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flosho
Joined: 01 Jul 2004
Posts: 3160
Location: Eau Claire, Wisconsin
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 Posted: Thu Sep 04, 2008 12:40 am Post subject: |
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I just use a cone filter in the original placement... works fine.
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Rob the plumber
Joined: 25 Aug 2008
Posts: 122
Location: Utica, Michigan
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| Posted: Thu Sep 11, 2008 9:25 am Post subject: |
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| flosho wrote: | | I just use a cone filter in the original placement... works fine. |
I thought about doing that, but there are two breather lines that the stock airbox evacuates. It might be a good idea to leave them attached to an intake source.
Today I opened up the front of my airbox with a grinder, and painted it up nicely. Now the airbox has a much larger area to draw air, and it is also taking in cool air from the openings between the headlights.
I have to say that there is a definite seat of the pants improvement as far as acceleration goes, and a bit more noise from the turbo. I will take it a step further and replace the stock filter with a panel type K&N replacement.
Also note that I am running 12 psi of boost, so a smaller gain may be noticed at the stock 6 psi boost level.
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Fri Sep 12, 2008 9:58 pm Post subject: |
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I'm running a Ractive washable cone filter with a heat shield, in combination with a custom tube I had fabbed up. Looks like this:
 
Here is a related thread.
I can't say that I've noticed any improvements in terms of how the car runs. I did it mainly to dress up the engine bay and because the rubber straps on my stock box were broken. It was also a chance to play around with some ideas, and with the washable filter, I won't need to buy new air filters as often.
I can tell you that there is a noticeable increase in "induction roar" audible in the passenger compartment with this setup. I am still noodling about building an insulated box around the cone to prevent the induction tube from breathing any hot air from the engine compartment. The cone filter is currently positioned in a pretty good spot, where it can draw air from roughly the same spot as the stock air box horn, but from 360° instead of directly toward the engine.
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Rob the plumber
Joined: 25 Aug 2008
Posts: 122
Location: Utica, Michigan
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| Posted: Fri Sep 12, 2008 10:32 pm Post subject: |
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I see you reconnected the two breather hoses. Good idea. A lot of people eliminate little stuff like that.
I was also thinking of "foaming off" the area between my fabbed hole in my airbox and the grille openings so it primarily draws outside air only.
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Fri Sep 12, 2008 10:39 pm Post subject: |
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| Rob the plumber wrote: | | I see you reconnected the two breather hoses. Good idea. A lot of people eliminate little stuff like that. |
Yep, I still need to install a proper oil drain, but it's functional for now.
| Rob the plumber wrote: | | I was also thinking of "foaming off" the area between my fabbed hole in my airbox and the grille openings so it primarily draws outside air only. |
Probably a good idea, based on the reading I've been doing over at Autospeed (see aforementioned links).
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flosho
Joined: 01 Jul 2004
Posts: 3160
Location: Eau Claire, Wisconsin
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| Posted: Sat Sep 13, 2008 3:49 am Post subject: |
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So, would you guys recommend, I re-attach my black canister oil vapor thinger (below the brake booster)?? Right now both the hoses go to nothing...
Dan, you got an extra one for cheap? 
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Sat Sep 13, 2008 4:15 am Post subject: |
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No  Sorry, no extra air-oil separator. I had to cannibalize the one from my UWB to put onto the 941 as it was.
You might take a look at a couple of these articles...some pretty good ideas on how you might be able to build one inexpensively yourself.
Pots and Cans
DIY: An Oil/Air Separator
Building An(other) Oil/Air Separator
Which brings up occasion to ask a question I've been noodling about. I read somewhere that PVC was a good oil- and petroleum-resistant plastic. I'm wondering if you could inexpensively build an air oil separator like the one in the first article above, but make it out of PVC instead of welding one from metal. The stock unit is plastic. Why not PVC and then paint it???
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jrcook320
Joined: 02 Nov 2005
Posts: 67
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| Posted: Mon Sep 15, 2008 4:16 am Post subject: |
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Here's mine, basically the same thing as ideola's, aside from the fact that it's not a 931...  There was some good info on those links. I have an air box about half built right now. The beauty of my application is that the filter is already open to the grill.
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Rob the plumber
Joined: 25 Aug 2008
Posts: 122
Location: Utica, Michigan
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| Posted: Mon Sep 15, 2008 4:46 am Post subject: |
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That looks like some long piping. Also that engine bay looks phenomenal.
I made a home made cold air kit for a supercharged 5.0L Mustang that I had a while ago. I used 3" PVC, a few bends and put the air filter down low by the foglight hole.
I was tuning it on the dyno and for some odd reason, I decided to take off the cold air piping, and reinstall the 180 degree bend, open element K&N that came with the kit.
I picked up about 40 rwhp by eliminating what I though was a good idea. It obviously had too many bends, and undersized piping.
I replaced it with a 4" version sold by many performance places and got the power back.
This car made about 550 hp, so it may be like comparing apples to oranges, but the principle may still apply.
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jrcook320
Joined: 02 Nov 2005
Posts: 67
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| Posted: Mon Sep 15, 2008 7:05 am Post subject: |
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| Rob the plumber wrote: | That looks like some long piping. Also that engine bay looks phenomenal.
I made a home made cold air kit for a supercharged 5.0L Mustang that I had a while ago. I used 3" PVC, a few bends and put the air filter down low by the foglight hole.
I was tuning it on the dyno and for some odd reason, I decided to take off the cold air piping, and reinstall the 180 degree bend, open element K&N that came with the kit.
I picked up about 40 rwhp by eliminating what I though was a good idea. It obviously had too many bends, and undersized piping.
I replaced it with a 4" version sold by many performance places and got the power back.
This car made about 550 hp, so it may be like comparing apples to oranges, but the principle may still apply. |
The same principles apply, but it depends on the CFM you need to flow, the diameter of the pipe, the number of bends in your pipe, the quality of each bend (meaning the radius of the bend), and also the inside surface finish. A 4" radius 90 degree bend is going to be a greater head loss than an 8" 90 degree bend. Also, there are large ridges at each joint with PVC, so there's additional turbulence and head loss at each bend that's not there with a welded intake. I only need to flow about 340 CFM, a 3" pipe with only 2 minor mandrel bends is more than adequate.
At 550 hp, a 3" intake is undersized for sure, especially if you have multiple bends.
If you're interested in the math, here's a calculator you can use to see what pressure drops you're going to get based on the properties of air, the number of bends you have and your pipe size. At 550 hp, you're probably going to be flowing around 700 CFM. Assuming an air density of 0.0749 lb/ft^3, dynamic viscosity of .0183 cP, 70*F, 14.7 psi, .05mm pipe roughness (for aluminized steel) this calculator gives a pressure loss of .16 psi for each 90* bend for a 3" pipe with a 4" radius, compared to .05 psi loss for a 4" pipe.
http://www.pressure-drop.com/Online-Calculator/index.html
Here's a calculator you can use to get a total pressure loss for the length of pipe and the type of bend you have:
http://www.engineeringpage.com/calculators/pressure_drop/fittings_u.html
For only 340 cfm, with a 30* bend it gives me a pressure loss of .01 psi.[/url]
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Last edited by jrcook320 on Mon Sep 15, 2008 7:39 am; edited 2 times in total |
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xEcUtEr
Joined: 11 Apr 2008
Posts: 30
Location: Lisbon - Portugal
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Fri Sep 19, 2008 4:53 am Post subject: |
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Back to the topic of air-oil separator:
| ideola wrote: | | Which brings up occasion to ask a question I've been noodling about. I read somewhere that PVC was a good oil- and petroleum-resistant plastic. I'm wondering if you could inexpensively build an air oil separator like the one in the first article above, but make it out of PVC instead of welding one from metal. The stock unit is plastic. Why not PVC and then paint it??? |
Anybody have any thoughts on this? Seems like it would be really easy and inexpensive to fab one up pretty much identically to the one described in the Autospeed article. The question I have is will the PVC and the glue used for assembly be OK coming into contact with oil?
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bruni
Joined: 26 Jul 2008
Posts: 114
Location: South Africa
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| Posted: Tue Sep 23, 2008 6:53 pm Post subject: |
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for what its worth I also thought it would have been better to take to air in from the front, however, I put a thermocouple into the air intake for the air-filter and found it to be ambient temp when moving anything over about 20kph. I also noted someone suggested to put the air intake close to the ground not good for many reasons, but mostly the black road surface acts as a heat sink and air temperatures close to the ground are much higher than say 2' of the ground check out the intake on an F1 car
This is my first post so don't beat me up to much, thanks |
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Tue Sep 23, 2008 10:57 pm Post subject: |
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| bruni wrote: | | This is my first post so don't beat me up to much, thanks |
Good first post 
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924turbo_sout_africa
Joined: 29 Oct 2007
Posts: 215
Location: Sout africa
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| Posted: Tue Sep 23, 2008 11:09 pm Post subject: |
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this is some good info ...that is why i think as long as you draw in air from the vents that is the best place to get it ......any where else well i think there will be alot of heat to me having the intake close to the road brings in it's own hassles like sucking in water and well that point about the road being warmer ...so very good post bruni...
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