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View Full Version : How to do a blowthrough correctly?



SWFL
07-03-2009, 01:59 AM
I was just gonna do 2 12's in the cab but figured why do that my truck is ready for a blowthough. I hear the value drops bad but the blowthrough can be welded back and never know it was there anyway in my truck. Its paid off so WTF why not. I have the hard bed cover ready and just waiting.

I wanted to attempt to do it myself with me and a friend of mine who is a welder and works with metal. What is the proper and easy way to do a blowthrough. Should the size of the hole be only as big as the loading chamber or what would be the proper size??

any tips please.

Thanks

SWFL
07-03-2009, 04:31 AM
no help

KHARPS
07-03-2009, 04:37 AM
go in the bed and outline the maximum amount of space you want to cut, physically draw it out with a marker, go to all 4 corners and drill from the bed through to the cab with a drill bit, that will transfer the bed to the cab, get to cutting, seal with an accordion boot, build your box.

SWFL
07-03-2009, 08:04 PM
http://i40.tinypic.com/2jb4jty.jpg
http://i43.tinypic.com/acfpv.jpg

heres what the two different cuts i would like to do dont want a huge blowthrough want it to come between the seats if possible

http://i42.tinypic.com/15g5ibn.jpg

this one would prob give me the best airflow
http://i40.tinypic.com/22fhpc.jpg


What do you guys think??

lil_italy773
07-03-2009, 08:24 PM
nice king ranch that should sound good. ive been playing with that idea but dont want to cut into my truck. like u said resale.

krainium
07-03-2009, 08:45 PM
If you do 4th order you can get away with a smaller hole.

SWFL
07-03-2009, 08:50 PM
Yea, well its paid off so I figured why not, plan to make it into a project. its a 01 and only 90k miles on it so hell still has low miles for a going on 9 year old truck only 10k miles a year average. Truck is in great shape. So I figured why not.

the bed dimensions are around 65x41x22 or 65x(42 maybe 42) x22

or I can do 65x48x20

so after just say 3/4 MDF might need double not sure just say one layer

that will be after MDF disp and plan to prob take 10" off for room in the back by the tailgate for battery and amp rack so

55x41x22=25 cu ft
55x42x22=25.7 cu ft

or 55x48x20=26.6 cu ft

Prob would do the 55x41x22 so I can get the 22" high and make sure it will fit and not worry bout stertching it to 42 to pick up .7 cu ft extra. Also with the 22 height i can do 18's even if i do 2 layers of wood. with only 20" high that limits me to 15's only

so 55x41x22 would be the best bet could even make it longer if needed to depends on how much room i need for a battery bank. Will have room on the sides as well for batterys since this box will go inbetween the wheel wells and another 7" inside of the wheel well so I will have around 10" wide in 4 spots so I could put 4 batteries in those spots would rather have them all in the back. so could just take off 8" for the battery bank most batteries are that wide anyway right and that would give me

57x41x22=26.3

IDK how much room I will have after the port displacement and loading chamber and all that good stuff, need a builder to give me a little help. If I did 4 18's I would need 2 layers of wood so would be 22.5 cu ft before sub or port displacement after 4 18's that will be down to 21.5 cubes. so i doubt i can do 4 18's. that leaves 5.4 per sub if before any port so 18's are out of the question right??

if I did one layer would give me 26 after subs 25 cu feet and that would leave 6.25cu ft for each 18 before any port still not enough I am assuming 18's need at least 5-6 cu ft per sub after port right

15s are my subs I figure would be the best to go with prob 4 15's or 6 15's w/e I can fit

more than likely a 15 will need 3.5 cubes after port so with 4 will need around 14 cubes after port and with 6 will need around 21 after port. if i am doing 15's i can do the box thats 55x48x20 that gives me 26.6 before displacement after subs will have 25.5 so I dont think the 6 15's taking up 21 cu feet leaving 4 cu feet for port so 4 15's would be the best best. 14 cu ft for subs and leave another 11-12cu ft for port and loading chamber

kinda long I know but wanted to see if anyone see what i am saying

KHARPS
07-03-2009, 08:51 PM
Those seats are bad ***. The cut will depend on your box size or vice versa. Mine is 35'' x 12'' for 2-12s.

SWFL
07-03-2009, 08:56 PM
Those seats are bad ***. The cut will depend on your box size or vice versa. Mine is 35'' x 12'' for 2-12s.

thanks, they are like brand new as you can tell how dark they still are the interior is flawless no stains or anything perfect shape, ask mobeious its a nice truck he built the previous box for me when i took out the console.

Thats how I had my 2 12's l7's but dont want a big *** box in the cab would rather since i am gonna have 4k watts and a HO alt, would rather put the batteries in the bed along with the amps and do the big *** box 4 15's in the bed and do a blowthrough.

I was thinking 2 subs on each side of the bed facing each other with the port comming from the tailgate and into a loading chamber into the cab

read above what I wrote kinda long but oh well.

I kinda dont want to cut the truck up but if its done right and save the pieces i can put it back togehter and the buyer would never know:laugh: j/k. The truck is paid off, plan to do it sooner or later anyway so why not now. Want to do this, and 24's or 26's and supercharge it:D but its gonna cost alot

KHARPS
07-03-2009, 09:01 PM
I've heard a few people having trouble with the port from the back. I think you should do like your saying but do a 4th order and have the port up front. There would be 2 subs on each side of the bed in their own sealed section firing into a common ported section. Then there would be an external square port that fires into the cabin. There are a few pics floating around that can give you some ideas. As for the 4th order design you should hit up 80inches but he's always pretty busy with designs.

KHARPS
07-03-2009, 09:03 PM
4th orders are pretty big though...imagine a sealed box for 4 15s and a ported for 4 15s combined.

SWFL
07-03-2009, 09:04 PM
send me the link for some 4th order or 6th order i heard about as well never messed or read about boxes like those??

also is it possible with a design like that to have a changable port so for daily can play low and if i wanted to meter then drop a higher tuned one in?

KHARPS
07-03-2009, 09:11 PM
http://img354.imageshack.us/i/gt19sz.jpg/

krainium
07-03-2009, 09:13 PM
Heres a good thread to check out
http://www.caraudio.com/forum/showthread.php?t=406481&highlight=blowthrough&page=2

SWFL
07-03-2009, 09:54 PM
ok thanks, still trying to decide whats the best way to go about the blowthrough far as how big

KHARPS
07-03-2009, 09:58 PM
Well 4 15s would need around 15 cubes or so. Then the port will take up quite a bit and so will bracing. Download google sketchup and practice designing boxes.

krainium
07-03-2009, 09:59 PM
It will depend on what type of enclosure and subs you decide on.

KHARPS
07-03-2009, 10:03 PM
DC LV4s, RE SX, Mach 5 IXL, Fi Q or BL, will all get the job done for you. Just pick one and stick with it, same with an amp. Second guessing yourself on equipment is pointless as the box is what will determine how loud you will get.

SWFL
07-03-2009, 10:47 PM
yea i am pretty sure on the amp prob an IA 40.1 and for an alt mechman or dc power. Just got to figure out how much room i have and how many subs i can run, and then pikc a sub

caps
07-03-2009, 11:10 PM
go funky pups

SWFL
07-03-2009, 11:14 PM
sure thing once u send them to me for 1k a piece

iamamp3pimp
07-04-2009, 06:51 AM
send me the link for some 4th order or 6th order i heard about as well never messed or read about boxes like those??

also is it possible with a design like that to have a changable port so for daily can play low and if i wanted to meter then drop a higher tuned one in?

instead of doing that, get it loud enough to do both.

:)

its not so easy dropping ports in in a 4th order.

pm me your number, ill call you. too much **** to type up here.

SWFL
07-04-2009, 03:21 PM
well i think on 4 15's IA 40.1 and good electrical i might touch 150. if not then i will pick up another 40.1

dB-SPL
07-04-2009, 03:56 PM
Where's TnT.. I want to see those 2 BTL 12's he mounted to the back of the cab. Or how he went about it.. I can't find a log on that build anywhere but I know I've seen one pic before.

-Bill-

SWFL
07-04-2009, 10:42 PM
yea, I want either 4 or 6 15's rather not mess with 18's would be too much of a ***** to fit them.

12's I jsut dont know wouldnt mind it but to run 8 12's gonna cost a shitttt load of money double running 4 15's

But I could run much more power

4 15's maybe 12k watts tops more around 10k for daily 2500rms per sub
6 15's 18k watts tops prob more around 15k
8 12's 16k with no problem 2k per sub could do 2500 maybe per sub or 3k tops so 20k maybe and 24k tops. Which those numbers to do that many watts are almost impossible withoout a **** load of batteries and around 5 alts lol

KHARPS
07-05-2009, 11:45 AM
Like I said man...4-12s can get insanely loud. I sat in DDbumps car with the 4-12'' Alpha Max and the were rediculous.

SWFL
07-05-2009, 04:28 PM
How much power was he running?? and what tune?

I think 4 15's would do exactly what I want

TnT_Sounds
07-05-2009, 05:05 PM
You would be surprised how 4 12's would do. It's all in the box. I've had 2 12's on 6k stomp 4 15's on 8k.

Like I said, box is key. The bigger you can cut the cut-through the more versatile it is.

Essentially the bigger the better

TnT_Sounds
07-05-2009, 05:07 PM
Where's TnT.. I want to see those 2 BTL 12's he mounted to the back of the cab. Or how he went about it.. I can't find a log on that build anywhere but I know I've seen one pic before.

-Bill-

this one?

http://i251.photobucket.com/albums/gg317/thumpster_18/0325081735.jpg
http://i251.photobucket.com/albums/gg317/thumpster_18/th_travishairtrick2.jpg (http://s251.photobucket.com/albums/gg317/thumpster_18/?action=view&current=travishairtrick2.flv)

KHARPS
07-05-2009, 05:09 PM
DDbump was running a 5750.1 at 0.5

KHARPS
07-05-2009, 05:11 PM
How much port area did you have in that box Trevor?

SWFL
07-05-2009, 05:24 PM
this one?

http://i251.photobucket.com/albums/gg317/thumpster_18/0325081735.jpg
http://i251.photobucket.com/albums/gg317/thumpster_18/th_travishairtrick2.jpg (http://s251.photobucket.com/albums/gg317/thumpster_18/?action=view&current=travishairtrick2.flv)

was that 2 12's or 2 15's?

TnT_Sounds
07-05-2009, 06:15 PM
How much port area did you have in that box Trevor?

beats the hell out of me:confused: I didn't design it.

It was a rear loading horn though.

dB-SPL
07-05-2009, 06:27 PM
this one?

http://i251.photobucket.com/albums/gg317/thumpster_18/0325081735.jpg
http://i251.photobucket.com/albums/gg317/thumpster_18/th_travishairtrick2.jpg (http://s251.photobucket.com/albums/gg317/thumpster_18/?action=view&current=travishairtrick2.flv)

Yes, this one. Looks like a sh*t ton of port area. What kinda box is it? Curious as to how you got the baffle like that without splitting it off the box. My cab flexes a fair amount from the bed while driving.