/lbs at the flywheel.
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post #6 of 13 (permalink) Old 06-08-2010 Thread Starter
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well then that sounds better!!
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post #7 of 13 (permalink) Old 06-08-2010
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Were did you get these #'s?

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post #8 of 13 (permalink) Old 06-08-2010
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Plus do you really the take word of someone that is trying to sell you something to improve performance. Sell a hell of a lot more SCT's with a 30 hp/tq gain than a 10hp/tq gain.

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post #9 of 13 (permalink) Old 06-08-2010
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What dyno was used makes a huge difference.
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Attached spreadsheet shows torque & power curves from 6 sources. There's quite a spread. All data is at rear wheels. I'll leave it for others to ponder/explain. The SCT auto trans data seems bogus at low RPM's, and the Edmunds (Insideline.com) data a bit too high.

I suppose different ambient test conditions could account for some of this spread, but it's also likely that inaccurate dyno data is involved. The Ford data, which is given at the flywheel, requires the assumption of a driveline loss factor to compute rear wheel HP. I've assumed 0.88, or 12% loss, based on various "expert?" opinions.
Attached Files
File Type: xls 2011 Mustang dyno tests.xls (212.5 KB, 175 views)

2011 GT Coupe - candy red, auto, all the options
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I wouldn't pay much attention to that. Not after seeing some of the times posted by automatics.

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Quote:
Originally Posted by wannapony View Post
Attached spreadsheet shows torque & power curves from 6 sources. There's quite a spread. All data is at rear wheels. I'll leave it for others to ponder/explain. The SCT auto trans data seems bogus at low RPM's, and the Edmunds (Insideline.com) data a bit too high.

I suppose different ambient test conditions could account for some of this spread, but it's also likely that inaccurate dyno data is involved. The Ford data, which is given at the flywheel, requires the assumption of a driveline loss factor to compute rear wheel HP. I've assumed 0.88, or 12% loss, based on various "expert?" opinions.

Nice spreedsheet! Also,one of the few advantages of the live axil is less power train lose than with IRS. I'ver heard up to a 3% difference.
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post #13 of 13 (permalink) Old 06-08-2010 Thread Starter
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hey guys sorry it took me a few to get back, here is the website with the dyno sheets, I hope they are defiantly off, because I have seen the times these automatics are cliping off at the drag strip and they seem too impressive to only be putting out this so called low torque of 326pd ft SCT Performance gains 28+ HP on a 2011 Mustang with just a Tune - Stang TV Forums
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