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Discussion Starter #1
Prior to picking up my 2007 duramax tmorrow morning, I test drove it today as well as my alternate deal 2006 Dodge Ram. Even with the 360 HP in the Chevy, it felt weaker than the Ram with 325 HP. Comparing both at spedds below 60. However, once above 60 they both had equal accleration. Any thoughts as to why the Chevy has less low end acceleration? Also, both 3.73 axle, and the Ram only a 4 speed auto.
 

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Line them up and tell us which one has better acceleration.
 

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Discussion Starter #4
Deagon Kennels;1601178; said:
Line them up and tell us which one has better acceleration.

The ram with less HP & Torque, and 600 lbs heavier, accelerates faster with better throttle responce. However, the Checy has more pep in 6th gear over 60mph w/o having to down shift to previous gear.

My question is, does it have something to do with the EGR, ad the Ram doesn't have an EGR even with its CA emissions.
 

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Are you going by SOTP or did you line them up side by side? I have never heard of a stock Cummins running 15s, much less mid - low 15s like a stock LBZ will do.
 

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How are you basing this difference in performance?

If it's SOTP (seat of the pants), it's a really lousy way to measure things.

We heard this with the LLY also, but nobody has yet to prove an LLY is underpowered when you actually measure the performance.
 

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Discussion Starter #7
McRat;1601225; said:
How are you basing this difference in performance?

If it's SOTP (seat of the pants), it's a really lousy way to measure things.

We heard this with the LLY also, but nobody has yet to prove an LLY is underpowered when you actually measure the performance.
SOTP may not be accurate within a second or 2, but this test was noticeabley night and day. The LBZ felt sluggish in comparison.
 

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ron54;1601205; said:
The ram with less HP & Torque, and 600 lbs heavier, accelerates faster with better throttle responce. However, the Checy has more pep in 6th gear over 60mph w/o having to down shift to previous gear.

My question is, does it have something to do with the EGR, ad the Ram doesn't have an EGR even with its CA emissions.
I'll bet dollars to donuts you are only perceiving this because the Cummins is so much louder than the Dmax.I just hope you're looking at more than just speed in your buying decision because obviously that's not what most truck owners are only looking at.I
 

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I test drove an 06 Dodge when I bought my 06 LLY. No comparison. The Chevy blew the Dodge's doors off. They have to de-tune that truck because they still don't have a tranny that can run with the big dogs - hello Ally!.
Also, my old truck was a 98 Dodge. Entire Fuel injection system is a mess and they are still using the same system today. In fact if you have problems with the lift pump (and you will if you buy one because they only get 40-50K miles out of them), the dealer will not replace it. They have a new directive to abandon the pump in place and put a new, separate electric pump in line. I loved my Dodge because it was my first diesel and just like my Dad's but I had a lot of problems with it over the years. Had it 7 years and only had 70K miles on it. They wanted $5,000 to fix the injection system (lift pump went bad and ruined the rest of the system - they think). Traded it in on the 06LLY! Just my 2 cents.
 

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I think the Chevy is so much quieter you don't realize what it is actually doing. Line them up side by side and see which one really goes.

Gearing could be different down low also, rearend ratios and tranny rations??

Tim
 

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ron54;1601252; said:
SOTP may not be accurate within a second or 2, but this test was noticeabley night and day. The LBZ felt sluggish in comparison.
"felt" and "was" are two drastically different words. I refer you to my earlier post. How many stock Cummins trucks do you see running 15s in the 1/4 mile. I haven't heard of an LBZ that didn't run 15s stock. My LLY ran a 15.7 and I'm at a supposed 50 horse disadvantage to the LBZ.
 

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The LBZ should smoke the cumminapart, I mean cummins!:driver:
 

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Discussion Starter #13
JoshH;1601280; said:
"felt" and "was" are two drastically different words. I refer you to my earlier post. How many stock Cummins trucks do you see running 15s in the 1/4 mile. I haven't heard of an LBZ that didn't run 15s stock. My LLY ran a 15.7 and I'm at a supposed 50 horse disadvantage to the LBZ.
Did anyone ever compare the LLY to the LBZ? Is it probable that because of the LBZ bigger EGR tube, that the actual HP at the fly wheel is less than the LLY?
 

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Colorado Christian;1601272; said:
Entire Fuel injection system is a mess and they are still using the same system today.
I'm sorry, but this is COMPLETELY AND TOTALLY incorrect. Other than the fact that both a '98 and a new dodge both use 6 injectors, there's not much else similar between them. First of all, which '98 engine are you referring to? The early '98 12v, or the 98.5 24v? If it's the 24v, you're right-the fuel system IS a mess. A mess of a dumbass lift pump that gives up the ghost whenever it wants to, and a vp44 that then dies as a result of the lift pump not supplying enough fuel to cool and lubricate the vp44. (Oh, and there's also the internal electronic failures plenty of vp44's have experienced even when the lift pump is good.)

If you're talking about the 12v engine, that one used the bosch p7100 pump in those days. That's probably the absolute most reliable injection pump ever installed on a diesel pickup truck. I'm not joking-that thing is a freakin legend. It's literally nicknamed the million mile pump, and for damn good reason-they hardly EVER go out unless contaminated fuel takes them out. Not coincidently I'm sure, that pump is the only one ever put in a dodge with a cummins that's lubricated by engine oil-it does not rely on the fuel for its lubrication. In keeping with that, the list of alternate fuels acceptable for use in a p pump-equipped engine is larger than for any other 5.9 in a dodge truck, because it can tolerate fuels with less lubricity than any other pump.

By comparison, the current ('03 and up) dodges use a common rail system. The injection pump for that is the bosch cp3. GUESS WHAT ELSE USES THAT PUMP? That's right-the duramax. Those seem to work ok, don't they? The pumps are not absolutely identical of course-one feeds 8 cylinders, the other only 6, and the routing of the various lines and wires attached to the pump is different. They're still both cp3 pumps. The gm uses no lift pump, which to me is an advantage-one less thing to fail. As most of you probably know, the common rail system is not at all like the earlier systems used on the older dodges (or older gm's for that matter). For starters, the injection pump on the older cummins is a completely different model, using different innards to develop the high pressure. The common rail has just that-a common rail, one fuel "log" from which all injectors are fed. The injectors are controlled electrically, like in an efi gas motor. On the older dodges (all injection setups, back to and including the bosch VE rotary pump on the '89-'93's) there's a separate line from the pump to each injector. The PUMP determines when any given injector "fires", the injectors are not directly electrically controlled. You can loosen an injector line on any of the pre-cr systems and will only lose that one cylinder. Not so on a cr setup-loosen any part of the high pressure system on a common rail motor, and none of the injectors will get enough fuel pressure to spray effectively. That's because they're all tied together by the common rail. Speaking of pressure, that's another major difference with the cr setup-the fuel pressure is MUCH higher than on the earlier systems. On the dodges, the spec for max fuel pressure developed on a stock motor (at least for the 5.9's) is 23,400 psi. The older systems are considerably lower, half that or less. (funny thing, not coincidental-the duramaxes and the dodges both need to go to a dual cp3 setup at basically identical hp levels. That's a direct result of them using the same basic injection pump.)

In fact if you have problems with the lift pump (and you will if you buy one because they only get 40-50K miles out of them), the dealer will not replace it. They have a new directive to abandon the pump in place and put a new, separate electric pump in line. I loved my Dodge because it was my first diesel and just like my Dad's but I had a lot of problems with it over the years. Had it 7 years and only had 70K miles on it. They wanted $5,000 to fix the injection system (lift pump went bad and ruined the rest of the system - they think). Traded it in on the 06LLY! Just my 2 cents.
Which generation of truck are you talking about? The '98.5-2002 24v? If so, you're pretty much right about lift pump life. I don't know what the dealers are doing with those, I'll take your word that they're replacing faulty stock lift pumps with something else. If you're talking about the '03 and up cr trucks, I don't know what you're talking about. There has been no rash of trouble with those lately. The '06 (or '05, can't remember) trucks use an in-tank lift pump, with good results. The earlier cr trucks use a lift pump mounted up on or near the engine. There was a moderate amount of trouble with those, but that seems to have really settled down. The dealers are supposed to replace those with an in-tank pump like the newer ones if they give trouble. In most cases, a failed lift pump on a cr motor does NOT take out the injection pump like it does on a vp44 motor. It might eventually, but the high rpm bucking and cutting out should tell any driver with functional brain cells to take it in to be looked at. Meanwhile, if the truck has not been driven for long periods while actively misbehaving because of a dead lift pump, the injection pump is usually fine.
 

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Oh, on the question if which is faster/quicker unloaded, I find it hard to believe that a stock 325 hp cummins would keep up with a stock lbz. I can't even see how it could FEEL similar, let one like the dodge was faster, unless something was wrong with the lbz. Like someone else said, I don't know of any stock cummins that will run in the 15's. I had an '04.5 2500 4x4 dodge that was STONE stock. I ran it in 4 hi so I could run it up against the converter and build boost w/o blowing the tires away. It ran a best of 16.48. The newer ones aren't really any faster stock, so how an lbz would get beaten by a stock dodge with a cummins is a mystery to me.
 

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The fueling system on a 98 Cummins and an 07 Cummins are absolutely night and day. Absolutely nothing is the same.

I trade a 2006 Cummins with the auto for the truck below. The Cummins makes an incredible amount of torque down low and feels very strong off idle through a couple of gears. However mine would get outrun anyday by fellow coworkers with DMAX trucks from any speed although it was less obvious from 0-60. A big ole inline just does not accelerate like a V8.
 

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Discussion Starter #17
COBRAJET;1601352; said:
The fueling system on a 98 Cummins and an 07 Cummins are absolutely night and day. Absolutely nothing is the same.

I trade a 2006 Cummins with the auto for the truck below. The Cummins makes an incredible amount of torque down low and feels very strong off idle through a couple of gears. However mine would get outrun anyday by fellow coworkers with DMAX trucks from any speed although it was less obvious from 0-60. A big ole inline just does not accelerate like a V8.
Exactly. In testing both the cummins had better low end, but once above 60 mph, the duramax had more power without having to downshift as often as the cummins.
 

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WHen I bought my 06 D-max, I test drove an 06 Cummins right after the D-max. I left the Dodge dealer laughing at the lack of performane. it may pull good, but in traffic, around town, and acceleration, it was a dog.
 

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I have been through this before you can only get a 3.73 gear axle ratio with the duramax, with cummins you can get a 3.90 or bigger rear axle ratio.People tell me all the time that the cummins feels snappier and quicker then I race one just to prove a point and they shut up.
 

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Discussion Starter #20
bubbatruck;1601416; said:
I have been through this before you can only get a 3.73 gear axle ratio with the duramax, with cummins you can get a 3.90 or bigger rear axle ratio.People tell me all the time that the cummins feels snappier and quicker then I race one just to prove a point and they shut up.
Cummins comes in 3.73 & 4.10. The 3.90 is only with the Hemi in a 1500 1/2 ton. The model I compared was with a 3.73.
 
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