1. #1
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    Default truck torque ratio?

    We are planning to purchase a Tanker Pumper with a minimum 2000 gal. tank and we were told to get a truck with at least a 330 hp engine because of the torque ratio. What does this mean? Thanks

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    Default Hmm..

    Are you sure it isn't torque rating? A 2000 gallon tanker is going to need a pretty good bit of grunt to get moving, and to get enough you may need to need to move up to a larger displacement higher rating motor. 330 horse doesn't seem out of line to move 45K.

    Torque Ratio has to do with how much torque is coming out of the transmission at launch versus how much is going in. Here's a blurb explaining it

    Acceleration is all about torque, and by definition, a torque converter multiplies engine torque. To accomplish this, the torque converter relies on a component called a stator, which increases the output torque by redirecting the oil flow into the impeller's inlet fins in the same rotational direction as the engine. The stator also incorporates a one-way clutch assembly to allow this process to occur when the converter is at stall, and to overrun when the converter is 90 percent coupled hydraulically. After measuring the torque output on the dyno, we can assign a value or ratio to the torque multiplication by using the equation: output torque / input torque = torque ratio. B&M's dyno measured 537 lb-ft of output torque, and we divide it by the input torque of 230 to find the torque ratio of 2.33 (537/230=2.33). This is the multiplication ratio produced by the torque converter. Torque ratios between 2 and 2.5 are common for most converters. Torque ratio is like having an additional lower gear in your transmission.

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    It takes a LOT of torque to get all that weight moving. If you speced a smaller engine, it would take a long time to get up to speed. I would go even bigger than 330hp, might look at 400+ hp. 2000 gal is over 8 tons of water.

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    Default Torque curves

    One thing that is overlooked all to often is an engine's horsepower and torque curves. The people who plug the smaller engines in order to win an order on low price don't tell you about that part (maybe they don't even know about it themselves).

    In addition to looking at the horsepower and torque ratings you have to study the curves. A torque curve that rises too slowly, peaks out at a high RPM or declines to rapidly will give you sluggish performance. Caterpillar and Cummins both show their curves on their web sites. I'm sure Detroit does too, but I haven't been able to find theirs.

    With that much weight you need big power to go and big brakes to stop. Don't skimp on either one. Unless you're on flatland with no traffic, the C7 and C9 Cats, the C and even L Cummins, the 40 Series Detroits and DT466 Harvesters aren't going to get it. Unfortunately, that also means going to the 4000 series Allisons which is considerably more bucks than the 3000s.

    Stay safe out there, everyone goes home!

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    Remember their wording to you: get at least a 330HP. I read that as saying a 330 will do it, but barely. I'm with the others, put at least a 400HP in there. If you're building a truck that will need to make at least 10 years as the 1st out tanker the last thing you want to get into is drivetrain issues. Underpowered trucks are one of the most common mistakes in building apparatus and end up costing more in the long run. It's not about being able to stand on it and lay down rubber tracks like back to the future, it's about being able to handle the weight without straining. It does depend on terrain like CE11 mentioned. Hills will make that truck slow down to a crawl. Around here we're flat so no big deal but we still spec 500HP+ in all apparatus to pretty much guarantee no drivetrain issues for the 20 total years we expect to operate the trucks.

    And certainly we're all playing with limited budgets, but it's more important for the truck to be able to get there safely than have some of the bells and whistles. Getting there safely means a truck with enough get up and go, and also enough stop on a dime action. Larger motor means more efficient auxiliary braking devices (at least that's the way I heard it but correct if wrong). If that means 1800 gallons for now to get the bigger motor, it might be worth a look. 200 gallons on a tanker shuttle won't make a difference in the number of tankers you invite on the 1st due alarm anyway. Most tankers aren't that different in configuration so slapping a larger tank on down the road when you have the extra bucks should be able to be done. And you'll have the drivetrain to handle the load already in place.

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    An L(now M) Cummins with the right transmission and rear end will move 2-3000 gallons of water nicely.Given the option,I would prefer the 14 liter engines to do the job,again I believe 375-425hp is a good starting point for a tanker.You wanna get ruined?Get a C-15 Cat and get yer motor running. T.C.

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    Quote Originally Posted by Ledebuhr1
    It takes a LOT of torque to get all that weight moving. If you speced a smaller engine, it would take a long time to get up to speed. I would go even bigger than 330hp, might look at 400+ hp. 2000 gal is over 8 tons of water.
    How much Torque are we talking about comming out of a 330 hp? Cant be to much. We are Putting a C-13 430hp w/1550 lb. ft. @ 1200 rpm in a 1000 Gal rescue pumper.

    You may want more power. You may also want to make sure thats not the peak for the motor. Ours had a range 400hp to 525hp. We are buying it with 430hp and if we had to at a later date and for a pretty penny we could boost the HP and Torrque output.

    Do you have a relitivly flat district? Cause that water will kill you on a hill.

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    The L and M cummins have nothing to do with each other and have existed side by side for years. Years ago the L10 was a small version of a full size motor, then it disappeared, then the L designation reappeared as a slightly overgrown version of the 8.3L C engine. (Jakes available though which makes it slightly better.) However any tender (tanker) needs to have a full size engine and powertrain same as any semi, dump truck, etc. Don't fall for the cheap low price high horsepower small engine, it will come back to bite you. Also horsepower rating is not what slows the truck, it takes engine displacement to do that. A big engine is a safe engine

    Birken

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    Default Big engines

    It all comes back to what we used to say as we were modifying our flathead Fords, putting Olds engines into '50 Mercs and other stuff teen age boys did in the 1950s - ain't no substitute for cubic inches!

    Stay safe out there, everyone goes home!

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    We have a 3000 gal Pete with a 330hp Cummins and some hills, plenty of power. A neighboring dept. has a 315 they are please with it. Talk to the engine people.

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    On the other hand we have a 3000 gallon tender with a 350 HP Cummins (ISC) and that thing is an absolute dog. I guess not all hills are created equal.

    Birken

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    The L is a 10 liter engine as opposed to the 8.3 liter ISC so there is quite a difference in performance.We bought a couple L's now we run the 11 liter M series.In a tanker in the Cummins line I would prefer the ISX(14 liter)although a 380-420 horse M will move water nicely.Or if you care to really abuse yourself,how about a 8V92TT tweaked and fueled? Hope you got a pair,'cause that's a quick little water hauler(3200 gal). A 350 Cummins is "generic",depending on who set it up they can be dogs or runners.Neighboring depts have one each,one is a dog and the other is a runner,pulls any hill you can throw at it with ease.How you connect the "squirrelcage" to the rubber can have a profound influence on performance. T.C.

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