Dyno!

[AH64ID]

 

 

which brings me to the last part,   the difference we feel  @ 1600 vs.   2500  in the same gear.  (thanks for clarifying  which gear you were in)         If  cummins'  numbers  are   correct,     theoretically,     the  1600   should  hold  the  rpm   steady  far easier than  the  2500..     Are  you  misinterpreting  the  fact  it's more   difficult  to   ACCELERATE   going up a hill   with  1600  as  the starting point??      

look at it as  TOTAL  engine demand.      1st,  you  need to maintain  speed.  It takes  X amount  to maintain speed.     it's pretty   easy  to see a  truck  in  5th gear  @ 1600 rpm  will be going  a lot slower than  the same truck  already  turning  2500.      So  you have momentum  already  on your side...    and  the resulting   ability to  MAINTAIN   isn't as  taxing  to the  torque output of this  engine.

When you approach the same hill  @ 1600,    you have far less momentum,    and  now  we have  2  needs to be met.   The original  torque to MAINTAIN,  plus  now  we  need  additional torque to replace  the lost  momentum (accelerate)   because the momentum  was never there to help out.       

Maintaining  rpms,  and   accelerating,   are   2 very different   load demands  on an  engine  with finite amount of  torque.

 

I don't have the long grades  you western guys  have,  but I do  have  the loads!      Can you explain  to me  how  I  hit the bottom of the hill  at   2500, in  5th gear,   and  within  1/2 mile up the grade        my rpm is  now  17-1900  and  HOLDING??  why does it  hold there??      It's  called  getting back into the  torque sweet spot.  or  'torque rise'.     when the load  is  greater than  what  5th gear  can hold,   I shift down again..   

If  horsepower  was such  the   savior,  I wouldn't  have lost  the rpm  @  2500  in the first place.       Torque is  the  ONLY thing coming  out the end of the crankshaft.

I am talking about maintaining speed, not accelerating.

The reason you settle to 17-1900 rpms is as much about power production, as it is about power requirements. The speed associated with 2500 rpms takes too much power to maintain and you slow down. When you slow down to a 17-1900 rpm your power output is now equal to your power requirement.

Torque rise is real, and I am not pushing that off but your beyond that. It also means you have to lug the engine to get there, which is not reccpmmended.

My example still stands. A truck with a flat torque curve struggles to maintain speed at peak torque of 1600 rpms, but can pull the same grade in the same gear at 2500 rpms without being WOT. There is more parasitic engine drag, and a higher power requirement from the increased speed.. Yet it's easier to maintain speed.

The acceleration difference is from the horsower. Yes the inertia helps, but it still takes an increase in power to accelerate.

Good times.

[rancherman]

uggg. 

 

Acceleration comes  from   applying  more torque to the rear wheels  than  the  total resistance  from  gravity,   road  and  wind resistance,  and  vehicle/load  mass    are trying to   hold the vehicle  back.

 

 

I  see what you are saying about  rolling over the hill starting  at  2500 rpm..   I  too    have    experienced this  with a lot of  heavy hauling  over the years!          I don't  lug  on  purpose either,        any engine  that  does not  respond to  additional  throttle  is  considered  lugging  in my  camp.    Doesn't have to be a lot of  response,  but   some..   we call it   'free to accelerate'.    If  I'm  running   half throttle @  1700,  and  desire more rpm,  I  mash down a little  harder..  if  I can't see or hear a fairly immediate   response in the   tach...  I   downshift..     

Please  don't lecture me  on  how to  handle a load.   I've  certainly paid my dues.    pickup trucks  and  small    20k  loads  are not  exactly   a   trip down   extremist  path for me.

Please  consider this:    lets  take a load,  one that will certainly tax our engines.   Start up  a    4% grade,  say  2 miles long.   First  pull will be started    at   1600, (which I've never  pulled down into in the first place)   1800  I'm more comfortable with anyways.(only from a  bearing and  piston  longevity standpoint)     Then  do it again  starting @ 2500.       In  5th (straight through)    MY  trucks  will all  be in   4th by the time I'm at the top of the hill anyways.      Soon as  I burn off  the momentum  from   hitting the bottom of the hill  @2500,   I'll be  in 5th,   then in  4th.  

After you burn off the momentum  from  the  original  speed  the   2500 rpm  gave you for  'free'... that is  when the true test  should start.   You are comparing  apples and oranges.

 

I'm all ears  and  eyes  for this  mysterious  'horse-o-meter'   Please    post.

[CSM]

Torque is static, by definition.  Horsepower is dynamic.  Torque at an RPM will move you... Torque at 0 rpm won't move you and torque at an RPM is, by definition, power.  

[Wild and Free]

This subject is kind of like all the liquid pressure versus flow debates.

 

Does a Vacuum cleaner suck or blow?....................depends on which end you are on.

[AH64ID]

I don't view it as apples to oranges at all. It's only apples and orages if you assume the engine will slow from 2500 rpms. If it hold 2500 rpms with 555-610 ft/lbs, but doesn't hold 1600 rpms with 610 ft/lbs (which it won't if the load is maxed out on the 2500 rpm run) then horsepower is what keeps you moving, not the torque.

 

I don't pull grades at 1600 either, just simply using the ratings. The Cummins 600 (04.5-07) has a peak torque of  610 ft/lbs at 1600 rpms. It makes at least 555 from 1400-2900. So torque at 1600 rpms is at least equal to, if not greater than, torque at 2500 rpms. I am talking about a fixed load, gearing, tire size, etc... That's apples to apples, the torque output is basically the same. The variable is rpms, which given a flat torque curve means more horsepower. More horsepower, the faster the work is done.

 

In my truck if I hit that grade at 1600 rpms in 5th I will be in 4th by the top. 41 mph in 5th is 1600, which is 2200 in 4th. But if I hit the same hill in 5th at 2500 rpms, 64 mph, I will make the top in 5th.. even on a 7-8% grade at 20K GCW on a 75° day at 7K feet.

 

There are ways to measure horsepower. Think about the original horsepower calculation. It's the ability to move 550 lbs 1' vertically in 1 second. If it takes 2 seconds you measured at 1/2 horsepower, or if it take 1/2 a second you have 2 horsepower. The torque is the same in both of them, so you are not measuring torque... heck it could take an hour and the torque is the same. That's how a chassis dyno works. To rotate the drum 1 time takes the same torque, whether you are at 1 rpm or 1000 rpms of the drum. The difference is horsepower, that's why they cannot tell you the torque output of your engine only the horsepower output. A water-brake, or other engine dyno's are the opposite. They measure the work being done, not the rate at which they are done.. they needs rpms to calculate hp. A chassis dyno needs rpms to calculate torque.

[Wild and Free]

Apples to oranges on both sides.

 

Engine specs are done at flywheel on a water brake dyno in controlled and specific environments with probably a large amount of engines to get a large pool to average from.  All else is as varied as our individual finger prints and DNA...............................................No amount of calculations and banter will change that. Change the humidity and temp by just a few digits and things change very quickly even if everything else remains equal.  Plus no matter what any specs are every hunk of iron is a very different animal even if they come off the same assembly line and are finished by the same person or robot on the same same day ect.

[rancherman]

Ya know, I just thought of something.

who in their right mind hits a hill at 1600 rpm, and floors it all the way to the top? NOBODY. It's suicide to expect this engine to produce it's max torque value for any length of time. What is MAX torque value anyway?? answer; the absolute end of any rpm gain. finito, the end. Do this on a daily commute, and it's lites out for even the baddest cummins ever screwed together.

life on the gerbil wheel is easy compared to a 3 mile long run. Why> because it's short. very short. Our engines are rated at wot balls out max production. Sure, the max numbers are quite neat to brag about, but when that 3 mile hill lures me up to the summit, I use the transmission, not the over fueled engine. for torque multiplication to the tires. I say overfueled, because that's exactly what any engine is considered that should only do it for a few measly seconds.

Ah, can you tell me just how bad your truck falls on it's face @ 1600? I'll tell you right now. my bone stocker when loaded with a 20k load will quickly lose it's 2500 on a grade, (forcing a wot situation.. which I will not tolerate) What I am saying, is I can keep throttle in mid fuel AND maintain 1600-1700. It'd be painfully slow, what? 45 mph?

Those max torque readings are from full fuel, wot. The difference is we are not driving a load wot.. any distance. Lets face it, going up hill, @ 2500, you are a lot closer to that point already. Tach numbers say nothing about how much fuel is being injected.. and as everyone knows, the more fuel and air, the more TORQUE will be sent to the rear wheels.

I don't know what mods you've done to your truck.. maybe you are well above the stock torque @2500, which is fine and dandy. But your 1600 level may not be linear to your performance @ 2500. Instead of the huge jump at your 2500, you are only gaining a little at 1600? Possible the wider gap is what you are feeling/complaining about?

Again, my truck at it's peak torque curve of 1700-1800 is a rock for holding rpm constant. At less than full fuel to boot. I can't say that at 2500. I'd have to bury the throttle, and this is not how a diesel should be operated.

This is all when loaded. I'm doing this exact scenario tomorrow morning. I'm headed out to Valentine Ne to pick up some cows. I'll make notes of me rolling through the Sandhills on the way home! (experiment, if you will call it that)

[rancherman]

I don't view it as apples to oranges at all. It's only apples and orages if you assume the engine will slow from 2500 rpms. If it hold 2500 rpms with 555-610 ft/lbs, but doesn't hold 1600 rpms with 610 ft/lbs (which it won't if the load is maxed out on the 2500 rpm run) then horsepower is what keeps you moving, not the torque.

 

I don't pull grades at 1600 either, just simply using the ratings. The Cummins 600 (04.5-07) has a peak torque of  610 ft/lbs at 1600 rpms. It makes at least 555 from 1400-2900. So torque at 1600 rpms is at least equal to, if not greater than, torque at 2500 rpms. I am talking about a fixed load, gearing, tire size, etc... That's apples to apples, the torque output is basically the same. The variable is rpms, which given a flat torque curve means more horsepower. More horsepower, the faster the work is done.

 

In my truck if I hit that grade at 1600 rpms in 5th I will be in 4th by the top. 41 mph in 5th is 1600, which is 2200 in 4th. But if I hit the same hill in 5th at 2500 rpms, 64 mph, I will make the top in 5th.. even on a 7-8% grade at 20K GCW on a 75° day at 7K feet.

 

There are ways to measure horsepower. Think about the original horsepower calculation. It's the ability to move 550 lbs 1' vertically in 1 second. If it takes 2 seconds you measured at 1/2 horsepower, or if it take 1/2 a second you have 2 horsepower. The torque is the same in both of them, so you are not measuring torque... heck it could take an hour and the torque is the same. That's how a chassis dyno works. To rotate the drum 1 time takes the same torque, whether you are at 1 rpm or 1000 rpms of the drum. The difference is horsepower, that's why they cannot tell you the torque output of your engine only the horsepower output. A water-brake, or other engine dyno's are the opposite. They measure the work being done, not the rate at which they are done.. they needs rpms to calculate hp. A chassis dyno needs rpms to calculate torque.

Again, no.

If your example engine is 2 horsepower, which can move the weight in half the time(which it certainly can)or double the original weight @ normal speed.... the torque MUST double.

Your example is impossible to achieve. why?? this theoretical engine doing the work is maxed out. there is no more rpm because it's at the end of it's rope. So, the only way to double the HP, is to DOUBLE THE TORQUE.

Why not just double the original motor speed to do the same you ask? well, sure! that would double the HP! unfortunately the original motor has nothing left to give! *this is how max values are based.. otherwise it surely wouldn't be a true test.

Now, lets take a simple electric motor. lets say one is 1750 rpm, and 1 horsepower.

lets also take another similar frame motor that is brushed for 3500 rpm and is rated at 2 horsepower.

now attach both of them to our test mule! guess what? The poor 2 hp motor will never spin up to speed.. it'll smoke it's way all the way up. why? The torque load will prevent the weight from going up any faster than 1 foot per second.. (jus working the formula backwards here too)

This is figured on the original motor being able to do 2 things! Maintain it's rated rpm of 1750, AND maintain 1 foot per second. if we were to add ONE more pound of weight to the test mule, rpms would suffer. and the weight would no longer make the voyage in one second. It's at the end of it's rope!

So now we throw the 2 hp motor on the mule.

lets even give it a chance to spin up to full speed before we engage the pulley! guess what'll happen!

The 550 lb weight will drag that motor down so it's buzzing away at half speed.. Why? because 550 lbs will slow this motor to 1 foot per second.. because it's got just enough torque to move the weight 1 foot per second. If it had double the torque, and the same rpm, it could be geared up and move the weight at 2 foot per second.. as long as the gear box was 100 percent efficient.

This example is based solely on 2 parameters! The ability to maintain speed of 1 foot per second, *means the motor cannot deviate from it's rated rpm and exactly 550 lbs. Even one tenth of a second off the pace is a failure.

Edited February 28, 2015 by rancherman

[rancherman]

another thing..

back in my caveman days of running a prehistoric water brake..

We'd for fun 'see' what the max was. We'd crank her down until there was zero throttle response. (maxed out so to speak) we'd throttle back say 100 rpm from max, crank down the brake, and see if it would spool back up.

typically, there was about 35-40 percent difference in torque from rated.. to max.

So, what does the gerbil wheel do here, that 'maxes' out our engines? This doesn't necessarily mean it needs to stall rpm progression, I'm sure they have algorithms that can figure amount of torque to accelerate a loaded drum to speed... This is probably where the 'calibration' part comes in.. to build a certain amount of load for each particular vehicle.. Can't really figure the same load for my Toyota.. It might not even get the wheel turning! (hell, It probably couldn't climb the ramp up to it!) with it's pounding 140 ft. lbs of torque!

[TFaoro]

I have results!

Smarty on 7 TST off: 372.66hp  801.88 Torque

 

Smarty on 7 TST on 9:  

Run 1: 499.80hp   1032.17 Torque

Run 2: 502.39hp   1038.48 Torque

 

I'll upload the graphs asap, but the smarty did NOT fall on it's face. I was rather impressed!

 

EDIT: Oh and the CR made 724.xx hp and 12xx torque... Guess I'm not too bad at tuning haha

[AGPTurbo]

That is amazing. The 24v made twice the rated power without porting, polishing, intake manifolds etc. Like a gas motor would need. That's more power than class 8 tractor trailers made until the late 90's!

Cool!

[Wild and Free]

I would put you in the 450 hp 800 tq range with the stack and smarty alone I would guess 375-400 ish.

 

 

I have results!

Smarty on 7 TST off: 372.66hp  801.88 Torque

 

Smarty on 7 TST on 9:  

Run 1: 499.80hp   1032.17 Torque

Run 2: 502.39hp   1038.48 Torque

 

I'll upload the graphs asap, but the smarty did NOT fall on it's face. I was rather impressed!

 

EDIT: Oh and the CR made 724.xx hp and 12xx torque... Guess I'm not too bad at tuning haha

I was pretty close hp wise but fell short on the torque a bit, did you do the runs in 4th or 5th?. Good numbers. What is all done and added to the 3rd gen?

As far as the smarty they have made so many updates they probably got it tuned in from the early days.

[CSM]

I am particular interested in your REVO settings and the smarty only curve if you get a chance to post it. 

[TFaoro]

I was pretty close hp wise but fell short on the torque a bit, did you do the runs in 4th or 5th?. Good numbers. What is all done and added to the 3rd gen?

As far as the smarty they have made so many updates they probably got it tuned in from the early days.

Exergy 100hp over tips on original bodies (@170k miles) Industrial 85% over cp3 South bend dual disk, stock 5600, phatshaft 62/65/14 over an s475/96/1.32, second gen 3 piece manifold, 5in straight pipe exhaust, fass 150 titannium, fass sump with draw straw, UDC tuned by me, custom traction bars, and I think that's it.

[TFaoro]

All runs were made in 5th gear. It was funny to see the dyno operator's face when I flipped the TST on for the second run He whipped around "DID YOU CHANGE SOMETHING??"

As you can see the smarty held up pretty well all the way to 2750 or maybe a little higher. The TST holds strong all the way past 3K though.

With the smarty I was right around 35psi of boost.

With the Comp my wastegate opened up at 45psi and egts hit 1300 or a little higher.

[IBMobile]

Those are some great numbers!   

[mulcher812]

Nice run TFaoro. Did you double your timing with the Smarty and tst?

[TFaoro]

TST doesn't do any timing... it's just a fueling box, so no. and thanks!

[Mopar1973Man]

Smarty handle the timing nd TST handles the fuel.

[rancherman]

how is the miss now?