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odd ball question about air boxes na&turbo

2K views 17 replies 6 participants last post by  marksbug 
#1 ·
I know the tops are different.are the boxes different? does the turbo box flow better?if so.. will the NA top fit the turbo box?if so who has a turbo box for cheep....Im not a fan of the CAI's. I just dont care for the looks of them...but I know they work,I know better boxes work. I di many expearaments 15 years ago with my 4 wheeler, the more you open up the box the faster it is the more jetting it needs ,even if the air box inlet is 4x bigger than the carb size, more is better. I may end up going CAI..a black one..hidden.. so..who has compared the gxp&na air boxes?
 
#7 ·
The tops are different, the bottoms, I think, are the same. The air filters are the same. Gotta check some part numbers but I'll be back.

EDIT: The bottoms have different part numbers so probably are different. .
I am curious about what is different, because the bottoms appear to be identical. Maybe the mounting, and possibly the inside of the resonator, but externally I can't tell them apart.
 
#4 ·
I know the tops are different,just wondered if the bottoms were interchangeable and if the gxp/turbo boxes breathe easyer. part numbers may be different and still interchangeable. I don't think a turbo box would need to "muffel" the pulsations that a NA box needs to do.thus they may breathe better.and may be interchangeable.it's worth a try any way if somebody have 1 of each they have taken off that they can compare.
 
#5 ·
The turbo box muffles the turbo whine and the blow off. The cold air intakes do nothing for the boosted cars
 
#6 ·
so we need 2 boxes to compare.wish I still had a flow bench. a high flow top would be nice too. 12 hp on the camarow stuff with just a top change,possibly a top spacer/wedge plate would help. k&n claims 5.4 hp on their cai.witch is about half of 12....time for some 3 d printed wedge spacers!! or complete tops made for better flow!! and of coarse some work to the bottoms wouldn't hurt either. I need to get a old box to play with. among other things.
 
#10 ·
Well if the bottoms are (or look) identical, and the filter is the same, then the OP's question has been answered. There is no reason to swap. Probably the outlet tube has the greatest effect, and you can't swap that!

Stick a fork in this thread... it's DONE!
 
#11 ·
One thing to remember about advertising claims - when a manufacturer boasts something like ('Get 200 more CFM than a stock intake!" it is enough to draw the naive and credulous into buying their item without thinking about the claim any further. They read the statement to mean 'You will get more power'

And that may or may not be the case. If the stock intake flows 400 cfm and the most a stock engine can suck is 300 cfm, then increasing the flow capability to 600 cfm is going to get you exactly zero additional power but it gets the manufacturer, who didn't (quite) lie to you, a bunch of undeserved cash.

Tests have shown that the stock air box flows more than a stock engine can use or needs. Will you eventually reach a point where that situation changes if you mod the engine and stick on larger and larger turbos? Quite possibly, but I don't recall seeing any hard data for that - if anyone has, speak up.

The other thing to beware of with these cars are the 'sort of false' claims. The engine management system will always adjust the torque output to a predetermined level unless you have a tune (in which case the level will be altered but still there). When you make a change in the engine, it takes awhile for the 'learn down' process to readjust back to the predetermined output level.

What several vendors have done is slap a mod on a car, dyno it and truthfully state that there is an increase in power of X bhp as shown on a dyno right after the modification. What they don't mention is that if you buy their product and do the mod, the week after you install it, your power gain will be back to a big fat zero.
 
#12 ·
the na and turbo boxes may look the same, but the turbo may be 1/2" taller or so in the intake portion.or1/4 deeper under the filter.or one of the "muffling boxes that have runners to the main intake of the box may be connected to the filter area. or, yup there are many variables that can up he flow.. or it could just just some of the water traps/drain's shorter for inter cooler clearance.... but it's the flow that counts for using on a 2.4 na. Ive just finished "porting" mine for better flow.it's got a good amount of sharp edges witch hurt flow. I will never know if it helps mine or not as it has a stock tune.and the stock muffler( witch I would love to see the innards of). but if a gxp box does infact flow more that would be the route to go and remove the sharp edges/flashing molding areas that are not aligned and hurt flow. Ive got a few hundred hours on superflo flow bench...and that being quite conservative, I'm pretty good at flow...now to find a good tune I can afford...that works...and gives 200 mpg, just kidding but I would love better mpg and more power. so who ever has a pair of boxes 1 na & one turbo if there not on cars please check them so we all know whats what!! thanks to all!!
 
#14 ·
It appears that I was more interested in this that I thought, or maybe just wanted an "excuse" to avoid yard work.

As far as I can tell from the catalog specs, my shop vac flows about 325 CFM, although this could be wildly inaccurate.
Using an NA top on both the NA and RL bottoms, I measured a 2" WC pressure drop across both of them.
Using an airbox bottom with the resonator and inlet trumpet cut off I measured 3.5" WC with the NA top and 4" WC with the RL top.
All measurements were done with the same filter that showed some dirt, but a comparison test with a new out of the box filter gave the same pressure drop.

My conclusions:
>The bottoms flow the same, and the inlet trumpet makes a big improvement in flow over a square hole.
>The NA top flows slightly better than the RL top, probably because of the shape of the exit. See the picture for a comparison, the RL is on the left.
 

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#15 · (Edited)
yes cutting the trumpit will screw up and lower flow a lot.a whole lot .I did not remove that. if you have one that has been done it needs a new one made for it with a bell mouth.you could even make it down leg to get fresh air from the incoming air stream(via a nicely trimed hole sealed good to the tube that feeds the radiator fresh air. or a nicely made nacca duct to scoop up fresh air. all air entrys need a bell mouth to flow thier max. and yes if your good a shop vac can make a nice flow bench. but remember day to day it will read different due to atmospheric conditions. and of corse the voltage. thus a flow bench has to be calibrated daily if the weather dosent change, if it's changing it needs it frequently.and a correction factor is computed. also CFM means absolutely nothing with out the pressure drop it was taken at. many company's fudge their CFM ratings by flowing things at a different rate. thus a item that flows 275 cfm may flow 25 cfm lower than another thing that flows 260 cfm......it's not lieing but it is "misleading" if you dont know that it was flowed at a different rate.thus the fudge factor may slow you down.

Im pretty sure if the turbo box top was belmouthed it would increase the flow a lot. and could be done with a heat gun and..some creative thinking ahead of time to get the shape right and not all wonkey.( make a wood puck that fits the tube perfectly with a nicce raidi( do it on a wood lathe) then cut off the portion that flat agnist the top. heat the right portion and slowely reform that inlet to a belmouth. free hp. the na box top is good in that dept. I was wondering if the trumpit cross sectoin area was deeper and or wider on the turbo box. I may add another trumpit to my box in the muffler portion that is connected to the main air box now ( I revized a wall with a nice rectangle hole about1.75x1.25 in size to breathe through it too.only one "muffling" box can be connected this way.the others do not intersect the common wall of the main filter box.)
 
#17 ·
The bottoms seem to be the same, and definitely flow the same, trumpets and all. If the resonators are different I can't tell with steady-state flow.
The bottom without the inlet bell is an un-finished project that is intended to move the box forward, and the inlet bell will be re-attached after the resonator is removed.
It has not been run so I don't know how it will sound, but it really won't matter because the supercharger will be between it and the engine.
 
#18 ·
ebay has some nice bellmouths that could be used.or...duck it down through the pannel below it into the real fresh incomming air with a proper inlet duck of coarse...mallard might work...they have pretty green heads.or a nacca duct would be better less feathers to ingest .there are also some turbo bumper inlet ducts that could be used. Im still thinking on mine... trying not to add a turbo or super charger but that may be the only way Im happy...or build the motor the way I want to but.....that could get expensive.and Im trying for better mpg and better power to save a little at the pump....so..stroking the crank,rework the pistons, ceramic coat the pistons&chambers,dfl coat all the bearings & oil pumpkenhousen thingy....possiably mill the head, but that may not be necessary with adding stroke & reworking the piston tops for higher cr&closer better quench&valve/piston clearance...then the add expensive of camshafts....and,.....woobly booger deleate ( balance shafts)and.... **** I got this car to get out of racing....sort of. yes I should of get a gxp. but this was so darn pretty!!!
 
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