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Reflash, Dyno Tune, Remote Tune, or e-Tune? Heeltoe's Advice On The Matter

  • Posted: 12-26-2015 12:59 AM
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Tuning the car's computer (ECU/ECM/PCM, whatever you want to call it) is the single-best way to improve power and efficiency. This is generally true no matter what degree of modifications you have done, or even if the vehicle is otherwise stock!

But not all engine tunes are created the same! This writing will help you sort out what tune is for you, starting from the most ideal to the least:


"Reflashing" is a process of over-writing the variables in the computer that help it determine how to run the engine with any given set of variables. In other words, the computer looks at inputs (the weather outside, how hard you are driving, and what target fuel consumption has been programmed in) and turns those into outputs that run the engine (how much fuel and timing are dialed in and when to turn on and off cam phasing, variable cam actuation, when to open wastegates, etc). The "thinking" that the computer does to decide what outputs to perform is the "tune."

By writing different rules into the computer (the "mapping" as it is called), the engine's character will change. This, is tuning.

A reflash is a tune. It is a tune that was determined by a tuner to be a good general program for most situations, or maybe a certain set of modifications.

For many street drivers with just bolt-on modifications, a Reflash is going to provide really noticeable results, such as was seen with the #HTSpecTSX after it was reflashed by Hondata some years ago.

However, with more modifications, such as changes to cams, intake manifolds, and adding boost, a custom reflash, or "tuning" is needed.

Dyno Tune

"Dyno" is short hand for "dynamometer." There are a few kinds of dynos but for purposes here we'll define a "dyno" as a tool for measuring the output of the engine. Dyno tuning is a process of measuring the power output of an engine, then making adjustments to the computer in a series of reflashes. Dyno, measure, adjust, reflash, dyno, measure, adjust, reflash, dyno, measure, adjust, reflash, dyno, measure, and so on until the engine's output is optimized.

Or, until you run out of money to keep your vehicle on the dyno for more measuring.

The benefits of dyno tuning are that you are taking real-world measurements in a controlled environment. The car is not moving, and the weather is consistent. This adds up to a good set of circumstances for taking measurements and making adjustments. Also, the fuel is typically the same. There is also a real-live operator running the dyno and making the adjustments, so if there are complications with the tuning the test can be stopped quickly and safely.

There are some negatives to dyno tuning, the foremost being that dynamometers are expensive pieces of equipment and they are not always convenient to get to. And the more one dyno is asked to serve an area the tighter the schedule becomes. Lastly, the process can become expensive. The more time on the dyno, generally the better the tune you will end up with. Power levels do taper off for simpler tunes after about an hour or two, but if you are boosted with larger injectors and adjustable cam angles are in the mix, budgeting a half day gets costly.

The last potential con is, who owns the dyno? Folks with Hondas may not trust the local tuner to tune their K-Series if it is BMW or Corvette specialist. Thankfully, to solve this issue, one can do a...

Pictued: Our own 1987 CRX Si Turbo being dynoed at Church Auto Testing

Remote Tune In lieu of driving to a dyno shop who is well versed in the sort of engine you need tuned, you can contact a remote tuner. Thanks to the wonders of the internet, a remote tuner, such as Jeremy Duarte of RedZone Race or Shane Tecklenburg, can begin a remote computer session with your hired, local dyno operator and make adjustments to the engine between runs.

The advantage here is that you can travel to a convenient dyno and always have confidence that the tuner is making the right moves with your engine. Of course, hiring the dyno is an additional expense to paying for the remote tuner as well, but given that the tune is the absolute master-key to getting the most out of your engine, it is a recommended step.

Safety is also an important factor. Not just to the engine, but to the vehicles and, oh, the PEOPLE, too. Dynos are the best places to measure power because of the controlled, safe environments they are installed in. Dynos are not immune to disasters, but people come away unscathed, even if the car doesn't.


The last type of tune on our recommended-method list is an e-Tune. e-Tunes are becoming very fashionable due to their low cost and geographical freedoms. There are some pluses and minuses to know about e-Tunes, though. But before that, we will explain how an e-Tune works.

Tuned maps that are uploaded or flashed to the ECU are simple files that are easily emailed to and from tuners and users. Modern tuning tools such as the Hondata Flashpro and the KTuner put the power of tuning right in the user's' hands. These tools also come with features call "data-logging."

Data logging is a process of "recording" the inputs the computer sees, and the outputs it creates, and putting them in a file that can be replayed later on a laptop. Data logging is commonly used to take snapshots of running conditions for investigative engineering work.

An e-Tuner is able to use data logs to make adjustments to the tune send and back a calibration file to the users to flash their computers with. Dyno, measure, adjust, reflash...

Wait...where is the "dyno?"

e-Tuners use a "virtual Dyno to simulate a chart of the power output of the engine. They gather some simple information and use physics to determine what dyno charts would look like, even though the car never sees a dyno. Your e-Tuner will have you report a vehicle weight, and then have you do a datalog from some different driving methods. You email them the datalog, which records acceleration data, and they email a map to you to flash to you computer. Normally the process is done a few times; a series of data logging runs, emailing, adjusting, and reflashing. And there you have your tune! Because there is no dyno expense, the e-Tuner can charge a lower rate than a dyno shop can.

So, cheap tune! But, there are some caveats to e-Tunes. One is, YOU are the one operating your car and you are doing so in an uncontrolled environment. The process of tuning is a scientific one, and while it may not be critical to make a perfect test to get a good outcome, the more particular you will be about your tune will command that a more accurate test be performed. The data logs almost assuredly are not being done in a controlled environment, and it also becomes difficult to get great part-throttle tuning.

Furthermore, the back and forth process can take many days or weeks to complete. e-Tuners are generally performing a good service, but there are limitations to how efficiently work can be done over email on both sides of the equation.

Without an ability to control your inputs, such as the weather at the time of your data-logging, variance in weight from different fuel levels, whether or not you have the AC on, and how consistently smooth, flat, and straight your test roads are; your tune may be compromised.

Add to the fact that if you want good full-throttle, high RPM data logs you'll need to make repeated high-speed accelerations over legal speeds, and you probably don't have access to a closed test course. End of the world? No. But, not something we believe a business should be asking customers to do.

The biggest wince we get regarding e-Tunes is the probability that you might not actually be getting as custom a tune you think, as everyone starts out with the same sort of base-map and tweaks are made from there. An e-Tune is in some way splitting the difference between a standard reflash and an a dyno tune, using math. So, the cost savings most likely comes with a compromise in both service and product.

Our Advice

Despite the generally glowing results from some demographics of drivers, numerous Heeltoe customers have provided feedback stating that the e-Tune process "worked" but was cumbersome to deal with after many weeks of continued adjustments. The process to some seemed never-ending, as various minor hiccups in running condition were not able to be ironed out. They ultimately gave up and settled on a tune when they became uncomfortable with continuing the process.

Customers have experienced stress of taking time off work to travel to dynos, but a good solid day at the dyno will make you a believer in that a good tune is worth its cost. The key to this working well is to be prepared, and committed.

Our advice is to tune on a dyno, and do so with as good a plan in place as possible for making sure the day is successful. The more mods you have the more difficult this can be. It might cost more, but you and your engine will be happier and safer because of it.


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