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      08-26-2008, 11:07 AM   #1
Johnnyr135
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how to dyno

How should I dyno with hood open or closed? What is the right way I am on my way there? Thanks
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      08-26-2008, 11:13 AM   #2
InsaneSkippy
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I've always done it with the hood closed, usually they'll tell you what to do.
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      08-26-2008, 11:20 AM   #3
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Thanks
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      08-26-2008, 11:21 AM   #4
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does it make any difference?
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      08-26-2008, 11:21 AM   #5
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You'll get a few pulls so try both.
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      08-26-2008, 11:26 AM   #6
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Funny, i've dyno'd cars with the hood open, and usually had a huge fan blowing into it.
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      08-26-2008, 12:17 PM   #7
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Quote:
Originally Posted by aponting389 View Post
does it make any difference?
Yes. Extras air flow and less heat will make a difference.

I like hood closed better, because the air circulation under the hood does matter. Unfortunately heat will build up because the fan alone does not represent real world conditions accurately (it is more conservative). Most parts vendors do dynos hood up and sometimes with real big @$$ fans. This will usually show better numbers.

The important thing is to stay consistent (same machine, shop and set up ) from Dyno to dyno so you know you are looking at your car changes not the set up changes.

FYI… don’t expect the same numbers that a parts vendor gives unless you are testing under identical conditions.
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      08-26-2008, 12:32 PM   #8
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http://www.n54tech.com/forums/showpo...26&postcount=1

this should be stickied somewhere around here. these must be followed to get comparable results:

"Ahead of time:

1) The brand of dyno matters. They all read (and work) differently so if you want to compare numbers with others find an actual Dynojet dyno.

2) If possible do a baseline dyno before your modifications so you can measure the power increase. For those of you using an off brand dyno, failure to perform this step will result in numbers that are impossible to analyze. If you can't do a before dyno and you're not using a Dynojet, don't waste your money or time.

3) Make sure the car is fully adapted to your modifications before you go. If you just added race gas, floor the car a few times so it can adapt to the higher octane.

4) Bring along a USB flash drive to take home your runs.

5) The better the fans, the higher the dyno numbers. Make sure the dyno shop you use has adequate fans and ventilation.

6) The N54 always dynos better in colder weather, despite correction factors. Take this in to consideration when picking a day to dyno and when comparing numbers with others. Corrected runs in 50 degree temps will generally result in higher numbers than those in 100 degree temps, all else being equal. So if you want to improve your chances for a dyno record, go on a cold day. Just be prepared for skeptics to complain about your optimal weather.

7) Correction factors do not properly take in to account altitude. If you live in a high altitude area, do not try to compare your corrected numbers to others at sea level. Try to find a dyno close to sea level.


Once you arrive:

1) To connect the RPM pickup use an allen wrench to loosen and lift the plastic engine cover. The tach pickup connects to the wire bundle going to a coil pack. If the dyno operator can't get a signal, just move to another bundle under there until you find one that works.

2) Measure air/fuel ratios from the right tailpipe. This avoids confusion if your factory exhaust flapper is not disabled. As a side note, ignore the dyno operator when he freaks out about how lean your air/fuel ratios are. The N54 is a direct injection motor and typically runs 14.5:1 air/fuel ratios in the midrange stock. Also ignore the power/torque dip around 4000rpm, it is a cam timing event.

3) Disable the traction control system.

3a) For manual transmissions: Do all runs in 4th gear from 2000rpm to 7000rpm.

3b) For automatic transmissions: This is very confusing and likely your dyno operator will not be smart enough to do this, so don’t be afraid to operate the car on the dyno yourself.

Shift the car in to 4th gear in sport mode, bring the RPMs up to around 1800-2200, and then floor the car to right before the kick down switch. If you floor it all the way, the car will downshift and screw up your run. If this happens abort the run and try again. The kick down is a small button at the end of the gas pedal travel and you can practice with the car off, or on the way to the dynoshop.

4) When analyzing your runs, move the correction factor to STD, and the smoothing to 5. The early 335i tuning gods decided this was the appropriate factor for the N54 so using the more appropriate SAE factor will likely result in your disappointment.

5) Copy your .DRF run files to your USB drive to take home. You can download Dynojet winpep software online free of change to create graphs, combine runs on to one chart, change correction algorithms, and analyze your runs."

(emphasis added)
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      08-26-2008, 04:01 PM   #9
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So how about those results Johnnyr!
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