I've been considering a cool air intake set-up for my S3 4.2L. It's not that she needs any more "go" really, but an engine that breathes better should logically produce some benefit.

I know there are mixed views about the worth of air intake mods in general, and I understand that air being sucked through a cone filter may not be all that "cool", even with heat shields in place, but FWIW I fitted one to my (now gone) X300 3.2L and it definitely made for a livelier engine (anyway, my brain thought it did, so therefore it did!).

Does anyone have any experience on cool air intakes specifically for the 4.2L? Also, if you are running one, any pics of your set-up would be much appreciated!

 

The first step is measuring the temperature of the air at the inlet with the present intake set up. You might find that while it's quite high while sitting idling on a hot day, it will soon drop as soon as the car is in motion. You might actually find that the temp is only a few degrees above ambient, making any sort of cold air intake system a waste of effort.

I measured the effectiveness of the factory cold air intake on my old Corvette and found that it gained me a neck snapping 0.47 HP increase.

 

I've done this on two cars, Tony, and I liked the result. But that's just me, purely subjective. Numbers be hanged!
(';')

 

Thanks Mikey. Although we refer to these things as "cold" air intake I am aware the drawn air won't be that cold under the bonnet. But they also have the effect of being a more "direct" air intake i.e. less constricted than the stock narrow pipe. Logically, considering more is better when it comes to oxygen, I would see the cone positioned as far forward as possible, on the widest possible pipe.

 

Thanks for your thoughts Elinor. It was also my finding on the last car. If your brain is registering a positive result....then the mission is a success!

 

And I've just noticed - I'm now a Veteran!! (do we get to wear a medal?? )

 

Again, the stock setups aren't really as restrictive as we might think. The cone filters (all the rage with the Honda f*rt-pipe set) might just be more restrictive than a stock filter.

If you're thinking ram air effect by pointing it forwards, that really has no effect below about 100MPH.

 

Just to be a pendant, the jag already has a cold air intake system. That's what the snout on the air filter enclosure is. Adding an exposed open cone under the hood is a hot air mod. It may sound better but it will produce higher intake charge temps than stock.

There's also no restriction in the default system until you reach ludicrous speed and rpm. If you want to improve the flow ( which is of questionable benefit imho ) then remove the snoot and use an extension the diameter of the air filter box opening and run it straight to the firewall opening. Add a K&N in place of the original filter if you like.

There's no room to pipe through the firewall at that diameter and the inboard light cups impinge on the opening so you also can't pipe to the opening in front of the firewall. I did add an extension from a right angle elbow just inside the grill opening that dumps out at the end of the radiator just short of the light cup. This was just to provide a path for cool air to dump at the snout. No high speed pressure on the air filter or anything like that.

The real added benefit of a K&N at the opening of the AFM is auditory. And, as you already said, if it makes you feel faster it works!

 

Tony,
I copied this from my thread, did it last week. Maybe helpful.
I believe it makes a difference. Better sucking cold air from above the radiator than sucking heated air from behind it.
It is also about twice the size opening to suck air.

 

Thanks Clarke, just what I was visualizing, not sure how I missed this!

 

Tony, the cold air intake was a simple task. using a piece of 2" flex pipe allows fitment inside the intake tube above radiator panel and the cut the trumpet intake at air filter box to suit sizing. allow a small amount of slack to counteract engine movement. very simple task. has to give more positive benefits than a intake system drawing warm stale air.

 

It was tagged onto the "Preparation for track day" thread, I didn't think it was worth a new thread. But now is in yours to be found.

 

But the numbers don't lie. Somebody please measure the intake vs. ambient temps on a stock system, then measure the temps at the planned intake location, all under the same driving conditions.

Remember, it takes an 11*F drop in intake temp to realize a 1% gain in power. Most drivers don't notice a 5% change in power.

In my tests with the Corvette, I achieved a 1*F drop in temp comparing the 'cold' air intake vs. 'hot' engine air.

 

If ya had a V8 ya could do something like this:

Uses the hole for the OEM snorkel slightly enlarged. Perfect fit (after husband reamed it out a bit).
(';')

 

Its not noticeable powerwise, but more the cleaner idle and smoother take off.
When we used to visit the MIL in the colder part of Australia the cold air made the same difference. Always got home saying to my wife how much better the car felt when driving down south.

 

Yep, that pretty much sums up the gain I had in the X300. I don't delude myself that HP will actually increase! If I get even a slightly smoother idle, that alone will be enough to make it worthwhile.

 

there is a cars and coffee happening around my area soon, its at a performance place, and they are letting people do free dyno runs! its first come first served, with limited spots, if i get to be one of the spots i will make tuns with and without the shnoozle, to see if it makes a difference! I am running a k and n filter and i know that with the snout removed, it sounds more aggressive, but not really sure it makes much of a difference!, stay tuned...

http://flacarshows.com/events/event/...f-cars-coffee/

 

Tony:


I can claim to be a veteran on several levels. Medals, haven't seen any!!


All:


Cold vs warm intake air is a slightly complex topic. Adding in the sound complex makes it even more so. Add in K & N style vs various paper pleat filters adds some more complexity.


And, most will accept as fact that cool air is more dense than warm air.


Oh, a lot of folks, including factory engineers build in warm air to improve drivability.


So as to provoke thought, I'll stop there.


Carl

 

Of course it is, nobody disagrees there. 'How much cooler' is the topic.

True again, but that's only used during engine warm up.


Is there nobody that wants to measure some actual temperatures on their car?

 

Mikey:


One more. Warm air intake yields cleaner exhaust and better
gas mileage.


Carl