Dyno Numbers and you- What do you need to hit XXX hp?

[Defiant Autospeed]

There are a lot of posts asking what it takes to hit a certain HP number, but almost none of them ever give the info we need to give good advice on this. There is almost never enough info, and a lot of misconceptions.



First thing you need to know is that there is no 100%, black and white, sure thing answer. All cars respond differently and what makes 300whp on one car, will only make 280 on another, and 320 on yet another. ON THE SAME DYNO.


Second thing you need to know is that all dynos read differently. So if your goal is 300whp on a dynapak, what you need to get there will be INCREDIBLY different than what you need to hit 300whp on a Mustang dyno.

Even when looking at the same type of dyno, some read lower and higher.

There is fully a 100whp difference between the highest and lowest reading dynos. So if your goal is 300whp on a Mustang, be prepared to shell out a LOT more money than if you want to hit 300whp on a dynapak. And again, even on the same model dyno, some read +/-15+whp.

Where you live makes a BIG difference, elevation severely changes power output, as does the quality of your local gas. Its a lot harder to hit a given hp level on California's 91 octane than on 93 elsewhere.


When are you doing this? In winter, 20 deg ambient temps on winter mix gas? Or in summer in 100deg temps on summer gas?


And most importantly, are you trying to make this power level at the WHEELS or at the CRANK. Take for instance an 04 STI. It makes 300hp. But only about 240hp at the WHEELS. (on an average dyno that is)



So, when you ask "what do I need to hit XXXhp" you need to give us the following information


1. HP at the WHEELS (whp) or hp at the CRANK (chp)?

2. What type of dyno are you going to be shooting for this number on?

3. If possible, tell us what shop it is. Someone may know how high or low that particular dyno reads.

4. Where do you live? If not a well known city, what is the elevation?

5. What kind of gas will you be using? (octane level)

6. Are you opposed to a FMIC? (this way we dont recommend one if you dont want it, or we DO recommend it if you DO want it and it would be beneficial to your setup/goals) (sp?)

Please note, that even with this info, while we can give you a good idea of what it will take, we cannot give you a 100% surefire recipe for making an exact number. You may make even up to 30hp more or less than your goal based on what we tell you.

However, with the above information, we can give you a pretty solid path to take to hit that goal.


But simply asking "I want XXXhp" will get you nowhere. You will get answers that on a given dyno will make WAY more or less than each other, and the cost difference between them will be huge.



The last thing to know, is that in general, people will give you answers based on an "average" reading dyno. Unless you directly state, "I want to make this power on THIS type of dyno"


Hopefully this helps some people out. I see these posts all the time, and the threads get confusing at best with the huge range of setups that people suggest.

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[FlatironsTuning.com]

There is some good information in this thread, and I thought I would add some information about a correction factor as that also related to how much power you end up making (or appear to be making) when you get your car tuned.

This is from this thread on www.AWDPirates.net

A chassis dynamometer, or “Dyno”, is tool that calculates your car’s horsepower and torque output. They can do this through a few different method’s, but the most common are by looking at the rate that your car accelerates a known mass (inertial dyno’s), or by measuring your car’s ability to produce an electric current(Eddy Current, or load based dyno’s).

Regardless of the method used to calculate your car’s power, as long as a dyno is calibrated correctly, the reading’s should be within a few percent of each other. However, because an internal combustion engine burn’s air and fuel to make power, there are a few more variable’s in play, the biggest one being the air that the car is consuming to make power.

If you were standing at sea level, and capped off an empty 1 liter bottle, you would have one liter of air. If you were standing in Denver, Colorado and did the same, you would have the same 1 liter of air. However the amount or mass (not weight) of air, and oxygen for that matter, would be different in each bottle.

The reason for this is that Denver is approximately 5,280 feet above sea level, and we have a lower atmospheric pressure (about 12.2 lbs./in^2 versus 14.7 lbs./in^2). If you would take that sealed bottle down to sea level, it would actually be crushed a little because of the pressure difference, and would suck air in when you opened the cap. Conversely, if you took the bottle from sea-level up to Denver, it would actually bulge out because there would be less pressure and it would let air out when you opened the cap.

To put it simply, there is a difference in air density between the two bottles. By air density, we mean that there is a difference in the mass of the air (how much stuff there is) between the two bottles. Atmospheric pressure is one main cause for a difference in air density, but two other’s are temperature and humidity.

Generally speaking:

A decrease in Atmospheric/Barometric Pressure will cause a decrease in Air Density.

A decrease in Temperature will cause an increase in Air Density.

An increase in Temperature will cause a decrease in Air Density.

An increase in Humidity will cause a decrease in Air Density.

A decrease in Humidity will cause an increase in Air Density.

So, if you put it on a dyno in Denver, and an identical dyno at sea level, it would not produce the same power because it is not getting the same amount of oxygen, and there for not producing the same amount of power. For that matter, if you put your car on the same identical dyno in Denver in winter when it was 10 degrees out, and in the summer when it was 100 degrees out, the reading’s would not be the same either.

This is where a correction factor comes in. The Society of Automotive Engineers (SAE) decided that it would be really handy to be able to compare dyno output’s from a variety of conditions in a meaningful way. So they came with a formula to compensate for differences in testing conditions, and give you a reading that you would get in ideal testing conditions (60 degrees Fahrenheit and minimal humidity at sea-level). This formula basically generates a number to multiply your actual number by to get your corrected reading, and is largely based on the barometric pressure, temperature and humidity at the time of the test.

To put it another way, if you are making changes to your car and testing it to see how effective they have been, you don’t have to wait for a day identical to the one where you performed your baseline test to see how much of an improvement you have made.

Now, with all that being said, there are a few other things to keep in mind.

First and foremost, when you get your car tested, ask what the correction factor is, and if you can get a chart with a corrected number, and an uncorrected number. This is for two reason’s. First, even though a corrected number is more useful to compare to later tests, your car made the power that it made, and it might be handy to know what that is. Second, you can compare the two, and see if your corrected chart makes sense. (ie. If you made 170 horsepower uncorrected, but 350 horsepower corrected, that is one heck of a correction factor).

Second, keep in mind that the correction factor will most likely (and should for that matter) be different every time you test your car. Even if you start testing in the middle of the day, and finish at the end of the day, there is a very good chance that a different correction factor will be applied (though in this case, it would likely be just slightly different).

Lastly, remember that the dyno is just a tool, and if you are making changes in the hopes of making more power, the power difference before and after is what is most important. If your car is making 50 whp more when it leaves after tuning than it did before, it doesn’t matter what the correction factor is, you have made a substantial improvement in power.

J. Cooley
Flatirons Tuning Project Car
Flatirons Tuning F.A.Q. Blog
Flatirons Rally Team Blog

[ekw]

Originally Posted by Defiant Autospeed

First thing you need to know is that there is no 100%, black and white, sure thing answer. All cars respond differently and what makes 300whp on one car, will only make 380 on another, and 320 on yet another. ON THE SAME DYNO.

I'm sure you meant "280".

[Jubert69]

Wow great post! I was afraid to get flamed at to make a thread like "How much XXX hp can I get with XX mods". Now I have a guideline. Thanks a bunch!

[4x4GGG]

I'll put it up for a little while.

[Audiosavvy]

Dave, this thread brings tears to my eyes, it's about freakin time someone did this.

[Smoke]

Wow, this was long overdue!
Thanks for posting this!

Now I know what I can take note of when I consider my goals for the future.

[Defiant Autospeed]

Originally Posted by FlatironsTuning.com

*bunch of really good correction factor explainations*

Thank you!!!

I understand all this, but had no way of explaining it. This should help out a lot of people as well.


Im gonna PM a mod and see if they can move this directly under my first post, that way people see it as well.

Originally Posted by ekw

I'm sure you meant "280".

Yeah oops

[toutanje]

Great post Defiant, should help clear some things up.

[Defiant Autospeed]

Originally Posted by Da-Risin-Smoke

Now I know what I can take note of when I consider my goals for the future.

Exactly my point!

Most people live in an area hanging out with a couple other subbies, and they usually have a single shop, maybe two that they commonly use. They then usually base their power level goals on what cars from that shop are doing.

So telling us, hey, I want 950whp on an XXXbrand dyno, I live in XXX and I use over9000 octane fuel, we can give you a good path to start with.

Like having a goal of 300whp on MZM Tuning (the big local dyno tuner near me) will take a LOT more money, Think 20G or larger, and really, should include a built block. Going for 300whp on Andrewtech's dyno takes a turboback and a tune (on an STI)



This is why when you see someone ask what does it take to make XXXwhp, you will see people saying very little mods, and others saying a lot of mods. I personally try to go with what it takes on an average reading dyno. Which if the crazy mustang at MZM is a 0 and Andrewtech's is a 100, the "average" dyno would be somewhere in the 65-70 range (using a 0-100 scale)

[parat75]

Great post, it was LONG overdue!

[Audiosavvy]

Originally Posted by Defiant Autospeed

I use over9000 octane fuel

That's a little higher octane than my Q16. It's 76 that does the 9000 octane, right? I can't find it locally, best I've found is $17,000/gallon and it's in LA, 2 hours south

[Defiant Autospeed]

Its a new fuel by the chanoprah petroleum distributers.

[orchidrider]

i like it. it answered a bunch of my noob questions about this

[truracer001]

Theres alot of good info on this...I noticed that alot of wrxs react differently to bolt ons. Ive seen a stage 2 wrx(turbo back and up pipe and intake) with 240whp and another one with alot more with less whp..

[smurfwrx]

Awe, Dave.... you're just showing off now!

good work.

[Davenow]

Originally Posted by truracer001

Theres alot of good info on this...I noticed that alot of wrxs react differently to bolt ons. Ive seen a stage 2 wrx(turbo back and up pipe and intake) with 240whp and another one with alot more with less whp..

That is the other thing people dont understand (well, many dont)

take 10 identical cars
bolt on identical mods
dyno all 10
10 different whp numbers. Varying up to and often over 20whp from highest to lowest.


Heck man take all 10 BONE STOCK and dyno them. 10-15whp differences are not super uncommon.

[Audiosavvy]

Hell, the same car will put down different numbers if you dynoed it every 15 minutes.

[Davenow]

true dat.



or something

[Ace41912]

I had just found this post as a sticky. Haven't been on here in a bit. Having earlier posted a question about what mods to get XXX horsepower, this post will greatly help me reform my questions so I don't get flamed again. Awesome Help!!

On another note, I have heard about the Mustang dynos being "harder" to generate numbers on.?... is that necessarily true? and why or why not?

Thanks in advance from a noob.

[Prevent]

Originally Posted by Ace41912

I had just found this post as a sticky. Haven't been on here in a bit. Having earlier posted a question about what mods to get XXX horsepower, this post will greatly help me reform my questions so I don't get flamed again. Awesome Help!!

On another note, I have heard about the Mustang dynos being "harder" to generate numbers on.?... is that necessarily true? and why or why not?

Thanks in advance from a noob.

Yes its true. Mustang dyno's generally read lower then other dynos. However some shops have setup their dynojets (P&L) to give similiar "low" reading numbers to the mustang. IMO these are more "real" then any other number created on the dynojets/dynapacks.

The mustang dyno by me is like a rolling road. It will apply it's brakes to a certian percent to give resistance/drag depending on the vehicle weight.

I put down 220whp/230wtq stock and 262whp/286wtq stage II. Obviously those numbers are FAR from impressive, but the car can still do 12.9 in the 1/4 and whip you back in your seat.

A dyno should be used as a tuning tool, and used to compare numbers vs stock form. the 262whp/286 means nothing to me. gaining 42whp and 56wtq while stage two on the same dyno means something to me.

Im no dyno expert and i kinda rambled, hope it somewhat helps you.

[Ace41912]

Thats what I had heard. That mustang dynos produce more "real" numbers because of the "real world" inertia or load that your car has to push against to put down the numbers. A truer number i suppose if this gets one closest to real world conditions, like pulling down the road. Thanks for that input.

Those seem like great numbers to me for a stock and stage 2 readings. And a 42 whp and 56 wtq gain between the two! Thats impressive to me!
Looking forward to more modding! I also didnt realize that stock subs were putting down those numbers! FTW. Thanks for the Help Prevent!

[ken-rex]

There is light at the end of the tunnel, food for thought! This thread has actually helped me understand how to explain to the hungry...

[FlatironsTuning.com]

Originally Posted by Defiant Autospeed

Thank you!!!

I understand all this, but had no way of explaining it. This should help out a lot of people as well.


Im gonna PM a mod and see if they can move this directly under my first post, that way people see it as well.

Thanks for starting this great thread. We have run into this many a time, but I never thought about putting all the answers together in one place

J. Cooley
Flatirons Tuning Project Car
Flatirons Tuning F.A.Q. Blog
Flatirons Rally Team Blog

[4ST-AIR]

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