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Dyno cell design

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I know the main focus of the forum is tuning but since this section is not really directly about it I thought I'd ask here.

For those of you who have their own dyno/cell how did you go about choosing your cooling /extraction setup?

Have you tried to create an air flow or just opted for cooling fans and exhaust gas extraction?

What have you done to control noise?

Does your design have any improvements that you'd like to make?

I have a building warrant in place to build a cell, I'll post up the design later, and was wondering how everyone else is doing it.

Is your design ready, just curious about the dyno cell design

I designed the cell in my old shop and all things considered I'm still happy with it. Plenty I'd change though. Noise control wasn't quite as good as good as I had hoped. I basically built a room inside a room with an air gap between the walls. This was an expensive way of doing it yet still not 100% effective. Doing it again I'd look at a solution from the likes of Industrial Noise Control. They specialise in this sort of product and it would likely end up cheaper than what I did - http://www.industrialnoisecontrol.com/custom-engineered-solutions/powersports-dynamometer-test-room-solutions/inc-dyno-test-rooms

For airflow, again I think I would have benefitted from more extraction. The problem is that the larger your cell, the bigger your fans need to be to change the air often enough. I used two extraction fans in the ceiling and a cooling fan directly in front of the car.

My biggest tip for anyone with a dynapack dyno is make the room larger than you think it needs to be. Most people don't give enough room to jack both ends of the car, or to get the hubs on and off comfortably. My cell was 6 metres wide and 9 metres long which sounds huge but in practice was almost perfect in my opinion.

This is the design we came up with, not quite as big as what your old one was Andre.

The fans at the rear are 7.5 kW each and we estimate our air exchange to be approx 3-4 seconds at full fan speed. the design is a tweaked version of another one we've seen at another company, who use it with complete success, as well as a wind tunnel idea, there should be no need for a cooling fan as the extraction should generate a flow of high enough velocity and volume, in theory.

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Hi Chris,

The basic design looks solid however I'll give you a couple of thoughts on it:

1. Your dimensions look workable but I'd be a little concerned about length. Measure out the proposed design, put a car in there (as big as you ever normally see) and try working at the back and the front with a jack to see if you have sufficient room.

2. The wall design looks similar to mine. Here we have a product called NoiseLine (it's a domestic wall lining product - http://www.gib.co.nz/systems/gib-noise-control-systems/). I didn't find it that effective as it tends to reflect noise inside the bay. This does attenuate the noise outside but makes it harder for the tuner as the cell actually ends up noisier. I'd strongly recommend at minimum some perforated panelling inside with a noise absorbent product behind. You'll know you have it right if the room feels 'dead' when you walk into it - Hard to explain but when you feel it you'll know exactly what I mean.

3. If possible, put your air inlet in the roof rather than the door. This way you can build a large inlet 'plenum' with a couple of walls to deflect sound - Done correctly you can stand above the plenum and shout into it and someone in the dyno cell can't hear you. If you put large holes in the doors then you may as well have no doors since sound is going to come straight through the holes/louvres (or whatever you intend to have there).

4. I'd strongly suggest a false wall at the rear of the bay that comes down to about 500 mm off the floor. This forces the fans to pull air from under the car. Without this, the fans just pull air from the middle of the room which will do less for cooling.

5. I'd be very surprised if you can pull enough air past the car with just extraction fans to not need a dedicated cooling fan too. I hope you're right but at a minimum I'd factor in a cooling fan to your room size calculations (and budget) just in case.

Of course most of the above will depend on the available space and budget so may not be that useful to you.

The length is the minimum that we were thinking would be workable floor space, an example of a typical car would be a 200SX S14 which is 4500mm in length so we'd have 2500mm to work with, since the car would be parked close to the doors this leaves a clear space behind to work.

The interior lining of the walls I know exactly what you are talking about, it is something we've yet to decide on but since it's not structural it's not needed for this planing permission/building warrant.

The fans would be enclosed behind false wall, if you see the little diagram above the floor plan with a 500mm opening as you're suggesting, glad to see we're on the right track.

The air inlet is at the door to create a flow along the bottom of the room, we'd probably add the ducting to the outside of the doors as you're suggesting but it's something we'll need to experiment with so hasn't been added into the plans here. The company who sell the Dynapacks in the UK use this design and have very little noise leakage due to the air flow into the room preventing the sound moving forwards.

Here's a video of the design we're basing the plans on:

https://www.youtube.com/watch?v=Bo171nISp9E

https://youtu.be/UMeA1HGEVcw This is the design of what Andre was talking about. Ive been in that cell even with a car idling at 10:1 for testing purpose at their EFI 101 class few years back ,you cant even smell anything. At full throttle and on the outside of the booth is almost silent. Chris from Xenocron told me it was about 80k USD for the whole complete setup with fans installation and wiring. He said the best part is going home and not smelling like fumes every night.

Sorry Chris, I missed the false wall in the drawing. As you were :)

Agreed, often the actual design is a compromise between what is perfect and what will fit in your facility and be workable. I've seen a few dyno cells that were too small to be useful fitted in workshops that would have easily taken a much larger design though, and given the money a well designed cell ends up owing you, that can be a very frustrating mistake.

Dynapack in NZ used an air inlet through their doors due to the building design. They had a kind of insulating box on rollers that they wheeled into place once the doors were closed. It worked but was a little awkward. I guess there is no 'perfect' design though and everything is a case of making livable compromises.

The other area to consider is the ability to enter and exit the cell in an emergency situation, I saw a cell a few weeks ago that was similar to the one that Andre described where there was the requirement for another person external to the dyno cell to remove the fan from in front of the door to allow access, there wasn't a personal access door either, so if something happened inside the cell, you where stuck in it until the fan was removed. I refused to do any work in this cell for that reason.