924 Tech Specs

[SoCal Driver]

Just scanned this in:

[drew1]

SoCal,

It sure is good of you to do all of this.


drew1

[SoCal Driver]

Have to have a focus. Been out of "real" work for over a year. Grabbing anything I can to keep the landlord off my back. These manuals and such keep me from walking the streets between the temp employment.

Note: Mechanical Engineer - Automation Specialist looking for meaningful work in the So Cal area. Will wash windows!

[ronin]

all the more reason to start your project

[drew1]

SoCal

I hate to see an ME out of work, kind of wish I had gone to school to be one.

I have a question for an ME. When knowing the flow at a certain pressure & you want to calculate what the flow would be at a different pressure, do you use absolute or gage pressures for your calculations?


drew1

[Pike]

Hey SoCal, I was wondering if one of the books in your wonderful library had wiring info for a '77 era 924 NA. The haynes guide is ok, but I have some wires that are on vacation and I need to figure out where they are supposed to go.

[SoCal Driver]

All the 924's and 944's come with extra wires.
Where are these wires located and what are their codes?


Subsonic or hypersonic? Restricted flow or unrestricted? Temps? Density? What accuracy do you want?

[Pike]

I don't know what you mean be codes, but here they are:
1. A red/green wire that is not attached. It should belong to the right running lights, but they work, so I am not worried.

2. A grey/yellow wire that goes up through the firewall, might be for the foglamp option that I don't have.

3. A brown ground, seems to go on the terminal G9, but the wiring diagram shows that terminal as being empty. I am not sure where it goes to.

4. A larger red wire that comes in from the firewall, probably off the battery. It also seemed to be assosiated with the 'G' terminals, but I could not see a blade that had been connected at one time. All if the other connections on that section of the box are accounted for. This is the one that concerns me the most.

[ronin]

not to ask stupid questions, but what's the difference between supersonic and hypersonic?

[SoCal Driver]

The extra wire at the tail light is for the German fog tail light. These are the extra lenses that don't have any bulb bases in them. You can add the bases (and lamps) if you find a VW dealer that has them in stock.

-------------------

OK Add supersonic.

[ronin]

lol. Hugh, I honestly didn't know if there even is a difference, but I figured if anyone knew it would be you.

[Pike]

Fog tail light? I have no reverse lights, but assumed that that problem was with the linkage switch. I have the bases but have not put them in.

[drew1]

SoCal,

There are two things I want the formulas for. One is a compressible fluid (air) & one a non compressible fluid (liquid). I don't have the formula I found handy now, but it has variables for a known flow at a known pressure and alows you to figure out the flow at a given pressure or pressure. It involves squares or square roots. What I need to know is if you use gage pressure or abslute pressue in the figuring.

One project, I worked on building a frame for it this afternoon, is a back yard flow bench for cylinder head work. Obin Robinson gave me the idea from a post a couple of years ago. In this I will be flowing air though restrictions, orfices, to tap off a water U tube. Since a vacuum cleaner will be the air mover I am going to try & see if I get measureable difference for the inside & outside of an elbow. If so I am going to compare it to the orfice (made 3 sizes) at the same flow and see if I can come up with some kind off Constant or coeffient (I reckon thats what you call them). I think the elbow will be better than an orfice using just a vacuum cleaner since you don't loose as much though it. I haven't tried anything yet, so don't know what Reynolds number or sub or hypersonic flow I will have.

The other thing I'm interested in is flow through injectors at different pressures.

I will be using the flow bench at the range of ambient temp and atmosheric pressure in SC. If I can get the standard 28" of water pressure that standard head tests are run at with the flow bench I would be happy, but I don't think I can get this at full valve lift with a vacuum cleaner. I guess I would be working in the + & - 1.5 gage PSI or 42 " of water at the most. If I can get read with 1/8 " of water for accuracy, my eyes will be doing good. I don't think changes in air temp, & the changes in atmosheric density will affect me that much since I will be taking readings at a pressure with one end of the U tapped into my pipe & the other open. My readings will come off 2 both ends of a U tapped at an orfice or elbow.

For the injector flow, I have an idea for water injection using a micro controller. I have one I've been playing with simulating changes in IAT, MAP, & RPM. Using PWM to simulate an electric injector on off duty cycle, I can get a change. A better way may be an I to P or V to P transducer varying the pressure using a CIS injector. This is on back burner now.

Thanks for your interest, I really apreciate it.

drew1

[SoCal Driver]

Somewhere I have the figures and method for testing the injectors flow. There is a visual requirement of checking the fan or spray patterns. Have seen a strobed video system being used to check jet engine injectors.

Using a manometer for differential air pressure is great for constant flow low pressure systems such as furnace ducts and clean room work benches. For higher flow rates I would look at using a venturi and transducer. Although the flow in intakes is dynamic and not static. This is where the riser length comes into play.

Gesh. My old work notes are in the garage in three rings. Search the internet for industrial stainless steel spray nozzels. Can't recall a mfg. at the moment. These sources have the flows figured out and give quickie engineering calc's to figure out what the end user would need. Should be able to use their calc's.

Old man Reynolds! Found out that water flowed through rough pipes faster than smooth pipes. Was an engineer redoing the NY water system around the late 1800's. Has to do with the size of the air/water molecule verses the roughness of the pipe.

[drew1]

SoCal,

I'm not wanting to check injector flow, but am wanting to calculate the change in flow from known flow & pressure if pressure is changed.

the flow bench. Tested today with a tapped orfice along with the elbow. I am not getting much change on the elbow u tube. I took the data down & will look how they compare with each other. By roughly calculating a couple of orfice flowws, from NACA chart & formulas, & comparing to elbow, 12 CFM = 0.1 ". I was hoping for better resolution.

drew1

[SprintStar]

Originally posted by SoCal Driver
Just scanned this in:

Hey So Cal,

I'd appreciate it if you can email me the scans. Thanks!!!!!

Sprint.

[J1NX3D]

me too!!

jae.ekman@nzdf.mil.nz

cheers!!

[SoCal Driver]

The "scans" take up 45 megs. As I'm on dial up till I find my next fortune it's just a bit of a pisser to the wife if she can't use the phome for the next two days.

Send me a PM.

[J1NX3D]

uv got mail!