Well I finally got my "baseline" dyno done tonight. I say "baseline" because it's not 100% stock. I have the HKS RS intake, forge d/v (which does really nothing at this point without a BC) and a grounding kit.

Run on a Mustang MD-AWD-500 SE, here you go:



I should get my guy to run the scale a bit narrower, but you get the idea.

Now I just saw someone else's dyno on the same type of machine, and while they made less "HP @ 50mph" (11.5) they made more max hp and torque than I did.

The peak HP/TQ in this chart is perfect, 6750/3750 respectively... but I can't figure out why this dynometer is reading so low. I believe the SAE correction factor was something like 0.97.

Is this the weight you are all using on these dynos? I noticed a bunch of you have dyno'd on these things.

Do they typically read pretty low compared to your standard intertial resistance type dyno?

The guy running the show at Dynamx told me he has nicknamed this dyno "the heartbreaker" because so many people walk away wondering where all the power went...

Any ideas/input would be great. I'll get an AFR chart up tomorrow.

 

The funny thing about these active load bearing dynos is that you can get wildly different results just by pushing a few buttons. It's all a matter of what loading factors and ramp rates the operator selects. Since the operators can select whatever values they want, this makes comparing numbers with others extremely difficult.
All dynos can show varying results due to enviromental conditions and selected correction factors, but beyond that all inertia dynos (like Dyno jet) read about the same. Active load dynos like Mustang, Dyno Dynamics, etc, have these same variables plus the operator selectable load factors. These programable load factors alone can cause measurment variations well over 20%. Just look at my stock EVO base line done on the same type of Mustang dyno only with a different shop/operator.
So if you want some sort of reference, you need to compare yourself with other EVO's done at this particular chassis dyno, and hopfully the operator/programing was consistent.

 

Silver Surfer, always on top of things with the good info buddy.

Can you list some of these operator selectable factors?

Also, my dyno place is getting new software (PowerDyn) which will probably be installed by the next time I go down there. I wonder how much of a difference that's going to make.

Your dyno looks exactly like I thought a stock evo dyno should be. My dyno represents a 30% drivetrain power loss from the flywheel... =/

I really only did this to get a baseline before my exhaust went on, but man I was expecting some better numbers that's for sure. THIS would be the least ego-friendly dyno around IMO.

 

Interestingly, it also appears to be that you CAN run the Mustang eddy current dynos in inertia mode, which would definitely yield a higher output.

I was just reading about this eddy current brake dyno technology and it does seem to have a good tuning advantage. Since it increases the roller resistance as your speed increases (as would happen in the real world) you can actually more accurately tune the engine especially up in the higher rpms where it matters more.

Silver Surfer, were you running in inertia mode or are there other eddy current mode factors/settings that can be adjusted? I didn't get a good look at them all and google is failing me for more info.

Also, is this the standard wideband o2 sensor setup for most dynos?

 

Additionally, all of my runs were done in 4th gear from ~45mph - ~105mph.

Here's an interesting little write up from AWE tuning:
http://www.awe-tuning.com/pages/faq/...ain.cfm?FAQ=22

 

Unfortunately no, I tried asking the owner/operator at this shop but he was not very forth coming with the information. All he would tell me was that these were the same settings he uses on the WRX's. The shop info is on the sheet so maybe you or your shop can contact them and get the information.
BTW after a EVO dyno day at this shop we saw 230 to 242WHP, on a variaty of stock EVO's, so the average EVO measures around 235WHP with these dyno settings. They say that the average WRX measures 180 to 190WHP, and STI's around 265WHP, so that jives very well with the manufacturers fly wheel HP numbers. This also gives you good reference points, assuming similiar drivetrain losses, and I see no reason to beleive there is a significant difference with these vehicles regarding drive train losses.

Most runs are done in third gear, but we did try one fourth gear pull on this dyno, it actually showed slightly higher WHP. On the AWD Dyno jet I have tried second, third, and forth gear pulls, there was a big difference in spool up/low end torque but the peak WHP numbers did not change much at all. I prefer third gear, it provides enough loading/time to see any potential inconsistancies in your maps, but does not stress the car as much as fourth gear pulls do.

Inertia dynos can only test and allow tunning under acceleration. For tunning on a dyno these active load systems certainly have advantages. Most of what I have seen, is shops with these fancy expensive load bearing dyno's and all they do for test and tune are simple acceleration runs! A much cheaper simple inertia dyno can do a fine job in that regard. It seems like a waste to me, but maybe they use them differently when no one is looking and then hide all of that data .

IMO no shop chassis dyno (load bearing or not) can accurately simulate real world conditions. Differences in airflow alone can have a significant impact on tunning/performance. If you really want your car tunned properly you need to test and tune under real world conditions, and it needs to be done under the conditions the vehicle is actually used. Tuning a car for normal street driving with occasional bursts of acceleration and then taking it to a road course on a 100 degree day are two very different ball games.
Chassis dyno's are great for initial/ruf tunning, and they are good for getting reference values and troubleshooting certain types of problems. They are also usefull for testing the impact of certain modifications, but even there not all modifications will show there true worth on a chasis dyno. For example a cold air intake or a bigger more efficient IC cannot show it's true value without proper air flow as they would see under actual conditions so...

Just got my Gtech Pro in, hopefully that will provide some interesting test data if I can use it properly.

 

I totally agree, there's no way a dyno can simulate everything. It's more about resistance, you know taking into account air resistance, weight, hills, etc. I did only do 4th gear acceleration runs, and for that I probably should have had him put it in inertial mode so I could get a more "world-based" number, but since I'm going to be tuning on this dyno in the near future I guess it's better off that I went with the simulated run.

FWIW all the SSB (non-inertial) dyno manufacturers recommend a 1:1 gear for dyno testing, and I guarantee you that's why my numbers are lower. I know 4th allows for more peak boost longer, but 3rd is damn close and pulls like a bat out of hell compared to 4th. On an inertial dyno it probably doesn't do much more than just give you a longer data sampling time frame, right?

At any rate I'm glad I got a baseline, going to be back next week for a buschur 3" exhaust test (after I install it this weekend). Maybe then I'll be close to "stock" numbers.

When I go back in for the exhaust test, I will do inertial and SSB runs to see how much they differ, and I'll be testing the a/f again.

Thanks for your information SS, always good stuff.

 

Also here's a great great article explaining the difference between the results from a Dynojet inertial dyno and a Mustang ESSB dyno, as well as a real-world road test comparison:

http://www.mustangdyne.com/Articles/...article-01.htm

 

FWIW, I think if you are just looking to see what the max power output of your engine is after the drivetrain, an inertial load dyno is probably the easier/better way to go. Since my shop's dyno can do both inertial and ESSB testing, I will do both from now on so I can have the "big deek" dyno chart and "real world" dyno chart.

 

You have to keep in mind that all of these chassis dynos are trying to show HP and torque at the crank. There is more actual torque at the wheels in lower gears, but they are also spinning slower (doing less work). So even though a car pulls harder in a lower gear, that does not necessarily mean that it will show a higher HP/TQ at the crank, or that more work is actually being done.

The 4th gear 1:1 ratio is recommended to try and reduce drive train losses. On these AWD platforms this does not seem to make much difference, so most err on the side of caution and go for the similar but less stressful third gear.

This test is conveniently located on the Mustang web site . Even so, the results do seem to support what I was trying to tell you, such as the fact that all of the test methods show higher power results in the higher gears.

With the Mustang dyno calibrated and set by the factory, the difference between it and the Dyno Jet was only four to seven percent. Your test data if off by more than twenty percent! Something was obviously not right here, do other EVO's read that low at this shop?

Keep in mind that an AWD Dyno Jet has about twice the inertia load of the 2WD systems, (two inertia drums instead of one). So the acceleration times/load factor with the 4WD Dyno Jet should be a lot closer to the Mustang, compared to what you see in this test. Maybe that is why some Mustang dynos setup differently actually show nearly identical values compared to the Dyno Jet AWD system?

This is my biggest beef with these load bearing dyno's, the test data is only as good as the person operating it. None of the graphs show the setup values, so you don't even know if two graphs from the same dyno are comparable.
The inertia load on the Mustang has to be very small, so even in inertia mode it still has to rely quite a bit on it's electric load device (eddy current brake), and of course the settings entered by the operator.

So trying to say what is "big deek" and what is "real world" can be very subjective. It's not perfect, but when I see a Dyno Jet graph I can reasonably tell what that translates too in real world performance. The Mustang can be setup to show very similar results to a Dyno Jet, is that wrong? I don't think so, I think it provides meaningful comparable test data.

If you have test methods/values that cannot correlate with anyone else's test methods, the data has little to no value for comparison/sharing.
As you said it has value for your own reference and modifications, but it has no reference to what everyone else is doing. Where is the fun in that ! You will have to go to a drag stripe just find out what these numbers mean. Then you can try and start applying some correction value but IMO that just muddies the water even further.

I said it before and I will say it again, "like it or not, for better or worse, Dyno Jet test results are the industry standard". Dyno Jet WHP numbers can almost be considered a unit of measurement unto itself. IMO whether they are truly accurate does not really matter at this point.

 

Well point Silver!

If everyone has a yardstick of different length than everyone else, whats the point..

As things evolve (heh), not only knowing how the measuring device is operated, but also what is being tested is operated is going to muddy the waters a lot more..

http://www.caranddriver.com/article....rticle_id=8020

 

SS I completely agree. I am in good with my shop guy so I will get those parameters so we can see if any are way off. Also if you wanna see some pics of the dyno itself, check out http://images.330i.net/evo/dynos/dyno_04262004/ ...

I also agree that a dyno is really more for show... I mean yes it's nice to know your supposed wheel hp but honestly, as long as I know that what I'm doing on this dyno corresponds to a standard stock evo (say, 235hp / 260 ft-lbs as someone else got) I am satisfied. The real interesting part will be my next dyno session in which I'll be testing my new full 3" turboback w/ test pipe running an inertial load (manual load diagnostic test in the MD-7000 software) and an eddy SS mode (to compare to my previous runs).

I have already verified that my operator doesn't change the parameters/settings around at all, so we can be sure of a consistent rating on this dyno for my car at least.

No other evos have run on it, only a couple of scoobies, but I don't know what they pulled.

More to come as I investigate this further...

SS what do you think about my assertation that tuning will be much more "real-world like" on this machine as opposed to a standard constant load dynometer? Will it make a difference? I think so, but then again with power levels being output like mine above I can see an issue with under-tuning the car. =/

We'll see how it all pans out.

 

Well, I have actually tuned my car on both types of dyno, that's why I do most of my tuning on the street now . At WOT acceleration tuning, they will both provide similar tuning results.

The advantage of the load bearing dyno is the ability to tune all of the part throttle settings, at various load points and RPM's. This takes a lot of time and effort, and most custom tune sessions do not encompass this type of tuning. Unfortunately every one is usually just concerned about WOT max power/acceleration. These other part throttle load points can be just as critical to performance and reliability, but they are seldom given the attention they deserve. These load bearing dynos can really help you get these other points dialed in, but you still need to fine tune them on the street, just like WOT. Trying to adjust these points on a pure inertia dyno is nearly impossible.

IMO this is the main reason for the added cost and complexity of a load bearing dyno. Not that they are necessarily more accurate at measuring WOT max acceleration WHP, IMO I don't think that they are. But as I said they have other advantages/features that justify there added cost and complexity.
That is why I think that a shop with one of these fancy load dynos that only ever uses it for WOT pulls, are truly under utilizing the capabilities of these wonderful tools. Not to mention they spent a lot of extra cash for no good reason.

I have spent hours tuning WOT on the Mustang and Dyno Jet, A/F ratios are great we are making good smooth power, good numbers, no knock, then we take it on the street . It feels wonderful, but after a few pulls it's knocking all over the place and we end up pulling timing and adding fuel here and there.
The problem is just that no matter how good a simulation it might be, it's still just a simulation, there is just no substitute for the real thing. You just can't drive a car on a chassis dyno like you do on the street. Load variations and operating conditions change so much in the real world, you just cannot simulate all those conditions on a chassis dyno, no matter how good it may be. Plus the air flow is completely different, that's important.
Why do you think all the car manufacturers run test mules with all sorts of telemetry equipment and then they run them in all sort of different environments, mountains, desert, snow, etc.
I have even found that you can have your car tuned perfectly for normal/aggressive street driving, then you go to a road course and things change. There are thermal dynamic/load conditions with road racing that you just rarely if ever see on a dyno or the street.
Now if you’re just doing mild upgrades and using the stock ECU, it should already be able to correct for a wide variety of conditions. Once you start modding to the point that you’re making thirty, forty percent more power and beyond, those stock ECU tuned corrections start to go out the window. This is why if your going this route people invests in ECU's with data logging and gauges to monitor vital engine parameters. The tuning process never really ends at this point. People planning to make significant power over stock understand all this, or they learn about it, usually the hard way.
A lot of people who think they want a 400-500WHP street monster don’t seem to understand this. At that level you have to be prepared to work with it, or have enough money to have a tuner/mechanic at your beck and call, or just buy a Viper, Z06, etc .
If you tune the car on a chassis dyno or the street for that matter so that it is just below the knock threshold at that particular day and time, as conditions change you can easily go beyond that threshold. This is why you usually leave HP on the table and build in a nice safety cushion so hopefully you don't go over the edge.

Sorry for the ramble

Good luck with your test and tune, I would be very interested to hear what you find.

Regards,

Eric

 

Eric, indeed I am only going for a solid 320-350whp (depending on gas). I don't plan on going stand-alone or anything insane like that, and I do plan on leaving that safety cushion open, so in all reality I could probably tune just as well on an inertial but it will be those critial partial throttle/load points that I get to tackle which will make the difference.

BTW did you check out the a/f pipe above? Is that standard for reading the post-cat a/f levels on a dyno?

 

Here's my hp. vs. a/f graph for the above dyno run:



Pretty rich no?