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06-26-2013, 09:38 AM
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CC Member
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Join Date: Jun 2013
Cobra Make, Engine:
Posts: 1
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Not Ranked
How much torque at 2000 rpm?
When I was speaking with the folks at American Powertrain about the T-56 Magnum 6spd, they cited a ballpark of 300 lbs-ft at 2000 rpm as a good indicator of whether you can maintain speed rather than losing it in 6th gear.
I plan to use a Keith Craft 427FE based engine, most likely their typical 482 build. Gave them a call regarding this question, but they offered no data below ~4400 rpm.
Does anyone have a similar build that has been on a dyno and can share their torque numbers around 2000 rpm? Thanks in advance.
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06-26-2013, 09:48 AM
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CC Member
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Join Date: Oct 2003
Posts: 4,078
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It's fine to to want to know the torque produced at 2000 RPM but virtually no builders (as Keith told you) seek those numbers.
Just don't operate your 482 at 2000 in 6th gear. That's worse than loading the brake on a dyno. I also don't think a 600HP 482 can make 300lbft at 2000 but I may be be wrong.
__________________
Chas.
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06-26-2013, 10:02 AM
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CC Member
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Join Date: Dec 2001
Location: Louisville,
KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,417
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I'd say it would be close to that, but none of us load the engines on the dyno at this low of an rpm.
I would skip the T-56 altogether. There are ZERO benefits to that transmission.
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06-26-2013, 10:43 AM
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Half-Ass Member
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Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 22,005
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Not Ranked
I'll save you the math, but in a Cobra, to maintain, say, 70 MPH on the interstate, you will need less than 35 horsepower. At 2000 RPM that's less than a 100 ft/lbs of torque. Why are they quoting 300 ft/lbs?
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06-26-2013, 04:42 PM
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CC Member
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Join Date: Mar 2007
Location: Waco,
TX
Cobra Make, Engine: Lone Star Classics / Roush 427 SR
Posts: 280
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Not Ranked
Guys,
Certainly don't want to start a big fuss, and I don't know what torque number it takes to maintain speed in my car in 6th gear. All I can verify is what I know to be true from what I have experienced in my own car for over 30,000 miles since September, 2007.
I have no idea what the torque number is on my Roush 427 SRTW #444 at 2,000 RPM, but I know it is enough for smooth operation at 2,000 RPM with the Tremec T56 in 6th gear with 3.89 rear gears and 25.5 inch tall rear tires.
The car cruises smoothly at 2,000 RPM in 6th gear and has no problem at all maintaining speed in 6th gear at that RPM.
I have had zero problems with the Tremec T-56 transmission and the valve covers and oil pan have never been removed from the engine.
If any of my combination breaks tomorrow, I will be happy with my past service and performance and would gladly replace whatever breaks with the same parts without hesitation.
Jody
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Roush #1
Lone Star Classics
Roush Edition #01
Roush 427 SR #444
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06-26-2013, 07:11 PM
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Senior Club Cobra Member
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Join Date: May 2001
Location: Florence,
AL
Cobra Make, Engine: RCR GT 40 & 1966 Fairlane 390 5 speed
Posts: 4,511
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I have a small block stroker. 354 c.i.
I have had it dyno'ed three times at two different shops. Both started at (about)2200 rpms.
Before I stroked the motor I had it dyno'ed at three different shops, all started at 2000-2200.
My 354 makes 325 ft lbs of torque at 2200.
I have a couple of buddies with KC 482s and they cruise at 2000 rpm about 70 mph with no trouble. I don't think you will have to worry. When WE want to pass we do not have to down shift!
Dwight
__________________
''Life's tough.....it's even tougher if you're stupid.'' ~ John Wayne
"Happiness Is A Belt-Fed Weapon"
life's goal should be; "to be smarter than inanimate objects"
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06-27-2013, 06:38 AM
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Senior Club Cobra Member
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Join Date: Mar 2001
Location: Southern Connecticut,
CT
Cobra Make, Engine: SPF - 351W, 944 non-turbo
Posts: 2,105
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I know I'm really anal abut this stuff but torque is measured in "LB-FT", work is measured in "FT-LBS". I know, you guys checked your torque wrench and it says "Foot-Pounds", but they're incorrect on the units. That's because Craftsman and Harbor Freight never took a physics course. You don't have to believe me, go to a Ford or GM internet site and check the engine torque numbers for yourself.
Bob
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06-27-2013, 06:41 AM
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CC Member
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Join Date: Dec 2001
Location: Louisville,
KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,417
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Foot pounds is a measurement of energy. However, if you really want to get anal about it, there should just be a "dot" in between each abbreviation, denoting that the units be multiplied together. With that in mind, you are technically able to write it in either way as torque is defined as lbs of force multiplied to a moment arm.
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06-27-2013, 07:41 AM
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Half-Ass Member
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Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 22,005
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Not Ranked
I still haven't gotten an answer to my question on where the 300 ft/lbs came from and why. Most of us have enough strength in our arms to keep a Cobra moving down the highway at 70 MPH, at least for a short while.
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06-27-2013, 09:14 AM
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CC Member
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Join Date: Aug 2012
Location: Eatonton,
GA
Cobra Make, Engine: Superformance 2729, 351W
Posts: 52
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Not Ranked
The dyno sheet on my engine starts at 3000RPM - 243HP and 425.3 LbFt torque. I try to keep the motor above 2000RPM on the street and it pulls smoothly; not race conditions but not jerking around.
4600RPM - 409.9HP and 468LbFt torque
5800RPM - 476.7HP and 431.7LbFt torque
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06-27-2013, 02:25 PM
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CC Member
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Join Date: Dec 2001
Location: Castalia,
Oh
Cobra Make, Engine: EM cobra, 450 inch sbc running a best ET of 9.14..so far..ALL MOTOR...approx 800 horse.............ERA with 482 FE..All Aluminum Engine
Posts: 1,395
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The last time I was on the dyno I had 681 lbs at 2700 rpm and then spun the tires on the dyno....the graph looked like falling off a cliff when the tires spun
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Jack
XSSIVE .....
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06-27-2013, 02:52 PM
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Join Date: Oct 2000
Location: Crystal Lake,
IL
Cobra Make, Engine: Everett-Morrison, 434 cid
Posts: 977
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A more relevant question might be... "will your cam, intake, and carb combination support a part-throttle load at 2000 rpm?" If it will you will have enough torque. With my current motor I can cruise at 1600 rpm in 6th gear and I know the motor isn't making 300 lb-ft of torque at 1/8 throttle at 1600 rpm.
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06-27-2013, 06:25 PM
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Senior Club Cobra Member
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Join Date: May 2001
Location: Florence,
AL
Cobra Make, Engine: RCR GT 40 & 1966 Fairlane 390 5 speed
Posts: 4,511
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I forgot to say my six pulls were on a chassis dyno's.
If you buy a KC 482 you will not have any trouble cruising at 2000 rpms. I have driven two Cobras with his 482 motors and both can and do cruise at 1800-2000 rpms with no problem.
Dwight
__________________
''Life's tough.....it's even tougher if you're stupid.'' ~ John Wayne
"Happiness Is A Belt-Fed Weapon"
life's goal should be; "to be smarter than inanimate objects"
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06-27-2013, 08:02 PM
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CC Member
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Join Date: May 2006
Location: St. Louisville,
Oh
Cobra Make, Engine: A&C 67 427 cobra SB
Posts: 2,445
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Quote:
Originally Posted by patrickt
I still haven't gotten an answer to my question on where the 300 ft/lbs came from and why. Most of us have enough strength in our arms to keep a Cobra moving down the highway at 70 MPH, at least for a short while.
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I agree they likely pulled 300 out of the air, but it is not a silly stupid number either. Yes to maintain speed on the level you need less than 100 lb-ft (hey there is no dot on my keyboard ) of torque, however to go up a hill or accelerate you are going to need considerably more. If you have to down shift at every hill you wouldn't be happy. Considering most people are thinking about cars that weigh considerably more than a Cobra, it's not that bad of a number.
Last edited by olddog; 06-27-2013 at 08:06 PM..
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06-27-2013, 08:19 PM
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Half-Ass Member
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Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 22,005
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Not Ranked
Quote:
Originally Posted by olddog
If you have to down shift at every hill you wouldn't be happy. Considering most people are thinking about cars that weigh considerably more than a Cobra, it's not that bad of a number.
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Alright, I'll buy that -- you're probably right.
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