tooslick

VERY interesting... thank you

ak_slick

A lot of good information Steve... especially about the base CAS timing... so many idiots out there who think they know how to tune or work on cars.

I have to disagree with you on one point though because personally I have never had any issue with it.

Having tuned on a Mustang Dyno frequently I have never had any problems with the steady state moving around. It has always been rock solid. Other than that everything else is good.

Except for the one dyno being good for NA motors versus turbo... a motor is a motor. If the dyno can handle the power it doesn't matter. Sometimes I don't know where people get these things. They just need to sit down with a couple engineering textbooks and educate themselves as opposed to asking some random person across the internet.

A lot of shops do tune on a Mustang or DD to get a good tune and then run on a cheaper dyno that yields inflated numbers. I know of quite a few personally and I think it is a very dishonest thing to do to the customer.

I always find it personally gratifying when a 300whp/tq car of mine beats a 500whp/tq car from one of those inflated shops though. Something about an idiot will destroy his own stream of revenue and then I don't have to deal with stupid kids... just enlightened ones.

jspaeth

Steve, here's 3 questions for you!

In this coming year, I hope to get some time on a Dyno Dynamics and do some steady state tuning to refine my fuel and timing maps.

1) Once one gets "into the groove" of how to do this, how long would you say nailing down a single cell takes?

If I understand correctly, one would lock in the RPM for the desired cell, and then use the throttle to change the load.

Once locked in on a cell, I would guess you first get the AFRs into check and then start slowly bumping the timing and monitoring the torque output.

...given this is all occurring in "real time", I can't see how it would take any more than a minute or two to nail down a single cell.

...The reason I ask is because I am wondering how long one should expect it to take to do a whole 20x20 map.


2) On a load-bearing dyno, can you also go into cells with a load well below that of where you would be if you were at constant speed or accelerating?

For example, can the dyno apply a load to keep the engine spinning at 5000 RPM but with your foot completely off the throttle so that you can tune the lowest load cell in the map at that RPM level?

2b) Can you get into cells that seem like they are not physically meaningful (i.e. 2000 RPM and 10 psi).....if not, what does one do for these cells? Does the car even ever see them (maybe on fast upshifts?)


3) In practice, if you wanted to do a REALLY good job tuning a car (let's say your own car, for example)....

Do you hit EVERY SINGLE cell....or do you every other (would reduce a 20x20 grid down to 100 cells rather than 400)....or what...?

Hit every single cell in the heavy load areas and interpolate in other areas? Just curious.

Thanks!

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steve shadows

You are never going to hit EVERY single cell in a map because every car traces through different regions or collections of cells, depending on build, the amount of load etc.

On a dyno dynamics you can hover in one exact cell, raise the timing up and up while watching tractive effort (or torque) in real time. Once you read the best possible torque in a given cell and your addition of timing to said cell begins to not give you any return in power you know you should back track a couple of degrees lock it in and move onto the next cell in the range.

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jspaeth

Thanks for the response....but I am truly interested in my 2nd question....

Can the dyno apply negative and positive load?

Can you hit cells that you would only hit if you were at closed throttle and letting the car decelerate (dyno is applying the power to keep the engine turning, even tho the throttle is closed enough that the car would normally be decelerating)?

Can you hit cells that are in higher boost (i.e. dyno works as a brake.....so you keep builiding boost but the RPMs don't go up)?

j

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hexdmy

OEM manufactures use engine dyno's that can do what you are saying, which is to actually motor the engine to simulate deceleration to calibrate those area's. I have not seen a chassis or engine dyno in the aftermarket that can do that. In practice, if I need to calibrate those area's, I can drive the car on the street or decelerate against an inertia dyno. Certainly you cannot do this steady state, so you use your logged information to go back and make changes. As to hitting cells in "higher boost" with a steady state dyno, you can hold the rpm's anywhere you want, therefore you can tune as high in the map as the turbo will spool. In practice, when you are doing calibration work, most tuners will do a combination of power sweeps and steady state to tune a car, not just hold the car in steady state through every cell.

- Chris

jspaeth

Thank you man

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eh?

Here's a bit from Eric Hsu from cosworth/XS engineering.

"This is an inertia type chassis dynamometer and does not have "load control", but is the absolute most accurate and sensitive dynamometer available. The method of horsepower measurement is fixed and is unaffected by PID closed loop controls from modern chassis dynamometers with eddy current power absorber units. In other words, there is no computer algorithm required to control the load and therefore possibly affect the horsepower measurement. The intertia type Dynojet is very simple and has a pair of 4,000lb rollers (a fixed mass) and the time needed to accelerate this fixed mass is the amount of power the car generates. It is so sensitive that it even measures bent wheels, cylinder misfires, rough engine running conditions, etc. that other chassis dynos cannot measure. If you can tune a car on an inertia type Dynojet with a perfectly smooth dyno graph at 0 smoothing on the graph, you can bet for damn sure that the car will run smoother than a baby's ass. Even to this day, the Dynojet remains my favorite chassis dyno and I've used them all.

While a dyno with load control is certainly convenient for mapping an engine from scratch, it isn't "necessary" for mapping AT ALL. If you want to map specific cells on your ignition or fuel tables, all you need to do is vary the throttle in different gears and you can very easily map entire fuel and ignition tables in no time. If you need more load at part throttle go up a gear. If you need more load at full throttle, go up a gear again. The Dynojet 248C has a 200mph speed limit. Don't let all those young fools or FFF tell you that a Mustang, Dyno Dynamics, or Dynapack is better because "it can control load". If you really think about it, when are you driving on the road and the car is held at a specific rpm or speed? The only time that happens is when you're doing 170mph in top gear on the way to Vegas and your STi is aero and/or gear limited. Otherwise your engine is ALWAYS accelerating and decelerating isn't it? This is also the case on an inertia type Dynojet. How's that for real world conditions?

Anyhow, this may sound like I'm giving a full on sales pitch here, but I'm not. A lot of what Koji and I learned when we were tuning regularly at XS was because of the sensitivity and accuracy of the inertia type Dynojet. While forums and younger tuners may have you thinking that "loading" dynos are better, the reality is that it's how good the tuner is. If you gave Tiger Woods some Wal Mart golf clubs and you had the latest and greatest Ping irons and Callaway drivers, you can bet your ass he'll still smoke your ass in 18 holes (probably even just 1 hole). "

Dynojet 248C Chassis Dynomometer

hexdmy

Some of the points that Eric makes I agree with, however, steady state tuning becomes more important the lower the engine speed and load, due to lower port velocity. Real world, as Eric says, is a combination of various engine loads, speeds and acceleration rates. When you are cruising down the freeway at 75 , that would be considered a steady state load, as you are running at a specific rpm, and are at a specific load. The problem with sweeping through light load lower rpm map area's is that you get transient fueling which will greatly skew what the steady state fueling requirements are at a specific rpm/load site. You can see this clearly on a steady state dyno when you bring the engine up to a specific rpm/load site and hold it there it will take a couple of seconds before the mixture stabilizes. In the real world, I would agree with Eric, that tuning a car on a inertia dyno by someone who knows how to tune, is much better than having an incompetent person tune your car on a steady state dyno.

- Chris

jspaeth

Is this why when I am cruising on the highway in 5th gear and then blip the throttle (just enough to build a psi or 2 of boost), it takes an extra 1/2 second or so for my AFRs to go slightly rich?

.....in other words is there really a noticeable dealy between the engine's operating conditions and when the air-fuel gauge detects the mixture?

If so, this screams for the need to do steady-state tuning in those portions of the map

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slider2828

^^ I believe so, but also in 5th gear, air velocity being driving by exhaust is much slower. Before I brought my car to steve, it was tuned on a dynojet. As far as I can tell it looked like more guess work than anything. I believe doing a steady state and full load sweep is required to do a perfect tune... And most steady state dyno tuners do that.... Its just the lower load areas are where DD's are great! But to adjust from a blank table, DD's are more efficient in doing the work.... at least thats my observation

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steve shadows

If this is true then why do I always have cars in the shop FROM OTHER shops who need to use the DD because they are unable to tune portions of their cars maps while trying to simulate load regions?

It's impossible to hit many regions of these maps by just TRYING to simulate load by bouncing in and out of the rollers. It's also impossible to check tractive effort in stead state. To really put things in perspective he is also from a shop that has a reputation for using a load bearing dyno to do the actual map tuning and then throw their cars on the dynojet for big fat numbers to make clients happy...nothing wrong with that but XS used to always use load bearing dynos to tune their cars

We have cars in all the time from Dynojet shops who need to use the dyno dynamics because they have problem regions on their maps that they cannot hit no matter how hard they TRY to simulate it by bouncing in and out on the roller dynos

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holemilk00

Just wanted to take a minute and point out that this statement is false, Dynojet makes an entire line of loading dynos, most shops are just too cheap to buy them.


Other than that, this is a very good thread.

Carry on.

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steve shadows

Yes they do,

however they are not true brake eddy, they use a BELT or they are ADD - ON design where you add a break to your DRUM to simulate steady state.

Just wanted to correct you on that

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jspaeth

by Steve

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holemilk00

Model 250i Load Control System

* About Model 250i Load Control
* The System includes..

LOAD CONTROL SYSTEM DESCRIPTION

The Dynojet Load Control System was developed through years of experience with over 5,600 dynamometer installations worldwide. The design is easy to operate and provides the function of steady-state load control.

Dynojet's Load Control System uses the latest in eddy current power absorption technology, which combines with our easy-to-use software to give any technician repeatable, consistent results. The Load Control software provides a technician with the ability to control vehicle RPM or speed at any throttle opening. Through our exclusive closed-loop software design, the vehicle is automatically held at the pre-determined setting.

With the addition of the optional torque cell package, the dyno has the capability of a more complete range of tests, including step and sweep tests and wind drag simulation.





Quoted from their site. They are Eddy current load controls, I've used one, and was involved in its install at National Speed in Wilmington NC.


Yep, you are SOOOO right.

That one just happens to be on a Motorcycle dyno, but the same holds for some of their more top end models such as the 424xLC2, which also has an eddy current load control system.

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jspaeth

First of all I was just joking, second of all, did you need to post 3 times consecutively?

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S14DB

No, Especially as a premie...

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Bmadd

Q: I had my RB25det tuned on DD, got the dyno sheet, and the RPMs were way off. The shop said they only reved the motor to 72, where the soft limiter is set to, but the sheet had it revving up to 9000! I also read of another guy who had the same issue. Is this just laziness on the shop's part?

S14DB

Sounds like they didn't set-up/isolate the pickup correctly for RPM. Easy to screw up on COP.

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slider2828

Yes they were lazy....

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janders211

There is a lot of good information posted here
this seems a bit of fear mongering, and totally ridiculous in response to a stock swap question.

It's retardedly easy to line up the CAS - ans setting it to proper timing requires a 3rd grade education.

A properly stabbed CAS, say at 15 deg TDC making 210 rwhp on a stock swap will make +/- 50rwhp b/c of base timing being off?

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someguy

That information on the Dynojet brand is SO OLD AND INCORRECT that it's not even worth posting. Circa 1996 or 1997? Dynojet has offered load controlled dyno runs on the 224 series automotive chassis dynos for over 10 years!

Wow, where to begin? So much bad info...I'll do my best to give the actual, correct information to refute the outdated, bad or erroneous things here.
Quote:
Originally Posted by renzo088
Come to find out..
A mustang dyno & dyno dynamics are much much better for tuning

False. Load style dynos do things differently than inertia style dynos, but once you add a PAU (power absorption unit) to an inertia style dyno, it can then do BOTH. Quote:
Originally Posted by renzo088
here is an excerpt ive taken from another website that really talks about the difference.
Quote:
DynoJets are inertia dynos, and have been around for years, much longer than any type of load cell dyno.


Incorrect. Load style dynos have been around much longer that Dynojet has. Inertia as a design principle has been around for longer than Dynojet too...we didn't invent the idea - just did a good job of offering it to the public at an affordable cost. Quote:
Originally Posted by renzo088
Quote:
Inertia dyno's work on the principle of the acceleration of a known mass over time. Their rollers are the known mass. Weighing in at over 2500lbs or so. Your car gets strapped down to the machine, and the dyno collects it's data. It is able to calculate horsepower by measuring the acceleration in rpm of the rollers in regards to RPM.


Most of this is correct, but the acceleration of the drum is measured by TIME, not RPM. The Dynojet inertia dyno will accurately collect data and display HP vs. speed with no RPM input at all. This is the most basic dyno run it can do. Add RPM information from the engine and then it can calculate torque off the well known forumla that TQ = (HP * 5252) / RPM. Quote:
Originally Posted by renzo088
Quote:
This is why gearing can affect the dyno results, more on that in a bit. Now that the dyno has recorded the horsepower curve, it can take the integral of that curve and get the torque curve. Since the dyno’s power calculations are based on the acceleration of mass over time in regards to RPM, gearing is very important. Since a vehicle with a lower gear ratio can accelerate the mass to a higher speed using less engine RPM, it will show a higher horsepower number than a car with a higher gear ratio. If a car is able to accelerate the dyno’s rollers from 200rpm (roller) to 300rpm (roller)in 1500rpm (engine), then the dyno is going to record more power than a car that did that in 2000rpm (engine).


Also incorrect. Gearing has no bearing in the horsepower/torque figures displayed. Gearing does have a bearing on the FORCE put to the dyno drum, but this is all relative per gear. 2nd gear will have more mechanical advantage and accelerate the drum quicker than 4th gear, but the delta (change in) speed is not as great. If you look at a given RPM range (let's use 2000rpm to 6000rpm for ease), then in 2nd gear that may translate to a dyno run that goes from 20mph to 60mph, where in 4th that may be from 35mph to 100mph. While it takes longer to make the run in 4th, it also has a greater delta speed.

Also to note here is that in our example above, in 2nd gear, more of the HP the engine produces is going to be used to accelerate the inertia of the drivetrain, engine internals, etc. over that shorter timeframe. In doing so, less HP actually gets to the wheels. This is why you will typically see less HP in gears that are not a 1:1 ratio, and the further you get from 1:1, then less power the vehicle will put to the wheels.

The exception to this is large turbo applications with big torque - like turbo diesels - that have far more torque than HP. They need the extra run time of the taller gears to build boost and load the engine over a very short RPM range. Quote:
Originally Posted by renzo088
Quote:
Now we go to Mustang dyno’s and other loaded dyno’s. Our Mustang MD-1100SE dyno’s rollers weigh 2560lbs. That is the actual mass of the rollers, much like the DynoJet. That’s about where all the similarities end. When we get a car on our dyno, we enter two constants for the dyno’s algorithms. One being the vehicle weight, the other being what’s called “Horsepower At 50mph”. This is a number that represents how much horsepower it takes for the vehicle to push the air to maintain 50mph. This is used as the aerodynamic force. Mustang dyno’s are also equipped with a eddy currant load cell. Think of a magnetic brake from a freight train. This magnetic brake can apply enough resistance to stall a big rig. Off one side of the eddy currant load cell, there is a cantilever with a 5volt reference load sensor (strain gage).


The setup referenced here using a PAU and a strain gauge is exactly the same setup used on the Dynojet 224xLC and 424xLC2 dynos. One MAJOR difference though, is that there are no "constants" that need to be added to the Dynojet software. Giving the operator this control gives them the ability to fudge the numbers. Think I'm full of it? Next time you're on that Mustang dyno, enter a vehicle weight of 3000#, make some dyno runs and then change the weight to 4000#. What happened? The HP went up? Why would it do that? Are you telling me that if I put friends in my car on the way to lunch and the car is heavier, that now my engine makes more HP? How can that be? LOL
Quote:
Originally Posted by renzo088
Quote:
I like to state it like this. . . I start by asking how much your car weighs, lets say 3500lbs. Now you take your car and you make a make a WOT rip in your tallest non overdrive gear, how much mass is your engine working against? 3500lbs right? Now you strap your car on a DynoJet and you make a WOT in the same gear, how much mass is your engine working against? 2500lbs right?


Yes, OR NO. With the load controlled Dynojet dynos, you can setup sweep tests, step tests or custom load test using the PAU in the same method as the other load style dynos. We actually have one routine that allows the user to input how much load to add versus either engine speed, time or road speed. For instance, we can have the load increase as vehicle speed increases, to simulate wind drag and aerodynamic loads. We even provide our dyno centers a spreadsheet they can use to input the vehicle weight and aerodynamic values (coefficient of drag and frontal area) which calculates the custom load profile for them.

The load is then added during the run. This slows the acceleration of the drums, which means we measure less HP to the drum, but then we record the strain gauge data as to how much torque is being absorbed by the PAU during the run, and do the math to calculate the total HP as if the load had not been applied. Quote:
Originally Posted by renzo088
Quote:
Now you strap your car on a Mustang dyno, how much mass is your engine working against? 2500lbs. Plus the resistance being applied by the eddy current generator. We’ve seen anywhere for 470lbs of resistance to over 700lbs of resistance as measured in PAU force in the data logs. So which one is more accurate? Well they their both accurate. If a DynoJet dyno says you made 460rwhp, then you made 460rwhp. If a Mustang dyno says you made 460rwhp, you also made 460rwhp. Now which one of those numbers best represents what your car is doing when its on the street. That’s a different question.


See, same result - the information quoted here is SO OLD that it doesn't take into account that Dynojet has offered this same technology for over 10 years! Quote:
Originally Posted by renzo088
Quote:
For instance, my 2002 Z28 with a forged internal LS6 Heads/Cam/Intake, makes 460rwhp on our dyno. I thought that was a little low, since I’ve had cam only LS6 Z06 vettes make 450rwhp. So I overlaid the dyno graphs. Guess what, the PAU force for my car was almost 200lbs more than the C5Z06 that made 450rwhp with cam only. So I entered the weight and horsepower at 50 number for a C5Z06 and did another horsepower rip with my car. The only reason I did that was to compare Apples to Apples. This time my car made 490rwhp, no other changes. Now I don’t go around saying my car made 490rwhp, I say what it actually did with the correct information entered into the computer. It made 460rwhp.


So, the operator changed a number typed into the software and the HP changed? (I think I mentioned that above). So what good is a dyno that the operator has the control over to make it read whatever he wants? The whole point behind the dyno is to have a CONSISTENT and REPEATABLE testing tool that cannot be manipulated to show different power figures. If this rule is not followed, what guarantee does the vehicle owner have that gains shown on the dyno printout were truely made? On a Dynojet dyno, there is no value that can be entered to change the HP displayed. Quote:
Originally Posted by renzo088
Quote:
Now which one is more "real world" is a totally different question. I like to explain it like this..... If you drive your car in a situation in which you have no mass and you're in a vacuum, so basically if you do intergalactic racing in space, use a DynoJet. If your car sees gravity, and has an aerodynamic coefficient, and you race on a planet called Earth, then use a Mustang Dyno.


I think we've now illustrated the point that this is completely false. Don't let the sales mumbo jumbo and 10 year old quoted speeches give you bad information.
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Whew, almost done...

Quote:
Originally Posted by renzo088
whats the difference between:
dynojet Giant Drum at a given weight, Dyno reads how much energy the car has to use to push against the given weight. Often reads the highest of any dyno due to the fact you cannot apply additional load. The weight is the only resistance on every car for every run/chassis/weight etc of the car- You cannot tune the low end or mid range cells on a dynojet, You can only tune based on straight power pulls or on-off attempts to simulate load.

This has now been proven false as well. Anything you can do with a load style dyno you can do with the Dynojet (properly optioned) as far as loading the car for simulated dyno runs. Quote:
Originally Posted by renzo088
dyno dynamics
Dyno Dynamics is the best dyno for the money imo. It reads lower than all other mainstream dynos on the market because it uses an Electromagnetic Brake that is slowed by the magnets applying a force to slow the rollers the HARDER the car trys to push against the applied force. This dyno also allows the operator to apply various amounts of load conditions, simulate highway speeds, acceleration and other driving conditions that cannot be simulated with any other dyno.

I think I've also discussed how everything this dyno can do, can be done with the Dynojet dyno as well. Not to mention, Dyno Dynamics is now out of business. Support and repair parts for these dynos are now non-existent.
Quote:
Originally Posted by renzo088
If you want your car tuned properly take it to a Mustang or DynoDynamics dyno

Links
Dyno faq - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

In conclusion, that last statement is completely FALSE. I believe that I've stated all the pertinent facts to show that the Dynojet dyno has all the benefits of a load bearing dyno (as it can be one when optioned with the PAU), and all the benefits of the repeatability and consistency of an inertia dyno. There is a reason why nearly every NASCAR team in the country has a Dynojet inertia dyno. This is why discerning performance shops like Beyond Redline, AMS Performance, Hennessey Performance, Borla, K&N and many others choose a Dynojet dyno. When it comes to testing and getting repeatable and consistent results, you can't beat a Dynojet.

or a link if that is unclear http://www.gencoupe.com/engine/28966...no-tuning.html

steve shadows

So in conclusion the reason why a dynojet is just as good as a load bearing dyno is because Nascar uses it?

Nascar runs PRE TUNED, in many cases CRATE MOTORS!!! bwahahaha

Are you fucking kidding me?

YOU CREATED AN ACCOUNT JUST TO POST THIS LIMP WRISTED BS RESPONSE????

....BECAUSE YOU'RE A DYNOJET REP!!! BWAAHAHAHAHHAHHAAHHAAHHAAHAHAHAHAH

I was looking through that thread you posted, You are spreading the most loaded cattle car pile of BULLSHIT I have ever seen!!!!!

Dyno Dynamics OUT OF BUSINESS? NO SUPPORT?

What the fuck do you think this is FedEx vs. UPS? Totally spread disinformation because you're only interested is that DYNOJET sells more of their shitty toy dynos.

I am a tuner, I have no interest in supporting sales of any particular part. I have however used all of the dynos listed for various different cars over the years and by far, without a second of thinking about it the Dyno Dynamics BLOWs all of the other dynos out of the water. Even if you just compare it to how fast and refined the cars are after tuning alone. It's NIGHT and DAY. The dynojet cars are weak, very peaky power bands with very little mid range and low end power and torque. The DD cars come off feeling like I added 2-4 cylinders to the motor. The amount of free power hidden in the low to mid-range hard to reach cells is AMAZING! So much hidden power in those hard to reach spots. But with the DD I can simulate any fucking cell I want to hit any time and rad tractive effort in read time cell by cell by cell for PERFECT cylinder pressure and power output down to ms and down to a hundreth of a ft lb of torque. Show me a dyno slut jet that can do that, even with the gay-ass shitty fucking add on brake with the belt/ pulley, what a piece of shit

Dyno Dynamics is now combined business with Haltech USA, they work out of the same office and R and D facility in KY. They are alive and well and have complete support for all of their units...

Have you no shame?

Dynojets are good for ONE THING, consistent WOT comparisons.

For actual cell by cell map tuning it's garbage

Sorry but for me I care a whole hell of a lot more about how FAST my car accelerates and handles then how big of a number I can simulate based on a controlled experiment trying to spin a given weight

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jspaeth

TKO by Steve

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soreballz

Flawless victory

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steve shadows

you cant just waltz into zilvia, start an account then copy and paste some bullshit post from another thread that was posted by a Dyno Jet Sales rep...fail

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nachos14

steve, can i buy u a beer? a stone ale. Tuned to perfection. MMm lol

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fckillerbee

that was a great reading. lol

homeslicej2

Steve, are there any East Coast (specifically GA or surrounding states) tuners that you recommend for the SR20? I suppose I could just have Scott at Enthaply do a mail order ROM-tune when the time comes, but I just wanted to know your thoughts. I do not have a standalone, nor the current budget to purchase one, so ROM tune would have to be my route in the near future.
thanks