[astroede]

Since joining the forum I have been intrigued by the airbox modification. I haven't tried it since I really don't want to look at the holes, honestly. But I would like to have the extra bit of horsepower and the sound. Someone in one of the MANY postings on this topic suggested that holes could be cut in the BOTTOM of the airbox instead of the front, perhaps as shown below (white poker chips in possible hole locations). This location would take advantage of the space between the radiator and the bottom of the box. My thought was this: cut the holes there, and leave the snorkel on to bring in cooler air to mix with the additional warmer air coming from underneath. The box still looks like new, but might you also get (some of) the extra horsepower and the sound? And what impact would the radiator have on it?



Has anybody tried this? Sorry if someone did and already posted the result; there were a LOT of threads related to the airbox mod that I searched through. Seems there is always interest in this topic!

Partial Post: Please Login or Register to read the full post.

[flash]

by removing the plastic barrier piece below the airbox you introduce a LOT of heat from the radiator and essentially preheat the intake. this is a VERY bad idea. half of what the airbox mod does is due to the air entering it being colder than before. the snorkel location is a very hot source. it is right in front of the 200 degree oil cooler. the airbox mod deletes the snorkel and allows the new air to be from the upper grill of the car, which is MUCH cooler.



with the SC kit i actually include a sheet metal barrier with heat barrier material attached to it. this results in a huge drop in intake temps, as the new airbox has an even more reduced entry of heat than the plastic barrier made.



so, in short, yes, it has been tested. i did it both with the airbox mod, and with the SC development.

Partial Post: Please Login or Register to read the full post.

[flash]

additional note - by removing the piece you also reduce the efficiency of the cooling system because you relieve the positive pressure in front of the radiator and reduce the negative pressure behind it. this is not unlike removing the belly pans. both are a very bad idea.

Partial Post: Please Login or Register to read the full post.

[astroede]

Flash, I understand your point about the temperature of the air by the radiator. But are you saying that the temperature of the air introduced through the snorkel in the normal configuration is warmer than the air in the engine compartment at the front of the airbox?

Partial Post: Please Login or Register to read the full post.

[flash]

yes



the air at the front of the airbox is nearly ambient when the car is moving. this is because it does not pass over nor is near any heat source.



the air at the snorkel location is generally about 30 degrees over ambient when moving, and considerably higher when at low speed or sitting still.



we found this sort of by accident when doing the chip shootout dyno testing.



sorry



there are plenty of both unmolested airboxes and drilled ones out there for sale now (lol - i think i know of at least 30 drilled ones that are no longer being used), so i wouldn't worry too much about maintaining anything

Partial Post: Please Login or Register to read the full post.

[astroede]

Thanks, this is very interesting. I would never have guessed the difference in temps at those intake locations. I'm definitely going to take a closer look. Being an engineer, I can't seem to stop thinking about how the airbox mod could be accomplished without being so darn...sorry...ugly. For instance, could a molded insert be designed that would include optimized openings (size and shape), which could be easily removed after the autocross without hauling around an airbox....hmmm.....

Partial Post: Please Login or Register to read the full post.

[flash]

by the way, there was a decent reasoning behind the OEM placement. it was twofold



1. germany has the strictest sound standards. placing it there made for the quietest intake.



2. the temperatures there are fairly stable. the oil cooler has a thermostat in it that maintains the oil at about 200 degrees. that makes emissions much easier to control, and makes the programming of the engine simpler.



that doesn't mean it isn't a great idea to change that up. it just means that there are things with which to contend when you do

as for making it more attractive, this seems to work pretty well:



   

Partial Post: Please Login or Register to read the full post.

[MB968]

[quote name='astroede' timestamp='1346901873' post='132221']

Thanks, this is very interesting. I would never have guessed the difference in temps at those intake locations. I'm definitely going to take a closer look. Being an engineer, I can't seem to stop thinking about how the airbox mod could be accomplished without being so darn...sorry...ugly. For instance, could a molded insert be designed that would include optimized openings (size and shape), which could be easily removed after the autocross without hauling around an airbox....hmmm.....

[/quote]



You could pickup the trim that the 92 has in that area. With it you don't see the front of the airbox

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

[quote name='MB968' timestamp='1346902847' post='132224']

You could pickup the trim that the 92 has in that area. With it you don't see the front of the airbox

[/quote]

Yes, very true, but I suspect those pieces aren't easy to find...

Partial Post: Please Login or Register to read the full post.

[flash]

lol - not too bad. there are a couple of them up for sale right now. i haven't decided to sell mine yet, but i might soon. it all depends on what i want ot keep around for spares for the white car.

Partial Post: Please Login or Register to read the full post.

[Gotter]

Are you talking about the shroud that has the "glove compartment" onthe right side by the coolant reservoir? If so, I would be willing to part with it. Now, what did I *do* with that thing.....?

Partial Post: Please Login or Register to read the full post.

[ds968]

So after 92 all 968s were circumcised, and now there is a demand for the foreshrouds to cover the otherwise unattractive front of the engine ?! Hmm, there must be a Porsche moil ( correct spelling ? ) somewhere with a bunch of those for sale, LOL

Partial Post: Please Login or Register to read the full post.

[mbardeen]

You can still buy them new, IIRC. Also, there's a post on another site where Jeff (the seer of all factory 968 options) mentions that most cars up to 94.5 came with the front cover. Something like 1800 of 2200 North American coupes came with them. I wonder where they all went?

Partial Post: Please Login or Register to read the full post.

[JWahlsten]

I have one in my 1993, but my 1994 didn't have it. I like it, and it makes a nice seal for the cool air coming in from the outside... Pete makes a pretty cool aluminum box that works much the same as well. Saw it on one of the cars he and Max put together.

Partial Post: Please Login or Register to read the full post.

[rxter]

[quote name='flash' timestamp='1346902058' post='132223']



as for making it more attractive, this seems to work pretty well:





[/quote]



Indeed. $4500 for the snazzy new airbox and cone filter. I hear it comes with a free supercharger though.

Partial Post: Please Login or Register to read the full post.

[judge]

I think that with a bit of imagination the holes in the airbox can be made to look reasonably functional, if not actually pretty, and they do make the exhaust note much more authoritative.



.    



Flash, I left the snorkel in place, as you can see. Should I remove it and/or blank off the hole to lower the temp. of the air going into the box?



BTW my Sept '93 cab supplied new to Australia does not, and never did, have the front cover. I suppose this was probably a result of the belief that it's always hot here.

Partial Post: Please Login or Register to read the full post.

[flash]

i'd remove it. you will get more air in, and it will be colder

Partial Post: Please Login or Register to read the full post.

[astroede]

Further to Judge's question, if you remove the snorkel, should you block the piece left in the bumper area or leave it open, given that the air coming in is significantly warmer than the nearly ambient air you are now pulling in the airbox holes? Would the airbox then be pulling in much warmer air from hot areas in the engine compartment for lack of a supply from the snorkel piece? Arrrrrgh...you know what I mean...what setup will get you the coldest air going into the airbox?

Partial Post: Please Login or Register to read the full post.

[flash]

lol - the positive pressure from the grill overcomes anything from the other area.

Partial Post: Please Login or Register to read the full post.

[bombfactory]

I'm thinking the throttle-body heater-feature would negate any air temp advantage of the airbox mod. What do I use to do the by-pass - anyone got a pic?

Partial Post: Please Login or Register to read the full post.