Competition Dyno Talk

[Gary - K7GLD]

"I ran on David's dyno jet, I had the same boost 37psi on it as I did on the highway. "



PERHAPS - but did it go to that PSI and STAY there, as it would in a hard pull, or merely SPIKE up at that PSI at first stab on the throttle and then drop substantially lower?



If it only momentarily spiked, then fell, it did NOT reflect a true loading of the engine. OR adequately indicate the true maximum power output across the test RPM range!

 

[CumminFast]

Wow. I don't even know where to begin. Talk about proliferation of misinformation, David, you've earned a gold star for the day.



You're clearly chest-pounding knowing full well that your intended customer base is realizing that the machine you own is far from being the best dyno out there. I don't make it my business to shoot down folks that own equipment built by my competitors, but when it's brought to my attention that a thread like this is going on, I feel compelled to jump in.



I don't even know where to begin. . . . . how about this assertation that the corrections don't apply to forced induction engines. I beg to differ. Turbocharged, blower, or otherwise. . . . changes in atmospheric conditions affect almost all engines in the same way. Turbocharged diesel engines are a bit different though. Still, atmospheric corrections when used properly will result in repeatable test results regardless of weather or altitude.



I can go on and on. . . but I'd really like to hear your side of why you started a thread on this subject? Tired of losing customers to facilities with load bearing dynos? Afraid to concede to the fact that inertia dynos ARE NOT state of the art nor 100% repeatable as many inertia dyno owners may assert? I'd be willing to bet I can test a more powerful truck on my dyno than you can on yours, no wheelslip, no bed full of sand/engine blocks/people/etc.



So, please. . . . what motivates you to start this thread?

Wow I can't believe you just said that. You have obviously never met David, because you would have more respect for him than that. What are your qualifications giving you the right to make that remark? How many years of experience do you have dynoing diesel trucks? and you think David posted that thread to get business??? and you think he actually loses business to loading dynos? and what is the most powerful vehicle you have tested on your dyno? What world are you living in man?

 

[J.Davy]

I agree with your point of 40psi at sea level vs 40 psi at 8000 feet, but how many people are running electronic wastegates or wastegates that are not adjustable?You only have to crank up the the boost to 42. 5 pounds in Denver to duplicate 40psi at sea level. Anyone can adjust there wastegates if they are dynoing for max h. p. there are way to many variables and inconsistincies with turbocharged engines. If you setup a engine at 8000'to make its peak h. p. it will recorrect to some *****ing big number. Bring that same engine back to sea level and redyno it and it will not be the same as the recorrected number ,or the flip side of that it will not survive. Your B. M. E. P will determine your power output and correct me if I am wrong but the theoretical max volume of air the engine can ingest will determine power output and the volumetric efficiency of a turbocharged engine can be altered with boost control.

 

[J.Davy]

As for a load dyno vs a enertia dyno I would have to think the load dyno would be far better for control,If you can't duplicate your trucks"street" rate of acceleration on a enertia dyno you are going to get some funny numbers especially low rpm torque readings. Now if you could input the weight and have rollers duplicate the resistance needed to hold back a 7300 pound truck doing a 14 second run then you would have something. Just my 2 cents.

 

[justinp20012500]

First off I have much respect for David. We had a few email correspondence between us right after he started this thread.



As for this...



I would like to try some real world examples. I have run on "one" Superflow (Edge Products Dyno) "one" M1750 (Edge Products other Dyne) and "one" M1750 (Gillett Diesel's Dyno) and some dual roller huge dyno at Smith Detroit Allison (they use their "load" dyno to test "big rigs")



I know what my truck makes on a M1750, there is a shop here in Utah that has a 248c Dynojet. I will go and run their's and post a dyno sheet. And since my last M1750 dyno run I have done NO OTHER MODS since then. Except fire rings and studs, which should show an negligible difference.





Justin

 

[DavidTD]

Wow. I don't even know where to begin. Talk about proliferation of misinformation, David, you've earned a gold star for the day.



You're clearly chest-pounding knowing full well that your intended customer base is realizing that the machine you own is far from being the best dyno out there. I don't make it my business to shoot down folks that own equipment built by my competitors, but when it's brought to my attention that a thread like this is going on, I feel compelled to jump in.



I don't even know where to begin. . . . . how about this assertation that the corrections don't apply to forced induction engines. I beg to differ. Turbocharged, blower, or otherwise. . . . changes in atmospheric conditions affect almost all engines in the same way. Turbocharged diesel engines are a bit different though. Still, atmospheric corrections when used properly will result in repeatable test results regardless of weather or altitude.



I can go on and on. . . but I'd really like to hear your side of why you started a thread on this subject? Tired of losing customers to facilities with load bearing dynos? Afraid to concede to the fact that inertia dynos ARE NOT state of the art nor 100% repeatable as many inertia dyno owners may assert? I'd be willing to bet I can test a more powerful truck on my dyno than you can on yours, no wheelslip, no bed full of sand/engine blocks/people/etc.



So, please. . . . what motivates you to start this thread?

First off, if this post made it appear I was "Chest-pounding", that was not my intention at all.



But Brian, notice I never said one negative remark on loading dyno's. Unlike you I can appreciate more than one tool. I also stated that I DIDN'T want to take away from loading dyno's. This was not the purpose of the thread.



The purpose of my thread was to help those that discuss on these boards their dyno numbers, and why they vary from machine to machine, area to area, uncorrected and corrected. And yes to defend the Dyno Jet as being very capable of accurately measuring the output of a turbo diesel from those that have been lead to believe they cannot.



But Brian, since you felt it necessary to attack me and my dyno explain a couple of things to me.



Correction and at elevation. If as you say, you can adjust waste gates to overcome the air quality differences, how many guys do this? If they make NO changes to their truck, do you feel they will make the same power? Do you believe a 15 - 20% correction factor is valid on a turbo diesel?



Loading - do you agree that the parameters entered into a loading dyno impact the output? If I tell you my truck weighs 8000 pounds and it is 6000, will it not result in less than accurate outputs? If you enter a road load factor for this vehicle and you estimate that value, will that impact the results?



Brian, unlike you, I don't sell dyno's. As a matter of fact, I purchased my machine for purely selfish reasons which did NOT include public use. I decided to go public, when I felt I might be able to help some that had some very poor dyno experiences by operators that did not understand diesel performance, and netted poor results from their machines. I actually ran on loading dyno's before I purchased my machine.



I ran a 2000 24v Dodge with 275 injectors and Edge Comp on a loading unit. It made 231hp and 907tq. Sound accurate? It made 347/771 on my machine. I've seen bone stock trucks make over 600tq on a loading unit and then high 400's on mine. I've seen new 325/610 Dodges make nearly 290hp and 540tq on my machine. Sound accurate? Am I to assume then that a truck like Comps that weighs less than 3000 lbs will never get the potential out of his motor because it is not in a 7000 truck? If I cannot get accurate results because I cannot load enough, how do three trucks tuned on my machine within 50hp of each other yet one weighs 6200, the other 5850, the other 3850 all calculate out with trap speeds? According to you, wouldn't the heavier trucks actually had more load therefore more power on the track?



And this boost issue and not seeing max on the dyno, well believe what you want. My dually makes 32 psi max. In most all driving conditions though it is about 28psi, loaded pulling my junky dyno. At one very narrow rpm range it will make 32psi. So I guess I need to run my truck there since my boost guage says that is where I am making my power? Amazing because that is not where it peaks power on the dyno, nor is it where it pulls the best. Shame on me. OR how can I make 550hp at 35psi and then change the gate to 40psi and not make anymore power? Does more boost ALWAYS mean more power?



And finally Brian, I have tried to provide a fair and most of all a fun dyno experience. But as in every business, you will have unhappy customers. I don't have many, but it does happen and I can't do anything about that if I have done my best. But as far as losing business to you or loading dyno's, I am sure it has happened, but I can't name one person. But I CAN tell you at nearly every event I do, I have at minimum one person that I am asked to explain why his truck made 280's/600's on my machine, yet on another loading unit, it made 230's/900's. I'm sure some will say it was because I could not load it. I just try to explain that you will not make 900tq out of less then 300hp. If you believe it, great. I don't.



To everyone else, if I offended anyone in my post, I apologize. Not the intent at all. I was simply trying to answer some questions that I get frequently at events. I'll now return to the sidelines...

 

[J.Davy]

Brian,after thinking of a easier way to explain this, here is a simplified version. A diesel is fuel throttled vs. a gas engine being air throttled. Lets say for ease of making the point that the engine is a isbe set to deliver all the fuel the cp3 pump can pump, you give it enough air at sea level to burn all the fuel or give it enough air at 8000 feet to burn all the fuel. End result same H. P.

 

[DavidTD]

I have never had my truck on a dyno,but I have e few questions. Can a inertia dyno duplicate the weight of a vehicle?Is there any adjustment of load or rate of acceleration?

An Inertia dyno does not simulate anything for the vehicle. It uses the simple rule that HP is distance over time. You spin the rollers and it measures HP based on a known mass (the drums/rollers) then calculates torque using the measured RPM.



As I said in my original post, trucks with huge turbo's, especially huge singles will sometimes leave HP on the table with an inertia dyno. But interestingly enough, most cases can be corrected with tuning. The same trucks that won't build boost on my dyno, are laggy trucks on the street.



And again, "hear" what I said about Matt's truck. Matt Stuckey makes over 700hp, with diesel fuel only. He makes 80 psi on the dyno with a 40/3b combo through a stock intercooler. This truck drives like a dream on the street, with very minor lag for a truck that has enough fuel to put the fire out if asked/tuned to. I had the same questions/concerns most here talk about with inertia dyno's. But over the thousands of runs I have made, my concerns turned out to be mostly unfounded.



Most will believe what they want to believe. Most will give the credit to the dyno that gives them the number they want to believe are correct, and blame the dyno that provides the number they don't want to believe.



One example of this. A 822hp (engine dyno) Mustang got on my dyno and made 550hp. Do you know how mad this guys was? He said my dyno was junk, said it was not right, said a lot of stuff. I asked him what the car ran and weighed. He provided me with scale #'s and time slips. 2900 pounds and it ran 9. 4's at 141 mph. He and I calculated out his car. It came to 552hp for 141 mph. Now this guys is asking me why has he lost so much power (and he had the engine dyno graph too) and I told him it felt like too much converter stall and the more stall you have, the less efficient the converter. He then says he had a 6500 stall converter. He has not been back on the dyno but I did get a call from him. He went to a 5500 stall and picked up 3 tenths and increased his MPH. No, this is not a diesel, but this is a prime example of someone questioning what the dyno says. He listened, and went faster. IF this guy would spend a little more time on the dyno, he'd go faster yet.

 

[Turbo Thom]

Well now. For the longest time we all thought Greg was just full of himself. Then we meet in Houston, talked, and now see Comp461 is just very excited about what he's doing and the promotion of the diesel drag racing. Really a good guy with tons of enthusiasm. Then comes a real nut that thinks his areo space knowledge makes him a diesel guru. What a dork. Why Texas? It deserves better. This fellow's manner of speech is just so much self promotion. Tech information that will not equate on the track. Ask Scott about the difference. When there is a good product on the market, time will tell what the assets are. But alas, here comes Brian to explain all, before we even ask. Thank you, thank you, thank you. Yes, I know David. Yes, I've been on his dyno. And this I can say for sure. Before I ever got on yours, I would just prefer to stay in the dark as what the upgrades did for my truck. . Sorry boy. You ain't Southern enough for me. Wrong atittude.



Bye now.



. . Preston. .

 

[Gypsyman]

Brian,



Piers has one of your Dyno's in his shop. They're about as close to sea level as you can get yet it takes a 1. 17 correction to bring the stock run numbers in line with what most see and this was not just on my truck. I saw quite a few rigs run that week so I believe my numbers to be correct. Any idea why they need such a heavy correction factor?



Richard

 

[J.Davy]

Brian ,the whole point went over your head,it is simple ,so once again diesels are fuel throttled, you burn all the fuel at 8000' or sea level what is the difference? You are not adding any more fuel at 8000'just a rough equivilant of air to make up for the loss. Once you hit stoich all you are going to do is cool more with more air. I see by you getting a little petty over . 4p. s. i. (I was just trying to keep it simple for you) , that I must have offended you, I appolgize ,but its just math you figure it out. The amount of fuel burned determines power. In a naturally aspirated gas engine fuel input is determinded by avalible air ,way different. This is when standard correction applies. The reason I have keep repeating myself is you don't seem to understand,why not?It,s simple for the rest of us.

 

[J.Davy]

Sorry I forgot to comment on your sentence about volume of air means nothing. Well it does if you are trying to figure out the volumetric efficiency of a engine as it is the relationship beween the theoretical volume of a cylinder compared to the actual amount of air it ingests. Otherwise we will have to change the name to massumetric efficiency. Maybe you can come up with a better word?

 

[justinp20012500]

Brian,



Piers has one of your Dyno's in his shop. They're about as close to sea level as you can get yet it takes a 1. 17 correction to bring the stock run numbers in line with what most see and this was not just on my truck. I saw quite a few rigs run that week so I believe my numbers to be correct. Any idea why they need such a heavy correction factor?



Richard

WOW!! 17% correction factor??



Maybe Trashdawg will chime in and let us know what Gillett uses for a correction factor.





Justin

 

[Gypsyman]

That's what Mark, the tech, told me. Seemed odd to me also since the stock numbers on trucks all week jived with what you would usually see. Since the stock numbers seemed correct for the baseline runs I'm assuming that the runs with mods, boxes turned on, and such were also correct. 268hp and 495tq is pretty close for a stock '03 in my opinion.



Richard

 

[Sled Puller]

Once again, David Dunbars integrity, POLITENESS, knowledge IN THE FIELD of dynos, and Diesels, smokes other dyno owner posters.



However, after running on old Mustangs, new Mustang 1750,(at Mustangs plant) Dyno Jets,and a few others, I kind of like the Super Flow!!

 

[J.Davy]

Brian I figured I better put one last blurb in before you critises my logic,yes I agree with all those fators that you listed can effect h. p. and yes if input temp increases there will be pumping loss and yada,yada,yada. The fact of the matter is that none of them effects h. p. to the extreme of using S. A. E. corrections . Do a google search it is stated in numerous sites that you can not use S. A. E. corrections for turbochaged engines gas or diesel. S. A. E. does not work properly for two strokes either. If you don't believe me go ask any pilot,that was the whole purpose of turbocharging airplanes , duplicate sea level h. p. when you are at altitude . I thought I guy like you would have known something like that ON Edit, if you really wanted to apply a correction factor to the equation with a gas engine you would have to apply it to the h. p. made from atmosphere air meaning the first 14. 7 psi if you were at sea level or 12. 2 psi in DenverThe rest of the h. p. could not be corrected therefore the greater the boost the less the percentage of correction . Meaning if you are at 10 pounds atmosphere and add a additional 30 psi of boost your correction factor would be 75% less than S. A. E.

 

[Gypsyman]

So your saying that my stock baseline run of 268hp and 495tq from a 305/555 is really only 222hp and 410tq? Seems awfully low for a stock '03.



Richard

 

[RWS]

First off I have to say what a great resource the TDR is, I just wish it could be done with a bit less attitude. This thread speaks to me in volumes. For the last 15 years I have done research on the affects of high altitude. Living and working at over 9700' has given me REAL WORLD data.



I will say Brian's data is accurate. Math is math. I feel what is not so evident is why?? Most people understand as altitude increases barometric pressure decreases. What does this really mean to our CTD or any other engine? If you take a 1cf sample of air at 8000' and a 1cf sample at sealevel, what you find is not less AIR but less molecules of OXYGEN. Remember we breathe only 20. 8% oxygen. Each molecule of oxygen has the same purity, but there are LESS of them at altitude. Oxygen is an accelerant to the combustion process, with LESS molecules we have an engine that is less efficient (turbo or not) at burning fuel with the same volume of intake. As Brian has noted it would take a tremendous volume to come close to matching what is available at sealevel.



So can you make the same HP at altitude by just turning up the boost? Well yes and no. It depends on what motor at what altitude at what base HP. An inefficient low HP motor at sealevel can be brought back to stock power at 5000' with 4 to 7 psi. A fire breathing 5. 9 CTD that makes 800hp at sealevel would likely melt down trying to accomplish that at 8000'



Just my . 02 YMMV!

 

[fest3er]

For some reason, I keep coming back to thinking that the main difference between low-altitude and high-altitude diesel engine operation is mostly in the turbo operation.



The effect of air density on motion is either negligible or nearly so. The effect of air pressure on fuel pressure should also be negligible, because fuel is mechanically compressed to high pressure, and cylinder pressures are relatively high at either altitude.



It should be obvious to most folks that a turbo diesel engine tuned for low-altitude operation will not perform as well at high altitudes, and a turbo-diesel engine tuned for high-altitude operation will not perform as well at low altitudes. (Hence the East v. West 'wars'. ) With all other factors (fuel for instance) constant, the only difference can be the properties of the charge air. If one uses one turbo for low- and high-altitude operation, either the absolute manifold boost will differ, or the charge air temp will differ. How many boost gauges are calibrated to read absolute pressure? Don't most of them display boost relative to ambient air pressure?



If a low-altitude driver wants to adjust for the lower density of high-altitude air to maintain the same absolute manifold pressure, he has to compensate for two things: the pressure differential across the compressor and across the turbine. He must compensate for the different efficiency of the intake side and the exhaust side. (Over the road, he also may have to compensate for the different efficiency of the inter-/after-cooler; I think the cooling capacity of air differs with the density of that air. ) The same goes for a high-altitude driver wanting to adjust for the greater density of low-altitude air.



So sled pullers and drag racers who want consistent results around the country may want to have different turbos for different altitudes. DHRA Pro-Street Shootout racers take note: be sure to test your engines on a dyno while simulating the difference in altitude; this'll go a long way to preventing inexplicable losses in performance.



Now, to return to the thread's topic, dynos are all very good testing tools, provided they are operated consistently. Some may be good at one set of tasks whilst others are good at a different set of tasks, but they're all really just testing tools. The truth will come out on the pulling track, the drag strip and/or the road, depending on the driver's/owner's/tuner's objective.



As to a jet engine de-fueling at altitude, I would expect this to be done because 1) less power is required to move the craft through the air at altitude, and 2) the pilot shouldn't be required to adjust power based on altitude, just as he shouldn't be required to adjust trim based on remaining fuel. But I suspect the real reason is that, just like turbochargers, the jet engine's compressor is 'fixed' to a best-compromise between low- and high-altitude operation.



Dave's a good man, cares about his avocation, and gets consistent results that he's able to correlate with 'real-world' performance with a fair degree of repeatability. With practice, he'd do that with any dyno.



My tuppence.



N

 

[banshee]

Wrong. I'm not even going to try to explain this for you again. I think the politically correct term for you is 'learning disabled. ' If you want to discuss this further, feel free to call me at the phone number shown in my signature.

You know, it's posts like these that make guys not even want to post on the TDR anymore. Whatever happened to disagreeing with someone without being a prick about it? You may know a lot about dynos Mr. Kennedy, but your attitude on this board SUCKS, and I can't believe the moderators allow it. I would add my 2 cents on the subject, but it's not even worth it.