Alfa Pages

[Eddie W]

HI all
Here in NZ a number of the racing guys swear that the standard air filter configeration gives better results than a seperate filter setup. Naturally they are using performance elements if at all. Allowing for cold air supply to iether system, is the difference in the extra inlet tract length provided by the curved elbows from carb to filter box? Would a twin pod setup,placed to collect cold air on iether side of the rad,and a properly designed plenum over each carb not be an improvement? Does anyone have experience in this area? I will be interested in any info.
Regards Eddie

[Serpent33]

[alfa-alex]

when i bought my 33 1.7 16V (fuel injection model) it already had a pipercross performance air filter instead of the standard air box. on cold mornings it used to run better, i attributed this to the filter sucking in warm air from the engine bay.
to combat this i ran a piece of ducting from the hole in the bumper (next to the fog light) to the hole in the engine bay where the standard air box takes its cold air from.......makes a big difference but next i want to place the air filter just behind the bumper next to the fog light...anyone tried this yet?!?! would be interested to hear your views

[paddy granger]

We have a K&N panel filter in our S3. Does the open filter system with ram pipe really provide that much more cool air than the standard layout with K&N panel filter? The panel filter is pretty big anyway, and the standard inlet tube surely won't be any smaller in diameter than a custom ram pipe.

[Serpent33]

[James Granger]

Paddy's my bro and as he mentioned we have the standard setup with K&N filtercharger. It runs great, but the inlet is obviously hidden behind the front bumper, which obstructs the airflow greatly. Basically the rear side of the front bumper is like a vacuum, so I'm convinced that there is a slight power gain to be made with another setup.

I'm tempted to run a long tube from the filter box down to the small grille near the RHS foglight - basically a ram pipe. This would mean a totally free air supply. The drawbacks are that the lack of anything in front of the inlet (other than that small grille), would result in the filter getting potentially very dirty. At the moment the bumper protects flies, spray, and other stuff from being sucked up into the filter housing. Therefore if I do go down this route, I'd probably fit very fine gauze over the inlet hole, although even this would not stop spray from being sucked in. A way round this may be to step the tube slightly.

Any ideas to build on this - it would be interesting to experiment?

[Eddie W]

Being a cheapskate and an idiot I adapted a K&N from a beemer to our 1700. In the process of adapting the filterbox I added a second inlet on the r/h side with a hose to pick up more cool air from down beside the rad. Don't know if it makes a difference but the growl as it hits 4000 is something else. I work on the theory that the less restriction, then the less work the engine has to do as a suction pump.
Regards Eddie
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A LITTLE FURTHER A LITTLE FASTER

[Matt Stolton]

The original s1/2 airbox is good, and does feature trumpets, even if they are bent through 90 degrees.

A large improvement can be had by flowing the aluminium castings, and radiusing the mouth of the trumpets. Further more the airbox itself can be 'flowed' to minimise its effect on air entering the trumpets.

Lloyd at clovertech did a mod to a series 2, and put a slightly smaller rad in, with a larger fan. This increased the gap between the body work and the rad, to allow a trumpet to feed cold air directly into the filter. This worked very well, however the car is now up for a 16V conversion, as it appears to have run lean and holed a piston.

I would recomend anyone doing major mods to airflow to make sure the increased airflow is matched by your carbs ability to deliver petrol. It is likely to require rejetting, even if only a little, to stop the mixture leaning off at high rpm.
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Regards

Matt

Ex Alfa 33 'GTA' (P4 with Knobs On)
Now cruising in a 166 3.2 Ti!!

[87SprintQF]

[Matt Stolton]

The bottom end, as long as it is not inherently noisy or known to be worn, is generally good for the few more horses that could be achieved through messing around with the air box.

The trumpets are very 'roughly' casted, and can be radically improved from simple grinding. You do not want mirror smooth, more so you can see the fine scratches left by 400-800 grit paper. Theory is that metal to air friction value is higher than air to air, as rough metal will 'hold' a layer of air static over it. Smooth metal looses it grip on its air cushion, and you have friction between air and metal.

I would only radius the first 1-2 cm of the trumpet, and try and keep the rest evenly tubelike. Once the air is in from the trumpet, it will gain speed in a constant pressure behind it. Yoo may even want it to taper gently to a slightly smaller end diameter to exactly match the top of your carb. This will assist gas speed a little further, assisting torque.

If you read Les the Gringo's site, he has many tips and diagrams that explain the theory better than I can repeat them, but he also mentions how cheap, in terms of BHP per pound, rolling road tuning is. If you go down the improved airbox route, it is pointless getting more air into your carb, if there isn't fuel to match. Mapping for injected cars, and rejetting for carbs, on a rolling road has got to be the way forward.
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Regards

Matt

Ex Alfa 33 'GTA' (P4 with Knobs On)
Now cruising in a 166 3.2 Ti!!

[tvatavuk]

[RFlower]

[paddy granger]