HO comes alive at 2k, why the wait?

[Wheaties]

Hi All,



I know we've talked about this before, I think I read every thread before I got my truck. Now I can't recall what the outcome was on this issue.



I have the ETH/DEE and recently got together with the Northeast TDR folks (soon to be Northeast Diesel Power? 8)) and of course, we spent some time test driving each other's rigs. What a great bunch of guys!!



Anyway, I kind of was left wondering why I have such a long lag time between when the pedal goes to the metal and when the power really arrives. I always thought this was turbo lag, but some more test driving with the guys suggests that everything happens at 2k rpm. This is about when you feel a second and substantial push back into your seat.



I don't have boost and egt gauges yet, it will be some time before I do, so I can't report back on that.



Is this part of the ECM? Is this normal? Or what?



Thanks,

Matt

 

[MCummings]

Originally posted by mwheaton

... I know we've talked about this before, I think I read every thread before I got my truck. Now I can't recall what the outcome was on this issue...



... Anyway, I kind of was left wondering why I have such a long lag time between when the pedal goes to the metal and when the power really arrives. I always thought this was turbo lag, but some more test driving with the guys suggests that everything happens at 2k rpm. This is about when you feel a second and substantial push back into your seat.



I don't have boost and egt gauges yet, it will be some time before I do, so I can't report back on that.



Is this part of the ECM? Is this normal? Or what?



Thanks,

Matt

As I don't have the time to really explain what *I* Have learned. I'll say what I can.

The delay in the power is to ease the load on the drivetrain.

A stock Dodge/Cummins is nearly a Dog below 2K. . WHY??

This has to do the Cummins/Dodge Engineers decisions...

Keeping the power "off" below 2K heps keep EGT's low, and damaging drivetrain vibrations down. The inherant design of an inline 6 cylinder lends itself to bad (damaging) vibrations below about 1,800RPM. IF the power were to come on Below 2K many many consumers of Dodge/Cummins trucks would be driving around, and towing below 2K RPM,, resulting in many many more broken parts.



I just "BOMBed" my truck,, I thought my truck was cool, and descently fast for a Diesel,, I drove around town going to Wide Open Throttle (WOT) from idle, to 3K RPM and never thought twice about it.

NOW, with the addition of DD1's and a PE COMP, besides the smoke, if I go to WOT below 1,800RPM there are some hideous grinding type noises,,, Sounds like an old Jeep in reverse, Just alot deeper,, maybe like a tractor.

Also, If I go to WOT at that RPM my clutch slips alot easier than if I am at 2,500RPM.

(Did I say the truck is way fast now?,, well, it is )



General rule for the Cummins,, Keep the RPM up!, below 1,600RPM is considered lugging. Lugging is VERY Bad for the Cummins,, It is better to be at 2,600RPM for hours on end than to settle for 1,600RPM. (or even 2K RPM).



Let me say what Bill K. taught me. . ,, and the experiment I did...



There is a hil by my house, it's maybe a 6% grade about 1/4 mile long,, the speed limit is about 45MPH, If I go up this hill in 5th gear I easily exceed 15Lbs of boost, just maintaing speed.

Same speed, in 4th gear. . I can stay close to 5Lbs of Boost, and can accelerate and stay under 10Lbs of boost.

Less Boost=Higher MPG

even though it seems like an oxymoron that I can get excellent MPG at 2,600RPM and Bad MPG at 1,600RPM it is very true. (That is Towing)



High RPM will extend the life of the entire drivetrain,, and will not be detrimental to the motor,, enev if it is,, and say you take off 50% of the motors life,, you can still get into the 200,000 mile range.



I don't know if you have heard of the "5th gear nut" problem, (on 5-speeds), this problem is when the Nut on 5th gear backs off and allows the gear to slip of the only partially splined gear shaft.

Why Does This Nut Back Off ??

Driveline vibrations,,,, Seems the Cummins sets up vibrations in the transmission below 1,800RPM that,, no matter how tight, or how much "lock-tite" is used the nut will still back off. General rule of thumb is either don't drive in 5th gear below 1. 8K RPM or don't get on the fuel below 1. 8K. (Best thing is to do both, No fuel, no drive, below 1. 8K). This is hard for me to do, as the speed limit in most places here is about 45-55MPH.





Oops,, another long post,,, Hope I didn't confuse you.



MerrickNJr



P. S. I coulda just said, "Bean Counters" wanted the Higher RPM wait for power. Hope this helps.

 

[Sixspeed]

Why does it feel like at anything above 2200 or 2300 rpm's. The engine is reving higher then it wants to. At 2000 rpm's the engine just purrrrr's even towing my trailer. Or is it that I am to much of a puss to let the engine run at those rpm's

 

[MCummings]

No puss. . just "normal"



My Dad showed me,, by owning this vehicle for 75K miles that 2,600 RPM gave better MPG under full load than did 2K RPM. Full load is a fat, overweight trailer (30K trailer alone) (Different story with weight)



If you are pulling lighter than MAX GVWR, or MAX GVCWR 2K is perfect,, this is actually a sweet spot.



The best way for me to tell you to find out where the engine is happy,,(1,600 vs 2,600RPM) is for you to be outside a truck that is straight piped. Listen to the motor under WOT at 1. 6K and WOT at 2. 6K.



2,600 RPM IS Spinning fast,, your not a puss just cautious.

My truck at 2,600 RPM sounds like a gasser spinning 4,000 RPM.

2,200-2,300 is about peak usable power.



What my 18yr old brain is trying to get out here. is. .

If you have a choice between 1,600-1,800RPM WOT and 2,000-2,800RPM WOT is,, go for Higher RPM.



Where's Bill Kondolay ???? He made is sound so simple for those guys with auto's.



MerrickNJr

 

[Wheaties]

MCummings,



Thanks for the info. I had thought that this was specific to the ETH, the other trucks I drove at the last meet didn't have this 'second push', just lots of power all over the tach. Also, I didn't hear anyone volunteering that their ETC was like this before it was bombed.



Still what you have to say makes sense.



Are there any HO drivers out there with the same experience? Or does this just happen on my truck?



Thanks,

Matt

 

[RonaldLarson]

Huh?

This site is supposed to help members understand their trucks. There appears to be a lot of boggus info to be had in this post. Please look at and absorb the factual data available in the pamphlet that shows you where the torque and horsepower are at their most usable RPM's with this engine. Your Dodge dealer has the pamphlet. The Cummins diesel does NOT develope it's most torque at any thing above 2100 RPM. The sweet spot is between 1600 and 2100 RPM. Run it there, and all the advantages of this great engine will treat you well for many years.

Ron

 

[Wheaties]

Ron,



Don't get me wrong, I love my truck, and I love this HO. I was surprised to discover that the other guys' trucks weren't quite the same. I am very interested in answers and information.



Matt

 

[JJW_ND]

There is a difference between 12Vs and 24Vs

I have 200K experience on a 96 12V 5sp pulling hard. And now 20K on a 2001 24V 6sp. The older 12V loves 2000 RPM WOT all day and all night. Tested may times. It continues to pull hard as done to 1800 ( I usually shifted then) Best MPG at or below 2000 towing and running empty.



The new 24V does just fine at 2000 RPMs WOT but does fall on its face real quick below that. It does like to rev but the MPG drop like a rock pulling.



Both trucks have 3. 54 gears and even in the new truck would not a lower gears. That is what the 6sp is for.



I would say the 24V likes it 200 RPMs higher then the older 12V.



These are just two trucks and here expericence might be totally differenet.



jjw

 

[HEYBOSS]

Originally posted by mwheaton

Hi All,



I know we've talked about this before, I think I read every thread before I got my truck. Now I can't recall what the outcome was on this issue.



I have the ETH/DEE and recently got together with the Northeast TDR folks (soon to be Northeast Diesel Power? 8)) and of course, we spent some time test driving each other's rigs. What a great bunch of guys!!



Matt

Would you like to borrow my Edge EZ?



Fred.

 

[Neal Cassady]

I'm with ol ron

My truck pulls real strong from about 1600 to 2200, after that the show is over. It will spin up to 3000 but there isn't any "push" left, just noise.



Dave

 

[nps]

Got the same operation on my ETH. About 1800-2000 the power really comes on. Was real noticeable new, now not so much with 10K miles and a couple of hard tows. Is it me not noticing? Or the engine smoothing out the transition? The mysterious 'break-in' limiter that has been rumored to be in the controller program. Don't know.



On a thread sometime back (a MAD ECM one I think) it was speculated that there is a programmed power-on around that RPM - as restated in this thread. Maybe the ETCs make less power stock so the power-on step isn't as noticable???



Anyway - mine went away from my consciousness on it's own. Think any box will probably smooth it out also.

 

[RustyJC]

Originally posted by mwheaton

Anyway, I kind of was left wondering why I have such a long lag time between when the pedal goes to the metal and when the power really arrives. I always thought this was turbo lag, but some more test driving with the guys suggests that everything happens at 2k rpm. This is about when you feel a second and substantial push back into your seat.



Is this part of the ECM? Is this normal? Or what?

Yep, since about 1500 miles, under hard acceleration (unloaded) our ETH/DEE really starts pulling hard at about 2100 RPM and keeps pulling up to at least 3000 RPM. Sorta reminds me of my old Yoshimura Road & Track-cammed Honda 750-4 or my Crane Z-300-8 cammed 1965 289 Mustang! I'm hoping the Edge EZ will fatten up the midrange some - the dyno curves for it look like it will.



Rusty

 

[mikel]

I have the same experience with my truck. It just doesn't "wake up" until about 1800-2000rpm. It will pull much better all the way to about 3200rpm than my last truck would. The last one was a '99 auto and it was all done at about 2800-2900rpm.



Just my experiences with my trucks, YMMV.



Mike

 

[Sixspeed]

I know when I installed my VA box and I'm sure the EZ box does the same thing. That the way it changes the timing and the fueling really made a difference starting at 1500 rpm's up to 2100 rpm's. Then the engine seems to go flat from about 2200 to 2500 rpm's. Then comes on strong again to about 3000 rpm's. Which I think (I am no expert here) has something to with the torque curve having to fall off before HP curve can start to go up. Anyway thats the way my truck does it's thing.



Les

 

[MCummings]

Re: Huh?

Originally posted by ol ron

This site is supposed to help members understand their trucks. There appears to be a lot of boggus info to be had in this post. Please look at and absorb the factual data available in the pamphlet that shows you where the torque and horsepower are at their most usable RPM's with this engine.

Ron

Woops, sorry,, to many opinions in one post.



Look at brochures.



All I can say is the trailer we towed, if I was at WOT at 1,600 RPM RPM would not noticeably increase (in 3rd 4th or 5th gear) yet at 2,600RPM I could go ahead and speed up. Of course WAYYY Over GCWR.



MerrickNJr

 

[nps]

Brochures

Originally posted by MCummings



Look at brochures.



MerrickNJr

Maybe I'll find my missing vanity light and pull handles there too.

 

[MikeR]

Having owned two 24v/sticks,and driving alot of 24v trucks... all I can say is all 24v's have the 2k rpm spike. Adding a timing box or the Torqus ecm changes the power band.



-Mike

 

[MCummings]

#ad




Because the 24V Cummins is electronicly controlled it has a Flat Torque Band. The ECM controlls the torque and HP. There is a TDR magazine out that explains this. (between issues 31-33 not sure which)



MerrickNJr



Edit: Whoo, 430 posts,, Tried to make them all good. These weren't my best. .

 

[Diesel Freak]

2K powerband Hit

I have always had this.

With injectors it is even more pronounced, so that leads me to believe that it has to do with the ECM fueling curves. The HP/TQ graphs in the brochures are suspect after seeing the actual TQ/HP curves for my truck with just 275's. The only thing I agree with on the brochures is the RPM where peak HP comes in at. With 275's I had 233 HP at 2750 rpm with peak torque at 2250 rpm. When I added the puck, the attitude of the engine changed completely. The smooth transition to the 2K "hit" was gone. Now it rips and snorts from 1600 rpm... that is why my clutch died... wet pavement is also a real PITA!

 

[RustyJC]

Yep, I've seen the torque curves, but the calibrated seat of my pants says something different when running unloaded - I really don't notice the "2000 RPM spike" when towing the 5ver. Again, running unloaded, the ETH definitely wakes up at 2000 RPM on the street. If fueling boxes like the EZ "cure" this characteristic, I'd say that it must be a function of retarded injection timing or reduced fueling rate programmed into the ECM below 2000 RPM at less than maximum load.



JM2CW



Rusty