Hi,

I decided to go back to my stock airbox and filter and was wondering if there are any better filters than just the run of the mill paper replacements.

Why did I go back to stock?

1. So much quieter. I am so past the stage in my life where my vehicle has to be really loud, make cool noises, black smoke, etc.

2. A post by KTA on the firstgen.org forum

3. Might sell the ASA intake for a little cash

4. I keep hearing bad things about oiled fiber filters letting stuff through, especially at high pressures. My HE351 had some damage to its compressor wheel, was wondering if was why. I have never used a prefilter though, so maybe that is why.

I did lose 2 psi in doing this, and gained a little EGT but not much. So, was wondering if there anybody made some better filters for the stock airbox, besides K&N.

Thanks

 

The 1993 box is supposed to flow a little bit more and the filter is different as well.

BTW what did KTA say on the 1st.gen forum?

I have a BHAF on the crew but I found the intake popped apart and a lot of dirt inside the intake tube :-(

Now I have it clamped correctly so this will not happen again but I hope I didn't do any damage. The turbo was fine, but it is on the shelf now as the HE351CW is in.

 

AFE makes drop in filters for our trucks, Part number for 89-92 is AFE71-10031 , its a high flow filter. I think the pro guard series. Link- http://afepower.com/shop/details_new...ue&&brandID=59 .. I think they also have a dry series. I'll try to find that.

Pape, I've had a 93 box and 89-92 box next to each other and the box and everything is exactly the same, with the exception of the 93 air filter is a push on style, it just pushes on snug and seals.

The 89-92 style has a metal stud that you slide the filter over and screw a nut on the end, the 93 style seems chinchy to me as the filter could pop off or fail to seal really well.

 

Different filters in the stock air box will not affect airflow because the intake tube (or hole in the box) is the restriction, not the filter. The stock paper filters are rated around 450cfm.

Install a filter minder, then make a coulple WOT test runs, one normal and one with the cover open an inch or 2. Then you will understand what I am talking about.

With your setup I'd be looking to do a BHAF, stock pot style or something similar.

 

how much do you want for ur asa?

 

I want to say I saw that the HE351cw can flow UP to 700cfm.

John, why not a paper BHAF? I don't notice a BIG noise difference when using the stock, rubber hose to the turbo vs. the other truck with stock set up.

 

Yes. What it will flow in practice depends on the tune of the truck, and I'm pretty sure Head's truck would be pushing the limit of a stock replacement filter. Yes, the expensive drop-in AFE's K&N etc. will flow more, but not without airbox mods.

 

i noticed a 200* drop in removing the air box and went to a 2790 napa filter on my 93 with the stock exhaust and turbo. something in the air box is restrictive, i dont care what it is, but it is restrictive. on my 91 i saw a 100* drop when i put 4" aluminum pipe and silicone 45* boots for my homemade intake. (similar to BC847's intake) so their is 300 degrees you could loose by getting rid of the stock airbox and ripple tube and go to a full 4" intake with a BHAF, just did this last week

 

I like my Amsoil dry filter, I run a pre filter with it too.

 

its that tiny rectangle intake that comes up behind the grille a "ram air scoop" i guess you'd call it, its dead smack behind the grille so no air gets to it anyway!!!

and besides that, the little rectangle duct peice is tiny anyway, if one were to cut out that part of their grille and let nice cool ram air go through there i bet it'd help. but i wouldn't do that to a real nice grille.

 

you could also cut out a rectangular opening in your sheet metal trim which is the trim right behind your bumper. Cut out the opening directly in front of the stock box intake piece, which will give you a homemade ram air. This is what Ace and myself did. I feel it made a difference. My egt's never hit 1000, and once in a while hit 900. This is with my power mods shown on sig. What is not shown in my sig is that I removed the stock intake rib hose, and used 2 5" 45 degrees elbows w/ reducers to fit the stock box and turbo inlet. I have a piece of 5" aluminum pipe in between elbows. The original reasons for doing this is because of engine appearance, and the piping offered a great solution as a better way to install a filter guage and a better way to mount my propane injection fitting. I feel that set up opened it up a little more as far as airflow.

 

He said he has switched intakes when dynoing and found little difference, he also thought the stock filter & box is good for trucks making up to 350 whp.

I actually have a BHAF. I have tried it before, but found it would detach from the tube. I must admit, all I did was put the BHAF on the tube, and did not make a mounting bracket or pot like BC847, it just sat there. I also think this would be more louder.

Actually the sound wasn't the main reason, it was the bad posts I had been reading about oiled filters allowing grit and stuff through. My HE351 was damaged, I didn't consider it resellable. I have never ran a prefilter though.

Is a BHAF comptable with the ASA intake pipe? I will have to check tomorrow.

 

It's designed to go OVER a 4" pipe. I too have my stock tube on it trying to clamp onto the little neck of the filter. Dave told me it's designed to have tubing go in it, and the hose clamp is to clamp onto the little neck of the filter. Made way more sense when he said that.

 

Yes, the BHAF is 4" ID....

For two of my trucks I used a 4" OD PVC coupler to clamp to. No issues, except when I tried to get away using only 1 tbolt clamp instead of 2.. (one on the BHAF and one on the rubber 45degree elbow...)

 

This is what Crossy's Son and BigRagu are talkin about, I just cut out a rectangular piece right below the grille where the plastic "scoop" is sittin right behind it, I got my handy sawzall and cut it out, I'm sure it helped get a little more cold air in and you don't even notice it.