dyno question
Thread Starter
Racer
Joined: Nov 2001
Posts: 370
Likes: 0
From: st.louis missouri
dyno question
Is it normal to run a big fan in front of car during dyno? does that skew #'s..base run 311 no fan tune alittle next run 328..more tuning fan turned on and 345hp on that and next 2 runs...is the fan turning on helping these #'s...34hp seems high for a tune...dynojet was used..all about 10 minutes apart..ls2edit was software..thanks for your help..car is a6 stock except magnaflow mufflers..
Le Mans Master
Joined: Feb 2006
Posts: 5,762
Likes: 4
From: Chandler Arizona
Originally Posted by dan-t
Is it normal to run a big fan in front of car during dyno? does that skew #'s..base run 311 no fan tune alittle next run 328..more tuning fan turned on and 345hp on that and next 2 runs...is the fan turning on helping these #'s...34hp seems high for a tune...dynojet was used..all about 10 minutes apart..ls2edit was software..thanks for your help..car is a6 stock except magnaflow mufflers..
Why would anyone leave the fan off? The car is going to overheat without air flow through the radiator. So, it's possible that they did it on purpose to make the car dyno lower on the first run on purpose in order to impress you with all the power they picked up for you.
Mind you, I still think you made good horsepower with the tune, but I'm betting you only picked up about 10 rwhp.
Last edited by glennhl; Nov 3, 2006 at 12:51 AM.
Drifting
Joined: Jul 2005
Posts: 1,533
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From: az
Originally Posted by glennhl
He turned the fan off for the first run? Sounds like a tuner's trick to me. To give you an example, I ran back to back pulls with my stock A6. Both pulls had the fan on. First run I made 334 rwhp, then on the second pull the car made 316 rwhp because it got a little hot and pulled some timing. The LS2's pull timing for inlet air temps of over 86F and coolant temps above 212F.
Why would anyone leave the fan off? The car is going to overheat without air flow through the radiator. So, it's possible that they did it on purpose to make the car dyno lower on the first run on purpose in order to impress you with all the power they picked up for you.
Mind you, I still think you made good horsepower with the tune, but I'm betting you only picked up about 10 rwhp.
Why would anyone leave the fan off? The car is going to overheat without air flow through the radiator. So, it's possible that they did it on purpose to make the car dyno lower on the first run on purpose in order to impress you with all the power they picked up for you.
Mind you, I still think you made good horsepower with the tune, but I'm betting you only picked up about 10 rwhp.
Thread Starter
Racer
Joined: Nov 2001
Posts: 370
Likes: 0
From: st.louis missouri
thats what i was thinking..he acted like he forgot. he was running around like crazy when i got there..he is a new friend and long time friend of friend...great guy...first 2 pulls were no fans 3rd is when he turned it on..
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Safety Car
Joined: May 2005
Posts: 3,990
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From: Corpus Christi Texas
Around 2 years ago, a local dyno guy did the same thing to my 03 Cobra. He claimed it was how some company's might gain power from simple things like a cat-back. He did a dyno run without the big fan on and immediately did a back to back run with it on. There was around a 20rwhp difference between the two (with the fan on, the power being higher of course).
Thread Starter
Racer
Joined: Nov 2001
Posts: 370
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From: st.louis missouri
Originally Posted by bunk22
Around 2 years ago, a local dyno guy did the same thing to my 03 Cobra. He claimed it was how some company's might gain power from simple things like a cat-back. He did a dyno run without the big fan on and immediately did a back to back run with it on. There was around a 20rwhp difference between the two (with the fan on, the power being higher of course).
Le Mans Master
Joined: Mar 2002
Posts: 6,885
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From: Corpus Christi TX
little story here...I had at the time a cam "only" 02 z06 with a package from vendor A. Had it for several months and it dynoed 410ish SAE just about every dyno shop I went to. I just happened to be at vendor "B" one day for a dyno day. My car came up for dyo and it was obvious a bump stick was there at idle. The vendor B guys kept asking who's cam I was running and I just flat told them vendor A.
Well...next thing I know vendor B is having "issues" dynoing my car. Said "it's breaking the tires loose on the drum...." and they kept jacking around until my coolant temps must have been 225. They then got two big dudes to "lean" on the rear of the car to "keep it from breaking the tires loose..." Now mind you, this a 410 to the wheel car - lol
long story short, it dynoed about 395 that day and they made sure everyone present knew who's cam package I had. Never went back to that shop ever again...and quite frankly told them they were full of poopoo for that stunt. :o
Well...next thing I know vendor B is having "issues" dynoing my car. Said "it's breaking the tires loose on the drum...." and they kept jacking around until my coolant temps must have been 225. They then got two big dudes to "lean" on the rear of the car to "keep it from breaking the tires loose..." Now mind you, this a 410 to the wheel car - lol
long story short, it dynoed about 395 that day and they made sure everyone present knew who's cam package I had. Never went back to that shop ever again...and quite frankly told them they were full of poopoo for that stunt. :o
Melting Slicks
Joined: May 2006
Posts: 2,891
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From: NJ..."the way I saw it, everyone takes a beating sometimes."
I completely agree with glennhl, and some of the other stories are exactly why I don't like dynos. Yes they are helpfull tuning tools and good to get an idea of the powerband but people put far too much stock in dynos. Like some of you posted, there are a lot of tuners and dyno operators who know how to manipulate the numbers to show "results". I don't care how much more I may get on a dyno. If I can't feel it on the street or if it doesn't show up at the track, then it's just a number to brag to people about.
Thread Starter
Racer
Joined: Nov 2001
Posts: 370
Likes: 0
From: st.louis missouri
Originally Posted by BLU-BY-U
little story here...I had at the time a cam "only" 02 z06 with a package from vendor A. Had it for several months and it dynoed 410ish SAE just about every dyno shop I went to. I just happened to be at vendor "B" one day for a dyno day. My car came up for dyo and it was obvious a bump stick was there at idle. The vendor B guys kept asking who's cam I was running and I just flat told them vendor A.
Well...next thing I know vendor B is having "issues" dynoing my car. Said "it's breaking the tires loose on the drum...." and they kept jacking around until my coolant temps must have been 225. They then got two big dudes to "lean" on the rear of the car to "keep it from breaking the tires loose..." Now mind you, this a 410 to the wheel car - lol
long story short, it dynoed about 395 that day and they made sure everyone present knew who's cam package I had. Never went back to that shop ever again...and quite frankly told them they were full of poopoo for that stunt. :o
Well...next thing I know vendor B is having "issues" dynoing my car. Said "it's breaking the tires loose on the drum...." and they kept jacking around until my coolant temps must have been 225. They then got two big dudes to "lean" on the rear of the car to "keep it from breaking the tires loose..." Now mind you, this a 410 to the wheel car - lol
long story short, it dynoed about 395 that day and they made sure everyone present knew who's cam package I had. Never went back to that shop ever again...and quite frankly told them they were full of poopoo for that stunt. :o