sstevojr

iTrader: (7)

Here lets make this simple:
Would you rather have 20% more power or 40% more power?? On one dyno 50whp is a 20% increase in power; but on another dyno 50whp is a 40% increase in power (arbitrary numbers of course).

TheBlade

iTrader: (1)

His system is when you're using the same dyno, not different dynos (which yeah, sometimes when you're tuned might be different tuner, different dyno, different day), but what he's saying is if you take 1 car, and base dyno it, then mod it and then redyno, you can accurately measure the gain, despite what the numbers are. This is meant to compare your gains against yourself, not others, hence promoting a friendlier environment.

Let me use your numbers for example since they are relevant to you:

Stock --> Stg2(low dyno) 210 -> 260 = +19.23%
Then what he's saying is like this, lets say the person with this stg2 gets new exhaust and goes to 270hp

Stg2(same low dyno, new part, retune) 210 -> 270 = +22.22%



Then what he's saying is that someone using a different dyno, in a different city with a different tuner does :

Stock --> Stg2(high dyno) 265 ->315 = +15.87%

And that person buys the same part, and is retuned on the same high dyno, but because it's a high dyno it doesnt show +10hp it shows +12hp

Stg2(high dyno, new part, retune) 265 -> 327 = +18.96%


Both cars gained +3%hp from that part, but because this is keeping the comparison as a percentage off of your baseline, statistically its sound. So if the person on the low dyno posts numbers, people wont resort to "Only 50hp ? That's weak, ...."


Remember 50hp is not 50hp. It's relative to the vehicle. His example with a >1000hp car, +/- 50hp isn't that noticeable, do +/- 50hp on stock 96 Civic LX with 92whp... is a big deal, and very noticeable. Obviously we are all talking about EvoX's so we all have a feel for what +50hp feels like, but it's all relative to what we are base-lining on any given dyno, with given humidity, temperature, and correction factors on the dyno.


Hope that helps


EDIT:
LOL Steve beat me to it

EvoForumUser12

%ages are for losers. We should be using basis points.

sstevojr

iTrader: (7)

Not everyone understands statistical finance (Financial Analyst, right here), so I'm trying something user friendly. And look how 'difficult' it is for people to grasp already, could you image actually trying basis points on this crowd....

EDIT: Thanks Blade

SudzRA

iTrader: (2)

I like this method. However, shouldn't we be comparing gains to what hp you had when stock, not versus what you had after tune? If so, we should be using a percent gain calculation.

Percent gain: P = 100 ([V2-V1]/V1)

P = percent change between V1 and V2
V1 = initial value
V2 = ending value

Example: (New-Old)/(Old)*100 - this gives gains above what you had.


Second thing: Gains are based on the dyno you were on, and will vary between dynos.

Scenario: You go to a shop that had both a mustang and a dynojet, and get baseline numbers on both. You then add your parts and tune, then get new numbers on both dynos. Your parts should add a percent gain, and therefore NOT get the same whp gains on one dyno versus the other.

Example:
Car A - Dyno A (high reading dyno)
Before part XYZ - 250whp.
After part XYZ + tune - 300whp.
Difference: 50whp
Percent gain: 20%

Same car, different dyno.
Car A - Dyno B (low reading dyno)
Before part XYZ -200whp
After part XYZ - 240whp
Difference: 40whp
Percent gain: 20%

This is what you should expect to see when going from one dyno to another. Why? The parts you add and tune you've done have taken your motor from power A to power B. You had 250whp, now you have 300whp, on dyno A. Your mods have added +50whp. This translates to a 20% gain.

You switch to dyno B, where your baseline now reads 200whp. Why would the same mods still give you 50whp, when your motor baselines at 20% less power? Spoiler: you wouldn't see a 50whp gain here. Dyno reads 20% less power from your motor, so it reads 20% less gain from your mods. Your gain is now 40whp (again a 20% gain above baseline).

Confused? Here's more confusion.

Scenario B (same as sstevojr):
Bob, with a stock Evo X, buys parts XYZ, has them installed and tuned at shop ABC. He baselines at 230whp, after parts and tune, he is at 300whp. Bob comes to forum and posts up a +70whp gain.

Joe, also with a stock Evo X, buys parts XYZ, has them installed and tuned at shop DEF. He baselines at 270whp, and puts down 350whp after mods and tune. Joe sees Bob's post, and says: "Yo Bob, ur tunr is crap, dood. I made +80whp, and now I'm putting down 350whp."

Joe and Bob meet at the track. They pull off the same numbers. Joe's confused. He's up +50whp on Bob??

Bob - (300-230)/230 = 30% gain
Joe - (350-270)/270 = 30% gain

Edit: that's 3000 basis points, for those who really like big numbers.

sstevojr

iTrader: (7)

Edited OP: Will not work for dyno hoppers
Also the beuty of this is that so long as you use the same shop (dyno), as mos of us do, you can track progressive gains:
Stock to Stage 1 netted 20% increase (240-200)/240
Stage 1 to Stage 2 netted an additional 20% increase (290-240)/290
Stock to Stage 2 netted a total of 31% (not 20% plus 20%) (290-200)/290

SudzRA

iTrader: (2)

I think it can work for dyno hoppers. Since we're just talking about percentages, and engine output difference for mods varies linearly from one dyno to another (see my above post), this method should work just fine.
A 20% gain is a 20% gain, no matter the dyno. The numbers themselves can be considered arbitrary.

sstevojr

iTrader: (7)

It will work for dyno hopping so long as you are only measuring a relative gain and not absolute. Well....actually that's ok cuz this is Relative D (sounds FAST right )

SudzRA

iTrader: (2)

If you have baselines from both dynos (most likely people don't, but for the sake of argument), then you can measure absolute too.

sstevojr

iTrader: (7)

Sudz, our formulas are the same, you just move the decimal point in the formula, I move it after

sstevojr

iTrader: (7)

That would assume people will reverse all the work they already did and start from scratch on every dyno. I don't know about you, but even I say TOO MUCH WORK haha

SudzRA

iTrader: (2)

Bahaha I totally agree. You'd need to get both baselines when the car is stock. Who does that?

Our formulas differ in one simple way. Mine is (new-old)/old, while yours is (new-old)/new.
At least that's how you wrote it... lol

Also, if people are into that sort of thing, absolute percent difference can be used to get a decent estimate of current crank hp.

(V1)(V2)+V1

V1 = Crank hp
V2 = decimal value for percent gain (30% = 0.30)

Factory crank hp (V1), Evo X = 291.

Example: Evo X making +30%, decimal 0.30
291x0.30+291

Current crank HP=378.3

Or (easier)
Take decimal value for percent gain, add 1. Multiply by stock crank hp.

0.3 + 1 = 1.3

1.3 x 291 = 378.3

For AMS 900x Evo X - 782 whp

(Using estimated 235whp for Evo X GSR baseline)

(782-235)/235 = 233%

2.33+1 = 3.33

3.33 x 291 = 969.03 crank hp

sstevojr

iTrader: (7)

Yes but using 'old' as the denominator will give you over inflated gains. That's why this is Relative D and not % (which I'm pretty sure COBB uses).

EDIT: Well either one can be used (its all perspective at that point), so long as it's standardized as one or the other.

SudzRA

iTrader: (2)

The issue with using new as the denominator will mean that you're no longer measuring how much you've gained, rather you're measuring how much you'd need to lose to get back to where you were before.
For example, if you caculate for a 500whp car, using new as the denominator, and old as stock (I'll use 250 for that value) the math shows that you'd need to lose 50% of your current power level to get back to stock. Using old as the denominator shows that you've gained 100% above what you had when you were stock.

750 vs 250? Lose 66.7% to get back to stock, or gain 200% over stock.

sstevojr

iTrader: (7)

That's what it makes it relative. Normally if you add 20% to a number it's not the same as taking 20% from the new number:
100*(1+.2)=120
120*(1-.2)= 96

However this will work either way, so there are no claims over over-inflation, and more importantly % can be used across different dyno's to get accurate readings:
Incorrect
(150-100)/100 = 50%
150*(1-.5) = 75
Correct:
(150-100)/150 = 33.3%
150*(1-.333)= 100

Works forwards and backwards, this is what makes it relative