I'm trying to build a cold air intake on my 3800 swapped 84. I tried using a v6 Silverado duct work cut in half only to find out my the filler neck for the fuel tank is in the way. I tired to have the cold air intake exit out the hole on the other side of the filler neck, but the wheel well doesn't go back on with it that way. Anybody have a solution? or am I going to have to replace the filler neck with a 85+ one for the cold air intake to work?

With the 3800SC you only need a 3" intake. I mig welded 3" flanges on the intake and exit of the OEM filter can and attached 3" silicon elbow to the TB and used a 3" elbow at the bottom of the filter can and then to a 3" aluminum pipe and out to a modified side scoop. It does fit OK.
My engine currently runs the LS1 MAF that is 75 mm or 2.95". With the MAF screen it probably cuts the space down 25% so I believe that a 3" intake system flow covers it.
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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 11-11-2024).]

I have no room for it to come out of the factory location. the filler neck is in the way, I think the 84 filler neck is different than the 85-88. its either that or the factory intake exits differently.

[This message has been edited by GreggDauer (edited 11-05-2024).]

i also have an 84. i used a 3" plastic elbow - like used for drain pipes, and with some tape to take up the slop in the fit, it went into the rubber of the 3800 intake. This was attached to a piece of 3" pipe down to below the engine and i put on a cone filter there to pick up the relatively cool air below the engine.


Showing the elbow into the rubber of the 3800



Showing the clearance with the coolant rubber line as well as the clutch slave cylinder.

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Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.

Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.

I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 3800SC, 4-wheel drifts are fun!

[This message has been edited by longjonsilver (edited 11-06-2024).]

I didn't know that the '84 was different for the hole in the engine bay?
As said above, 3 inch pipe is what you need. I'm nearly at 4 inches (100mm dia) with my setup, and that passes:

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"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM

3" is is ok for a stock 3800sc, but 4" is doable and is recommended for any mods to airflow thru the engine - including a more free flowing exhaust than came on the FWD setup.....

Even if your engine is bonestock, it will benefit from a larger than 3" intake.

Less intake restriction = Less KR at high rpm = less timing retard = more usable powerband