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Patton wrote:
[quote]Steve, thanks for posting the ideas. A cross section using severeal governing bodies with racers of years of experience is something to be considered.
I’m not sure that…
Since I’m not sure, I’ll back away from the keyboard.
RP[/quote]
Update by changing the greeting from Steve to All. Update by saying that this is not a democracy. (I can argue both sides.) And now we have 4 pages of dialog.
I’m not sure that…
Regards, Robert Patton
The conditions the dyno runs are made under matter - even with the same dyno. The same car dyno’d in Jan on a 36 degree day will make more power than it would on a 105 degree day in August. How much difference? I don’t know, but I would be willing to speculate it’s significant. The same argument can hold true for elevation(Eastern NC - sea level vs Colorado Rockies - 1500’? above sea level) The Colorado location would yield lower results due to the “thinner” air.
Using a device such as Traqmate or MaxQdata will yield different results than a chassis dyno. Their results are based on calculations made from observed and input data. Varying data for such devices are:
Weight entered for the car - even if you entered the weight you just measured on the most accurate scales before going on the track, the car’s going to get lighter with each lap. Gas weighs about 6 lbs/gal. Then you have scale accuracy considerations as well.
Wind resistance - HP in a GPS device is calculated from how fast the car accelerates over a distance. The power required to overcome the wind resistance increases with speed. This is not factored in on a chassis dyno.
Slope in the track - The HP rating would not be accurate at any point on the track. Going down hill, you’ll register a lot more HP than you will going up hill. A valid HP rating should only be considered from a point on the track where there is an opportunity for a straight line acceleration on level ground.
GPS accuracy - GPS accuracy for the public domain can vary by as much as 20 feet.
The HP results obtained with both methods need to be taken with a grain of salt. I don’t think you can legitimately use chassis dyno results unless all the runs were made on the same dyno under the same ambient conditions. This would foster the dyno at the race path.
I like Carter’s idea about using a GPS devise for policing. I’m sure he’s looking at the MaxQdata because it’s most cost effective. But a lot of us have Traqmates, so I think some correlation between observed MaxQdata results and Traqmate results need to be made and accepted. Ultimately it would be great if everybody just submitted their Traqmate data at periodic requests and the data compared for one particular segment of the track.
Regardless of the method employed for policing it needs to be consistent. I think a max HP at the ground value should be established and a standardized method for measuring it determined. The standardized method should somehow account for variations in ambient conditions - maybe some kind of table that gives correction factors based on temp and elevation(do you think relative humidity should be included too?).
So let’s say a 160 HP max at the ground at say, 20 degrees Celcius at what ever the elevation VIR’s front straight or northern paddock is as a starting point?
I think this got posted before but I think its worth posting again as it pertains to the discussion.
[quote]Truth, Lies, and Dyno Runs
Part 1
A popular thread that continues to surface in various enthusiast forums is related to the
results attained from various chassis dynos. In the following paragraphs, I’ll attempt to
explain the various types of chassis dynos and their operating principals, how they’re
used in the field, and how to interpret the results. I know that you’re thinking, “oh boy,
the VP of Dynojet is going on a sales pitch”, and that couldn’t be further from the truth.
I’m an avid automotive enthusiast, and no, that doesn’t mean I just plop down cash for
the latest exotic car. I’ve made thousands of dyno runs, tuned 1000’s of automotive
ECM’s, designed and fabricated my own turbo kits, and made hundreds of passes at the
strip. I hope to educate the sometimes confusing subject of chassis dynos and how
they’re used in the field.
There are generally two types of dynos that are used for performance verification and
tuning, “inertia type loading”, such as the Dynojet 224x or 248, or “electric type
loading”, such as a Mustang 250, 1100, Dyno Dynamics, or Dynojet 224xLC / 424xLC.
Traditionally Dynojet has offered the inertia loading dynos, whereas Mustang
Dynamometer and Dyno Dynamics have been electric type loading dynos.
The major differences in the two types of dynos are their principals of operation. A true
inertia dyno (such as the Dynojet 224x or 248) uses large steel rollers that contain mass.
This mass is fixed, it can never change, and for those that remember high school physics,
Force = Mass x Acceleration. Based on the time that is required to accelerate a mass (the
steel drums in this case), you are effectively measuring force. Ok, so now that we have
force, how does an inertia dyno come up with horsepower? Simple, force (lbs) multiplied
by speed (ft/sec) effectively yields horsepower. Since every Dynojet dyno on the face of
the earth has a mass that has been precisely quantified using a proprietary process, and
that value is stored in the dyno software for each dyno, not only are the horsepower
numbers consistent every morning, noon and night, but each and every Dynojet is relative
to one another. Go ahead, take your car to 25 different Dynojet dynos, run it up, and I
personally guarantee the horsepower will repeat to within 1/2 HP (no one else would dare
make that claim). What if the numbers aren’t the same between the 25 Dynojet dynos,
well, it’s quite simple to explain, and you need look no further than the vehicle. Most
modern powertrain management systems have a lot of authority when it comes to how
much power they ultimately put to the wheels. Capturing OBD2 parameters such as
spark advance, engine coolant temperature, inlet air temperature, mass air flow, and other
critical PID’s provide the insight required to determine why the vehicle did, or did not
repeat.
So let’s take a step back before we move on and look at this from a practical perspective.
As an enthusiast, you may be wondering, “what are the variables that exist when I dyno
my car on a Dynojet, there has to be something”. I would respond, “A Dynojet dyno
operator CAN NOT change the data that determines what the power reading will be
(remember the physics thing?). What ever power is being put to the drums will be
measured and displayed, period.” Once that power has been measured, there are two
ways to look at it, corrected or uncorrected. Since every Dynojet dyno is equipped with
electronics that measure the atmospheric pressure, temperature, and humidity, the results
are able to be analyzed as a “corrected value”. This allows an “apples to apples”
comparison when testing in regions that are at different altitudes, which affects the
atmospheric pressure, and different temperature. This is also important for comparing
results at the same dyno shop, for example, here in Las Vegas our atmospheric pressure
stays relatively consistent, but our temps vary from 38 degrees to 118 degrees. So the
same car with no changes will certainly make less power on the hot day compared to the
cool day, but applying the SAE CF allows us to make an “apples to apples” comparison.
If you take anything away from the last few sentences, it would be to ask your dyno
operator to make sure that he is showing you SAE corrected HP figures, and before I get
off my soap box, I will say that there are certain Dynojet dyno owners who apply the
“STD” correction factor, and that’s not proper to do. The STD CF is an older standard
that yields slightly higher HP numbers, so don’t allow yourself to fall into the trap (just
use the SAE CF!!).
Ok, lets move on to “electric type load chassis dynos”. These types (Mustang, Dyno
Dymamics) of dynos utilize rollers that usually have very little mass, hence they’re not a
true inertia chassis dyno. In order to present any type of physical load on the vehicle,
there needs to be a PAU (power absorption unit). Typically this PAU is in the form of
electrical coils that utilize eddy current technology (think of this as a big electric brake).
Now having a big electric brake is all very nice, but we need to use a chassis dyno to
measure power at the end of the day. Since the mass of the rollers isn’t known (like a
Dynojet), there needs to be a means to measure power, so how this is done is with a
torque cell, or sometimes referred to as a strain gauge. As the big electric brake absorbs
power, the strain gauge is actually measuring torque. Now here is the kicker, the strain
gauge really doesn’t know the difference between 2 ft-lbs or 200 ft-lbs until you calibrate
the device, so in doing this, you’re introducing a potential margin of error and
inconsistency. This would apply to any “loading type dyno” that uses eddy current load
control and a strain gauge, even our own 224xLC which is a hybrid inertia / electric load
style dyno. The strain gauge needs to be calibrated to make it consistent and repeatable,
but there are other user defined (by the dyno operator) variables that makes things very
interesting. Once the strain gauge is calibrated properly, the dyno operator must enter
certain parameters about the test vehicle that determine the rate of acceleration the dyno
will allow, and are ultimately directly responsible for the power and torque readings that
are displayed on the graph (WOW!). At this point you may have connected the dots and
are either appalled, or still rather comfortable with the dyno graph you have in your
hands. The question that pops up, “my car made 280 rwhp on a Mustang dyno, what
would it make on a Dynojet”, should be countered with the statement, “I’m not sure, but I
do know this, you’d most likely get 10 different numbers on that same Mustang dyno, let
alone another Mustang dyno that’s installed in the field”. Now this isn’t meant to bash
Mustang dyno or Dyno Dynamics, but some dyno owners just can’t resist “tuning the
dyno”, instead of tuning your car. If you’re “measuring stick” isn’t consistent day in and
day out, then how can you be certain your tuning and modifications are actually working?
If these dynos are set up properly, they can provide relatively consistent and repeatable
results. For what it’s worth, we do not allow dyno operators to adjust “certain parameters
about the test vehicle” on our hybrid electric brake / inertia 224xLC dyno.
So, in any case, there are a couple ways that even when testing on the same model
Mustang dyno or Dyno Dynamics dyno (or even the same exact unit) that the numbers
are subject to a few variables. These variables are ultimately responsible for the power
numbers reported from the test session.
Then the argument comes out, “well, I need to have my car tuned on an electric load type
dyno”. This is not necessarily the case, I’d be more concerned with the ability of your
tuner / calibrator. A car that needed a “ground up mapping session”, ie. complete
development on a stand alone system or “zero map”, then a loading dyno would be
VERY beneficial. When you do testing on a loading type dyno, ask your “tuner” to
supply you with a plot of calculated load, along with as many other parameters you can
get your hands on (spark advance, MAFv, IAT, etc). Log these types of parameters on a
loading dyno, and then on an inertia dyno and let me know what you find. As an
enthusiast, I would urge that you arm yourself with this type of data, it’s much more
important than concerning yourself about which dyno you should test on. Tuning, or
refining an ECM calibration is one discipline that requires specialized tools, but for “no
bull shit numbers” there is only one consistent means of measurement, and that’s a
Dynojet dyno. I’ll go into detail on this subject another day, so until then, enjoy your
chassis dyno experience.
*** For the record, Dynojet has offered “loading type automotive chassis dynos” since
2003, although a majority of the 1400 Dynojet automotive dynos in the field are “inertia
only”. Currently there are about 200 224xLC and 424xLC’s in the field, the “LC”
designation indicates that it’s an electric load type dyno. The LC dynos that we offer can
be operated in either mode, inertia only, or inertia combined with eddy current load
absorption.
Dan Hourigan
Vice President, Dynojet Research, Inc.[/quote]
rrroadster wrote:
Wrong. Dynos use a correction factor to minimize that input to an acceptable level.
All valid points, which indicates that all laps for a given session need to be reviewed in aggregate for the data to be reliable and meaningful.
[quote] The standardized method should somehow account for variations in ambient conditions - maybe some kind of table that gives correction factors based on temp and elevation(do you think relative humidity should be included too?).
So let’s say a 160 HP max at the ground at say, 20 degrees Celcius at what ever the elevation VIR’s front straight or northern paddock is as a starting point?[/quote]
To deal with data at different points in time, you have to isolate as many variables as possible. Except during the same session, I don’t think you can reliably compare data from a device that does not factor in environmental factors.
Steve D.
Patton wrote:
I am an optimistic guy… Hoping for “benevolent dictatorship.” I work for one, and it’s pretty good if you know how to offer conflicting perspectives.
I wish you would fill in your “I’m not sure that…” because you know a lot about a lot AND have a long history with the cars and players here.
Steve D.
Steve D wrote:
[quote]9d3 wrote:
Forgot to address this earlier.
In the SSM program, we are planning to have set limits for HP & TQ every 1,000 rpm from 4k to 7k. I agree that you need to spec the limits AND the area under the curve.
What this will beget is a lot of testing by the guys who want to snug up to the limits. I’m OK with that.
Steve D.[/quote]
This is the key, because certain engines with certain mods are effected in the power curve differently. If you just pick a max or peak number, someone can have tons more mid and low range power and have a competitive advantage. If you specify an area under the curve limitation, a few points here or there is in the statistical noise and probably doesn’t justify a DQ. At that point, too much money and time will be spent picking up fractions of a hp in a certain rpm range and prove to be a waste.
Good stuff.
So an inertial Dynojet has the least amount of subjectivity.
So let’s say Ground HP ratings will be determined by an inertial Dynojet with SAE correction factors. You have an annual dyno sheet you keep on hand for inspection. You get it done once a year, give or take a few months(3?). If anyone seems suspect after a race you dyno them.
So what’s the best corrective action to take against the offender? Intake restriction or power/weight?
I don’t think any of us like the idea of somebody messing with our motor and would a restrictor really produce the desired results? Could it result in too much of a penalty? How long would they have to run with it?
Power/weight would seemingly be easy with a set of good calibrated scales - but you got to have them. And what if the penalty weight caused the total ballast weight in the car to exceed the limit?
How about the offender is DQ’d and continues to runs so until new acceptable dyno data is presented?
This is Spec Class racing for fun, giggles. The rules should be straight forward and simple.
Steve D wrote:
[quote]rrroadster wrote:
Wrong. Dynos use a correction factor to minimize that input to an acceptable level.
[/quote]
If you don’t see a true SAE corrected number, you can’t truly compare results. This adjusts the measurements for standard temperature, pressure, humidity, and any other environmental factors that effect power productions.
Different dynos may or may not be an issue, but dyno calibration definitely is.
On the dyno correction factor thing, isn’t there a number associated with that? Something like using SAE factor of 2 or 5 or something?
Michael
#36
Great Lakes Region
Steve D wrote:
[quote]Patton wrote:
I am an optimistic guy… Hoping for “benevolent dictatorship.” I work for one, and it’s pretty good if you know how to offer conflicting perspectives.
I wish you would fill in your “I’m not sure that…” because you know a lot about a lot AND have a long history with the cars and players here.
Steve D.[/quote]
Thanks, Steve for the kind comments.
I am sure that this is a good discussion and that there is a rules group that is participating in the discussion.
How 'bout this: I am not sure that you are available to meet at La Cazeula for dinner with Chuck Taylor, any other SE racer and myself to discuss this stuff further.
Advise…770-886-2500
RP
jlucas wrote:
[quote][quote]9d3 wrote:
I’ll say this - if I really was building to the extent of the rules and planning to finish top 5, I would probably want to buy a dyno run or two on that exact same dyno at the track when a race was not on the line to be sure I was in compliance. [/quote]
And what would you do if your newly built motor was over the magic numbers?[/quote]
I think it’s unlikely because the extent of his data in hand is from nationals competitors which I would expect are most built to the extent of the rules. But I do think there is a huge advantage in having variable data from different dynos, temps and altitudes before setting anything that could cost guys a motor or a DQ. In my mind, anything less is a crapshoot.
My head hurts…I think I am going to get drunk and hitch a ride to the Walmart.
Al
Racing :LeMons this weekend…
FARTBREF wrote:
[quote]My head hurts…I think I am going to get drunk and hitch a ride to the Walmart.
[/quote]
Isn’t that what caused the headache in the first place? :blink:
Steve D.
ilateapex wrote:
I think the latest is SAE J1349:
Of course, it goes without saying that:
cf = the dyno correction factor
Pd = the pressure of the dry air, mb
Tc = ambient temperature, deg C
The pressure of the dry air Pd, is found by subtracting the vapor pressure Pv from the actual air pressure.
Or something like that.
Steve D.
PS - It’s far easier just to say “Y’all sumbitches is cheatin’!”
jlucas wrote:
Spec E30 racer Carlton Goldthwaite offered the idea that the unit not be required but that if a driver finishes in the top five and has chosen to not have a Traqr, his/her car will be repositioned to 6th place. With that, midpack drivers can choose to not buy a Traqr, or to buy one later. This is an interesting idea and we are certainly willing to review all other ideas.
…[/quote]
Hey, Now you’re talking. I’ll show up at a SE event with my 220 hp stroker motor. With that, I should be able to get to the top 5. Then maybe I’ll get the coveted 6th place trophy! 
Don
Wait, what if you already finished in 6th place? Do you get bumped down to 7th without a big brother box?
Guys:
I haven’t read all the comments here…but I will tomorrow.
Regardless, we want everyone to know that the Spec E30 Regional Series Directors and I have been discussing this and we are 100% in the “Research Stage.” No rule changes have been discussed and we are planning to use this season to continue testing the Traqr. As the testing proceeds, we will give regular updates to the drivers.
We have found one minor glitch in obtaining the Road Horsepower from a driver’s personal MaxQData unit (not a Traqr) that he is allowing us to use. Because this is a big part of the testing, I’ll talk to the MaxQData guys this week. Also, during the testing and if/when we go to the next step, Spec E30 officials will only see the Road Horsepower data. We will not look at other data provided by the Traqr and all drivers are welcome to observe the downloading of data, the comparison reviews, and the deletion of data after the comparisons.
Again, we’re just throwing-around some ideas, we’re just testing the units and our abilities to use the data effectively, and more updates will be posted on the Forums.
Carter Hunt
Spec E30 National Series Director
Let’s simplify this and mandate that everyone has to make his or her own:
http://www.ianwood.com/news/story.asp?sid=36
We can also self police since everyone can have access to everyone’s data in real time on the track. Just point out the window to a competitor suspecting of cheating to pull over into the pits like a cop.
The best part is how obviously, all LeMons cars truly benefit from live telemetry with so many on-the-fly adjustments available to the driver right in the cockpit… adjustable sway bars, computer controlled dampeners, brake bias controls, real time engine management, you get the idea…
I promise you will see one of these in Chi’s car at the next event. This just wreaks of a Chi project.
TheRedBaron wrote:
my system already does that except it uses SMS.
oh besides, I’m too busy right now. One word. KERS
I can not diverge too much detail right now but I can say start collecting all the rubber bands you can lay your hands on. Carry on.
Absolutely new to Spec E30, but lots of races in Formula Vee (and a few in Formula First). Both are spec classes - and have the same (or worse) problems with guys spending mega bucks on “National” engines that cost 3-4 times what “Joe Regional” can spend to build one himself. Net difference - maybe 2HP out of 55HP on a good day - in Formula Vee at least.
Formula first attempts to eliminate some of that problem by mandating a restrictor plate below the carb. Two reasons - they want to limit the HP of the 1600cc engines vs the 1200cc Formula vee engines (keep lap times close) AND they want to stop the guys who will spend ANYTHING to have the best heads, carb, and intake. In FFirst, you can spend all you want, but the plate is going to restrict you to about 80HP, so why bother?
Never seen a dyno at an SCCA race - so that’s never been mentioned as an option. I think you NASA guys already have some classes (camaro-mustang challenge maybe?) that need to measure HP every weekend - so it’s a no brainer to dyno the Spec E30 cars?
So… how 'bout a restrictor plate behind the throttle body? You could mandate a size that should limit everyone to 150HP - then let the guys spend mega-bucks on heads, intakes, cams, etc - it won’t be of any benefit. Some guys might have more area under the torque curve below the airflow choke point - but they won’t be out-horse powering you down the back straight at Mid Ohio.
Unless it’s me, of course, because I’ve learned to fart Nitrous after eating Mid Ohio track burgers - so I’m always passing gas (and people) into Turn 6…
Jim