Hemi's in 1 tons

[Prairie Dog]

Steve, I guess I dont understand why you multiply the diesels by the trans ratio of . 69 but not the gassers? They also have a similar transmission ratio.

It seems like you have to calculate the gassers the same way to make things accurate. With either engine equipped with an auto, torque multiplication is the same. Ditto the manual transmission.

As far as grabbing another gear, our CTD's don't need to. I cant count how many times I've passed 1/2 ton gassers on hills and heard that little V8 screaming as I went by. All because we make our torque at half the engine speed they do.

I will agree with you on one thing, that I6 in your ford was long lasting engine. I think they discontinued them because of emissions.

 

[DPKetchum]

And discontinued them because of almost uncontrollable spark knock/pre igntion. Lots of them burned holes through pistons. I sold reman engines for ATK of North America for a while. Lots of 300 fords with holes in pistons. The re-mans used aftermarket pistons that were thicker and a thicker head-gasket to try to control this. Delta uses them in almost all ground equipment and when shopping Atk for engines this was a BIG issue with them. Claimed that GOOD re-mans out lasted factory new for that reason.

 

[Trizae]

most of my customers are getting 15 plus with the HEMI's,, that with 3. 73 gears. . I 've got one customer who has gotten as high as 22mpg with a 1/2 ton HEMI. The biggest difference between a Gas and Diesel if $35,000 or $45,000 MSRP



That and if people are trading every 2 or 3 year,,,,,,, they really arent getting the investment out of the diesel,,





with that said,,,,,,,, you know what i'm driving

 

[Prairie Dog]

I hope I don't sound like I'm beating a dead horse here but Steve's torque mathematics aren't accurate. (I dont know why I didn't think of this last night when I responded) Torque is not multiplied when it goes through the transmission and rear end, only RPM's are. Torque remains constant (minus some parasitic loss). Dyno results reflect this.

 

[Steve M]

"Torque is not multiplied when it goes through the transmission and rear end, only RPM's are. Torque remains constant (minus some parasitic loss). Dyno results reflect this. "



Wrong. Dyno's calculate engine rpm and wheel speed to determine gear ratios in their formula as they compute flywheel HP/torque. I wish the dyno's would print out simple torque/mph readings regardless of engine rpm or gear selection. You'd be surprised.

Any gear reduction multiplies torque.



http://www.fourwheeler.com/techarticles/68958/index1.html



Here's another. Go to the bottom of the article for the topic at hand.



http://www.elephantracing.com/techtopic/hpvstorque.htm

 

[Prairie Dog]

I guess we'll have to agree to disagree on that one as I found a number of errors in those articles. Check out the torque ratings of the AAM diff and NV5600 trans - Both well under 600 Ft lbs. I've run on the dyno many times and I don't remember entering gear ratio's. Maybe thats why dyno runs are usually done in the most direct gear.

At any rate enjoy your ride whatever it may be.

 

[Trizae]

my biggest beef with a 3500 HEMI is that they dont offer it the application that makes the most sense,,,,,,,, 3500quad short bed,,,,,,,,, you can by on in a reg long bed or a quad long,,,,, with or with out dual rear wheels,,,,, but you cant get a short bed,,,,,,,,

 

[Steve M]

"Steve, I guess I dont understand why you multiply the diesels by the trans ratio of . 69 but not the gassers? They also have a similar transmission ratio. "



Because at 70mph with a HEMI you 'can' lockout O/D and still be just getting into the power band. With a 4. 10 ratio you can't lock out O/D with the diesel. If this doesn't make sense, head out on the interstate and try it. You'll be at redline and not making power.



Please feel free to enlighten me on some of the errors you found on the web site I linked to. HP and torque are calculated on the dyno. You can't simply read HP and torque at the rear wheels. It has to be calculated using many variables. Gear reduction multiplies torque. Gear overdrive reduces torque. If you're reasoning were correct, putting a cheater bar on a wrench wouldn't give any torque leverage. Block and tackle wouldn't work and bicycles would all be single speed.



http://vettenet.org/torquehp.html



Here's another site. It uses an extreme example of a high torque/low rpm waterwheel and how gearing up reduces torque. But I suppose he's all wrong too.

 

[Cummins Cowboy]

one place I worked at had ('94 and 95)ford ecnonline vans 2 where powered by 351's and 3 where powered by 300ci i6 fords. We loaded our vans with about 2000#'s of carpet cleaning equipment and water. I can tell you that the 351's would leave any of the 6's in the dust wasn't even a race. And the i6's got the same or worse mileage cause you had them floored at every possible moment. A cummins with an auto feels kinda like driving a gelding the power seems wasted through the auto. however no 300ci I6 ford gasser will even come close to out pulling any cummins I have ever driven and that includes my old first gen with 160hp and 400 tq. You guys that claim all this great mileage with gassers, well all i will say pulling loads and driving many different combos of vehicles and trailers etc my experiences have been greatly different. the 5. 9 dodge gas engines in our 1/2 tons got about 12mpg unloaded with a mix of city and highway. our van that I mentioned above got about 10mpg with a mix of city and highway. isuzu NPR box trucks with 350 ci chevy v8's got around 6. 5 mpg mix of city and highway weighing about 11000#'s gross. I don't think i have ever seen less than 11 MPG from a cummins pulling any load in any condition. And when pulling any kind of a load the gassers mileage quickly drops to around 6-6. 5 be it I6,v6,v8 etc. My experience has involved fleets (at 2 places I worked we had over 25 vehicles at each place)of vehicles of all different makes and types and different drivers. Clearly my experinces have been different than some of you guys, all I can say as when a load needs to be moved I wouldn't put anything else besides a cummins in front of it

 

[DPKetchum]

My experiance has been the same as years. Fuel mileage with a gas is ROTTON I dont care who's gasser it is.

 

[Big MAK]

sorry about the bump but this seems more like a 'which is good at what' discussion not necessarily third gen cummins diesel.



fwiw; I had a 454 in a GMC crew cab -- it had one of those unbalanced cranks from the 91/92 batch. Couldn't keep anything connected to the belt working more then about 3000 miles. New alternators, water pumps, pulleys, new belt ever 500 miles, ... GM wouldn't take it back -- but after LESS THEN 3mpg towing 11,000lbs (was barely making it from gas station to gas station driving across S. D. running 60mph on a windy day) it didn't stay in the driveway long until I had a Cummins and I've been driving them ever since. Too bad about the GMC though; just a lemon. A guy 2 blocks over from me has been driving it for three years up until a couple months ago when he finally traded it. I talked to him about it; apparently GM finally recalled those engines and replaced them all. After my third fan belt and first round alt/pump/etc I told them it had an unbalanced crank -- wouldn't believe me of-course. He had a really good truck after the engine swap; lucky dawg; GM wouldn't help me with it.



My neighbor is getting 7-9mpg with his Hemi. He also owns a Cummins (lawn service business). He's thinking of trading the Hemi on another Cummins. In the interests of full disclosure he's also making 2 points less compression then the Hemi is supposed to make; but so far Daimler-Chrysler is refusing to help him. It's spent several weeks in the shop. Funny thing; to keep his business going they rented him a Ford from the Ford dealer! The Dodge dealer didn't have any trucks to rent out.

 

[PRout]

Hey, I love my Cummins, but I don't love the VP-44. Replace 1 or 2 of those at over $2,000 each, and you may wish you had a hemi.

 

[Pit Bull]

Originally posted by Shortshift

Hey, I love my Cummins, but I don't love the VP-44. Replace 1 or 2 of those at over $2,000 each, and you may wish you had a hemi.

$2000, you most buy the gold plated ones.

 

[mcoleman]

17mpg is about the tops I've seen with the Hemis. I'm not impressed with their performance at all. The 2 wheel drive short bed 1/2 tons are only running low 15s And I still haven't seen any of them with traction problems on the line. They have no bottom-end torque. My last two 4 wheel drive Suburbans with 350s both got 18mpg on the highway. But wouldn't get squat when towing as they had to be held on the floor climbing hills. Took a friends V10 Dodge to Indy once. We were both almost broke by the time we got back home. 9 to 10 mpg tops. But at least the Dodge V10 has a little power to go with the poor mileage. The Ford V10s seem sluggish with no more power than the 351s but I have heard a few guys claiming they get 13mpg. Shortshift How many VP44s have you had to replace? And why are you paying $2500. 00 for them. They run around 700. 00 to 800. 00 and shouldn't be failing unless you are running without a fuel pressure gage on dead lift pumps. I know of several trucks with over 100,000 on the stock VP. 1 has close to 500,000 on his and another has 174,000 miles with no problems. I could see one failing when installing a box but not otherwise if fuel pressure is watched.

 

[drives mopars]

did u read the truck mags

trucks mag did rd test said hemi mileage was bad

but they loved truck not sure what mag it was



as for power it will run with me at light

after about 40 iam gone ive ran one already

up hills in od it was easy to pass

driver was employee who i did not know until he approached me

and said the normal thing you whipped me



see if a hemi is still doing hd work after 200 k miles