Sonic Dyno Thread

[biged83]

stock as in the car was stock? good numbers, but know that Mustang dynos are known for usually being optimistic.

Looking forward to the graphs.

Yes stock as in nothing done to the car at all. the numbers were a bit surprising. my scanner is messing up ill have the sheets up tonight

 

[DeweyD]

stock as in the car was stock? good numbers, but know that Mustang dynos are known for usually being optimistic.

Looking forward to the graphs.

Correct me if I'm wrong but Mustang dynos generally read much lower than Dynojets at least. As much as 90% of a Dynojet. Of course you can always set up a dyno to give you a range, but Mustangs and DynoDynamics are usually referred to as "heartbreakers".

That being said the posters numbers are way too high for stock.

 

[rsSteve]

Correct me if I'm wrong but Mustang dynos generally read much lower than Dynojets at least. As much as 90% of a Dynojet. Of course you can always set up a dyno to give you a range, but Mustangs and DynoDynamics are usually referred to as "heartbreakers".

I was always under the impression that MustangDynos are more of the real world HP to the wheels dyno, where as Dynojet will give you closer to crank numbers being more optimistic. Even tho both are measured from the wheels.

 

[DeweyD]

I was always under the impression that MustangDynos are more of the real world HP to the wheels dyno, where as Dynojet will give you closer to crank numbers being more optimistic. Even tho both are measured from the wheels.

All this highlights is that dyno to dyno, car to car, operator to operator, and location to location; it is extremely difficult to compare numbers. It bothers me a little that I never had a baseline done in my car, I just know the tuned dyno number. I don't know what the real gain is, I can only assume I know where the car started based off of other peoples stock dynos.

 

[ChrisJ]

I was always under the impression that MustangDynos are more of the real world HP to the wheels dyno, where as Dynojet will give you closer to crank numbers being more optimistic. Even tho both are measured from the wheels.

Seems like an impossible assumption as there is no way for a dyno to know what losses there are after the crank.

 

[mitdr774]

Having watched a car dyno in both a dynojet and a mustang, the numbers were within a single digit range of eachother. Then the Mustang operator changed few things and gave the guy the "dynojet" number that was a whole lot higher than the car actually produced on an actual dynojet.

 

[94383Z71]

Hmm. I was always told Mustang dynos read high.

But, as was already stated, so many factors go into what makes that number- hence why there's several different STP's and correction factors- that there's no great way to quantify that. Even outside of environmental factors, there's the Dyno calibration, operator, rigging setup, cell airflow etc.

I was just offering a small anecdote; all you can really do is find a reputable, quality facility and trust them.

 

[ChrisJ]

That's one thing that has confused me for years.
Why are there corrections made?

1 HP = 746 watts, if the car can generate enough mechanical power to produce 149,200 watts then it is producing 200HP. What gets corrected and why?

The typical formula used for engines is torque x rpm / 5252 = HP. Not sure how or why this came about, but I guess it does the job.

 

[94383Z71]

It's corrected for temperature, barometric pressure, vapor pressure and maybe a handful of other things.

It's understood that the only numbers that really matter are what you make where you are, but it allows bench - racers a way to compare somebody in Denver to somebody in Miami to the Salt Flats without Miami guy getting the short stick because it's 20*F hotter there so he makes less power.

As a quick and dirty explanation

Edit: it's also to help hard core race teams to know what to expect, etc, but that's less pertinent to our situation as enthusiasts

 

[ChrisJ]

It's corrected for temperature, barometric pressure, vapor pressure and maybe a handful of other things.

It's understood that the only numbers that really matter are what you make where you are, but it allows bench - racers a way to compare somebody in Denver to somebody in Miami to the Salt Flats without Miami guy getting the short stick because it's 20*F hotter there so he makes less power.

As a quick and dirty explanation

Edit: it's also to help hard core race teams to know what to expect, etc, but that's less pertinent to our situation as enthusiasts

So basically if you're on the dyno under perfect conditions they drop your number a percentage and if your on the dyno under poor conditions they raise it?

 

[mitdr774]

Essentially

 

[94383Z71]

Yes, that's pretty much right.

One of the SAE standards (I forgot which, there's 2-3 prevalent ones) is 29.92 InHg (103.3 kPa), 0 vapor and 60*F

So if you're on a dyno at 29.92 InHg, 0 vapor and 50*F you get knocked down a touch.

If you're on a dyno at 29.92 InHg, 0 vapor and 70*F you get touched up a bit.

They don't always do it, but it's a common practice. Most facilities will provide you with both if you like

 

[biged83]

That being said the posters numbers are way too high for stock.

Im just saying what the dyno showed. my numbers arent to challenge for highest stock or anything. they are just baselines for the testing of different products.

the operator of the dyno has serious drag and race cars and they know what there doing so i doubt he inflated my numbers.

im running 93 octane it wasnt super hot and the car was just a happy little beast that day maybe. but all i am worried about is having the numbers for a baseline

 

[ChrisJ]

And why is 117HP to the wheels way too high for stock? That's a 21HP loss if the engine did 138HP.

Sounds completely reasonable for a manual transmission.

 

[94383Z71]

He may have been referencing BigEd's post, which can easily be interpreted as a stock car making 138hp and 154tq at the wheels.

That does sound WAY high to me. Those are the engine numbers you're using.

 

[DeweyD]

And why is 117HP to the wheels way too high for stock? That's a 21HP loss if the engine did 138HP.

Sounds completely reasonable for a manual transmission.

Actually 117hp sounds perfect to me I was referring to to stock 138 number. I think dynos are great for measuring % increases over a baseline, which you can then use to infer crank hp. For example stock factory crank is 138hp. You dyno 125 stock and then tune it to 150 for a 20% increase. Apply the 20% to the factory crank 138 to get 166 estimated crank. About as good of a way to do it as any. Of course this only works if the manufacturer's factory numbers are accurate. (Talking about you BMW!)

 

[krakenredbeard]

Subbed October I'll be posting my own numbers

 

[ChrisJ]

Ah, yeah there is no way you're going to get 138hp at the wheels if the car is rated 138hp at the crank.

Either someone misunderstood or someone lied.

 

[biged83]

Dyno Sheet as i said

 

[cndctrdj]

I made 130 to the wheels stock