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Resident Ford Nut
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10,102 Posts
Discussion Starter · #1 · (Edited)
So I finally got around to pulling out the dyno sheet's from 2007 to compare un-corrected numbers:

2007 DTS dyno : uncorrected

Baro Pressure: 29.2
Humidity: 41%
Air temp: 84*

6,000 706 lbs ft, 804 hp

6,200 699 lbs ft, 825 hp

7,000 643 lbs ft, 857 hp
========================


2011 Super Flow 902 dyno: uncorrected


Baro Pressure: 29.02
Humidity: 45%
Air Temp: 91*
Density Alt: 3,400

un-corrected:

6,000 691 lbs ft, 790 hp

6,200 691 lbs ft, 816 hp

7,000 632 lbs ft , 845 hp

=======================

At 6,200 I get both dyno's at 1.1%, at 7,000 I get 1.5% I wonder what % the conditions are worth?


S CP :)
 

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Red Blooded American
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15,853 Posts
do you know the actual elevations at both locations, and the dew points for both days???
Identical headers? Identical weather conditions? Identical adjusted altitude? Intake air supply? Engine temp during the pull? A/F ratio identical? Bolt-ons identical? Any one or combination of these and other factors could easily produce slight differences even with the same dynamometer much less completely different test equipment.
 

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Bostick Racing Engines
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1,063 Posts
So I finally got around to pulling out the dyno sheet's from 2007 to compare un-corrected numbers:

2007 DTS dyno : uncorrected

Baro Pressure: 29.2
Humidity: 41%
Air temp: 84*

6,000 706 lbs ft, 804 hp

6,200 699 lbs ft, 825 hp

7,000 643 lbs ft, 857 hp
========================


2011 Super Flow 902 dyno: uncorrected


Baro Pressure: 29.02
Humidity: 45%
Air Temp: 91*
Density Alt: 3,400

un-corrected:

6,000 691 lbs ft, 790 hp

6,200 691 lbs ft, 816 hp

7,000 632 lbs ft , 845 hp

=======================

At 6,200 I get both dyno's at 1.1%, at 7,000 I get 1.5% I wonder what % the conditions are worth?


S CP :)
Well... beside what has been already mentioned... different test equipment, room dimensions, room pressure, etc, etc... the weather alone will make a difference... perhaps not as bad with a carb as with mechanical injection but...

One test was done at DA of 2916' and AD of 91.7% and the other at 3,400' DA and 90.4% AD... so... even excluding the entierly different test parameters... you still see ablut a 1.3% difference in air density which will make a difference, albeit a small one.
 

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335 Posts
You guys are missing the big one. What SAE dyno correction factor to standard conditions did they use? There are several.

We did this on two Stuska dynos on the same day. Both were set up the same but the rooms were a little different. They were 15% apart, after really looking at what was going on... the correction factor built into the dyno was different.. most guys don't even look at this.
 

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Resident Ford Nut
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10,102 Posts
Discussion Starter · #6 ·
do you know the actual elevations at both locations, and the dew points for both days???

Unfortuntley no......... can you determine dew point with knowing air temp and humidity?

I'm quite happy the numbers are as close as they are. Both dynos must be in calibration or they are equally out of calibration ;) my guess is they are both in.

Jon
 

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Resident Ford Nut
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10,102 Posts
Discussion Starter · #7 ·
You guys are missing the big one. What SAE dyno correction factor to standard conditions did they use? There are several.

We did this on two Stuska dynos on the same day. Both were set up the same but the rooms were a little different. They were 15% apart, after really looking at what was going on... the correction factor built into the dyno was different.. most guys don't even look at this.

Steve at Westec and I had a conversation about this.


Nice to see you still "lurk" over here from time to time.

S CP :happy:
 

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6,590 Posts
Unfortuntley no......... can you determine dew point with knowing air temp and humidity?

Jon
jon, please try to spell shit right. when you're older than gn, you can have a hall pass..:D UNFORTUNATELY, the answer to your question is no...

Well... beside what has been already mentioned... different test equipment, room dimensions, room pressure, etc, etc... the weather alone will make a difference... perhaps not as bad with a carb as with mechanical injection but...

One test was done at DA of 2916' and AD of 91.7% and the other at 3,400' DA and 90.4% AD... so... even excluding the entierly different test parameters... you still see ablut a 1.3% difference in air density which will make a difference, albeit a small one.
james, it was great bs'ing with you at bayfair. but you forgot the most important factor that would result in these differences. you even mentioned it while we were bs'ing. it's a ford...:)
 

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Highaboosta
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3,431 Posts
I was told this was a geographical phenomenon.

One of the largest HP engine builders in the country built a drag car engine for a west coast guy and dynoed it at 800 hp.
They shipped it to the west coast and the owner reported that it now made 900 hp at the wheels. :thumb:

I also was told by several engine shops that big dyno numbers make money and small dyno numbers don't make money.
Fortunately for me, my dyno time was free.
 

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Resident Ford Nut
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10,102 Posts
Discussion Starter · #10 ·
Oh man you have to put me in the same box as GN......... damn that's harsh.


S CP ;)
 

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Resident Ford Nut
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10,102 Posts
Discussion Starter · #11 ·
I was told this was a geographical phenomenon.

One of the largest HP engine builders in the country built a drag car engine for a west coast guy and dynoed it at 800 hp.
They shipped it to the west coast and the owner reported that it now made 900 hp at the wheels. :thumb:

I also was told by several engine shops that big dyno numbers make money and small dyno numbers don't make money.
Fortunately for me, my dyno time was free.

actually that is not the question at hand. I think both these dyno's were "screwed down" pretty tight. I'm sure of it and glad they are.

S CP
 

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Premium Member
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25,975 Posts
I was told this was a geographical phenomenon.

One of the largest HP engine builders in the country built a drag car engine for a west coast guy and dynoed it at 800 hp.
They shipped it to the west coast and the owner reported that it now made 900 hp at the wheels. :thumb:

I also was told by several engine shops that big dyno numbers make money and small dyno numbers don't make money.
Fortunately for me, my dyno time was free.
Mark, sadly this arguement is older than democrate VS republican, north VS south, GM VS Ford, etc. It will never be settled. You could say the same thing about two dynos anywhere in the country. The east is just jealous.:))eek:))


Jon, maybe I just woke up and am still a little punch drunk. But are these 2 different builds. Same engine with different pistons rings, etc. Geez Jon, even same day, same dyno, same operator repeatability has variables. Thats why places like Hendricks spend a zillion dollars on air flow, and "artificial weather" control in their dyno rooms.

One of the biggest factors I have seen in a dyno room that really effects the results is AIR FLOW, and exhaust. When we redid the dyno room exhaust on Carroll Shelby's dyno rooms, they lost over 2% on known engine assemblies because of the required re-routing of the exhaust 20ft up thru the roof, as opposed to 3 ft thru the wall. And increasing the size did almost nothing to improve the situation.
One of the reasons Steve's place makes good numbers is the air flow in the room. Its a huge deal.



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Unfortuntley no......... can you determine dew point with knowing air temp and humidity?

I'm quite happy the numbers are as close as they are. Both dynos must be in calibration or they are equally out of calibration ;) my guess is they are both in.

Jon
45% R.H. @ 91*=67* dew point
41% R.H. @ 84*= 58* dew point

The relative humidity and or dew point isn't the issue. One or the other works, its not knowing the altitude that crearts the unknow.



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Sleeper - hard to compare since two different mfg dyno's, 2 different locations, etc,etc,etc.


Funny but sad dyno story:
Go into a new to me dyno shop for a restricted rules engine they hired me to make a spacer(s) for . They build many of these type engines so I was to make several different variations while there all to be tested and the 'winner' would be what they'd want multiples of. Walk into the dyno room which only maybe 3 times size of the dyno itself. Barely any room to walk around motor/dyno itself. I saw no vents/fans/etc. The exhaust was routed thru the wall. I asked where it went and owner said down into a large covered pit so neighbors wouldn't get pissed. Interesting.Asked about the dimensions of piping and pit and got "not really sure...why?" Then asked about venting and fan set up and he said "what venting ? If it get's too hot in here we open the door." The door is a normal walk in door mind you. Obviously with a room that small the controls are just outside the room along with the water tanks,etc.

Anyhow, I walked to the soda machine, grabbed a soda, grabbed my stuff, jumped in my truck, and drove the 2hrs+ bact to work. What a waste of a day that was. Expensive soda. Very eye opening trip though. Got more of these stories.....not just the dyno rooms themselves.
 

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Premium Member
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Sleeper - hard to compare since two different mfg dyno's, 2 different locations, etc,etc,etc.


Funny but sad dyno story:
Go into a new to me dyno shop for a restricted rules engine they hired me to make a spacer(s) for . They build many of these type engines so I was to make several different variations while there all to be tested and the 'winner' would be what they'd want multiples of. Walk into the dyno room which only maybe 3 times size of the dyno itself. Barely any room to walk around motor/dyno itself. I saw no vents/fans/etc. The exhaust was routed thru the wall. I asked where it went and owner said down into a large covered pit so neighbors wouldn't get pissed. Interesting.Asked about the dimensions of piping and pit and got "not really sure...why?" Then asked about venting and fan set up and he said "what venting ? If it get's too hot in here we open the door." The door is a normal walk in door mind you. Obviously with a room that small the controls are just outside the room along with the water tanks,etc.

Anyhow, I walked to the soda machine, grabbed a soda, grabbed my stuff, jumped in my truck, and drove the 2hrs+ bact to work. What a waste of a day that was. Expensive soda. Very eye opening trip though. Got more of these stories.....not just the dyno rooms themselves.
I can show you no less than 3 dyno rooms that fit that almost to a tee with the exception of the exhaust. And the exhaust was no better, just different than you discribe. Bottom line, the rooms have nothing in common with my boat.
But then, any idea how manyboats with enclosed engine compartments are out there starving the engine as well?

So the guy gets dyno'd at Westech, which is like tesing on an open stand outside, all the air in the known world, gets his numbers and then takes the engine and drops into a boat with one 2" vent on each side of the boat that were really meant for the bilge blower air inlet and thinks its good to go.



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Headed your way Doc

Identical headers? Identical weather conditions? Identical adjusted altitude? Intake air supply? Engine temp during the pull? A/F ratio identical? Bolt-ons identical? Any one or combination of these and other factors could easily produce slight differences even with the same dynamometer much less completely different test equipment.
The answer is simple. Get a dyno of your own and remove all guesswork. :D
Doc, after much thought, I've decided to let "the boys" practice their dyno skills on one of my engines, maybe mid October.... I just have to finance the gas for the trip.....
Ray
 

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Resident Ford Nut
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10,102 Posts
Discussion Starter · #19 · (Edited)
Mark, sadly this arguement is older than democrate VS republican, north VS south, GM VS Ford, etc. It will never be settled. You could say the same thing about two dynos anywhere in the country. The east is just jealous.:))eek:))


Jon, maybe I just woke up and am still a little punch drunk. But are these 2 different builds. Same engine with different pistons rings, etc. Geez Jon, even same day, same dyno, same operator repeatability has variables. Thats why places like Hendricks spend a zillion dollars on air flow, and "artificial weather" control in their dyno rooms.

One of the biggest factors I have seen in a dyno room that really effects the results is AIR FLOW, and exhaust. When we redid the dyno room exhaust on Carroll Shelby's dyno rooms, they lost over 2% on known engine assemblies because of the required re-routing of the exhaust 20ft up thru the roof, as opposed to 3 ft thru the wall. And increasing the size did almost nothing to improve the situation.
One of the reasons Steve's place makes good numbers is the air flow in the room. Its a huge deal.

On air flow...where I dyno'd in '07 was one of the nicest rooms I've ever seen......... dyno cell was engineered by DTS it was a match for Westech's


I thought I had a pic of the hood, but you can just see the bottom of it here:


I don't have an issue with either set of numbers....I'm surprized that they are actually with-in 1.5% that's absolutley killer, eventhough I was expecting a bit more out of this re-build. As I stated...I'm pretty sure both dyno's were " screwed down" neither is giving anything away......these numbers were earned on both dynos.

Something to test next time: I know where one is sitting....



will it help or hurt? might depend on the direction of the airflow in the room?

S CP
 

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Resident Ford Nut
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10,102 Posts
Discussion Starter · #20 · (Edited)
45% R.H. @ 91*=67* dew point
41% R.H. @ 84*= 58* dew point

The relative humidity and or dew point isn't the issue. One or the other works, its not knowing the altitude that crearts the unknow.
I sure wish I knew the DA the test day in '07. would be interesting to know.

S CP
 
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