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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. |
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. |
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. |
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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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 |
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 |
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 |
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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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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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 |
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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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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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 |
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