8V71 turbo specs

[lostagain]

I think the torque is more significant than HP. The seat of the pants feel of a turbo Detroit is of sustained pull throughout the power band. On my 6V92TA, that is between 1200 and 2000 rpm. Going up a hill, it seems to settle a bit and then power steadily up the hill. It takes a serious incline to have to down shift.
I noticed that same thing after I turboed the 4-71 in the Courier 96. A natural will lug and slow down until you have to down shift. After turboing, you can feel the torque pushing steadily up the hill.

JC

[RJ]

I think the torque is more significant than HP.

BINGO!!

[buswarrior]

BINGO!!

To elaborate: We have to re-educate ourselves. The car marketers many decades ago latched onto horsepower numbers as a way to fool us into buying things.

A busnut needs torque to climb hills.

Pay attention to the torque number, differences here will kick you hard in the seat of the pants.

happy coaching!
buswarrior

[luvrbus]

Problem is you need a certain amount of HP to develop the torque on a diesel engine cars just need hp and rpms for speed 

[Geoff]

If you watch the TV commercials​ on pickup trucks they always mention the torque specs along with horsepower.

--Geoff

[luvrbus]

Yep I been looking at new pickups (friggn crazy prices) they have the 6.7 diesels up to over 400 + HP and over 900 ft lbs of torque at 1800 rpms that is more a 8v71.Ford and Chevy are battling it out in that race Dodge and Cummins are getting left in the dust.
After reading seems like the small diesels are getting 2 ft lbs of torque for each HP and the larger truck diesels are 4 ft lbs per HP    

[TomC]

Yes that's true that there is a pickup truck horsepower/torque race going on. And those power ratings are only released from the engine computer under light load situations.
BUT-when the engines are installed in larger trucks, like the Ford F650 and F750, the power rating is restricted to 660lb/ft torque (Powerstroke 6.7). On the 6.7 Cummins when installed in a M2 Freightliner, 300hp @ 700lb/ft is the highest, and if running an Allison 2000 series, 660lb/ft torque. Good Luck, TomC

[Geoff]

Yes that's true that there is a pickup truck horsepower/torque race going on. And those power ratings are only released from the engine computer under light load situations.
BUT-when the engines are installed in larger trucks, like the Ford F650 and F750, the power rating is restricted to 660lb/ft torque (Powerstroke 6.7). On the 6.7 Cummins when installed in a M2 Freightliner, 300hp @ 700lb/ft is the highest, and if running an Allison 2000 series, 660lb/ft torque. Good Luck, TomC

That "light load"torque ratings make the commercial claims more believable.  I couldn't fathom how they could get such high torque readings out of a small diesel.

--Geoff

[luvrbus]

They lower the torque and HP on those engine for another reason as the engine in heavy duty truck are always under constant torque not like a pickup,those engines would not last 60 days in truck at 440 hp and continuous torque of 910 ft lbs

[sdc53]

The coach in question has N75 injectors and an upgraded, newer thinker rad.

[bevans6]

Scott, not sure what coach you are referring to but I have an 8V-71T with N75 injectors in my MC-5C with a stock cooling system in what seems to be great shape, and I don't have an overheating problem.  Towing 8,000 lbs in decent east coast mountains and 90 degree temps, I run below 195 degrees.  So it can be done, and you can control the power you produce with either smaller injectors or a controlled right foot.

I always laugh a bit when people talk about "it's torque that counts".  Power and torque are two sides of the same coin, they are exactly the same thing.  They have a little thing called time between them, like the center of a cookie.  Torque is like voltage, it is potential energy.  Time (in this case RPM, key on the minutes) is like current, it's voltage going somewhere and doing something, it's torque being used to do work over a period of time.  Power is torque times time, same as power (watts) is voltage times current.  Specifically horsepower is torque times RPM/5252.  The "divided by 5252" is just a fudge factor to make the units come out in HP.

Since power is what does the work (energy expended over a period of time) in an engine we tend to like it if we have a lot of power in an RPM range that is extremely useful to us.  So in a bus or a big truck we like to see a lot of power very low, so we see torque peaks as low as 1200 rpm, and the engine produces a lot of power at 1200 rpm, and we feel the effect in acceleration, or climbing a hill.  We call that a "torquey engine".  But if we change the gearing so the same engine could produce the exact same torque at twice the RPM,  we'd have twice the power to play with.  What's the bottom line?  In actual driving, we need the engine to produce enough power over a wide enough range of RPM so we can move the load at low speeds, accelerate briskly to high speeds, and pull hills on the highway.  The part that uses the most power is the accelerate part, so we like an engine that has great torque over a wide range of RPM so it can produce a lot of power over the working RPM range.

My truck engine, in a Ford F250, produces 570 ft lbs of torque at 2,000 rpm, on a dyno somewhere.  In the truck, it's completely impossible to make it produce that amount of torque.  The computer backs off the torque in first gear, and in any gear higher than that full throttle results in a far higher RPM range than 2,000 RPM.  That's because the computer wants the transmission to live in first gear, and in all the other gears assumes I want maximum power regardless of what the torque happens to be, and gives me the RPM range that produces maximum power, not maximum torque.

[Dreadnought]

I always laugh a bit when people talk about "it's torque that counts".  Power and torque are two sides of the same coin, they are exactly the same thing.  They have a little thing called time between them, like the center of a cookie.  Torque is like voltage, it is potential energy.  Time (in this case RPM, key on the minutes) is like current, it's voltage going somewhere and doing something, it's torque being used to do work over a period of time.  Power is torque times time, same as power (watts) is voltage times current.  Specifically horsepower is torque times RPM/5252.  The "divided by 5252" is just a fudge factor to make the units come out in HP.

Bingo!

You have the heart of an engineer.

Its good to see that I'm not the only one laughing.

Power is rate of torque, (just a energy is rate of doing work) basically.

[TomC]

Just a sideline to torque-Detroits DD engines are now producing maximum torque at 975 rpm with suggested cruise speed at 1,300rpm. With the low end torque, direct drive transmissions, 2.16:1 ratio, with 517rpm tires, that would give at 65mph cruise at 1,210rpm. Also with over 14:1 starting gears, they had to go to much larger U-joints. Even the new GHG17 engines, as clean as they are, are only a tad more expensive to run (mainly because going from 3% to 4% DEF burn in relationship to fuel burn) Good Luck, TomC

[luvrbus]

It always been torque starts you moving and HP keeps you moving.I like the torque on the newer engines they are not like a older diesel that long flat torque line is the best.

[TomC]

Yes-the torque curve (nearly flat) is a far cry from old days of 238 and 318 Detroits, Super 250 Cummins, 1693 Cats, Maxidyne Mack.