best airbox/filter set up?

[Trav]

International Auto has them in their catalog. www.international-auto.com It doesn't specify 40 or 45 mm

Quote:

Originally Posted by Sprintn . I think TWM also has air boxes that have an intake directed towards the front grill that a cylindrical air filter can then mate to.

[snj5]

Quote:

Originally Posted by Gary Williams I too have been told by the wizards that the Webers like the large plenum area. My engine has 1.5" TWM Induction ram pipes.

[Cali67Duetto]

Bump, I want to be able to find these pics quick.

[Gary Williams]

Just a follow-up on the air filter discussion. My engine came out to put on rings -- again -- because the new Deves rings didn't seat properly. Not their fault. We had troubles with the carbs that kept us from a proper break-in process on start up. The engine is now back in and the carbs have their new backing plate. I had one waterjet cut out of .090 stainless steel. It fits the GTV better than what ITG offers and is made better than the junk Pipercross sells. I use it over DCOE 45's with fully-radiused TWM ram pipes, covered by an ITG JC50/S/75 air filter. If you need a strong backing plate for your GTV, you can download my pattern from the Alfa-yahoo racing forum or e-mail me. It's an Adobe Illustrator file that CNC machinists should be able to import.

[Shaun C]

I overheard an interesting discussion this weekend regarding a simple modification to "supposedly" get more air directly to the airfilter, and was wondering if anyone can provide further comment from their own experience(hopefully no one has asked this before as I didn't get a chance to read through all the postings on this thread).

We were looking at a Giulia Super (race car) where the second (smaller) headlight had been removed and a tube/hose (similar diameter of the hole) run from the front, directly to the standard airfilter. A wire/mesh "cover" is fitted where the headlight used to sit to stop large objects from going into the tube and airfilter.

Now I've never studied the properties of air but the guy we were chatting to suggested that the mesh, even though it has fairly large holes, was enough to actually restrict the air flow moreso than one would expect and coupled with the fact that with the airfilter could now only obtain air through the tube and not from the engine bay, could actually render this modification worse than the standard set-up. And supposedlygets worse the faster you go.

He also made reference to other forms of racing where they actually place the air filter as far back as possible in the engine bay and modifying the vents/grill below the windscreen to source the air from there (hope that makes sense), which he says is better, as in general, the aerodynamics of a car, will have more air flowing over those vents/grills than can be taken through the front of the car.

I've also heard of a hot Mini Cooper S (the 60's type) with a fancy cross-flowed head, where they originally had made a scoop in the bonnet/hood to take air directly to the air filter, which was quite high in the engine bay. These guys then refitted a standard bonnet, becasue they found at higher speed, the change in airflow actually messed with the air/fuel set-up.

I was thinking of doing the same mod to my Giulia race car as was done on the other Giulia (seems so simple and logical), but now am unsure. Anybody have any experiences with the above?

[genericwood]

Well, I've given this a lot of thought recently. In my opinion, the best place to draw air for the carbs would be through the stock ventilation system at the base of the windshield. This is a natural high pressure area, and wouldn't hurt aerodynamics. What is difficult is plumbing the air to the airbox through the fire wall. That said, the headlight opening probably has little effect on the relatively "dirty" aerodynamics of our cars. If the mesh is coarse enough, and the diameter of the inlet large enough, I doubt is has any significant effect on air flow. The filter most certainly will. I am not currently running a filter on my race car. I just accept that I will have to do the valves more frequently. But if I do run a filter, I will find a way to put a cone shaped filter between the inlet at the grill and the air box. Don't put it near the carbs unless you have to, as any restriction near the air horns will disrupt flow.

No matter what you do, make sure you are not drawing air from inside the engine compartment! You want it to be as cold as possible.

Erik

[Shaun C]

Thanks Erik:

If I choose to run with the standard filter (prefer to sacrific hp at this stage above extra work/money as I'm not at the stage yet where I can work on the motor myself) what do you think of the following:
Remove the light, and fit with mesh with fair size holes will should improve general airflow to the filter regardless, but do I,
a) Fit large piping/tube to get airlflow directly from light to the airfilter or
b) Leave airfilter to gather air as originally designed with hopefully the extra air source from the "removed headlight" generally providing cooler air in the engine bay

I also read elsewhere in this thread, something about drilling more holes into the centre tube of the standard air box. What do you think of that, bearing in mind at this stage I'd prefer to run with the standard box in place.

Has anyone seen/know of the set-up in a TI Super? From the pics I've seen, the inside headlights were removed - what was the set-up there?

[genericwood]

No matter what else you do, make sure you have a direct supply of cold air to the air box. I'm not sure about the TI Super, but most Alfas have had a hose providing direct cold air from the front of the car. You really aren't trying to achieve a "ram" effect, as any pressurization will be minimal. But you will lower the temperature dramatically.

I'm not sure about the additional holes in the air box since I don't run a stock one. But I have also heard that drilling holes in the inner tube is helpful when using the stock box.

Erik

[Shaun C]

Thanks Erik

Your advice is appreciated.

Erik, if you have pictures of the set up you currently run in your race car, could you perhaps post these? I'm fairly new to all this so I need to put a picture to the terminology used around here. I think I know what Ram tubes/pipes are, I'm assuming "horns" are the same thing. I think I've also seen what I'd think to be Ram tubes fitted with air filters (1 filter for each carb), but I'm assuming you run with just the Ram tubes. What do you then do with your oil breather? Do you still run an air intake hose to/near the ram tubes? What I have also seen is that some guys just take the airbox off and race like that (replacing their box for the drive home as most of these are road legal track cars) - how do ram tubes improve on this? I'm assuming it has something to do with pressurisation.

If anyone out there has any experience with the drilling of holes in the inner tube of the airbox let me know (i.e. how many extra holes is enough/too many)

So many questions, and I apologise if they are a little elementary, but I guess we all have to start learning somewhere.

Thanks for all the help.

[Blu Hollandese]

Hi guys,

one of my fav' threads this one...

I will also install an open airfilter ontop of my Solex carb (see avatar), not for performance, but for good looks, and sweet sound...(I'll lose some weight though.. )

I can understand that making shure that cold air gets to the air intake on the carb make's sense when you are going for max HP, but what is the effect of not providing a cold air supply, shurely not a drop in performance I hope?

Also, does it really make sense to provide cold air to the carb, when you know that the intake manifold holds very hot cooling water, especially to heat up the mixture before it goes into the cylinder? If I recall correctly, this helps keep the fuel atomized while underway...

Also, on many original intake systems, a special shutter in the intake pipe can be set on Winter/summer...where winter make's shure your intake systems take's in pre-heated air coming from the engine...

So for sheer drivebility, I don't think hot/cold air doesn't make much difference, correct?

[Nomad]

I wanted to keep the stock look to my car so I (as Papjam suggests) simply drilled more holes in the intake tube and amde all them twice the size as the original holes...result...much better breathability, nice sound, and it still has the stock look...not to mention I have the stock option of switching from cold scoop air to warmer engine bay air with the little lever on the front of the airbox

[Gary Williams]

<I can understand that making shure that cold air gets to the air intake on the carb make's sense when you are going for max HP, but what is the effect of not providing a cold air supply, shurely not a drop in performance I hope?>

To know the answer to that question all you have to do is drive your car on a hot day and a cold day and compare how it feels. Early morning and mid-day where I live (California) is good for that sort of comparison.

With cold, moist air the engine is much more lively. That's why a cold air box is better than what I have. At least what I did looks nice and sounds wonderful.

[genericwood]

On the Giulietta, Alfa didn't bother to build a cold air box. The downdraft Solex draws air from the top rear of the engine compartment. But of course the Veloce version with side draft Webers did have cold air routed from the grill area. By the time the 101 Giulia came out, even the Normale had a cold air box.

To Blu Hollandese, I don't think you will find much of a difference on a street car. But if you plan on putting your car on the track, I would look for a way to get cold air to the carb.

Erik

[Sprintn]

Gary,
Your engine bay is VERY nice looking!
Cheers
Sprintn