A word about dynos, and why simply asking “what's your WHP” is silly

[JBezugs]

Hey everyone - I've had this post catch on in a few places, so I figured I should also post it here for information, and to hopefully bring along a healthy discussion.

Mods, if this is in the wrong forum, please feel free to relocate as necessary.

I have seen constant posts in Facebook groups that I’m a part of for the FRS/BRZ/86 platform that go something like this: “What are your mods and WHP numbers?”

What ensues is a complete **** measuring contest. I’m tired of seeing it over and over, so here is a long-winded post about why this bench-racing effort is mostly futile, and what the most viable solutions are to this issue. I’m sure this same thing happens within every circle of car enthusiasts.

The most important factor: every dyno reads differently.

A bunch of us in these groups/clubs have had our cars on the dyno with a variety of different modifications. But, there is no one “reference” dyno that everyone uses. We have all used a variety of different tuners who use different types of dynos (Dynojet, Dynapack, DynoDynamics, Mustang, etc.) that all bring their own ways of reading wheel power, and with that, have different correction factors. Even two dynos of the same exact model won’t read exactly the same. Calibration and correction factors once again can swing numbers around.

In summary: The tape measure you use matters just as much as what your packin’ if your talking strictly numbers.

Just asking for numbers from people is irrelevant w/o knowing what the baseline of a stock car is on the same dyno they ran their vehicle on - ideally the same car before/after mods and tune, on the same day.

With the baseline, you can get the truly important metric when measuring engine modifications - percentage gain, as well as the increase in area under the curve.

Here’s an example with my “Stage 2+” (I think) 2017 BRZ. My mods are as follows:

- JDL 4-2-1 EL Header

- Stock Air Intake with a new OEM Paper Air Filter

- Stock Over Pipe

- Stock Front Pipe

- Invidia R400 Catback

- Custom Dyno Tune from OnPoint Dyno

My car was tuned by Sasha with OnPoint Dyno. For reference, stock BRZ/FRSes make anywhere from 140-150ish whp on this dyno. How can I prove this? Check the link and come back and keep reading below:
https://tougetuning.com/intake-exhau...-dyno-numbers/

This basically stock FRS in the link above dyno’d at 155whp with the stock tune, an axle back exhaust and a Grimspeed Intake, which is the only aftermarket intake that actually produces reasonable gains on the factory tune (anywhere from 6 to 10whp depending on the dyno). From talking to Sasha as well as conservatively looking at the gains from the Grimmspeed dyno, you could estimate a completely stock FRS/BRZ/86 to pull around 150whp and 131wtq.


My car made 176whp and 153wtq on the same dyno. Note that the baseline on my graph is not accurate as the car already had the mods installed on the vehicle.

Therefore, high level, the approximate percentage peak gains are about:

- +17.3% WHP

- +16.8% WTQ

And these are just the peak gains, not including the significant area under the curve increase (especially around the torque dip).

Now, when scouring through the ft86club forums, generally, it looks like Drift Office’s DynoJet is representative of an average baseline for most places, with stock FRS/BRZ/86‘s putting down around 167whp.

That baseline number is an +11.5% difference compared to OnPoint’s baseline dyno.

With this information, I decided to do some maths. Take that “forum average” baseline, and then apply a correction factor to my OnPoint numbers. The correction factor would be the 11.5% difference between the two dyno’s baseline numbers.


See how my car is at almost 200whp now? The percentage gains didn’t change at all from baseline to Stage 2+! Only the baseline number has increased.

Now is this method perfect? Of course not. Even compensating for “correction factor”, this is still a theoretical value given that the baseline cars were two different stock cars, where there can be variance between them.

So now, what’s the best method of comparison then? If you want to look at numbers, Dyno Days are usually the closest you can get when comparing cars side by side. This means that any car that wants to participate will be running on the exact same dyno, under the exact same conditions, on the exact same day. That way, the most important variance in comparing cars and their mods/tunes (the Dyno) has now been removed.

In having a few stock vehicles as well as a whole host of cars with different modifications and tuning methods - this should provide the most objective base of comparison that we can hope for.

But above all else, if you’re shopping for parts and trying to compare the increase in performance, look at the percentage gains - not just raw numbers.

[DarkPira7e]

While I agree with the sentiment and appreciate all the work you've done, this happens in any place where a performance measurement can take place.
There are always variables in anything because measurements aren't perfect and instrumentation, conditions, honesty, etc are inconsistent.

I'll give an alternative argument- What is so bad about asking for generalized modifications and the associated " dyno" numbers. Even if they are subjective, it's still fun.
I come from another performance world- overclocking. It's exciting to overclock and change things to squeeze more performance out of an already fast product. When someone asks " WHAT GPU/CPU COMBO ARE YOU RUNNING AND WHAT IS YOUR FPS IN CRYSIS???" it's like " Where in Crysis? In a benchmark, or real game? What about longevity of the chip from being handed 1.5v? What about the RAM and MSAA Anisotropic filtering level chosen? Draw distance?"

There are accurate ways to measure performance of a specific component, sometimes. Getting people to use the same method of testing and benchmarking is tough, though. Keeping them honest is tough too.

At the end of the day, it's fun and harmless, leave it to the people who are affected by negativity or feel the need to boast to do what they;re going to do; this is no different from someone in the gym flexing their huge biceps and you asking " yo, how much can you bench br0? What protein do you take?" You get my point. I value your data and most here can agree with what you're saying. I just want to remind also that it can be fun, too. My real pet peeve is when someone posts an "after" dyno sheet that starts at 4k RPM, and only highlights from like say 250whp and ends at 400 (peak), vs the "before" graph that shows 0rpm to 8000, and the graph range for power is from 0 to 600WHP (to make it look flatter).

I know that stock, my car hit my local dyno at about 150whp and about 120 something torque. With headers and a tune, that came up to 171whp and 131wtq on the same dyno. With the turbo, it came to 300whp and 240wtq. These were all on different days, with different temperatures, but at least they give me some insight as to what effect the modification had for me.

[86TOYO2k17]

Lots of good points, kind of common sense for the people who already know and will understand this, and the people who don't, will never understand. As this has been stated 100s of times already. but at least you have a lot of solid data points.

The one factor you didn't seem to equate is you have a 2017 MT, the baseline is a 2013, which dynos at least 5whp lower or roughly 3% lower. also grimspeed cai without a tune is maybe 2-3whp no where near 6-10whp, or even better (according to this bases of this post) a 1.25-1.75% whp increase not a 4-5% whp increase. which means your baseline calculation is probably way too low, and then your percentage increase is a lot lower. and then your "high reading" dyno conversion number would be a lot lower.

So to fix your calculations
baseline 155whp (being a MT 17+ will more then make up for a untuned CAI so i am being generous here) after 176whp or a 14% increase.

converting to a 167 baseline with a 14% increase would be 190whp. (once header and tuning are added the benefits of being a 17+ are almost all negated so no extra conversion needed maybe another 1% if i am being generous so call it 192whp)

WHP numbers are just numbers at the end of the day, its more to validate if somethings works, rather than to exactly what extend.

doing something like a 40-100mph or 60-120mph on the same road in similar conditions would be a much better way of telling how much of an impact and how beneficial a mod is. or even better to eliminate more variables of shifting do a 4k-7k rpm pull in 4th or 5th gear and time the before / after difference.

[tomm.brz]

great thread

[mathewbarnes]

this is nice thread informative (Y)

[bfrank1972]

He covers some good topics about power (and other important real world concepts). He skips gearing when talking about HP, but probably to not over-complicate what he's trying to convey.


In general:
- dyno's are best used for relative comparison, ideally back-to-back with tuning etc. You can compare dyno results from similar dyno types, but keep in mind results are likely not consistent due to environmental configurations, dyno calibration/configuration, etc.
-comparing peak HP/TQ numbers is pretty meaningless. Even between two similar cars those numbers are misleading. My Vortech kit might make 270-280whp peak. Some other person's turbo kit might make only 260 whp - guess which one is going to be faster? (hint, not my Vortech kit) They will also feel very different (supercharger will typically have noticably superior throttle response in the higher rpm range).

[DarkPira7e]

Originally Posted by bfrank1972

comparing peak HP/TQ numbers is pretty meaningless.

Area under the curve is the most important inference you can make with the comparison!

[Lantanafrs2]

Delta, delta delta

[vagthomas]

I agree with everything you say on the way a dyno measurement and relevant tuning gains shall be made and calculated.

However your examples are a little mixed up the way you put them, since the basic line you have taken to compare your car is an assumption and not actually your car. Therefore, the 17% of power and torque gains are quite good but still are indicative.

It should be your car prior any mod and your car after all mods and tuning in order to be as accurate as possible for any gains.

For example, below is my graph with my car completely stock and after specific mods and tuning at the same exact dyno (dynapack). The only difference is that they are not the same day, therefore they are as accurate as they can get.

[JBezugs]

Originally Posted by vagthomas

I agree with everything you say on the way a dyno measurement and relevant tuning gains shall be made and calculated.

However your examples are a little mixed up the way you put them, since the basic line you have taken to compare your car is an assumption and not actually your car. Therefore, the 17% of power and torque gains are quite good but still are indicative.

It should be your car prior any mod and your car after all mods and tuning in order to be as accurate as possible for any gains.

For example, below is my graph with my car completely stock and after specific mods and tuning at the same exact dyno (dynapack). The only difference is that they are not the same day, therefore they are as accurate as they can get.

Absolutely. Same car, same or similar conditions, completely stock vs mods and tuned is the best way to do it for a basis of comparison.

Like I've noted, I am making assumptions that my car would make similar numbers stock as that reference vehicle - in reality @86TOYO2k17 notes that my car is a 2017, so I would be seeing less gains from a header vs. a pre-facelift car. In further discussion with my tuner, 2017+ 86s/BRZs put down around 155whp on his dyno, on average. So the numbers can shift any way you like.

It's more to illustrate how different dyno's can affect your final whp number, and how people tend to live and die by that. Percentage gain and your area under the curve is the biggest indicator.

[Grady]

They only Dyno you should worry about is your butt dyno!! If it feels better and makes you happy then who cares what the exact/real numbers are.

[jflogerzi]

All good points here. I want to see gain's under the curve, power delivery, and how smooth things are. Also given a set of mods it does give you a rough idea where you are at in reliatvive to other cars on the same Dyno with similar mods.

Sent from my GM1915 using Tapatalk

[humfrz]

As the title reads "A word about dynos, and why simply asking “what's your WHP” is silly".

I agree. Back in my day, before dynos were readily available, we didn't have all this TALK about HP and torque.

It was simple. Drive out to the edge of town, line em up, get set, GO on three. The first car to pass the big post at the end of farmer Browns corn field - WON!

Simple.




humfrz

[86MLR]

Originally Posted by humfrz

As the title reads "A word about dynos, and why simply asking “what's your WHP” is silly".

I agree. Back in my day, before dynos were readily available, we didn't have all this TALK about HP and torque.

It was simple. Drive out to the edge of town, line em up, get set, GO on three. The first car to pass the big post at the end of farmer Browns corn field - WON!

Simple.




humfrz

Yeap, and it still works today.

I've walked passed many a car at the drags that posted big hp numbers, sadly the trap and et's never matched their claims.

Lots of excuses though, in the end they still pay up no matter how lame of an excuse.

And by "pay up", with our local club we race for a bag of cinnamon donuts.

A dyno is a tuning/diagnostic tool, or somewhere to break in a new engine without the risk of attracting the wrong attention, nothing more.

I want cinnamon donuts now....damn it