OK-OK Intake Heat; Air Box versus Cone-Filter

junglejustice · #1 (**permalink**) 04-15-2004, 01:46 PM

Well, I didn't want to "bleed" all over Eminence's questions on intake vent-plumbing, but this subject came up again, (sorry April) so I do want to post a new thread and pose some thoughts as well a quest for some real-world testing...

This whole cone-shaped air filter charger (K&N and others), versus the standard air box (hot air vs. cold air induction) subject, has had me going for a good bit now... We can all agree that cool air is better, so this obvious point aside:

Maybe at a complete standstill, no fan blowing, right at the moment when you spike that throttle, there is a small difference in air temp going down, but once you’re rolling? Once this car is moving, there is so much air (force) flowing past that damn engine (and filter), there "can't" be any (much) residual (ADDITIONAL) heat dispersing vertically (and forward) 12, 14 inches adversely affecting the volumetric air densities by anything measurable? Please read on before knee-jerking

I am sorry, but I don't buy it and I am about to tape a thermometer of some kind, (anal or rectal?) - first to the INSIDE of a standard air box application), then to the outside of it, then to the inside of the cone-filter and again to the outside of it - (assuming that this part of my highly technical research should at least produce matching numbers.) -all to prove that the differences are negligible!

Yes, cool-air plumbing vis-à-vis an air-scoop of sorts is going to benefit the application greatly, but it will do so FOR BOTH applications!

In any case, my standard setup had this huge (18 to 24 cubic inch gap ahead of the box where it would be sucking in all manner of heat under the pro-box theory.

Naturally I will be conducting my scientific research under idle and driving conditions.

As a side-note: Ask anyone in Houston, Texas for example. 1 hour in summer traffic and that air box of yours is so hot to the touch; you can't go near it to change the filter that's inside it. Seriously, the clamps burn the cr*p out of your hands – it has to be 150 degrees in there… (Since the air outside is already 100 at that point…

Let’s find out, shall we?

verdegrrl · #2 (**permalink**) 04-15-2004, 02:00 PM

exactly how much is lost by using a non-ducted cone.

When I worked at the VW/Audi tuner, we actually did back to back dyno (MAHA with 98kph full range fans pulling air from a box on the roof of the building) tests of high quality cone vs airbox on an A4 1.8t. Of course the Audi has a full belly pan to channel air flow, and the Milano is nowhere that sophsiticated. The loss on the Audi is between 4 and 6hp, depending on ambient air temps. Just sheilding the cone gained back between 2 and 3hp, depending on outside temps. We also played with cone inside airbox and lost around 2hp using that set-up. As for fan wash, it's not really so much an issue on the newer cars, as they have pusher fans, not the puller types inside the engine bay.

I can really feel the difference in throttle response when I install the airbox. It's the old intake velocity, tube diameter, intake length equals torque issue. Of course it tends to make the car more breathless at higher rpms. Nizam's 75 gained a lot of low end power when he installed the long 164 style intake runners.

I still use the cone because I just love the sound around town. Almost sounds like I've got a blower up front

That and the Supersprint makes it an aural treat

JoeCab · #3 (**permalink**) 04-15-2004, 02:42 PM

JungleJustice,

Someone did just the test you are contemplating when comparing the stock Spica air box and the Shankle Quadraflow set up on Spider. They used a thermocouple and drove around under various conditions.

The difference in temperature of the air in the airbox was startling - it was much cooler, even at highway cruise.

Joe

ar1750gtv · #4 (**permalink**) 04-15-2004, 03:36 PM

Joe,

The stock SPICA air box was cooler?

JoeCab · #5 (**permalink**) 04-15-2004, 04:17 PM

Yes, the stock Spica airbox was cooler under all circumstances than the Shankle Quadraflow with dual filter boxes and no air box.

Garrett, were you still there at the dyno day when Steve Hartung's '88 Spider GAINED 4 rwhp when he removed the cone filter and put back on the stock airbox?

BigSwede · #6 (**permalink**) 04-16-2004, 12:27 AM

Did he just switch the filter for the airbox or did he actually adjust the carbs/spica?
Just slapping on another filter without adjusting would hardly be the best way IMHO.

I changed the airbox for a cone on the 75 TS I had a couple of years back, made a serious heat shield and opened up the sheet metal in front of the filter (next to the radiator behind the grille) and I felt a bit more power around 5000 Rpms.
Naturally all this is very un-scientific, the extra peak was there but for all I know the whole power curve may have been moved down and just added a spike around 5K.

Loooved the sound though, everybody else too.

**Craig** · #7 (**permalink**) 04-16-2004, 02:27 AM

Quote:

Originally Posted by BigSwede

I changed the airbox for a cone on the 75 TS I had a couple of years back, made a serious heat shield and opened up the sheet metal in front of the filter (next to the radiator behind the grille) and I felt a bit more power around 5000 Rpms.
Naturally all this is very un-scientific, the extra peak was there but for all I know the whole power curve may have been moved down and just added a spike around 5K.

Loooved the sound though, everybody else too.

BigSwede · #8 (**permalink**) 04-16-2004, 02:46 AM

Well, nobody really says that the original paper filter is bad or are they?

It's the original installation on the TS which clearly is there for sound restriction purposes, the looong pipe with small diameter that is attached to the airbox and if you look at a used filter you can actually see that the whole filter surface isn't used, only a small part where the intake to the box is located is really dirty. You changed this when you built a RAM-pipe.

See the other thread for my thought on cone-style filters...

BTW. Have you felt the weight of that filter box??

**Craig** · #9 (**permalink**) 04-16-2004, 02:59 AM

Ok, we have basic agreement except I prefer the quiet.

Yes the standard air box is heavy, helps to balance out the battery

Craig
1988 75 TS
Melbourne Australia

eminence · #10 (**permalink**) 04-16-2004, 04:39 AM

Craig,

Where did you get the bits to build that "RAM" section? By that I mean where did you source that white ?plastic? item to go through the bulkhead?

Photos attached for clarity.

Thanks,
Simon

BigSwede · #11 (**permalink**) 04-16-2004, 06:58 AM

Looks like a speaker bass-reflex tube to me, commanly available and are usually the perfect shape for the job. Cheap too, and light.

eminence · #12 (**permalink**) 04-16-2004, 07:20 AM

Quote:

Originally Posted by BigSwede

Looks like a speaker bass-reflex tube to me, commanly available and are usually the perfect shape for the job. Cheap too, and light.

ar1750gtv · #13 (**permalink**) 04-16-2004, 08:43 AM

Quote:

Originally Posted by JoeCab

Yes, the stock Spica airbox was cooler under all circumstances than the Shankle Quadraflow with dual filter boxes and no air box.

Garrett, were you still there at the dyno day when Steve Hartung's '88 Spider GAINED 4 rwhp when he removed the cone filter and put back on the stock airbox?

**Bill** · #14 (**permalink**) 04-16-2004, 12:51 PM

Completely non-technical, but I had the chance to try a set of Quadraflow filters in place of the stock SPICA box for about a week last month as I was thinking about the switch, despite what Pat said in his book. WRONG!

What a difference!
It felt like she lost power in both the middle and upper RPM ranges, even though the sound was wonderful. Just did not seem to spool up as quickly either. And I lost fuel economy.

Again, all very subjective and just my opinion. I passed on the Quads., and am in the process of cleaning-up, painting, and taking care of my original SPICA canister.

What a marvel of engineering!