Engine/Transmission (1994 - 1998) Air Intake Modification

[SRehberg]

Back in an earlier issue of TDR, a feature was done on the air intake boxes. It basically came down to the fact the stock box was really restrictive at the fender well inlet area, and the truck ran better with the top cover off. Is there a way to modify the stock box to allow better air flow or is it just a waste of time? I know there are aftermarket filters, but is there any saving the stock one?

 

[illflem]

I have a Scotty air unit on my 3500 hauler and am very pleased with it, dropped EGTs about 150°. On my 2500 I don't pull a load much but with my right foot problem I still manage to get the EGTs up there. Since I had the extra air box I decided to experiment. Drilled 2-7/8'' holes in the left rear side of the the air box and another in the Scotty firewall location. Connected the holes together with 2 1/2 shop vac hose, a perfect fit. Also drilled some 1/4 holes in bottom of the air box to drain any water that might get in. I am running a K&N filter. Test results-on my "known hill" EGT is down 100°, engine is a bit louder, filter minder didn't move (before it went about half way). Before I could hit about 75 mph before backing off due to high EGT, now 95 with room to spare(ran out of hill). I'm sure that a Scotty unit will flow more air but this is a cheap inbetween, all it cost me was a little time and scrap piece of hose I had laying around. Sorry, never got around to pictures.



https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=6232

 

[SRehberg]

Illflem, thanks for the reply, but I am confused as to what was done. I think you connected the Scotty and the stock box together with the 2 1/2" vac hose plus misc holes to drain water? If the Scotty wasn't used, then I'm confused as to the function of the hose; I'm not familiar with the Scotty design as well, as this is new territory for me.

 

[illflem]

The Scotty has the option of drilling a large hole into the firewall so fresh outside air is forced in though the same area where the cab vent draws it's air, though the grill work between your hood and windshield. I didn't use a Scotty, only the factory airbox, just copied the Scotty's idea on where to draw the air. All I did was hole saw a hole on the dirty air side of the factory airbox and another in the firewall then connect them together with a large hose. It doesn't need to be a tight fit just as the stock snorkel to wheelwell is a loose fit. It's the same idea as the stock system of sucking air from the wheelwell, just a different location and larger hole. I left the stock snorkel and wheelwell intake intact, air is now drawn though two outside fresh air sources into the stock box. The result was very positive in lowering egts.

 

[SRehberg]

Illflem, thanks for the clarification and the idea sounds great, I'll try the setup you did. Seems easy enough to do, and any lowering of EGT's is a good thing, plus the extra air to these beasts.

 

[illflem]

Before you drill into the firewall fold back the insulation and tuck it out of the way. That way you can cover the hole if you don't like the extra noise in the cab that this mod will cause. It's not really obnoxious but you can definitely hear the turbo more. RV holding tank hose is readily available and works well for the connection between the airbox and firewall holes.

 

[SRehberg]

Illflem, thanks for the tip, I probably would have cut right through the insulation not giving a thought to the increase in noise. I'll fold it back like you suggested, that way if the noise is objectionable, it can be reversed and still look good. Thanks!