bbarnhill

iTrader: (1)

Virtual Dyno displays whp not bhp. I think with the previous posters statement that no matter what static CF you put in dyno vision you will not get the same values in Virtual Dyno because at different power levels a different % loss will be realized.

does that answer it? Or did I completely miss that one?

l2r99gst

iTrader: (2)

Ummm....I'm not taking sides of either program here, but are you guys serious?

Both programs are calculating/estimating whp from logs based on RPM and time. They are both measuring the same thing.

For some reason, it appears that Dyno Vision just has bhp lsited and gives you a correction factor to whp, where Virtual Dynp simply gives you whp to begin with. But, they are both measuring the same thing....an estimation of whp. A correction or adjustment should actually be made back to bhp.

Since I don't know the exact source code for Dyno Vision, I can't speak to exactly what's going on, but if you have questions, just ask the author. Maybe he can tell how it's being done. Then Brad can tell how VD is being done and you can compare that way (if either will tell...not that it's really a big secret either way).

But, my point is, that both of these tools are trying to estimate the same thing from logs. These are logs of the whole car, not just the engine on a dyno. I think it's a matter of simply how each author has the program setup and is presenting the final number. Maybe Dyno Vision has that 24% adding in?? I don't know. If so, I agree that it should be taken out, and if wanted, add a choice for a correction factor back to bhp.

evonut270

Thats laughable considering some of the over-inflated readings we see from your side. most of the time figures between your WHP and our WHP are consistantly miles apart. are you going to tell us how you manage this? WHP is flaud on any dyno end of story.

bbarnhill

iTrader: (1)

Im more than available to help anyone understand whats going on in Virtual Dyno ... just let me know. Im afraid we have sparked WWIII ... just let me know if I can help understand any part of VD.

deej1

I just loaded a log into your virtual dyno (which i think is a great program by the way) and loaded the same log into mine and BOTH numbers are exactly the same. The example was a 3rd gear wot pull - Dyno vision 434 Virtual dyno 429 - so like 5hp different - torque exactly the same. WE ARE measuring the same thing here and we are BOTH doing so very well

The only difference is what we call BHP you call WHP. simple as that. Both are estimated from vehicle logs, weight, frontal area, gearing, air density, rpm...and so on

its really that simple guys. Ive created this program for people to enjoy. Its free and efficient with some useful features that people can hopefully gain from when tuning.

just as an example, we calculate things like this in the UK

450 hp turbo max flow - someone gets a tune with it..
BHP (flywheel) = 440 hp (so good tune - only 10hp from maxing turbo)
BHP (Wheels) = 440 - % loss in drivetrain, tyre heat, etc
= 440 - (24% of 440)
= 440 - 105
= 335 hp (Wheels)

so Bhp = 440 Whp = 335.

Ted B

iTrader: (6)

Some people may call a penny a pound, but they are absolutely not the same, and there is not one credible source or reference that implies they are. Look into it.

When you see a rolling road estimate 'bhp', it is not referring to power at the wheels (whp). It's a result of the user asking the machine to take a guess at what power is at the flywheel. It's a guess because 'bhp' cannot be truly measured without removing the engine and running it on an engine dyno. But that is purely academic where actual running cars are concerned anyway, simply because bhp never sees the ground.

BHP (brake hp) - power at the flywheel with accessories installed and operating.

WHP (wheel hp) - power being applied against the road by the tires.

The two are never, ever the same, either in definition or value.




There is no such thing as 'bhp at the wheels' (you're misinterpreting the dyno results), and the 24% fudge factor is like saying one size shoe fits all. A factory EVO implies a 24% drivetrain loss on one dyno, but only 13% on another. So which is correct, and how can you prove that percent error is the same at 200whp as at 600whp across any of them? That is why proven software like VDR has different correction factors - to extrapolate the measured result across different dynos without implying that any of them equates to the absolute truth.

Using your algorithm and generous 24% fudge factor, my own car would register 720+bhp using my 650bhp max flow turbo and common pump gasoline, and good luck getting anyone to buy into that. Wow, that sure does sound good, but it's a fantasy.

l2r99gst

iTrader: (2)

Edit: I reread my response and didn't like it...so writing again:

I 100% agree with Ted about the bhp issue. The logs we do are measuring the whp, since all drivetrain losses are inherent in our logs.

The question really comes down to how is DynoVision calculating the bhp? Is it a simple correction factor (like the 24%) added to the same calcs that something like Virtual Dyno is doing? Is he then giving us the option of taking that correction factor back out for whp?

That's what we need to find out. But I agree that BHP is not what is being calculated. You should have an adjustable correction factor to get back to bhp if need be.

On that note though, I'm guessing that both programs are using the exact same, if not very similar math, to calculate their numbers. I think it may simply be one more correction factors being added in. I think it was that presentation choice that may be the difference here between the two programs.

deej1

Ted B, could you email a log of a WOT pull stating what you believe your WHP is?

couple of points,

if Dyno Vision measured in KW - you could still use it as a tuning tool because you can see your initial WOT pull in KW and final pull in KW and the differences in each plot, agree?

if it measured in the made up measurment of , Brake Dog Power (BDP) you could STILL use this to effectively tune your car because you have a before and after graph of your WOT pull and can see the differences, agree?

So. We agree it can be used to help tune your car and make improvemnts - which, incidently is what it is for.

if you want WHP simply check the "Calculate WHP" box with a correction factor of 1.0 - this is true WHP (and my HKS 450 turbo makes 335 WHP using Dyno Vision)

IF You want Estimated BHP at the flywheel, then just uncheck the box and enter your estimated drivetrain losses. Its really that simple.

95630706

Jeez, He's not asking you to buy it for a million dollars, he's offering another analysis tool for free. I think it looks pretty slick and I dig the x/y boost, RPM and HP outputs for relative comparison. Thanks for contributing and I will give it a shot when I get my motor back together.

Ted B

iTrader: (6)

Absolutely agreed.



Fair enough! I missed this part (my bad):

deej1

[quote=l2r99gst;8627544]
The question really comes down to how is DynoVision calculating the bhp? Is it a simple correction factor (like the 24%) added to the same calcs that something like Virtual Dyno is doing? Is he then giving us the option of taking that correction factor back out for whp?
quote]

l2r99gst,

Its all based on 1/2 MV Squared ( Kinetic energy of a body )

KE1 = 0.5 * Total Mass * Velocity * Veloicty (at Time T1 )
KE2 = 0.5 * Total Mass * Velocity * Velocity (at Time T2 )

KE difference = KE2 - KE1 - this is the Kinetic energy difference at the two time points - Once you know this you can calculate power ( energy over time )

KE difference / ( T2 - T1 ).

and thats how the base calcuation is resolved. Of course, there are other real world physical elements to consider, for example air resistance..

1/2 * Air Density * velocity squared * Drag Coefficient * Area m2

and air temperature.

intake_temp_change = Math.Sqrt((temperature + 273) / 290); ( in K )

Boosted Tuning

iTrader: (12)

[quote=deej1;8627814]All that and you didnt even answer his question about when the flywheel/wheel power correction is brought into the equation.

burgers22

He he, you say fender, we say bumper, you say trunk, we say boot, they are never a problem. So how come it all gets so tetchy over power. Is it because we measure our ******* in feet, and you guys have to use inches?

deej1

[quote=Boosted Tuning;8627836]
because it was answered in post #23 lol.

l2r99gst

iTrader: (2)

Thanks for all of the replies, deej1. I think it's a very nice program and there was just a little confusion. We like whp and you guys like bhp. But the fact is that your program is calculating WHP, but you give the option of a drivetrain loss to get back to BHP.

I think everything makes perfect sense. Thanks for writing the program. It definitely adds in a few nice features that no others programs have at this time.