dave dumbar's dyno

[PToombs]

The dyno I was on last week, owner said he could load it enough to stall anybody there.

 

[Don Tanklage]

it was computerized tho, right pete?



he rolled on the throttle at approx 1500 rpm and the dyno applied brake but still let the motor rev to max r's, right?



thats what you want



i dont know about this - put it on the gov and pull it down to idle stuff...



it would be harder than hell on your motor, i know that.



we tune on a dyno that tries to duplicate real world conditions



not pulling down to idle but also not just letting the thing run away and never making max boost



how would you tune for either of those conditions?



guess that is the question since the latter is what is at the shows for comparison numbers

 

[DValentine]

We had an old water brake dyno hooked to a hopped up 530 international at diesel school. It wasnt much but it would load the engine..... down to a stall. We hammered on that poor engine. But we got to see what it did under load. I agree with the discussion on the point of torque. How do you get an "accurate" number without being able load the engine down to peak torque. On our old test mule, you sure could tell when the engine fell off the back side of the torque curve.

 

[Don Tanklage]

dude is making 5 grand a weekend off of you guys



make him get a real dyno



end of story

 

[brianv31]

So what's the real issue here? Do you feel like you personally got screwed using Dave's dyno or what? Why would you start a thread the way you did, beat around the bush for several posts in your own thread, and then finally post what's eating at you?



Maybe you should invest in a "real" dyno and be the dude making $5K a weekend.

 

[Don Tanklage]

i build tune and drag race bikes



the races are on the weekends



maybe dave should just invest some of the cash he's made before someone else does exactly what you suggested?



tank

 

[MMiller]

We don't pull them down to idle, that would be pointless. We pull them down to peak torque, which in a farm tractor, or OTR truck, they are designed to take that kind of load for a period of time. This is how all OEM diesel engines are dynoed whether a engine dyno, a chassis dyno, or a PTO dyno. An old water cooled hydraulic brake dyno, you start at WOT no load, then pull it down in 50 rpm increments and check the reading. This rating you can plot a torque curve with. New dynos are all computer processed and turns out a print out quickly. Rated hp is usually around 1800-2200 rpms but peak torque for a Cat is usally around 12-1400 rpms. There is nothing like a 600 hp/1800-2000 ft lbs, C16 equipped, Peterbilt, bull hauler with 8" straight pipes getting loaded on the dyno! Nothing as exciting or quite scary as that. When many trucks are geared to run 60-70 mph in direct drive, then take that wheel speed and pull the big Cat to her knees. I've been trained to believe this is the most accurate way to dyno a diesel..... however..... A BOMBED CTD will not live being dynoed like this.



Michael

 

[bgilbert]

So what's the real issue here? Do you feel like you personally got screwed using Dave's dyno or what? Why would you start a thread the way you did, beat around the bush for several posts in your own thread, and then finally post what's eating at you?



Maybe you should invest in a "real" dyno and be the dude making $5K a weekend.

Well said.

 

[Don Tanklage]

So what's the real issue here? Do you feel like you personally got screwed using Dave's dyno or what?

no brian, i dont feel like dave has screwed me. i feel like many of you have gotten screwed tho. why did i ask the questions instead of just coming out and saying that? because if you just jump right in and tell everyone their trucks were tested on a pc of **** machine they are going to get defensive and not have a open mind and listen to why. right? i would too if someone told me something like that. it is human nature. but if you ask people questions and get them thinking for themselves sometimes they will figure it out all on their own...



then again some of them will just never get it





don

 

[2broke2smoke]

so what did you dyno on daves dyno and what did you dyno on a "real" dyno



talk is cheap ... where's the proof?

 

[Don Tanklage]

all i had to do was watch the video of my buddies truck zingin thru high gear on that thing...



it doesnt take a rocket scientist to figure it out



(he never got close to max boost)

 

[DavidTD]

Hi Don,



I appreciate all the kind words you have had to say about me, my dyno and my business.



If you don't like my dyno there is obviously no reason for you to test your truck on my machine. But I stand by my machine, and most of all I stand behind the service we provide to our many happy customers that use us each year multiple times.



And so that we clear things up NO DYNO can claim as being the standard in terms of who's numbers are correct. There is no way to prove it actually. And since you are a builder of performance motorcycles, you should also know that a dyno is simply a tool.



Just this past weekend I had one of my regular customers dyno at the track after he had made some passes. Based on the calculators, he predicted what he would run, and missed it by 1hp.



The "real" dynos you speak of are not perfect either. Operators can cause all types of problems if settings are not correct or calibration is off. I have however run comparisons with Mustang MD250's, Mustang 1750, Dyno Dynamic and Superflow dynos. Amazing that my peice of crap dyno that you speak of generated the same numbers as the 1750, Dyno Dynamic's and Superflow machines.

 

[Don Tanklage]

its your story...



i'll let you tell it





i agree that no dyno is perfect - it is just a tuning tool



and what works on a brake dyno might not work on the strip



that is seldom the case tho...





i have been around racing long enough to know that a inertia dyno is not the way to go





are you saying you have never thought of upgrading your system?



don tanklage

 

[dpuckett]

Michael, I stand corected on the load dyno technique, though 1200RPM isnt much above idle. Maybe it is- if idle is 6-700rpm... ... .



My question on the intertia dyno is will it load the engine at a low enough RPM to get an accurate torque reading? I woul dbe happier breaking 1000tq with "only 350-375hp than 500hp with the 1000tq. We start out with 160hp/ 400tq. Bill Gilbert has taken his engine up to well over 400hp, which if the ratio is maintained, should yield well over 1000tq, but he hasnt hit the 4digit torque yet. I admit, a lot of it is in tuning, and with a turbocharged engine, you give up some bottom end for top end performance with most single turbos.



But, could some of the "problem" (for lack of a better term) could be that the throttle is hit hard at around 14-1500rpm (just shy of true peak torque), and it takes time to build boost. By the time boost comes on, your torque curve is on its way downward, but power is coming up, and will 'til the governor cut off.



Or do the bigger inertia dynos factor this in with bigger rollers/ drums, and harder braking? Were can I find out about this stuff? I'm curious now. But, I am not going to spend that kind of money (at least right now) just to get an "official" dyno reading. That is why my HP is officially in the 200-300range, and torque in the 450-700range :-laf



DP

 

[Don Tanklage]

But, could some of the "problem" (for lack of a better term) could be that the throttle is hit hard at around 14-1500rpm (just shy of true peak torque), and it takes time to build boost. By the time boost comes on.....

the problem daniel is that without a brake the motor never makes max boost



just 'zings' it...



how you gonna make torque like that?

 

[DavidTD]

the problem daniel is that without a brake the motor never makes max boost



just 'zings' it...



how you gonna make torque like that?

Not true Don but it's your story I will let you tell it.

 

[DValentine]

David, if you would give a simple overview of how the thing works, I would appreciate it. As I said before I, abet 10 years ago, saw one work but that was a different kind of machine.



Thanks,



Dave

 

[Don Tanklage]

why would you deny something that everyone already knows to be true david?



(not you dave, was referring to david's max boost statement)

 

[Don Tanklage]

d. val - the rear tires of your truck spin a drum on davids dyno



there is a computer hooked up to the drum and it measures how quickly you can accelerate the drum and then it spits out hp and torque numbers



hp is kinda a bs number anyways - hp is torque vs rpm vs a man made constant



torque is a real number - but to get a accurate torque reading you have to load the engine



in order to do this with a inertia dyno you would have to have different size drums for every torque range (the drum for a 600-650 ft lb motor would be a lot larger than one for a 300-350 motor)



a drum big enough to measure the torque of a 900 ft lb diesel would be larger than i care to imagine



that is why real dyno's have a brake



don

 

[CSchafer]

I will be the first person to admit that on a dynojet 248 I did not hit max boost that I do on the street. The 6000lbs of drum was not enough weight to make my truck acheive max boost. But like said before a dyno is a tool. Especially when you have 1000's of people with diesel pickups trying to compare numbers over the internet you have to have a constant. Dunbar was lucky enough to get reconized as the the constant and that is a good thing because the numbers are compairable. On all the differnt type dyno's the dyno jet I belive is the most consistant due to the fact that the weight of the drums does not change and the system is all but tamper proof, unles you install 248 software on a motorcycle dyno's computer, (ever seen a 300hp yz 250?):-laf. On a load dyno who decides how much the truck should be loaded? Not to mention more or less load could help or hinder differnt trucks unequally. I would say that for the most accurate number you need a load type,set up perfectly for your perticular truck. For bragging rights on the forums you need consistancy and I think the 248 is the best for that. Besides people that get dynoed at diesel meets don't really care about accuracy they want to now how there truck compares to the one next to it and have bragging rights over all the other trucks that used the same dyno.

Now dyno jet has a new dyno out they call the heavy weight with 8000lb drums I believe. It also has a higher load capacity and is wide enough for duels but I don't think thy have it in portable form. I'm currently waiting for a lease return to buy so I can get one in my shop soon.