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Been researching all week and 500ish seem to the number floating around the duramax forums before it becomes a restriction. One guy says he’s making 600ish on a rear mount turbo setup ducted back to the stock airbox. Curious what guys have made hp wise or any hard data on either stock or modded stock box.
Looking to get rid of the open filter on my turbo setup.
The stock gmt800 airbox is a restrictive pos and probably wouldn't support 500 hp... it has tiny inlet holes. The gmt900 box interchanges with it and the whole side facing the fender is wide open... no airflow issues with those.
i know a lot of the D-max guys just take a hole saw to the front and/or fender sides of the stock air box & drop in a good filter - usually up to around the 500hp mark (making a lot more torque than a gasser).
i was actually contemplating that myself - i've had my stock box just sitting in the garage for the last 10yrs, and my cleanable AirAid open cone filter has seen better days.
I had problems with my stock box at 600rwhp, it was creating too much restriction and was causing my IAT to go wild. Switched out to custom intake and it's much better now.
hennessey/lingenfelter/callaway seem to keep stock airboxes up to the 700-ish HP mark.
w/ drop in filters & maybe inlet mods
opening it up w/ an aftermarket CAI will certainly provide more air on a boosted application
True. Trying to find the balance between providing a lot of warm/hot air and enough cooler/colder air.
Originally Posted by 1994Vmax
The stock gmt800 airbox is a restrictive pos and probably wouldn't support 500 hp... it has tiny inlet holes. The gmt900 box interchanges with it and the whole side facing the fender is wide open... no airflow issues with those.
Figured out today that the piece that funnels the upper hole is removable. But the hole in the fender is still small. I would assume the GMT900 fenders have the larger hole too, but looks like opening up the hole in the fender and putting foam around the box will make it pretty close to a GMT900 box.
Originally Posted by smokinlmm
I had problems with my stock box at 600rwhp, it was creating too much restriction and was causing my IAT to go wild. Switched out to custom intake and it's much better now.
Thanks. Good to know. Are you still on a sealed style intake?
Thinking opening up the upper hole on the fender or possibly even going as far as to opening up the entire side would provide enough air for 600-700hp. Maybe. Hopefully.
You figured it out lol...and cut the inner fender to match. That's exactly what I did with my 05 and my 2015 as it too suffered the same issue. The airflow increase was noticeable on both trucks scanning the maf after the mod...
I thought Trick was looking into building a replacement for the stock air box that worked for boosted applications but I could be wrong.
Yeah saw that but never heard anything final.
Originally Posted by 1994Vmax
You figured it out lol...and cut the inner fender to match. That's exactly what I did with my 05 and my 2015 as it too suffered the same issue. The airflow increase was noticeable on both trucks scanning the maf after the mod...
More so meant I just realized, not so much that I was the first in 20 years to figure it out. That’s the plan though.
04-15-2020, 03:11 PM
Max HP on stock air box?
