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· Former Moderator
4,081 Posts
Discussion Starter · #1 · (Edited)

Well I have part of my intake upgrade done but first a warning to the purist, a-retentive, brand name worshiping and style-over-substance individuals. Quit now and read something else. The curious may read on...

The Quest

After many logging sessions I am more convinced that IAT (Intake Air Temperatures) are a very important factor on our cars under real world conditions due to knock and subsequent pulled timing. After being lured by the siren of larger, smoother intake tubes and filters I noticed that unless the weather was cool the car lost enough power that even SOTP (Seat Of The Pants) sensors could detect it. After recieving my HP Tuners and doing much logging with various adapations of my stock box I found that the stock air inlet locations did not do the job. I had the large hole in my fender that I put in last year and the Aussie two hole mod. If I had the louvers on the radiator cover on the driver's side covered I actually lowered my IATs by pulling more from the cut hole. This underlined my point that the commercial "C"AIs (I use the term "cold" loosely) were just pulling air from a bigger filter and smoother pipe which helped somewhat but pulled air from the same location as the stocker and I observed from around the "heat shields" through large gaps. There were several of us that experimented with pulling air from other locations, the most promising being the hole below the stock box. The Hardcore intake was an evolution of those same ideas and I for one am a big fan of it. I believe that it was done before but he made it easy with specific intructions and a parts list. An obvious evolution of that setup was better heat shielding of the IAT and intake pipe. I've been using a thin foam tape on my JHP MAF pipe and IAT sensor while pulling air from the "Big ole hole" in the fender. The next logical step was to wed the two ideas and after looking for it I found the Armaflex tube I could use.
In the GTO owner's quest for cooler air first was the big filter and improved tube in the engine bay, then the shielded big filter, then the hole in the fender, the relocation of the big filter thru that hole and now the Soft Surface Intake or what I will refer to hereafter as the "SS Intake".

SS Intake

The Armaflex tubing came to mind quite a while ago but I've been too busy with my startup business to pursue it. Last week I walked into one of my supplier's places and happened to think to ask if they had any large diameter Amraflex. It's used to insulate refrigeration tubing and such. He said they didn't have any large diameter but I went back and looked and there was one 6' piece of 4" I.D. tubing with a 1/2" thick sidewall.

I thought that I would like an attachment point for the tubing and something to seal and finish the hole. I was already using 3" PVC tubing in some parts so I went looking for a pipe flange. Turns out they make all kinds of them for fastening toilets down! I picked up mine from Menards as well as 3" pipe, one 45* street ell and one 45* regular ell. I got my filter from Pep Boys. It is a Spectre 9738 9" cone with universal adapters. It fit nicely on the flange with the adapters removed. I had to cut away a part of the flange to fit by the wheel hump and headlight bulge.

I braced a board under the area so I could use a 4" hole saw to make the hole. The wires for the headlight and turn signal were rerouted so it could be pulled over below the hole to make more room for the filter. Foam tape was put down to seal the area and make a seal for below the flange. The flange was then fitted into place and excess tape cut away.

The pieces of pipe and ells were test fitted and marked for glueing. I reused my JHP pipe and the flex coupling that came with it and after sealing the IAT hole I worked the Armaflex over the top of my previously taped pipe. I used wire ties to hold the foam on the throttle body end.

After glueing I drilled a 3/4" hole for the grommet that holds the IAT sensor. The hole was placed near the flange end.

It was tight getting the filter attached to the flange below but it worked out perfectly. The filter ends at the same level as the bottom of the front apron.

And here is the view from the top. It's not quite as pretty as it was before but I usually drive with the hood closed. :~) I don't think it really looks too bad at all. The joint is where the flex coupling is and is there so I could piece it together.

SS Intake

I've been logging good VEs (and IATS) so I know she's breathing pretty well. In case you haven't noticed by now I've been running speed density and have had my MAF sitting in the garage for some time. With all the hysteria with big filters and removing the stock panel I thought I'd point out that the MAF is a smaller diameter than the throttle body plus with all the screening and assorted pieces in the path of air flow I would be suprised if it has 2/3rds the effective area as the throttle. Anybody remember geometry from HS?
Stock TB 78 mm = 3.07"
area of a circle = pi x r2
78mm = 7.4 sq inches (minus a little for the throttle blade)

MAF = ~2.75" dia = 5.9 sq inches minus a HUGE amount of restriction from the screening and junk.

Part 2 is whenever I can get around to it but there's an idea I stole and my skid plate that has to be finished. stay tuned...

· Registered
700 Posts
I'm interested to hear more about this. Seems fairly logical and easy-to-make, and your geometry teacher would be proud. hehe
I have had several ideas like this, but lack the time to bring them to life. I'm glad to see there are other free-thinkers out there, trying to improve efficiency and sharing with the world. Thank you.
Good Luck with part 2.
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