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Dyno Tuning: This is why you do it (56k beware)


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Disclaimer: Results ARE typical. For those that don't know I own a shop with a Dyno Dynamics Dynomometer. There are certain myths about tuning that I'd like to dispell, and would be happy to answer questions specifically related to dynos and what they can and can't do well.


Dyno Rates (using mine as an example)


If you live in an area with many dyno's you might find cheaper rates. These rates are in canadian dollars.


Baseline testing (3 runs): $89.99

Dyno Tuning : $149.99/hour

Full Day rental : $799.99/8 hours

There is a leaded fuel surcharge. (damages the O2 sensor)


These rates reflect the cost of our dyno, which is one of the more expensive ones out there. We are the only game in town, so we are probably slightly higher than what you guys in automotive hotbeds would see. NEVER EVER EVER pay $150/hr to tune on a dynojet... Nothing against dynojet, they brought dyno tuning to the masses, but it just doesn't have the capabilities to properly tune anything but WOT, and even there it isn't the best. I'd recommend dyno dynamics, dynapak, mustang...


O2 sensors


We include a AFR reading with all these runs, some places will charge extra for that service, as the O2 sensors are a consumable. (at about $400 a pop for ours in particular) For this reason most places will charge additionally for the use of leaded fuel as well. We use an Autronic wideband, without going into detail it is a very, very good, laboratory quality test instrument. The cost of the unit is in line with that, at between $4000-$5000. LM-1's are great for what they are, but be aware that they do have limitations as a result of their low cost.


Horsepower Numbers


OK, a big one here. I see disappointment all the time because people see big horsepower numbers on some internet forum and don’t really understand what it is that they are looking at. I will try to explain enough that you can intelligently compare numbers.


First off, any number spit out by a dyno is completely uncomparible to a number given by another machine. Period. In about 1 second I can vary the output readings of my machine by more than 200%, and other machines are no different. What this means is that I can take a 100rwhp car, measure it at that, then dyno the same car immediately and have it read 200rwhp. Then I can do it again and have it read 20rwhp. Is the dyno wrong? No. The numbers are only as good as your operator. For the most part most dyno shops will keep their machine on the same settings, so that you can use their machine over and over again to compare your gains. It is to their advantage to be consistant. But be aware that 200hp on dyno A does not equal 200hp on dyno B. The point is, you should only be comparing against numbers from the same shop.


Peak horsepower numbers: Again, most people make too much out of these. We had a car that made 6whp more after 1.5 hours of tuning and the owner was very disappointed… until he drove the car. With gains of up to 30whp all over the midrange, the car was very, very much faster than before it was tuned. We actually offered to refund his money/undo the tuning, he was so upset with the gains before he drove the car. After we checked back with him he was very apologetic and very, very happy with the results of tuning. Unless you are running a CVT or a super tight ratio gear box, you should pay no attention to your peak number when tuning, and worry much more about the area under your power curve.


Gains From Bolting on Parts


I see and read about guys spending thousands of dollars on performances parts without ever getting the results they should be able to get from them. Why? Because most people think that tuning is something that can be done by ear in the driveway. It simply can't. You can get the car drivable that way, but you will always have HUGE amounts of power waiting to be unlocked if you think that's all there is to tuning. So if you spend a few grand and just bolt things on, maybe tune by ear, you are looking at this:


1998 240sx - Blitz $$$$ exhaust



1989 Civic GSR Motor - $2000 in bolt on parts



1989 Ford Mustang 5.0 – Heads, headers, etc. Blue graph is the BEFORE mods graph.



The LEAST amount of money spent on these 3 cars for these gains was about $800.


Gains From Tuning?


So what happens if you actually "buck up" and pay for some tuning on a quality machine? I've got results like this coming out the wazoo, but here are some that were allready hosted.


2002 Acura RSX – Tuned with VAFCII



1996 Nissan 240sx KA24TURBO – Tuned with SAFCII



Same 1989 Civic GSR as above – Gains from Tuning VAFCII



1990 Nissan 300zxTT – Again, SAFC Tuning. This was his low boost setting.



1989 Ford Mustang 5.0 as above – Timing and fuel mods



1984 Mazda RX7 (351W powered) – Timing and Jetting



1992 Lexus SC400 – SAFCII Tuning



Probably the most money spent by any of the above graphs for tuning was about $300, or 2 hours. SAFC/VAFC's are a piece of cake to tune, but they are limited and the gains made are not as good as they could be with a full stand alone system. I believe that every person with those gains from tuning would spend that money again in a heartbeat after seeing the results a good machine and tuning session can produce.


The point? Spend your money on tuning before trying to throw more money at parts. You'll end up with a faster car and you'll probably save yourself some cash at the same time.

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That's some great info. I'm going to be visiting the dyno sometime in the next month or two and have a few q's about the entire process.


1. What kind of procedure do you have for preventing overheating of the engine? It would seem that an engine would heat up very quickly when kept at 5k at any 10psi, then 12psi, then 14psi etc etc. How do know the gains are not heat related after a cool off.


2. Do you tune every load point on the map? My fuel/timing maps are 16 x 16. Or is it better to go the dyno with a very good idea of where you're using the maps most of the time?


3. What are looking for when tuning? Do you first get the afr's correct for the start adjusting timing looking best minimum torque? This leads back to question 1.


That's it for now.

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Good questions for sure:


1. Cooling: I have 3 (yes, three) 14,000 CFM industrial fans at my shop, that move some serious air. A total of 42,000CFM if required. If your dyno facility doesn't take their fan situation seriously, you should be alarmed. A household fan is not sufficient! (don't laugh, I've seen it) Small squirrel cage fans that move a decent amount of air at a high velocity seem to work pretty well too. A rule of thumb, if it looks like your facility has spent less than $500 on fans, they are not serious about keeping your car cool.


There are always power losses as an engine gets too hot... just the way it goes. Sometimes we'll stop for 5 minutes with the fans on and the car idling to keep things in check. You can get a good idea of how much temperature is effecting power this way. You also tend to find out how good the temperature compensation of the EFI system is as well during this time.


2. Each load point: Usually I don't tune each load point, but it depends on the car and EFI system. If someone wants a balls out, perfectly tuned car I could go point by point and tune each one. Otherwise what I do is do some baselines at various loads/rpms and use that info to blend a map together. From there you can move on to tuning specific common points, like highway cruising, idle and 90-100% throttle. The law of diminishing returns applies, I can spend 20 hours tuning an EFI system to the absolute maximum power everywhere, or I can spend 2 hours getting 90% of that power. Most people opt for the 2 hour procedure.


3. I always start tuning with a visual/mechanical inspection of the car, followed by a baseline pull at full throttle. Usually I like to do the full throttle tuning first, the customer is more excited about it, and it's usually as good a starting point as anywhere. Our dyno is sensitive enough that it is very easy to pick up detonation. We watch AFR's and the HP curve very closely looking for lean conditions and/or power spikes that indicate detonation. Definately the first tuning step is to richen up everything to 11.0:1 or so and grandually lean things out to what is still a safe point. Personally I like to start with AFR tuning before timing as it gives more peace of mind knowing that the AFR's are in the safe zone. There will be some back and forth sometimes between AFR and timing, as small gains are made.


For our machine, finding optimal timing is easy. Pick a cell to tune, pick amount of load I want to hold the car at, and adjust timing at that load and speed until I get the maximum HP or tractive effort, without detonation issues. Usually I blend the curves afterwards rather than doing that at every load point.

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Awesome thread, and I do doubt Dynojet's dyno's, there are at the low end of the group. However, even with Dynojet's horribly progammed visual basic software in mind, surely that isn't a DOS mode software interface to the dyno... or is it?


I used to work at a Dyno shop, and after it went under and leased out to two other shops, I quit since (long story short) my new boss pretended to know a lot more than he really did, and constantly made me look like a fool in front of customers, when in the end I turned out to be right. I wish I could work for a shop like yours.


I'd also like to add the letting your car cool off between runs is worthless, if not harmful to your car. Keep it at the nominal temp, most likely when the thermostat opens or right before that for EVERY run. I hate people who want their car to cool off between each run to try and squeeze every hp possible.


And amen, AVERAGE HP is far more valuable than PEAK HP.

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This is an awesome post. This is the sort of thing I love to see from good dyno (Dyno Dynamics, Dynapac) owners. My buddy and I have recently opened a shop and a Dyno Dynamics single retarder dyno is planned in the near future. I have some quick questions for you.


- When tuning very light load areas how low of a load can the dyno hold. Is the dyno able to hold the rpm steady at near idle loads? Do you tune these lower rpm load points on the dyno?


- Do you many customers complaining about the DD reading lower than Dynojets?

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Yes it is DOS, and there is a good reason for this though it doesn't have the slick interface that it otherwise could. I have been told (but never confirmed) that the sampling rate when logging in a DOS operation is faster and more consistant than what it would be in a windows environment. Makes some sort of freakish sense to me, as you can still buy high end laboratory datalogging software that runs in DOS for some reason.


As I said there are some small advantages to letting your car cool a bit after some hard running. A) it is EASY to push the car harder on the dyno than it will ever see on any road or track B) even with 42,000cfm of cooling it isn't always enough with high strung turbocharged cars, being pounded on run after run C) In stand alone applications you can see how your airflow enrichment curve is reacting, whether it is accurate, or not.


Stinky, I would buy this machine again and again given the option. It is well worth nearly 3x the price tag of a dynojet if you plan on using it to TUNE. If you just want a cash cow that spits out dyno baselines, get a dynojet or dynocom. Your profits from the machine will be higher. However, don't underestimate how much you can learn from a good dyno, how much credibility it adds to your shop, and how the excellent results will keep people coming back to you for more purchases and tuning.


Light load - Never even thought about it before honestly. It's always done everything I needed to, so I've never pushed the limits. Lower load is pretty easy to tune in general, just lean things out a bunch. ;) But it has always held any rpm I've tried, even quite low.


HP Numbers DD vs. Dynojet - Awesome question. Remember when I said your numbers are only as accurate as your operator? Here is why. I have what we call the 'X' button. (surprisingly, all you have to do to activate the X button is hit the x on the keyboard on the bar screen) X is a standard muliplier, that you can make anything you want.


A bit more history/explaination here. Dynojets read high. The problem is the faster you spin that big drum, the easier it becomes to spin, and the less power that it takes to spin it. Dynojets are the industry standard because they are A) cheap B) have been around quite a long time and C) make money. So as a result, probably 75% of dynos out there are dynojets, which read high. As a result, peoples percieved power levels have shifted, what used to be a faster 400hp car is now a fast 475hp car. (for example, don't use those numbers as gospel) Throw the internet into the mix and everyone is reading dynojet numbers, because people brag about those numbers, because those numbers are higher than on other dynos. (most people given the choice tend to think whatever dyno reads highest for their car is the most accurrate one, go figure)


So the DD unit reads lower than a dynojet. Honestly we were so dead set against compensating for this, until it actually started costing us business. (people didn't understand, even with the explaination) A pure business decision was that we raise our power output readings by 17% (X=1.17) to correspond with dynojet numbers, and other DD operators in the general area. Am I happy about that? No. But with a $65,000 machine sitting there, even baselines are important when it comes time to make the monthly payment. Now that we've done it, I don't really have a problem anymore with doing it. All you can do is educate people as to why absolute numbers don't mean diddly, if they refuse to listen to you, so be it. But as a business owner I also want them to leave happy, while maintaining my own credibility. Now I educate my customers telling them why this machine reads high like a dynojet. Still being honest, just from a different angle. Customers seem happier with that approach.

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Guest ON3GO

thanks for the write up!

i hope to be dyno tuning my blue Z in the next few months.


question on a few of those graphs..


the mustangs, how did you tune those? was there a fuel controller or what?

didnt show it in the list of mods.

also with the 240sx with just the exhaust.... how would ya tune that if its just stock with a exhaust, you cant....

i understand what you mean though but whats somebody suppose to do if they just want/can spend there money on the simple mods like intake/exhaust/header.. they really cant get more out of it it with some type of computer.



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The mustang had some sort of fuel programmer, though I can't recall which one at the moment.


240sx couldn't be tuned in stock form, so we just show the exhaust gains. Most likely had he spent his money on some parts to make his car tunable, he would have had greater gains for less money.


Fuel management should be high on anyones priority list if they plan on modifying a car. Most people think it's not necessary, and that bolt on parts will take them where they want to go.... often not the case.

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There is one here in town that a Viper Shop just bought. And have heard good results from it.


Is it wierd that DynaPack and DynoDynamic Dyno Owners seem to think they are better than other people? Is it just thier sales people that get the purchaser into a state of mind that makes them feel better than others?


Don't take Offense - Its just something I've seen.

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What this means is that I can take a 100rwhp car, measure it at that, then dyno the same car immediately and have it read 200rwhp.


So that is how you got the measurements for your sig? Ha Ha, I owed you one :)


Have you used a dynapack dyno before? Just curious how they compare.

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Looks like Dynojet finally released their eddy current system in November 2005. For YEARS they advertised it without selling or having more than one working unit, but looks like they've got it working and they can finally step up now. From what I've read though it still won't give you real time HP & Torque numbers when loading, just load cell torque. Still a step in the right direction...


Moby - I haven't used a dynapak but did a lot of research before buying mine. They are a really quality unit, take a little longer to setup and from what I remember they are a little more expensive as well. Added costs and setup time without any extra features or quality were enough that I didn't bother. Good units though!


Is it wierd that DynaPack and DynoDynamic Dyno Owners seem to think they are better than other people?


You've got to be kidding me. Don't even start this **** in this thread.

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Drax, the last time I went to the dyno I gained 40hp. That's great, but there was no way I could run that tune on the street. How do you ensure that the tune made on the dyno will be street safe? My mass airflow dropped dramatically on my first dyno run compared to the street tuning I had previously done for the same boost levels.

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Thanks Drax240z! Great thread. A good dyno with a great operator is an equally great tuning device. The only one in our town is a SF-840 used more by racers than ricers and diesels looking for a big #s on the printout. Could you address how the figures relate from a Dyno to the 1/4 mile MPHs calculators we see all over the internet? Which dyno, Dynojet, Mustang, etc is going to give the most similar #s to the 1/4 mph equations? I know not everyone is tuning for the fastest 1/4, but It seems to be a common topics. John

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Not entirely following your question Bernardd... do you mean that you were able to put more load on your car on the street, and the dyno tune that was done wasn't safe for the street ie: not enough fuel/too aggressive timing?


That's correct. Afr's where 12ish, timing was 22deg, boost was well into the 20psi range before I could get the mass airflow reading that I ran on the street the day before at 20psi. Not sure it was because of the dyno or heat in the dyno cell or what, either way I drove away from the dyno and it would ping at the same psi. What would/could have been the problem?

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