home made true cold air intake

[jhandy]

Ok, first off I know that the car came with a cold air intake. But it was restrictive.
I then changed that out for a EVO filter system. After getting super high air intake temps/low fuel ecomomy/poor power/ high water temp... I decieded to make my own SEALED cold air intake.

KN Apollo filter 86$
Spectere coupler 8$
Lexan 5$
Epoxy 2$
Spectere 3" wall mount.
Cut off MAF mounting tube from the OEM box free$
MAF Air flow Straightener-20$
http://www.treadstoneperformance.com/product.phtmlp=2096&prodname=HoneyComb+MAF+Mass+Air+Meter+Airflow+Stra ightener

So what I did......There is a plastic tube that connects the engine bay with the fender. The plastic tube has three holes in it, this is what the OEM box bolted on to.
So remove the box, cut a sheet of lexan to cover the opening. Place a 3" port into the center of the Lexan. The KN filter came with a air trumpet that I epoxyed to the fender side of the 3" port. The epoxed the Lexan onto the engine bay side of the plastic pipeing. Put the pipe back in and bolted it to the body, sealing the intake system.
Then cut off the MAF tube from the OEM box (by the way it is 3" and my EVO MAF replacement tube was 2.7") Epoxyed the honey comb air straightener before the MAF. Then bolted up the Apollo sealed Air intake canister.

The car pulls better, I can tell it is happier not sucking in super heated air.

The only thing I would do different is drill a drain hole for water into the plastic pipe. I will do that this weekend.
Here are some pictures.

[jhandy]

more pictures

[j.fro]

Very nice work. I may engage in a bit of intellectual piracy

[The Radium King]

me too. insite did something similar in his 3.4 build, but with a bmc carbon dynamic airbox (85mm instead of 70mm, so no restriction on the 3" oem maf housing).

[sparker]

Good job - glad it worked out as per your plans!

PM me your paypal address and what I owe you for the MAF honeycomb, keen to install that in my carbon intake.

Cheers,
Sam

[jaykay]

ahhh heat shield! Was thinking the same thing and of course it has been done on here already

[Kroggers]

Nice, I have been considering the same thing.

Can I ask, how do you get the plastic tube that connects the engine bay with the fender out - can it be done with the engine still in the car?

[Mrmaddbrad]

Why do people feel the necessity to modify their cars like this? That air box was engineered for performance. I don't see how a $200 "cold air intake" will make a performance difference over the engineers that were payed hundreds of thousands of dollars to design a great intake..

[WhipE350]

Originally Posted by Mrmaddbrad

Why do people feel the necessity to modify their cars like this? That air box was engineered for performance. I don't see how a $200 "cold air intake" will make a performance difference over the engineers that were payed hundreds of thousands of dollars to design a great intake..

Not to start an argument, I tend to avoid them on the forum, however I have to respectfully disagree with part of your statement. I know many engineers that aren't worth their hundreds of thousands and many that are, either way they are often on a clock and time lines to get projects done and out the door. Rockets blow up and planes crash. How is it that these same engineers don't get it right the first time and seem to find more hp each year from the same engine. Even the new Boxster has reduced engine size and boosted hp. I'm not implying his mods are any better but to answer your first question I assume because he is creative and it is fun. If I wanted a Boxster to not tinker with I would have bought a 2011 and not a 2000. Worst that can happen is it throws a cell and he puts the old system back in.

[JFP in PA]

Actually, the worst thing that can, and usually does happen, is that the "trick" aftermarket system makes less power on the dyno. I do not know how many aftermarket "improved cold air" systems (which is a misnomer as the factory system is a cold air set up to begin with) people have looked at and properly tested before and after on a dyno, only to find they added nothing, or even took power away............. I think a truely more interesting experiment would be to determine how much time and money have been wasted on this.

[Topless]

Originally Posted by JFP in PA

Actually, the worst thing that can, and usually does happen, is that the "trick" aftermarket system makes less power on the dyno. I do not know how many aftermarket "improved cold air" systems (which is a misnomer as the factory system is a cold air set up to begin with) people have looked at and properly tested before and after on a dyno, only to find they added nothing, or even took power away............. I think a truely more interesting experiment would be to determine how much time and money have been wasted on this.

Or better yet, the "tuner" drops a screw inside the new intake.... where did that little thing go... no matter. He fires up the motor with his new high tech intake mod, the motor ingests the screw, it gets jammed in cyl #2 intake valve, piston goes TDC, valves bend and pistons break. True story if you substitute "Honda" for "Porsche".

YMMV

[jacabean]

i think a larger throttle body and tee would be a better project to do.

[JFP in PA]

You need to be careful there as well, as you increase the TB size, you significantly impact not only fuel/air mass, you also change its velocity is such a manner that engine response off part throttle acceleration can become sloppy because of the sudden mixture velocity drop in the intake runners.

These systems need to be carefully matched on the flow bench to maximize response and power out put; otherwise the end result can be questionable to drive. Anyone that has ever installed too big a carburetor on an engine knows exactly what I am talking about, high RPM power gains, lousy drivability............ Bigger ain’t always better.

[Topless]

Originally Posted by jacabean

i think a larger throttle body and tee would be a better project to do.

As long as you are attaching that larger TB to a shiny 3.6L motor you got a winner.

[jaykay]

Actually I think jhandy and sparker's intake arrangements are quite good and show some nice design sense.


Gentlemen some points to consider:

-Some are into design development and testing (hard to do accurately without lots of cash) and some are not. Perhaps a hobby to some? To each his own.

-To some an extra 10hp is worth looking for (track; racing...); optimization etc. Don't worry about it if you are just cruising about

-There seems to be some evidence to suggest that the 3.2L has been detuned. This would likely include intake flow area/lose restrictions. Of course you have to correct them all (and no warm air) in unisom in order to have some hope of good results.

-Of course big air box intake systems are likely the most efficient and the way to go

..... but I wouldn't be too quick to discard jhandy and sparker's intake arrangements and lump them in with crappy hot "cold" air intakes. They are actually very good conceptually; have a closer look and understand. They are sealed cold air intakes that could outflow the stock air box. One would have to test to know. Their arrangements are not unlike (perhaps better as they offer better filter protection) the set up now used on some racing Caymans.

-Have a look inside the stock airbox you will find a small snorkle in there. What is its flow area?

-Is the stock TB @ 68mm dia (less than three inches) an intake choke point?

-Is the the intake runner velocity ultimately metered at a 3.5" dia. for the left and right plenums and is this flow dia arrangement better served by a larger TB?

-What are the experiences of IPD plenum users with larger TBs?

[Ghostrider 310]

I agree with Jaykay, there are also the factors in manufacturing such as cost containment and especially German TUV noise standards. I think TUV is the reason the intake sounds are so muffled. Some 986 information seems contradictory, for example, there are numerous people saying reducing the back pressure with headers would reduce the HP as well. Theory was based on a given needed amount of BP for the flat six to run correctly. In my experience the headers made a difference, I didn't measure it but I did hear and feel it. I've also noticed when reading about modded Porsche cars in excellence, exhaust is frequently changed in diameter or configuration for more power.

[Gelbster]

The best aspect of this diy mod is deleting the huge, obstructing stock airbox. With the old airbox removed (but useful parts salvaged & reused) ,access to 4,5,6 from above is hugely improved.
One small detail The MAF tube is 3" at the intake end and 3-1/4" where it connects to the corrugated hose. So think carefully about that oddball 3-1/4" size(82mm+/-) before you just buy a 3" Spectre 9405 MAF tube.
I did buy the 9405 but made a rubber sleeve/adapter for one end.
The other idea is to use the cavity between the inner and outer fender as a cool-air plenum and air filter box. There are lots of creative ways of using UNI air filter foam in that space. And it should be a cooler location than the stock airbox which sits right above the Bank 2 header.
I found it very useful to remove the hinged ,metal body panel .Not just the engine cover,not just service mode, remove the entire rear cover that abuts the truck lid. It is the huge arc shaped 'lid' that fits forward of the trunk lid.It is just some pins and E clips.That makes it sooomuch easier.
This link may help:
intake install step by step with pics and video
The obvious problem in the diy is the hot,dirty location of the new air filter and the lack of detail on how to extract the airbox(disection is fastest!).The location issue for the air filter is addressed by the suggestions at the beginning of this post.

[Xpit77]

When I bought mine it had a diy CAI. Basically the PO removed the box cut the tube and stuck a KN cone filter on it. I replaced the cone with a barrel type KN and installed an Injen sheild. It`s not pretty but it sounds good and doesn`t throw codes.

[particlewave]

That's a hot air intake.

You should try to go back to stock. Your car will be happier.

[bwdz]

Originally Posted by particlewave

That's a hot air intake.

You should try to go back to stock. Your car will be happier.

I have to say that I agree. It looks like you located it inside the engine bay right above the hot exhaust manifold. How is that supposed to draw in cold air?