Engine/Transmission (1998.5 - 2002) ETH intake restrictions...?

[Gary - K7GLD]

Anyone have a clue as to whether most air intake restrictions in the stoch HO setup come from the element itself, OR from restrictions in the air tract INTO the filter housing?



I'm wondering how much, if any, improvement I might generate in airflow by simply drilling the airbox for more flow with the stock filter element...

 

[Mundgyver]

Your restriction in the stock housing is caused by the connector from the fender well to the housing. The air is required to make a 90 deg turn from the fender thought the connector. I believe John Holmes made this discovery awhile back while testing products for the magazine articles in TDR.

If you remove the connector from the box to the fender well, your restriction should be allot less.

 

[Whitmore]

Gary

Do one better yet and get a BHAF and throw the oem unit away, it will help your egt and spool up is quicker too, read the survey and test that was done in last months mag,,,,, its impressive... ... ... Kevin

 

[Crazy Horse]

This is what I did to my 2000 3500 and it made a big difference in breathability and lower EGTs. I getting ready to do my 2002 the same way.



12/20/2000 TDR Post (24 Valve Engines)

After posting my question on 12/15/00,I decided to go with the stock box K+N. I also decided to modify the box. I was after lower EGT's,More MPG's, and performance lastly. I drilled 2, 1 1/2" holes on the front and rear of the box,directly below where the filter sits. I then mounted 2, 90 deg. elbows in the holes I drilled. Off the front one I ran a couple joined sections of radiator hose,around the battery,out front,directly behind the right headlight area. That will be sucking cool air into the box. Actually you can put your hand over the hose and you can feel the air being sucked in,when the engine is running. The elbow on the back of the box,I turned directly downward to prevent water entry. After doing this today and driving the truck it has more power. As far as lower EGT's, we'll find out when we get to Key West next month with the camper and trailer on.



1/20/2001 TDR Post (My Findings)

Turbo Blades Clean as a Whistle.

This is just to report a finding that some may be intrested in. After modifying my stock airbox and installing a K&N airfilter my turbo blades are clean as a whistle and EGT's are running 100-125 degrees cooler,loaded and at highway speeds. Loaded truck weight is 11,820 and pulling a 1700 lb trailer. These finding came after a 2,000 mile highway trip with high rpm's and high air intake(65-80 mph). I modified the airbox by drilling two 1 1/2" holes just below where the airfilter sits and installed two 90 degree plastic elbows on the front and rear of the housing. Off the front intake elbow I ran a formed black radiator hose around the right battery out just behind the right headlight,downturned. When idling you can feel air being sucked into the hose with your hand. I'm very satisfied with the outcome of this and the prior information I recieved from the TDR discussion forms. I've been running with this load on the truck for almost 12,000 miles so far and this EGT was a big thing for me to lower. Finally you may be interested to know,when I pulled the factory airfilter out there was black on the turbo blades which I cleaned off prior to K&N. I also did add a small ribbon of K&N oil to each one of the pleats of the filter prior to installing it and let it sit for a couple of days prior to installing it. Final note do grease all sides of the sealing edge of the K&N to insure proper seal.

 

[JMarkos]

I just did something simaler, I took a 3" sheet metal 90 and inserted it in the box and ran a piece of dryer vent hose down and used one of the fog light holes in the bumper for the intake. It looks sweet the problem is I haven't gain squat. The only thing I can say is now my filter minder doesn't move.

 

[mikeberry]

My filter-minder used to click down when I pulled a load until I did the following:



Removed the snorkel to fender, and used a soldering iron plastics blade to cut a 2 1/2"x6" piece out of the box below the k&n on both sides. Could feel/hear the difference.

 

[Crazy Horse]

mikeberry, you'll get more air that way but, if you bring cooler air directly into the airbox you will lower your EGTs when towing or hauling. The problem I saw with just cutting holes in the airbox was sucking the heat of the engine in. That is why DC brings it in to the airbox from inside the fender.

 

[Big White Beast]

Crazy Horse.....

Several people including myself have taken temp probes into the engine compartment. I had mine tied to the BHAF on the turbo side. When moving there is very little difference between the air by the intake and outside air. When idling heat builds fast. My temp probe wasn't that fast but the temp dropped fairly quickly once moving. DC was probably more concerned with smoke at take off than total air flow.



Someone even mounted a probe in the intake horn and the intercooler does it's job. Same or similar temps to outside air, again once moving. Not that far off idling either. Even though the fan is clutched it still draws a lot of air.



I wouldn't concern myself with temps under the hood. The question is oiled or not. (I'll stay out of that argument) Or noise or not. All the higher flow filters are noisier in the cab to varying degrees. The ones drilled into the firewall being the worst.



Garrett

 

[Steve Campbell]

"Air horn" removal...

Lots of posts about this 1 1/2 years ago. I took mine out and found some foam about 1" thick and made a "gasket" to seal the airbox to the inner fender. No increase in noise, but better flow of air due to large size inlet than the air horn.

 

[Crazy Horse]

Here is a picture of the fix I do to the stock airbox for high EGTs when towing. Winter is coming on so the hose will stay off till next summer. I found a hose at Shucks that fits around the battery and out to the right headlight area perfectly (pt# E70548cs). EGTs are allot lower and the the engine breathes much better.

 

[Chipstien]

Seems the easiest thing is to remove the dumb airbox.

 

[Dane]

I pulled the fender to air box snorkle and drilled four 1" holes in the bottom of the air box. Then I replaced the stock air filter with a AFE. Flows MUCH better now.