Thread: Engine Hp?

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    Default Engine Hp?

    Looking for some input regarding HP for an engine we will be going out for bid on for delivery in 2006. Looking to bid a custom,1000 Gal. tank, 1250-1500 GPM pump with CAFS. A couple people on the truck committee think that we need a 450 hp/4000 series engine/trans combination. We cover about 25 square miles with only one big hill that we do not have to go down and back up too often. I would think that a 370 hp/3000 series engine/trans combination would be more than addequate. Looking at about an 18-20K difference in price. One truck committee member would rather give up AC,custom chassis, or CAFS to get bigger engine. I would rather not dictate what they do. One of our other engines has similar set up with a 330 hp, it could use a few more, but I do not think an additional 100.

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    How about letting the manufacture give you the options on horse power rather than specing one and have it be wrong. The horse power required for operation g the pump, CAFS system, A/C, Alternator, Generator, and any other load on the engine are genrally known numbers or can be calculated. Also if you write a performance spec that the truck has to go from a standing stop to 35 mph in a desired time and sat from 25 mph to 50 mph than you are gtiing the correct applacition for your needs. Also have the bidders quote different engine options as add on. Maybe you are a "Detroit Company" and a Cummins is the best fit price wise and will have the same performance.

    Just as a work of caution be carfullt with the Cat C-7 engine. I know there are a large number of Cat people out there and the other engines seem to be great such as the C-12, C13, and C15.

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    I agree, let the manufacturer assist you with it. There will be requirements for the pump, accessories. I will say that keep an eye on the torque as well though. HP is the number everyone shoots for, but torque is what gets you moving from a stop. I have an engine that carries 500 gal of water, and it has a 370 hp motor and a 3000 series allison trans. I would never stick this motor in a truck with 1000 gallons of water though. The motor has a smaller block and is just turned up quite a bit. The torque is lower on it because of this. That may be what the guys that are advising you about are shooting for. The the 400 hp motor has the extra torque to get the truck moving.

    That motor size is hitting the line between bumping up to the larger tranny (which is the expensive part). One thing you could do is lower your gear ratio in the rear axle. You can gain a little get up and go from the stop sign, but you give up top speed. In my opinion, the truck shouldn't go any faster than 70 -72 mph if you don't have any interstate. Thats even excessive on alot of back roads.

    I will say that DON'T GIVE UP THE A.C., Custom Chassis, or CAFS. If you have those in your spec already, those are things that are safety issues for your crew and the customers. The A.C. is an item for rehab in the summer time or just after time in a fire. As for the custom chassis, the cabs are plain and simple built protect the occupants of the truck much better than any commercial cab I've seen. The CAFS is going to help put that fire out much quicker and with most likely with less water.

    Talking with the manufacturer is going to be the best thing to do. THey have the info on what can be done and the best ways to do it. Its better to ask than guess.

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    Default engine hp

    The mfg has the curve for horsepower. I can tell you that Phoenix FD has just bought several pumpers with 455 hp cat motor and the next group will be the 505 hp. we have really no hills just flat land and they are running the high hp engines. also look at the epa rating for the year you will be getting your unit. this will be a big factor with all engines in the next year. good luck

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    Consider more than just the horsepower number. For instance, engine manufacturers generally allow their engines to put out quite a bit more horsepower in fire apparatus than in a commercial vehicle. I question the wisdom of this practice. A candle that burns twice as bright burns half as long. Do we want the components of our fire apparatus to be under more or less strain than their commercial counterparts?

    Another thing to consider is the vehicle supplemental braking system. There are four major types:

    The exhaust brake. Doesn't work for beans.
    The electromagnetic drive shaft brake. Works well but pulls a lot of electricity from the alternator and is heavy.
    The transmission retarder. Works well but puts a lot of heat into the engine cooling system. Also the extreme heat put into the heat exchanger has the potential to crack it thus introducing antifreeze into the transmission mandating transmission rebuild. To prevent this you have to replace the heat exchanger from $800 to $2500 every few years.
    The engine brake (Jacobs brake). Works very well, doesn't add any extra heat or weight to anything. One of its side BENEFITS is it requires a large engine. This way you won't be as stuck with an itty bitty engine pumping out too much horsepower. Mufflers are now available that take all the rap out of it.

    I believe I wrote in my wish-list for our next engine that the motor should have at least 75% of its horsepower available in braking, and 100% would be desireable. Braking is the most important thing IMO.

    Birken

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    Your thought process is good to much hp is good if this is what is needed
    But wasted if not needed
    I would suggest looking at about 400hp
    Reason being is the size pump and CAFS you may run into an issue with low rpm availlable hp
    With the diesel engines having to deal with emissions they are running leaner which means there is less hp at low rpm
    This is an issue that is amplified with hi hp draws
    Another thing to look at is go with a larger series engine and the lower hp for example rather than a series 40 at 350hp possibly look at the series 60 at 370 or 400 hp I believe you could still use the 3000 series trans
    or possibly look at what engine will give the best hp for the budget
    and not lock into a specific engine brand
    good luck
    stay safe
    Ray

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    Originally posted by flmslayr2
    In my opinion, the truck shouldn't go any faster than 70 -72 mph if you don't have any interstate. Thats even excessive on alot of back roads.
    Check your tire sidewalls.

    Unless you specify otherwise, many trucks come through with tires rated for 55mph and under.
    Last edited by Resq14; 10-16-2004 at 07:36 AM.
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    Our new one is 370/1250 water and we have PLENTY of hills.Not the mouse motor 370 either but the 11 liter version.Runs out at about 65 mph.Almost any of your "new big block"motors are laptop dialable meaning you can take them from 350ish to around 500 with no major hardware changes AS LONG AS the transmission can stand the torque input.Again your manufacturer can be a wealth of information,just be sure you have the right questions.Big brakes and compressor are a must too,they run cooler and last longer.A 370(big block) properly specced will horse 1500 water with no problems whatsoever.At 1000 gal I've hauled a lot of it with an Int. 549 gas so a modern Diesel is NO CONTEST! T.C.

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    I would put a ball park HP in your spec. They will tell you if its not enough for the vehicle and equipment. See if you can get a compromise with your group on a 400HP. Why do they want the extra HP? If its for speed, thats the wrong reason. I would be more concerned with the specs for the transmission, drive train and brake system.

    And whatever you do, DONT let them talk you out of the AC

    Dave

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    BirkenVogt welcome to the site! This is Ggg6 from TDS.
    Gregg, I have spent a LOT of summers in your area, that being said I know how hot and short your summers are. If your Dept runs an ambulance or a chiefs buggy to fires (who doesn't) then they could easily be used as the rehab area, thus sacrificing the AC on the pumper. All I am saying is consider the demographics MN v/s AZ or FL. I agree with Birkens thoughts on braking, and turning up a small engine. A 1250 pump is max for a 330 h/p engine, a 1500 gpm pump will require a bigger engine, and it will also knock you up a series in the trans and chassis (both commercial and custom). The larger the engine displacement the higher the torque will be, less likely for the engine to over heat due to it not running at maximum power, the more effective the engine brake will be, and the stress on the engine will be less or a given h/p. I have seen what the mfg's have speced for the "recommended engine rating" and I have driven them as well. Well I would say they were lethargic at best. So you might consider a certain % above and beyond the requirements for "reserve" power. After all as the engine gets older it will not be as efficient thus make less power.

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    Ggg - where are you getting your pump hp requirements from? 330 hp is good to a 1750 gpm pump. There are plenty of E-One Typhoons and many commercial pumpers with max 330 hp and 1500 gpm pumps. 1750 is not that popular, but you could go 1750 gpm on a 330 hp as well. And all you have to do is bump the 330 to 350 hp and you can drive a 2000 gpm pump.
    You might need more than 330-350 for other performance reasons, but not to drive the pump.

    GreggCaske - I have to agree with you vs. the truck committee - 450 hp is likely overkill and giving up Custom for hp????? Our district sounds about like yours, we went with 430 hp Detroit Series 60 with a 750 gal tank and there's a lot of extra hp that we don't need. I see a lot of 330 hp/1500 gpm Custom units out there and the Pierce Enforcer with a 400 ISL Cummins/1500 gpm is also very popular.

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    We have a 95 Spartan 1500gpm and 1000tank 300hp Cummins. We respond to 36 square miles a couple of good hills and interstate highway and no lack of power. Talk to the engine manufacture. Most of them wonder why we need so much hp. Torque is more important.

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    I'll put it this way
    when you are talking about pumps, and how much hp to drive trucks,
    the folks at Darley should know

    They brough a demo pumper to our facility. Wasn't what we went with, to big amoung other things, but it was a Darley truck - Spartan Big Easy chassis, 1500 gpm pump, CAFS (I think a 225 cfm compressor) and 1000 gallons of water. HP was not an issue with this truck.

    I think with a 330hp engine could handle CAFS and a 1250gpm pump. Remember, with CAFS you will not likely max out the pump and CAFS compressor at the same time. the above 400hp engines will necessitate a bigger trans, both of which drive up cost. It may also limit chassis/cab options. Bigger may not be better

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    Pfd,the mfg may "know"but here's what I know.A mfg IS NOT going to set a unit up with an 11,12,or 14 liter motor if it will function with a nine liter.Profits you know.A 9 liter motor(330 hp ISC)8.3 cummins has now been "Fire"rated up to 400hp(ISL).These are different motors but both are in the 9 liter and 330 ish range.That being said in one of my depts we have a 1250/1000 Spartan Advantage with a 330(Isc),in my other a Spartan Gladiator 1500/1250 with a 370 hp 11 liter ISM.These units are only 40 hp different but they are like are like night and day in terms of road drivability.Engine mfgs "tweak"small engines for Fire service use which I personally am opposed to.Let's use for an example the 3208 Cat.It started out life as a 190 hp delivery truck motor,got turboed and "juiced"for the Fire app to 250-275 hp and now the fishermen have got it to 400ish.What do you supposed happened to the reliability? Same goes for those 'lil 330's.Yes,I know everybody runs them with little or no problem.But for a life safety vehicle carrying an large load of water and material the is NO SUBSTITUTE for big power and big brakes.IE an 11 liter or bigger with a genuine Jake(not an exhaust brake)and heavy axles.These items cost you once but will save you over the life of the unit particularly if you keep them over 15 yrs.We average 25-28 before we fully take them out of service.This based on local economics not preference.So to say a 330 is adequate may or may not be a truthful statement depending on a whole lot of other factors.For my liking a 330 is a bit lean to run a big pump with Cafs.It will do it but there is a pretty good load with everything running.I'd rather be in the 400 range with your choice of Cummins ISM/ISX,the 12.7 liter Detroit 60 or the CAT 12,13,or 15 liter motor.And no A/C?I think not!On most trucks,it will cost more to NOT have it than to have it,as almost everything today comes with it stock.Used to be easy,would you like the six or the V-8?So many choices,so little time.T.C.
    Last edited by Rescue101; 11-13-2004 at 02:01 PM.

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    T.C., you said all the things I have been saying and then some. Excellent analysis. Especially the part about a "life safety vehicle." In the future I plan to strongly suggest to the administration that we purchase much larger motors in the past and I will definitely throw that little phrase in there. Like you, I fail to see the logic behind allowing manufacturers to install engines uprated over and beyond their commercial application power output ratings in fire apparatus. In reality these ratings are the same as RV ratings. In my world fire apparatus engines should be MORE reliable than commercial trucks, not less.

    Birken

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    RESCUE101-I'll agree with you

    The head mechanic at our closest full time department is adament that
    a 1500gpm pump will require 300hp. That's just the pump, and with the pump in good shape. His experience with some of his older vehicles is that when it's time to pump test, they make sure the engine is tuned first. their latest trucks are spec'd with Series 60 detroits @ 450hp & the big allison.

    With our latest vehicle, a rescue pumper, we went the other way. To get the chassis we wanted, we had to choose between a Series 40 Detroit or a Cummins ISC or ISL. We have the 330hp ISL, and kept the pump at 1000gpm. we determined that for the truck, we didn't need a "big" pump, especially with the on board foam system.

    I understand you problem with maxing out smaller engines. When is a engine going to be straining the most? Maybe up hill on the way to a fire, or at a fire if it is pumping max output. We've been fortunate, but for the fires we've had, the hardest our pumps ever work is during pump test.

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    Default HP

    You have got to look at what you are going to get for torque.. Torque is what runs the pump. The bigger the motor, the more hp the more torque. Also look at what the company is doing for communication between the trans and the motor, it can all be tweeked up to diff hps etc.

    Also, what I would recommend is if you go with the big motor you take a good look at the 60 series detroit motot. If you go with the mid range motor which I think you should go with look at the cummins for more options. In the process of specing an engine now and we originally looked at the detroit 40 series 330hp, and when I talked to the builders they changed my mind. For the same or little more money you can get into the cummins. The detroit is 330 hp @ 950 ft lbs, only option until the 60 series, the cummins 370 isl is at 1200ft lbs. For other options cummins also does 350,and 400 small block and a 400 big block plus there big line. many more options. but I like the 60 series detroit if your going with the big block.

    Stay safe

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    Mercedes is also putting out a decent engine with lots of torque. We are currently specing out a 3000gallon tanker with 400+hp and 18speed auto transmission.

    For a pump with 1700 galons of water do you need 500hp? What do you want to accomplish? Speed to me is not an option, It is a fire truck not a sports car. As long as you have the torque to give you the power to get the job done plus then thats what you should aim for.

    Other than that I agree with T.C.

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    Dave
    The more wear you have on a pump, the more HP it will take take to meet flow.

    The first thing to take in consideration is how much pump you need, how much hp to drive that pump, and then build in a safety factor to compensate for wear on both the engine and a pump.

    A 330 hp engine might meet pump test with a 1750 gpm pump. For a while....

    We had a demo truck in last year with a 1750 pump. The salesman is also a sharp firefighter, said the truck, if used by a busy FD would have trouble with pump test in years to come, not that the pump would be bad, just the engine/tranny/pump combo might not cert out sometime down the road, with our usage it might never be an issue.....

    Trucks in general seem to exude a bigger is better philosophy, not necessarily so IMO. A truck must meet the departments needs.

    I'm curious about some of these big pumps. How many people really use 1750 or more gpm at a scene on a regular basis? In my experience, the hardest the trucks are ever worked is during pump test. Unless things go backwards, and we start having more instead of less fires, our newer engines with 1250 gpm pumps will never see the use that the old backup trucks, with their 750 gpm pumps saw.

    Also, about speed of the trucks, the highest I've seen any truck builder or chassis mfg set top speed for is about 70mph. Our newest truck, when it arrives, is spec'd for about 65mph, tops. It's engine will allow it to do that in pulling most of the hills in our area, but I doubt it will be pushed to that.

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