warp9

iTrader: (35)

I own several vehicles that have been tuned on various Dynojets along the east coast. In every instance the power on that sheet of paper never translates at the track in terms of MPH. My conclusion is that the Dynojet is very close to flywheel HP, NOT the 15-20% they tell you to add for drivetrain loss.
I also have seen further evidence that Mustang dynos are not as low reading as the shops tell you either. If we can gather all the people who have run their car after having their car on any dyno we can start to see a pattern where the HP on that fancy piece of paper is overinflated.

To those who might be interested: Post your Hp # and what kind of dyno it was on(not the shop) and then post your highest trap speed and vehicle weight. Lets see whats going on here.

Billy@EnglishRacing

iTrader: (18)

yes they do

Goodi32

That's why people use corrected or uncorrected on the dynos.

warp9

iTrader: (35)

I have the most recent evidence here. I just got tuned on a dynojet and made 405 HP on pump gas. Without changing anything and on the same brand gas I went to e-Town this past friday and my highest trap was 118.8 MPH. That was on a good clean pass and a nice cool outside temps. My car weighs 3205 with me in it. That translates into 415 Hp at the flywheel on almost all HP calculators. See?

warp9

iTrader: (35)

But shops and tuners want us to believe that we are making fantastic power dont they?

MondoBongo

iTrader: (10)

they don't lie neccesarily, but they can be misleading.

what really matters is a/f ratios, knock counts, and how fast the car goes with you behind the wheel.

there can be a good bit of discrepancy between different tuners, different dynos, different air temps, etc... etc...

i've seen several people on this board say it before, and it rings true, a dyno is a tuning tool. it is certainly not the be all end all for the car.

Boltz.

iTrader: (42)

Your basing your question about if dyno's lie on the results of an online HP calculator?

an $80,000++ tool VS. a MPH/HP formula online. You be the judge

To add: Dynos don't lie, but they can be manipulated to produce a higher or lower number. Some dynos you can manipulate the correction factor to alter the numbers and other dynos you can actually input a multiplier.

dubbleugly01

iTrader: (24)

yup, the true benefit of a dyno is to measure gains as you modify, assuming you continue to use the same dyno. Dynojet numbers really do seem to be overinflated this decade, and mirror closer to flywheel hp in my opinion. But it's in the tuners/shops best interest to put up a big number, so more people buy their parts and services. It's extremely hard to find a level playing field.

cssaddictm4

iTrader: (13)

Have you ever heard of the "fudge factor?" DynoJet numbers were based of a Yamaha motor that Yamaha claimed made a certain wheel hp. Then you take into various drivetrain loss and drum weight, and wa-la you get a fudge factor that merely estimates whp. Within most Dyno software you can change drum weight so that your whp number reads higher or lower. Dynos are best used for tuning. The track determines your hp/whp IMO.

Blake.

warp9

iTrader: (35)

I agree with most of the above statements, but shops and /or tuners should not try to mislead their customers with an overinflated number. The truth will always come out in the end.

PhoenixEvo

iTrader: (1)

Only ricers or someone who likes to brag would want high peak #'s, tuners/enthusiasts want to see gains. IMO

warp9

iTrader: (35)

The MPH/Hp formula stands to gain nothing, its simple and truthful.

dubbleugly01

iTrader: (24)

The Shop comes to mind...... Highest reading dynodynamics in the nation!

Ted B

iTrader: (6)

Without going into a(nother) lengthy discussion, a dyno result should be taken as an indicator and not an absolute. Furthermore, a dyno doesn't tell us anything about things like boost recovery and time to rpm.

The same can be said for calculated estimations, which must fudge on a number of important factors, such as drag coefficients. I know of at least three different ones that give three different results. They are educated guesses, nothing more, nothing less.

Lastly, the one thing that can be said for Dynojets is they are relatively consistent. Eddy current dynos such as Mustangs and DD are better for emulating real-world conditions, but user-defined changes to a simple 'correction factor' and/or different mode settings will give different numbers as compared to another, otherwise identical machine.

wroblewskievo

iTrader: (2)

ams does my tuning and their numbers are pretty accurate. but even they have told me not to look at peak hp and just look at the powerband.