I know I maybe starting an argument here, but, here goes: What difference does engine displacement make in a truck (35k gvwr or more)? I have always thought I knew the answer, but some recent threads on here have made me think. If you can get 400 hp out of a pickup engine, why don't truck makers use them? I know that they make that hp at a higher rpm than a truck engine, and thus less torque, but with all the emphasis on lightening up trucks in some vocations, you'd think you'd see a few. I know there is a demand for big power in trucks today, but certain fleets are looking for low tare weights more than they are driver happiness. I see a lot of people on the internet advising each other that you can't gross 50k with less than 400hp, but I frequently do it with an L-10 270. I used to move D8s with a 237 Mack. Oops, hijacked my own thread, back to the subject: I personally have my doubts about a 5.9 Cummins lasting in a truck like a 11 liter, but maybe somebody here can convince me.
opcorn.
i do believe that there is no replacement for displacement but how many 5.9 cummins are in f800 dump trucks running around with a load dirt and a backhoe on the back with 4,5,600k im not saying that it will pull like an 11 liter diesel but compared to a gasser its worlds ahead as far as economy and reliability ive rebuilt bbc and ive rebuilt 6bt's i can tell you there is no comparison the size of the bearings thickness of the components its built to last compared to any gas engine. will it last 1 million miles who knows depend on the driver because if i wanted to i can destroy any cummins detroit or cat with some careless driving. i had some one bet me once i couldn't blow up his Toyota pickup( he was gonna swap in a sbc any ways) it took me about 5 hrs of intermittent driving and voila a rod out the side of the block.
I definitely agree it's way better than the gas engine, and I'm not trying to rehash our earlier discussion, I just got to thinking about this. And I wasn't picking on the Cummins, I don't know anything about the newer ones, but the older ones that were just Cummins engines, exactly like you'd find in a crane or something, were great engines. Even the DT 466 gets put in tandems. I'm not arguing, maybe you are right, I just got to wondering about this. Are the ones in the F800s like the pickup engines, or lime the industrial engines? What hp do they make?
I've pulled out the truck engines they use the same pump parts everything only difference is sae bell housing adapters. The 6b and 6bt in industrial applications have a different injection pump those pumps parts are not the same I've bought a 6b that was for a water to put in a swamp buggy needless to sayump was governed to only 2 rpm choices couldn't change so I had to source a timing cover pump lines exhaust manifold etc
When you have a big motor detune,it'll last longer and give you less problems since its not having to work as hard. With the smaller displacement motors, they are turned up and having to work harder. Also, the trq of a big motor at 400 hp can be 1000+ where on a truck motor is ~800-850. Big trucks can get 500k before needing major motor work where the smaller ones generally are around 250-300k on the high end. Just my thoughts and opinions Brett
While you can get high torque and hp out of a smaller diesel, you won't get the same efficiency. An engine that makes peak torque at 1,400 rpm is going to use less fuel to do the same work as an engine that develops the same torque at 2,800 rpm. There's also the cost factor. The engines in light trucks cost an arm and a leg.......and when the injectors need replacing outside of the warranty period, they'll cost a kidney.
As far as cost depends on the enginr I'm swapping a bad injector as we speak on my cousins idi 7:3 and it was only $45 for a rebuilt one from my local injection shop the one for my 7.3 are more expensive at $180. So it all depends on the engine. I do agree on the efficiency Note.
The 7.3 is a great motor, although I don't recall my '96 f250 putting out 400 hp and 800lbs of torque...lol- wishful thinking. I was thinking about the new Duramax's. My uncle is the service manager at a Chevy dealership. He said the bill on replacing 8 injectors is around $10,000. However, you can order a set online for the bargain price of $5,000.
On the Internet, Cummins was wrong to make any motor besides the 5.9. It can be tuned to any horsepower level and used in pickups, class 8 semis, mine haul trucks and large ferries and container ships with no concerns about durabilty. It is the perfect engine for any application.
It's easy to take a medium duty engine and put it in a pickup and have it last, especially when it's installed with a torque limiting device (aka Dodge transmission). The 5.9 has a better than average reputation because Cummins hasn't oversold it. Remember the 5.7/6.2 GM or the higher HP 3116's. There are lots of 170 HP 3116's out there doing fine, but apparently the engine wasn't up to making 350 HP regularly. There are lots of fine 5.7's out there too, they just run better on gas. Speaking of which, you can't compare the construction of a gas and diesel directly (as GM learned). The diesel has to be heavier to take the shock, that doesn't mean because it's heavier than a gas engine that it can make more HP and maintain durability.
I think some of you are taking things the wrong way. This was in relation to another thread about a c70 that had a gas engine. We are saying a b series Cummins for the reason its cheaper easier find and way easier to service than a 427. Yes any big diesel from a class 8 tractor would be better but you can't get a decent engine from a big tractor for 2k. But I've bought banged up dodge trucks for 2-3k and I'm thinking a Cummins doesn't need 400 but a 300hp 5.9 would still very reliable IMO and worlds ahead of a 427. Bigger would be better but some times its not feasible
Actually, I said when I started this thread that I agreed the that the 5.9 would be better to have in that truck than the 427, I just wasn't sure it was worth the work and expense to change it over, and I wondered if it would be reliable in a truck after it was suped up. Now in this thread I just was trying to start a general discussion.
There is only one way to find out lol
After going from a 350 or a 366 gassers in two different chevys, c-60 & 7000, to a 7.8 diesel in a Ford f-800, its a world of difference. I haul weights that I wouldn't have even though of with the ford, and do it faster, with less fuel usage. I was getting no better than 6mpg with the gassers, staying about 22k - 28k pounds, I'm getting mid 12's with the f-800 loaded into the mid 40k range. Oh, and the trucks all had 5x2 trannies. Now if I load my new f-350 6.7l to 30k it will pass the f-800 in a heart beat, it just get about 10 loaded like that. The biggest difference to me is the torque and the speed at which you loose rpms pulling hills, the diesels just carry the loads better.
Exactly. I know that they were put in large-ish trucks everywhere, but there is no reason to get one and then put the screws to it to make 300 HP. Just leave it at 220 or whatever it came with, that the CPL will allow, or change the parts necessary to get the rating, instead of just messing with the fuel settings and hoping the rest will hold up. 220 is fine for most places, the diesel will be cheaper to run, and you will never miss the 2 minutes climbing that grade that a hundred extra hp would have gained you, at the expense of reliability and availability of the truck. The rest of the time on flat ground or downhill or sitting in the field getting loaded, it goes just the same. All that being said if the total cost is 4000 bucks and the GMC gets 4 mpg and the cummins gets 10 then payback is in 6667 miles if my math is correct. That might be OK but I would still look for a used tractor with a road ranger and an air conditioner and air brakes, myself.
I believe your original premise was the difference between displacements in diesel engine and horsepower. In other words why would anyone want an 11 liter over a 15 liter for a highway application? The 15 liter will generally always use more fuel, weigh more and may be more costly to repair per occurrence. The 11 liter will get you where you want to go generally using less fuel. The up side of the bigger engine is that it will maintain speed over a wider variety of terrain and require less work on the part of the driver. In hilly terrain it can and many times does get better fuel mileage than the 11 liter. From my experience the bigger engine has a longer service life which usually gives it a better life cycle cost. They do get better resale value at trade in most of the time. I'll put it this way from experience, anyone who has run a 318 Detroit, 220 Cummins or 3208 Cat never wants to have to go back an do it again after they have run a Detroit Series 60, Cummins ISX15 or Cat C15.
I agree, and there is a safety issue as well. A truck pulling Donner, Cabbage, Snoqualmie, Grapevine, etc. @ 20 MPH is far more dangerous in heavy traffic than a bigger powered truck doing 40MPH. Then there is braking HP....
I agree Mitch. In my opinion Cubic inch is king when talking about horsepower,torque,& engine longevity in any vehicle.I think there are alot of mid range applications where the 5.9 would work fine in its stock horsepower rating,not 400 horsepower.The exhaust temperatures would be off the scale in a hard long pull and it dosent have the bottom end for it.It would be like compairing an 855 big cam cummins to the 5.9, Big difference in size everywhere,cubic inch,crankshaft/bearings ,etc. My first truck driving job was in a 1968 International fleetstar 2000 with a home made wrecker body,It pulled decent & got the job done. Looked similar to this www.truckpaper.com/listingsdetail/detail.aspx?OHID=4025509 It had a 270 small cam 855 cummins with 10 speed road ranger & 2 speed single rear axil .We drug everything in with it.Pulled in alot of loaded tractor trailers with it. Then we set up a W-900 Kenworth tandem axil with a 400 cummins & Holmes 750 bed.It was quite a change pulling with the Kenworth with the 400 engine . Another example I often think of is my old G 1000 Moline.Its non turbo & rated at 110 horsepower with a 504 cubic inch engine www.tractordata.com/farm-tractors/000/9/8/986-minneapolis-moline-g1000-engine.html We pulled a 21 foot disc with it and you bury the disc in the ground and bring the tractor down to an idle and the 504 engine would just keep chugging along at 500 rpm then runner back up to 1800 with no trouble. I also think modern engine horsepower is abit over rated as compaired to the more conservative engine ratings in the 1970's & 80's.
A local RV repairman with a clean 92 Dodge 5.9 added a later model Dodge duallie pickup with a cummins (so he could move RVs)...he bought it used. It has an aftermarket exhaust temp gage. On the short hills, the xhaust temp climbs but then he is over the hill by the time it is a problem....on a local grade of a couple miles at 6-7% he has to allow over 1000 degrees (and he has seen 1300 plus) or he has to manually downshift and slow it down...we advised him in the interest of his wallet to continue not hurrying up that particular grade.