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The G.F.I. Stage 3

122331 Views 387 Replies 73 Participants Last post by  Danny
So as I'm sure you all know, we have a bit of an intake heatsoak issue with the tC. Cramped quarters, hood insulation-- that's stuff I can't do much about. Some of you may have read about my initial step in bringing temps down: removing the stubby plastic pipe from the airbox inlet, and replacing it with 3" flexible tubing that extends down to the false-grille opening in the bumper. Of course, that helped a great deal. That was "Stage 1".

But I noticed that the heatsoak was still a problem-- for while cruising IAT had dropped 10 degrees or more, even 2 minutes at idle would push temps to 30º or more above ambient. Stage 2 eliminated the resonator box, and replaced the OEM paper filter with a K&N filtercharger. Again, good progress-- temps were slower to rise, and quicker to fall toward ambient once the vehicle started moving.

But I was noticing that long idling periods, say anything beyond 5 minutes, would heatsoak the parts enough as to leave the IAT 10-15º above ambient for a noticeably long period of time. In many cases, it would take as long as 10 minutes of driving to cool the parts down. I noted that the temp of the airbox, even after idling in hot weather, would not be as hot to the touch as any of the parts around it-- the thin ABS from which it is constructed don't hold much heat.

But the OEM upper piping... nice big, thick rubber tube-- is like a heatsink. After a drive to a few stores and back home (about 15 miles total), then leaving the car parked for around 30 minutes, the temp on the surface of the upper piping was over 100º-- even though the ambient temp was in the low 70s. So I had found the culprit.

Fortunately, Spectre had just come out with their "Poweradder" modular intake system, and the design seemed to fit the bill just perfectly. Sure enough, about $50 worth of parts, and the GFI Stage 3 is complete.

Results: Cruise temps remain 1-3º above ambient. Heatsoak is extremely slow to set in. Five minutes at idle will result in only a 5-7º increase. I drove it somewhat aggressively up to the store, where it sat parked for about 20 minutes. On my return, IAT was 112º-- a staggering 40º above the ambient (72º for those who don't like math.
). My first thought was, "Crap. I've wasted time and money... again."

I'm happy to report that I was too quick to judge. The first tip in on the throttle ingested the "settled" air-- IAT dropped to 96º immediately, then to 85º by the time I shifted into 2nd gear. By the time I reached the parking lot exit, IAT showed 76º. My mind was blown a little, I must say.

The GFI as it sits now has run me about $125, I'd guess. Sure, some may argue that's getting into the territory of a CAI or SRI... but that's not the issue. The SRI draws air from a horrible place. The CAIs draw it from about 10" lower than the OEM intake, so that's not much better. I wanted truly cold air (brought in from outside the engine bay), and I wanted to combat heatsoak as much as humanly possible.

Well, that went on far too long, considering how few pictures there were.
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Thanks for the update. I also noticed the heat sink effect of the OEM rubber tube, and that it's extremely soft when it is at normal underhood operating temp. What pieces did you get and what material are they made of?
Best as I can tell, the tubing itself is some manner of poly/plastic, that has actually been chrome plated-- there's even the copper layer underneath the chrome. The outside of the piping barely gets warm-- remains much cooler than everything around it-- cooler even than the airbox itself. If was way too blingin' for me, so the front pipe got the semi-gloss black treatment.

I'll get a better idea as to it's performance once I can put some more miles on it, and have the chance to run it with the GTech a couple of times. It feels smoother, but I can't assert yet as to whether or not it's making any real impact (aside from bringing the IAT way down).

For those interested, the Spectre "poweradder" parts list

(1) #8698 90º elbow
(1) #8668 60º elbow
(1) #8728 22º elbow
(1) #8771 3" x 3" rubber coupler (piping to airbox)
(1) #8751 3" x 2.5" rubber coupler (piping to TB)
(1) #8711 vacuum/sensor adapter kit (for crank vent)

The last part isn't really necessary if you have any 5/8" barbs and a grommet laying around, but I'm a sucker for packages full of fittings.
I'm guessing you could do the full CAI for around $150, and you can customize it however you'd like (even multiple filters and whatnot). The system is really neat, and the price isn't too bad at all.
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In your stage 3 picture I notice that the part on the elbow is missing. Did you relocate that and is that the temp sensor?
Steve in Waco
That part on the elbow is just a resonator box (which I deleted anyway). The IAT is right there with the MAF. Getting rid of the upper piping was the whole goal of Stage 3.
Is there any way you could get more/better pics? I'm still a little confused on what you actually did.
Originally posted by Zygote55@Oct 17 2005, 08:29 PM
Is there any way you could get more/better pics? I'm still a little confused on what you actually did.
To my understanding, he replaced the piping from the air-intake box to the throttlebody.
With something that doesn't conduct heat as well as plastic?
The problem being not that it conducts... but instead retains the heat. By getting something that is more resistant to external heating (i.e. thicker) you remove it heating the air as it passes though as well as remove the heat-soak issues during idle.
Is heat soak really a concern at idle? The car isn't going to overheat, so what does it matter if the temp goes up while idling?

(I'm not trying to argue, just trying to understand)
Originally posted by Zygote55@Oct 18 2005, 12:05 AM
Is heat soak really a concern at idle? The car isn't going to overheat, so what does it matter if the temp goes up while idling?

(I'm not trying to argue, just trying to understand)
The colder the air, the more dense it is. More air = more power, generally speaking.
I understand that, but at idle who cares how much power you have....
Originally posted by Zygote55@Oct 18 2005, 12:07 AM
I understand that, but at idle who cares how much power you have....
If the air intake has heated up during idle it will stay warm(heatsoak) for a good period of time even after you have started moving again thus increasing your intake air temps.
hmm...I guess I'd just have to see it proven that this will actually make a reasonable difference in power.
What's "reasonable"? I spent around $125 for an actual cold air intake, which is less susceptible to heatsoak than the OEM equipment. That's a fact. Any other CAI or SRI will provide hotter IATs, guaranteed-- they all either draw air out of the engine compartment, are made of aluminum, or both.

If a guy is willing to spend $200 or more on +6hp at the peak, a loss of low end, ridiculous heatsoak, and constant threat of hydrolock, what does that make me for spending $125 on my setup? Crazy, or smart?
Like I said, I'm not arguing. I wasn't even comparing your intake to a CAI or SRI... To me those aren't worth $200. I was just trying to figure out if yours was worth $125 to me. It probably is.

Do you ahve a thread showing your stage I stuff? I'd like to see exactly where you ran your cold air hose.
Replaced the short snorkel section with a 2.5" mandrel bent elbow:

Connected flexpipe to the elbow, and ran it down to the bumper:

Then connected the flexpipe to the opening for the false-grille:

Easy, and my cost for that phase was actually $0-- all leftovers-- but I included the cost of those pieces in the $125 for better accuracy.
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He ran it to the stock air intake system in the wheel well.

Stage 1- Correction, look above.
Stage 2- Remove air resonator.
Stage 3- Remove intake piping from air intake box to throttle body.
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