I got this article from a friend in New Zealand when I told him about my problems when dynoing my car with the 3071 turbo kit. It’s written by Julian Edgar a well reputed tuner and the editor of a car tuning and performance e-magazine at http://www.autospeed.com :

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Driving Emotion

Sometimes, the dyno is the worse place to do testing

by Julian Edgar



Car modification goes in cycles, in trends of popularity and enthusiasm. Sometimes stupid ideas are abandoned; other times they’re fervently embraced.

When I first started writing about car modification – it would have been back in about 1987 or 1988 – almost no workshops had dynos. Back then, performance claims were largely the stuff of description. You know, this exhaust will give your car just fantastic power, mate.

Paradoxically, some of the first companies to use dynos to ‘prove’ power gains were the very same companies that had no power gains to prove. But they knew that with so few dynos around, and with knowledge of how to fudge dyno figures commensurately low, their advertised dyno improvements would have credibility.

For a while at least.

But now every serious workshop has a chassis dyno. Mods which give no power gains are still being widely sold (polished throttle bodies, restrictive aftermarket cold-air intakes, exhaust systems with no engine management changes) but for the inquisitive, finding the efficacy of the mods is only a few dyno runs away. One dyno run at the place selling the goods and another at an independent workshop.

But the ubiquity of dynos is leading to an outcome which is nearly as bad as the times when they didn’t widely exist. Instead of simply taking advantage of the research and development tool that gives enormous flexibility and freedom, workshops are being increasingly constrained in their modification approaches by dynos. As in, some tuners spend literally all of their time on them. Which would be fine if their customers drove cars only on dynos... and not on the road.

We’ve driven modified cars that detonated like crazy when road tested – they’d never been off the dyno for final engine management tuning. We’ve talked to tuners who believe that all the mapping can be done on the dyno – despite the fact that their brand of dyno cannot replicate trailing-throttle events. We’ve talked to modified car owners who swear blind that their car makes more power on one dyno than another. And now we’ve got to the bizarre situation where dyno manufacturers no longer even have universal power measurement. Was this run done in shoot-out mode, sir? WTF? Are you telling me that a horsepower is no longer a horsepower? That kilowatts are no longer kilowatts? Well, in that case, how long is the metre rule that’s used in your workshop?

The slowness of the aftermarket to embrace electronic system modifications that don’t involve engine power is largely because modified car mechanics are becoming increasingly besotted by their dynos. Where’s the traction control, stability control and gearbox control interceptors? Where are the electronic throttle control mods? But hey, on a dyno you don’t turn any corners, the drive wheels aren’t supposed to ever spin, and there’s only one throttle position – flat to the boards.

As many of you will know, together with electronics magazine Silicon Chip I have been developing a range of DIY electronic kits. These will be able to modify pretty well any electronic system in the car – including such things as stability and traction control systems. However, they can also be used to modify air/fuel ratios.

And where did we do our prototype development air/fuel ratio tuning? Despite having access to a dyno, we did it all on the road. That way, every moment of the testing could also be used to assess driveability, ease of tuning, transient mixtures – and so on. Cos it’s a road, you see. And with a Motec air/fuel ratio meter for mixture strength, with amplified and filtered earphones for detonation detection, with an OBD readout (in cars equipped with this facility), all the information needed was readily available.

Of course, this way you spend plenty of time doing the tuning, and you need to have a mate along, but the end result is guaranteed good driveability. Because the tuning hasn’t been done in an artificial environment with poor airflow, non-representative acceleration rates, little throttle-lift inertia – and all the rest of the drawbacks that dyno operators never seem to remember to tell you.

In fact, I was prompted to write this column because I read in a discussion group some comments on one of our upcoming projects. Said one guy: I see that they’re doing an electronic boost control – I can’t wait to get it on the dyno and see how well it works.

Words almost fail me – the dyno is the very worse place to test a turbo boost control system.

Let’s take a look at the drawbacks.

1) The acceleration rate in each gear is not representative of what is achieved on the road. This one’s a killer because boost overshoot on transients is hugely affected by the rate of engine rpm increase.

2) Very few people do full throttle gearshifts on the dyno. You know, race up through the gears – to the redline, change gears, to the redline, change gears. Again, it’s in just these conditions that you look for boost overshoots and/or slow increases back to peak boost after each gear change.

3) I have never seen anyone do a full-bore launch from a standstill on a dyno. And how quickly boost can be brought up in these conditions – i.e. controlling wastegate creep – is a major aspect of good boost control.

3) On a dyno the intercooler never works as well as on the road, so in those systems that don’t use boost pressure feedback, the actual peak boost is likely to be different from that achieved on the road.

4) On the dyno people never bother trailing all the different combinations of throttle position, load and engine rpm that you’ll find in 10 minutes on the road.

A dyno is a great tool. But unless it’s inside a wind tunnel, can replicate all the different acceleration rates and inertial characteristics of the driveline, and is completely climate-controlled, it’s only a starting point.

And for many of the coming chassis control system modifications, it’s an irrelevancy.

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This might be no news at all but well worth a thought? I hope I don’t violate any copyright laws now

 

i think he probably makes a good point

 

Being that I don't know dick about tuning, I can neither confirm nor deny whether or not tuning is best on the street or with a dyno...sorry

 

let me add to that i dont know dick about tunin yet (gonna learn). but if u look at car when they are dyno'd it is in a controlled enviroment with air temps at nice cooled levels. levels that is not seen alot durin normal driving. but i have read a few post about evo owners takin there car on the road with a tuner to do the final tuning in a normal everday setting after they are dyno'd.

 

Does this Julian Edgar guy know ANYTHING about how dynos work? His write up has many flaws, some of which I’ll attempt to address below.

Let's dance, Julian!

And this is a bad thing somehow? A few years (and cars) ago, I bought a "snake oil" DC Sports header for my old 2000 VTEC Honda Prelude. Even after tuning, I lost 15WTq all throughout the midrange, and made 1whp at 7500rpm. Hardly worth the $360 retail it cost to lose power. Thanks to the dyno, I was able to report my before and after numbers to other consumers who would be fooled by this header.

I disagree 100%.


And I’ve seen several street tuned cars that run horribly rich and leave power on the table. The problem is an incompetent tuner, not the dyno. The dyno is a tool. If you use that tool incorrectly, of course the results will be poor. FWIW, I’ve spent a great amount of time of Dynojets and Dyno Dynamics Dynos, and when proper tuning is applied, the car behaves exactly the same on the street that it did on the dyno.

Trailing throttle is used for deceleration. Why in the heck would you want to quantify that? When OT is released, the car reverts to typical mapping. Trailing throttle allows you to apply driveline drag from the engine and drivetrain. No special tuning is required whatsoever. This is not totally different from partial throttle tuning, which is a breeze on a Dyno Dynamics dyno.

This proves the lack of understanding and maturity of the writer. Dynos were NOT designed so you can put your car on the rollers and whack off to the peak number results. They are best utilized for tuning. Consider other measurements that aren’t standardized between manufacturers, such as “lux” ratings on cameras. As long as you tune on the same dyno, you will see results of your work and efforts. Shops and companies that refuse to show proven power results from a dyno are likely hiding something. It doesn’t matter “how big your horsepower” is, it matters that you use the same repeatable tool to quantify gains.

This is a circle chase that is distracting from the main topic of the post. The dyno reads horsepower. What the heck do you expect it to do? Take out your trash, wash your dishes, take the kids to school? Man, I’m pissed at my radar detector; it only reads radar! I want it to pick up radio signals and satellite signals as well. What a piece of crap it is! The writer needs to get a grip; his rants are becoming ridiculous.

Ahh! So the truth comes out. You’re flaming dynos to peddle your own wares. So this whole thing is really an elaborate commercial? News flash: Wideband O2 sensors have been available to the general public for quite awhile already. You aren’t creating anything new under the sun.

Prototype- LMAO! See my reply directly above. This is nothing new. And any tuner worth his salt road tests the car he has tuned! So what if you have a really good air fuel ratio on the WBO2? How do you quantify that the mix of a:f, timing, and boost are making the most power at every point in the area under the curve? How do you quantify how much timing advance the car can take in different weather situations? How do you know how much to back it off? Do you test in higher load situations, say WOT up a steep hill? The tool you are trying to discredit as not being scientific enough easily eclipses your road testing methods.

Its called closed loop tuning and partial throttle tuning. You can do this on a dyno and greatly enhance the drivability of the car. You can tune specific cells at a specific rpm range with a specific dial-it-yourself load from the dyno. Try doing that on the street! You’d have to drive all around the city and find different incline and decline (load) situations, not to mention risk getting a ticket for looking like a nimrod when you break every traffic law in the land road testing.

Hey narrow-minded guy: Read these words and memorize them- Adjustable ramp rates.

Dang, this is going to be fun!

I’ll give you this one on a 248/448 Dynojet. But on a Dyno Dynamics, you can set the ramp rates to mimic reality and get identical spool times as the street in X:infinity load situations.

This is a fuel management issue and not a dyno issue. If your fuel computer controls boost, you can set it to not exceed certain ranges. If you’re running a manual boost controller that is a decent unit, you can achieve this as well. A boost gauge is your friend. Is your company going to prototype an all-new one of those? I have zero boost overshoots. There is a time to wait for spooling, but a MAF system that uses a recirculating BOV will hit intended levels within acceptable established parameters. If you’re spooling slower than you should, it could be a tuning problem or poor choice of upgraded turbo size. It certainly isn’t a result of using a dyno. If you tune all the rpm ranges correctly throughout a gear, you will not have a spool up problem on upshift.

Worst part of the whole essay yet! I can’t believe you actually wrote that for people to see. No tuning you can do on the street will appreciably improve a launch. If an almost stock Evolution can achieve a high 1.6 second 60 foot, it is obvious that the vast majority of the problems are in launch technique, not the level boost comes in. Wastegate creep is a non-issue on 99% of cars with intelligently matched turbocharger/O2 housing hardware.

I will agree that an intercooler is more efficient on the road than the dyno in higher gears. Your boost complaint is meaningless, though, because if you have a good way to control boost with your fuel/boost management system, this is a non-issue. The main thing that will change boost values is wild temperature variations, hardly a factor or fault of dyno tuning.

This guy is really hung up on trailing throttle without logical reasoning. Trailing throttle= closed loop. What is the problem here?

And so is a wideband or any other street tune. The problem is that there are a LOT more street tuned cars that are way off base and have so much free power left on the table. It is certainly possible to make a good road tune, but discrediting the proven benefits of a dyno is asinine. Anyone that ignores this is trying to sell something LOL irony.



-Seth