airbox / air intake 4.8 vs 5.3 vs 6.0

TGstring

Member
Well, I'm new to trucks having picked up my first late last year - a 2002 Silverado RCSB 4.8L with a 5spd.
The previous owner had tried to upgrade a few things but didn't accomplish any of it to my liking or standards of workmanship. What I mean is that some of the work done was not very neat. One of the mods was a K&N air intake with one of the big fat cone filters. (as a side note, I thought it was cute that there was a Toronado wedged up in the plastic tube a few inches before the throttle body! amazing... it was an authentic "tornado" branded one too!) When I looked into the available info on the intake (57-3021), K&N claims that there's a 9hp (4% increase) gain just shy of redline. The test seems to document that it was done on a 5.3L. There is virtually nothing different below 3500 rpm. 99% of my driving is below 3500 rpm.

http://kandn.com/dynocharts/57-3021_dyno.pdf

Now, I"m late to the game here, admittedly, but I've learned a few things in the last 6 months.

basically the airbox and design is pretty much the same for 20 years... I'm not sure but from what I understand the airbox (or at the very least, the use of the same air filter based on part #s) seems to be the same until 2019.
and
the 1999 to 2006 models share the exact same airbox whether 4.8 or 5.3 or 6.0L!

This leads me to believe that there is zero gain to be realized on any 4.8L by "upgrading" the airbox.
If the same airbox can supply enough air for a 6.0L , how could it possibly be undersized in any way for a 4.8L? Put another way, if the 6.0L is using the same 4.8L air box, there could easily be some power left on the table by upgrading that for those with the bigger engines?

Needless to say, I've gone back to an oem airbox (the one I got from the scrap yard was from a 6.0L) and I don't notice anything really different at all. It's a lot more quiet and I'm also intrigued by the visual air filter guage which I find pretty cool. I also like that paper filters are simply better filters keeping my high mileage truck hopefully around a bit longer.

I'd welcome your thoughts or discoveries on the air intake used on these trucks.
Cheers,
Tom
 

Mooseman

Moderator
You did good removing that K&N filter. As shown in this recent Project Farm video, it doesn't filter that well compared to good ol' paper.


The attraction of the aftermarket air intakes is the noise they produce (or don't muffle). CAI's have been proven to produce 0 HP or even reduce it.

There's way more power to be gained with other mods like exhaust, cams and tunes.
 

HARDTRAILZ

Moderator
KN is poison to an engine. Studies been out for many years showing they allow 97% more particulate through. I can't believe so many uneducated people still by them based on BS.
 

aaserv

Well-Known Member
If they did what they are called they might would do some good. "Cold" air intakes. Unfortunately most of the ones sold today are merely for looks and dont actually cool the air at all... What i cant figure is why anyone would put 1 on an Envoy or GM truck when they come with almost the exact same setup already minus the shiny pipe.
 
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TGstring

Member
I'm not done this tank yet but will soon calculate what the MPG diffrence is after this change. It'll be the first full tank with my tonneau cover, HD e-fans swap and denali DIC install which has (so far) calculated an average of 10.9L/100 km in mixed driving over about 400 miles
 
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TGstring

Member
got to the end of this tank earlier today
did 772km on 85.5L
my dic said 10.9L/100
calculator says 11.1L/100km
that's 21.2 MPG at roughly 60/40 hwy/city mix

I've only had this thing about 7 months...this is the best tank (so far)
I've heard of folks getting 23 to 24mpg and I look forward to getting that too with a bit more work
 

Mooseman

Moderator
That's better than my TB at 17-18 MPG combined.
 

Mektek

Well-Known Member
I'm thinking of converting my TB to use the airbox from a 2001 gmc pickup. I'll have to change the WW fluid reservoir too.
 
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TGstring

Member
if I were to change anything, it would be the following:
verify that the 2007 and up *LOWER* air box openings are larger or smaller than the '99-'06 - if they are, use that. If not, run with it. IF I had a motor bigger than the 4.8L, I'd OPEN up the lower air box intake holes (that mates with the fender), just as the GM Performance airbox did.
I'm still doing homework on this and would be happy to update as I discover what's out there
 
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TGstring

Member
another random update on the incremental changes to how the truck drives reversing the previous owner's "mods" that are popular but perhaps counterproductive to efficiency...

I recently put on some 18" silverado hybrid rims which were refinshed (painstakingly by my own two hands...and i'll probably never do that again) after having the cladding torn off. I love the look of these things. I've never seen another truck with these wheels. another topic for another day is why GM simply didn't sell/offer the wheels like this! Anyway, I also put on some new 18" tires that are the same diameter as the 16" wheels that were pulled off. New tires are 235/65/18" . I'd say (didn't get to weigh) the new rim/tire combo is a few lbs lighter but not much. Definitely not heavier which is a bonus. I ran the new tires at 36psi.

This tank came in at (512 miles) 824km on 87L.
The DIC said 10.7 but the calculator says 10.6 L/100km which I think is awesome
22.2MPG ain't half bad.
I'm pretty sure I'll be able to flirt with 9.9 or 10.1 on a dedicated hwy run keeping it at 65mph or less

if i sounds like I'm after MPGs, I kind of am, simply for the challenge and determining what it's capable of. I'm usually curious about this stuff when i get into a new car...this truck is no exception.

final mod which *might* help with MPGs is a belltech lowering kit (for getting it lower about 2-3 inches) and seeing if that's enough to get into the 24-25mpg range. And yes, I like the look of there not being 5" of fender gap considering I'll never carry more than 3 people and a few hundred lbs in the bed.

anyway, I'll leave it here for now :smile:
 

TollKeeper

Well-Known Member
Do you have a side view pic of before the drop and after?
 

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