jfh

iTrader: (38)

I am confused by the significant differences in reported HP between Vishnu's Dyno Dynamics Dyno and Air Power Systems' (APS) Dyno Dynamics Dyno. We are all aware of the controversial low measurements seen on Vishnu's dyno and have been asked to believe that it is more precise and therefore posts measurements that are closer to "actual" than any other dyno available.

APS aquired an NA spec Evo VIII for product development and reported 264.9 HP from their stock car.APS Dyno Dynamics Graph for stock US spec Evo

Seems that the controversial numbers are related to optional settings and procedures listed in the manual which provide significantly different results.

APS numbers were recorded using the "Shootout mode" settings and graph is labeled as "Power and Turbo Boost Pressure of the stock Mitsubishi Lancer Evolution "

N10S

iTrader: (4)

Thats pretty interesting info. Axis racing, located in the St.Louis area, just received and is installing a Dyno dynamics dyno as well. Makes me wonder how it will chart in comparison to the others?

I guess as long as you have a baseline and future dyno runs on the same machine it shouldn't make much difference. Obviously the base dyno "settings" must be different for that much of a swing in stock Evo hp/tq between like machines.

The shoot-out mode listed on the print-out allows for an overlay of multiple cars for "shootout" comparison?

N10S

SILVER SURFER

Don't you already know? It's a big conspiracy, it includes just about everyone in the US, Mitsubishi, perhaps government is really behind it.

I was actually planning to start a chassis dyno thread, just waiting on some test data and doing a little more research. Other than enviromental corrections, there is not much an honest operator can do to alter readings on an inertia dyno. Break dyno's on the other hand have several variables that can allow for a wide variance in readings. This is what your seeing here. IMO break dyno's have a much larger margin of error due to there complexity of design and operation. Shiv has already pointed out, you can make a break dyno read what ever you want.
Because of this fact, I find it hard to trust data from any of them.

Don't get me wrong, they are great tunning tools, I just would not use them to compare numbers with other chassis dynos.

gtr

iTrader: (6)

http://www.airpowersystems.com.au/un...hi/evo6_5.html

I think they convert their units wrong or it's some actual hp estimate? The evo 6.5 makes approx.

157KW=210.5 hp and

with unichip
184KW=246.7 hp

Looks like the usual low reading dyno to me.

shiv@vishnu

iTrader: (20)

Ah... Silver Surfer is useful as ever. For those who want to know the facts, Shootout mode is a Dyno Dynamics software feature that estimates flywheel horsepower. That's what the S_HP stands for... Shooutout HP. It basically multiplies actual wheel hp by some predetermined driveline loss factor (1.3-1.4, depending on car and output). While there is some science to it (DD does a lot of engine and chassis dyno testing), it's still an estimate.

I don't use it because nothing short of an engine dyno can properly measure flywheel output. It's a neat feature to show those who don't understand why wheel hp is so much lower than rated flywheel hp.

Using Shootout Mode on our dyno, most EVOs are putting down 260-270 hp. And WRX are making 220-230 hp. So, it can be quite accurate.

cheers,
shiv

Mister2zx3

Dyno jets self calibrating and measuring of barometric pressure, wet and dry humidity and temps make it fool proof in repeatable SAE measurements.

I don't see how a dyno that requires user measurement, of temp, wet and dry bulb humidty readings and barometric pressure can be trusted, since any of those values could be entered wrong, or heck maybe not even measured before each run.

Standards are in place for a reason. If I tell someone they need a 2 inch bolt and they have to figure in that Im located here and they're somwhere else and becuase I used standard meaurements not metric they have to adjust it and end up with a 1 and 3/4 inch bolt, there isn't a standard.

1hp SAE = 1hp SAE no more no less.

1hP SAE in 100'F may be less actual horsepower, but it's still 1hp SAE.

Around here in 100+'F with cars strapped on the dyno where it's usually closer to 115'F, SAE hp is always higher than actual.

But hey, then again maybe the whole standardization thing is a mytha and I can run *MY* 1/4 mile in 9 seconds.

SILVER SURFER

Shiv,

Your system can measure driveline loss through coast down measurements, so what does it show?

If you do constant load measurments with your system what do they show? Are they different from an acceleration run?

Could you also share how specific settings are determined on your system, and exactly what settings you use?

What exactly is different with your system and Dyno Comps?

Unfortunately DD does not share there manual online, or there FAQ details. There are some very interesting FAQ descriptions, such as:

How do I tell the dyno what the vehicle drive-train inertia is?
How do I measure vehicle drive-train inertia?
Frequently the maximum boost achieved on the dynamometer is less than the boost achieved on road.
What causes this?
What can I do to reduce this effect?
I ran this vehicle earlier/yesterday/last month, and measured the power. I have tested again today with no apparent changes to the vehicle, and the power is different.
What sort of things should I look for or check?

Care to enlighten us on these?

shiv@vishnu

iTrader: (20)

If you ask the guys at Dyno Dynamics, they might email you a copy of their tech and users manual. They are like that. It is very good and is worthwhile reading material. Even for those who don't have a dyno.

That said, I'm afraid that I don't have the time to answer each and every one of those questions to the depth they deserve. Especially when they can be read about in the manual, written by those who designed the dyno. Not paraphrased by a user like me who simply uses the dyno for tuning.

Also, in the last thread we engaged in, you left when things were getting interesting. Would you mind going back to https://www.evolutionm.net/forums/sh...&pagenumber=13 and commenting on my last few posts. Let's continue that discussion here since this thread subject is more applicable that the old one.

Regards,
shiv

SILVER SURFER

Sorry, that thread was to mixed, when I got back to it our discussion had gotten buried, I wanted to have some additional info before I started my own thread and responded to your last comments. Any way here is what I think regarding your last statements.

Considering that a viscous differential does not start transferring torque until there is a difference in speed, and that it is more effective at higher speeds and load. This does not seem unexpected or alarming. According to Dyno jet measurements they do catch up and run within 2% speed variation of each other, just like your dyno. Individual roller values that can be viewed on any Dyno jet seem to bear this out. (I will post graphs soon)

Rotational inertia is basically determined by the mass, radius of the drum, and speed. Yes for a given speed the larger drum has more load. But the smaller drum is actually spinning faster on an AWD chassis dyno, essentially equalizing the fore/aft load. Dyno Jet admits they are not perfect and could be off by as much as 17%. Driving on a racetrack around corners at full throttle I believe these differentials see variations far greater than this.
I do not believe there is any evidence to indicate that these dynos harm viscous center diffs or cause significant measurement errors.

This all sound nice accept the third/fourth gear testing that I mentioned was done on a Mustang dyno, where there is absolutely no fore/aft speed differential.
The reason cars show more power in fourth gear as opposed to third are:

1. There is actually more work being done for a given load/engine RPM, with higher loads the engine/turbo are able to produce and transfer more power for a given engine RPM at a given fixed load.

For example: lets say your riding a 18 speed biycicle on a flat surface. In first gear (granny gear) start pedaling from 0 up to say 100 RPM. Then switch to 5th, then 10th gear, and perform the same acceleration test. You should find that you can develop more torque on the pedal crank with higher load. Does this make sense?

2. There are less inertial losses due to the slower rate of acceleration.

3. In most transmissions fourth gear is direct, less gear meshing to rob power.


As far as I can tell, the rest of your comments like this are hear say and speculation. Accusing large groups of reputable individuals and companies of purposely putting out false information. In this regard I would like to stick with verifiable proven facts, or at least credible theories.


Kind regards

Eric

PS So will you answer my questions now? I am not sure that I am 100% right on all this, but I am pretty sure that you may be mistaken about a few things also. This is a complex topic with many gray areas, hopefully this discussion will bring enlightenment to us all.

I swear that sucker moved, keep beating it.

turbopoo2000

it's up and running, I helped Ron put it together a couple days ago. He just had an all night dyno party last night. I didn't know you were so close or I would have let you know about it. He has yet to get an evo on it yet though. We'll probably get mine on there sometime this week for a baseline run. He's still learning how to use all the features, Dyno Dynamics is sending a rep out soon to show Ron how to make the most out of all the features pretty soon. Any other Evo owners around the St. Louis area? The shop is located in Belleville, IL.

SILVER SURFER

Here are some roller speed measurements 2nd and 3rd gear pulls on my EVO, using a 248/224 AWD Dyno Jet.

N10S

iTrader: (4)

Wow, sorry I missed-out on the dyno party Keep me posted as things move forward I would really like to dyno my car in the near future to check the 93octane reflash and rear pipe. Are you the Evo owner with the xede and custom exhaust Ron was talking about?

Btw- I recently opened a thread in the local Midwest forum to let people know the dyno was here. I have talked with only a few guys via pm but perhaps we can pull together to have an Evo dyno day soon.Pm me and we can talk further.

Back on topic regarding the initial post, it sounds like the major delta in hp/tq can be attributed to the "shootout mode" calculating a crank horse number vs the actual wheel horse numbers. Thanks for clearing that up Shiv!

I do agree with Silver Surfer that the wide variation in set-up could result in a wide range of results, and that some form of standardization amongst owners of like dyno's could only lend credibility and benefit dyno owners and customers alike.

N10S

Mister2zx3

This is a little off topic, but that's a great way of showing how coming out of a corner with a few mph higher speed makes a huge difference. It takes 4 seconds to make up a 7mph difference. That's just to match speed, not even close to actually catching up on lost ground. That's also with a much more torque being put to the ground, 2nd vs 3rd gear.

shiv@vishnu

iTrader: (20)

And that's thanks to your center differential which is working quite hard to maintain the fore-aft speed match. It's doing it's job. And, in doing so, it is wearing. This point cannot argued. Now do 20 or runs a row and see that differential grow. Now do 100 runs and see how well things work.

Incorrect. A 17% wheelspeed differential is enormous. And most AWD race cars dont see anything that big significant. And what it does see, it sees for max for 1-2 seconds at a time coming out of corners. And that really only applies to AWD cars that have enough power to actually break traction up front. Competition cars that are subject to big fore/aft wheelspeeds almost never run viscious center differentials and install clutch-type units for their greater durability and better torque holding capacity. And yes, clutch type center differentials (as in the Porsche) don't take well to dynojets since they don't "give" when subject to stresses of mismatched intertial dyno rollers.

Could that be because no one has bothered doing any testing on this subject? Common sense would indicate otherwise. Not to mention that, the last time I checked, the Dynojets air brake only brakes one roller after each run. Again, a serious design flaw. One I hope they address one day.

Uh.. okay. When every dyno overseas reads within a few % of each other and the US Dynojet reads 15-20% higher, one can draw their own conclusions about calibration and accuracy. If you believe that Superflow, Maha, Bosche, etc,. are all wrong, so be it.

I'm as patriotic as the next guy. But I also tend to be believe the most likely scenario. Especially when its supported by evidence that I believe to be true. Clearly, you have your own ideas on this subject and they aren't going to change by the looks of it.

Cheers,
shiv

JRock

Anyway, aside from this massive side argument, I think the point of this thread intially was a good one - to get all 4-wheel dynos of the same brand/model to be configured the same way when Evos dyno so you can all compare numbers more accurately, instead of only being able to compare how much gain certain mods have given.

You know, it'd be nice to know how much variation there are in stock Evo performance numbers, but since everyone's got their dynos configured differently we can't do that right now without guesstimation and hypotheses about how to convert numbers from one dyno to another, etc.

So yeah, it'd be cool if we could get a set of standard settings to request to be used at the handful Dyno Dynamics 4-wheel dynos across the country that Evolutionm.net Evo owners dyno on. We could get Shiv to provide his settings and then just print those out and bring them with us if we go to another DD dyno elsewhere so they can set it the same.

That would remove much of the variation wouldn't it?