I am perplexed. The tube to the turbo is approx. 6 inches in diameter. The tube into the air box is approx. the same size although rectangular. How does drilling holes in air box increase airflow? Seems the 6 inch tube to the turbo is the limiting factor even if you make it possible to suck in more air by drilling holes. Things that make you go hmmmmmm? Reference the garden hose test. Attached a half inch hose to three quarter inch and measure the flow into a bucket. Then reverse and put the three quarter first then the half inch and the flow rate is the same. The dilemma, making a 12 inch equivalent input into the 6 inch tube results in zero gain? Can someone please set me straight?

 

Huh??

Actually, the intake tubing is all 4" diameter (with the exception of the big canister looking thingy in the middle). Drilling holes just allows more air to get into the air box....and it DOES make a difference (as many have proven by simply watching their Filter Minders).

 

simply stated,the water is under pressure, intake air is not

 

Have you ever had the stock air box out and looked at where it draws it's air from? It sucks it all through that hole in the fender. Problem is, the fender is sealed up pretty tight with no large openings to allow free flowing air to enter.

Back when "Gypsyman" was running his B1 turbo, he was using the stock airbox that he had drilled a 4" hole in the bottom (covered with screen to keep big trash out) along with a customized intake tube. He could run 45lbs of boost with the B1 with that setup before his filter minder would even move. That is pretty good. The stock airbox seems to support plenty of air for most of us if you give it another location to draw its air from.

Try something like what Hoss has done and you will probably be surprised at the results. He has some good example pics in his gallery. Most report 50*F to 75*F EGT reduction right off the bat.

 

I am almost convinced. I don't understand why pressure has anything to do with it, aren't we talken volume? My filter minder has never moved, if I drill holes will it move?

 

I think what they are trying to say is, drilling the holes in the airbox increases the amount of air available at the filter. Drawing it from the fender only is somewhat restrictive, they use the same set up for the gasser pick ups, which don't have near the air requirement of a larger, force fed engine. The weak point isn't the duct work, it's the fender.

 

Is your truck stock? The stock design should provide plenty of air for a stock truck (debatable). If your not bombed, the benefits may be nil and not worth messing with.

 

More turbo whistle is the only discernible improvement it made to mine, but I don't have gauges yet either.

 

Thanks for all the inputs. I sucked it up and drilled a bunch of holes in the bottom of the air box and then glued black screen underneath to keep the crud out. On the drive into work today my egt did seem to be lower. I will be able to see if there was an improvement this weekend with the new 5er hooked up. My truck is completely stock mechanically except for a home made torque tube and now holes in the air box. When warranty is up the muffler is the first thing to go!

 

you don't want to wait that long... unless your dealer is a real *****, they won't care if you have an aftermarket exhaust system or aftermarket muffler... they might frown apon a straight pipe, but you could always cut the end off the oem, burn the baffles and pipes out, and rebuild the oem muffler - internals...

 

you should be fine removing the muffler, just don't fool with the cat, or they may give you a problem.

 

I agreee with Stateline, unless you're altering the emissions equipment, the rest of it would require a dealer with such an attitude as not to be believed to get any trouble out of 'em. I've had mine in the shop a couple times since I got rid of my muffler and replaced it with straight pipe and a turndown, and have never heard a word about it.

 

keep typing guys! I emailed Mark at DPP? a while back cause I saw a post about a direct muffler replacement but it was for an 04.5 and not the 04. What is the best direct replacement muffler excluding the straight pipe from Geno's. I also have read that improving the airbox (like I did) and removing the muffler actually reduces the performance of the stock triple nickels. Meaning that removing the muffler will hurt more than help unless I get a box.

 

I have a early '03 model and right off the bat the filter minder was at 35%. By 5k miles it was showing 60%. So at 7k miles I changed the airfilter and did the air box mod by cutting a 4" hole and adding a 90 degree drain pipe elbow. Now have 15k miles on the filter and it's only at 40%. Also noticed the EGTs dropped by about 50 degrees.

MikeyB

 

MiekyB, you are one of the reasons I don't think my filter minder is working. Mine hasn't moved yet.