FI intake piping upgrade?

[madspeed]

Haven't seen any recommendations as to intake piping/cold air intake or the like to open up the breathing a bit. Does anything exist that actually works for the fuel injected Spiders?

[TimpanogosSlim]

The plastic plumbing between the airbox and the throttle body could conceivably be improved. I think i may have even seen something in silicone and mandrel-bent stainless.

The gains would be small, I think.

The panel filter in the FI airbox is actually kinda reasonable. The exact same filter is in my '84 jetta turbo diesel, and several late 80's jeeps with straight six engines.

Just use a quality filter, like Wix, Mann, etc.

You might add some plumbing to feed it air more directly from behind the grille, perhaps.

The vane air meter is a source of some restriction, but there is no replacing it with a MAF without some considerable hackery.

[RRoller123]

I have seen/heard about insulating the air tube since it runs above the exhaust, but I doubt that this makes much difference.

[bradartigue]

The capacity (that's not technically the correct way to describe it, but adequate) of the stock air hose exceeds the amount of air you could put into it with the stock AFM. If you want to force more air into the system you'll need a turbo.

[v6spider]

Spectre makes a universal chrome plated plastic system that is featured in the performance sections of most auto parts stores.. However it would probably only upgrade the look.. Not the performance. But you could possibly reroute the air intake with the universal pieces that they feature and move the air intake end in a place where the air is coolest..

Just a thought. ..
Rob

[TimpanogosSlim]

Spectre makes a universal chrome plated plastic system that is featured in the performance sections of most auto parts stores.. However it would probably only upgrade the look.. Not the performance. But you could possibly reroute the air intake with the universal pieces that they feature and move the air intake end in a place where the air is coolest..

Just a thought. ..
Rob

no need for that - the hardware store has all the black DWV pipe fittings you could possibly want. Since it's crapper pipe all the fittings have a smooth transition on the inside.

[ElGrande]

Hello,

I added two holes (about 50mm) in the front of the airbox , the next step is to connect them with a tube to get fresh-cold air in the airbox.

The next step could be a 3bar (43psi) fuel pressure regulator...

Norbert

[RRoller123]

I drilled a bunch of holes in the airbox and it seems to have made a small but noticeable difference. But it also makes the engine sound better, so for that alone it is worth it!

Since this pic I added a couple at the front of the box too. Let us know how you duct the cold air in, eh?

[v6spider]

Spectre makes a universal chrome plated plastic system that is featured in the performance sections of most auto parts stores.. However it would probably only upgrade the look.. Not the performance. But you could possibly reroute the air intake with the universal pieces that they feature and move the air intake end in a place where the air is coolest..

Just a thought. ..
Rob

no need for that - the hardware store has all the black DWV pipe fittings you could possibly want. Since it's crapper pipe all the fittings have a smooth transition on the inside.

On the cheap that would be functional.. But the spectre universal stuff is fairly inexpressive and looks ten times better.. And is designed to flow...

Rob

[toplessexpat]

Dumb Q - isn't the stock setup limited by the dimension of the downward facing snorkel? Is the dimensions of that really the maximum that the engine can ingest?

If so - then the K&N, Spectre and the like "upgrades" really make it *sound* louder/more raw/better...?

A

[ElGrande]

At the moment I'm still looking for a nice aluminum tube which is to bring the cold air directly to the airbox...

[davery]

Dumb Q - isn't the stock setup limited by the dimension of the downward facing snorkel? Is the dimensions of that really the maximum that the engine can ingest?

If so - then the K&N, Spectre and the like "upgrades" really make it *sound* louder/more raw/better...?

A

That's a good question. It reminds me of the conversations a few weeks ago about the exhaust system. The thought there was a smaller section of the exhaust created a Venturi effect, which actually increases the speed of the exhaust gases. Maybe the same thing occurs on the intake also.

[RRoller123]

If you assume that air at these pressures and speeds is not a compressible gas (reasonable), then the flow speed would increase at the snorkel, due to diameter decrease, then slow again in the air box. Net effect is that the snorkel is a flow resistor, similar to the left side of the coolant "T".

[TimpanogosSlim]

Spectre makes a universal chrome plated plastic system that is featured in the performance sections of most auto parts stores.. However it would probably only upgrade the look.. Not the performance. But you could possibly reroute the air intake with the universal pieces that they feature and move the air intake end in a place where the air is coolest..

Just a thought. ..
Rob

no need for that - the hardware store has all the black DWV pipe fittings you could possibly want. Since it's crapper pipe all the fittings have a smooth transition on the inside.

On the cheap that would be functional.. But the spectre universal stuff is fairly inexpressive and looks ten times better.. And is designed to flow...

Rob

You think crapper pipe isn't designed to flow? It's a cornerstone of civilization that it flows. The transitions and bends in modern household DWV plumbing are far smoother than most factory intakes and exhausts.

Anyway if you can get an inlet closer to the front of the car, for a ram intake, that may help a bit.

I still say that the air meter is the choke point. And since the air filter is integral to the meter housing (exactly like the 1992 vw cabriolet i have been painfully burning so much time on lately, fwiw), I don't see an easy or cheap way around it.

There are MAF conversions for porsche engines with a similar bosch air meter, but i suspect that most of those porsche engines are bigger than 2L, so they wouldn't have a direct application on a spider.

[TimpanogosSlim]

I drilled a bunch of holes in the airbox and it seems to have made a small but noticeable difference. But it also makes the engine sound better, so for that alone it is worth it!

Since this pic I added a couple at the front of the box too. Let us know how you duct the cold air in, eh?

I've seen several tuner builds of large turbo engines where the ultimate air intake configuration was a swiss cheesed factory panel-filter airbox.

Because the dyno plots proved it made more power than a sexier looking filter.