plusONETEN

iTrader: (1)

Im doing a vq35 swap into a 240sx (thread here) and im thinking about my options for the intakes.


the engine is from an '08, and i was just going to put in in as close to factory as possible, but i realized that my airboxes were crushed in the accident.


ive read the threads about intakes, and i hear mixed reviews... often bad though... should i buy some airboxes from another HR and just use them in my car? anyone have some laying around? should i just get some tube and some cone filters?

my MAFs are both fine, its just the boxes themselves that got crushed... i know that the engine can be picky about intakes, but im not sure why, so i dont really know how i would go about designing a 'good' airbox.



thanks for any input

SuperBlack350z

iTrader: (59)

enclosed box to keep the hot air out. It also gets the air from the outside opening. Kind of like a cold air intake. The 06+ has the velocity stack.

Italianjoe1

iTrader: (6)

The stock airboxes work well on the 350Z because they are a sealed system that works as a cold-air, almost ram-air system. Depending on your app, if you aren't feeding them as they are in the Z, you may not get the same benefits. You can't argue with factory tubing as far as MAF cals go and stuff like that.

plusONETEN

iTrader: (1)

i thinking that i may try and cut the plastic tubes off near the broken airboxes and just use the standard cold air intake type of cone filter.


if i made a custom velocity stack on the lathe and matched its diameter to the stock intake tubing, i could use a filter like the ones the pop chargers have.

i wonder if the length of the tubing between the filter and the MAF makes any difference... would i want to extend it a bit to make sure the air has stabilized and stopped swirling by the time it gets to the maf? i read in another theread that the MAFs could get thrown off by this...





i also noticed that the injen intake has an extra large diameter until right before the MAF sensor. does anyone know what the two diameters are? is the smaller tube the same diameter on the injen as it is on the stock plastic intake? and what does the tube look like when it necks down... im assuming its not just a 90, but something like a velocity stack perhaps?



either way, i intend to duct some cool air towards the intakes, as i have 2 leftover openings in the bumper that would be perfect for that...





anyway, heres a pic of what i mean. i would have to cut at the red lines, as the rest of the airboxes are smashed. atleast my MAFs are good though.

Italianjoe1

iTrader: (6)

The reason for the step down in intake tubes it to maintain the factory MAF calibration. You have to keep the size around the MAF constant, or the fuel trims will be off (car will be seeing less or more air than it's actually getting, because it's programmed for a specific tubing size).

There is no problem with using a longer or shorter tube between the filter and MAF, you just want something long enough so you get smooth airflow over the MAF sensor itself. Anything factory length or longer will work fine, and i'm sure you could even go shorter if space was an issue.

plusONETEN

iTrader: (1)

well, that makes sense to me, but i wonder, why not just make the whole tube factory diameter rather than just the part by the MAF?

i wonder if its to reduce total restriction, or maybe improve throttle response by having a little extra volume in the tube...

longer tubes of course reduce throttle response... if its enough to notice or not, im not sure...

Ziggyrama

iTrader: (15)

I would try to replicate the stock setup as much as possible. One of the most overlooked aspects of the intake is resonance. The factory setup was created with a specific length, diameter and airbox size to optimize intake resonance frequencies just as much air flow. This is why the stock setup is so good. People in lab coats spent hours tuning this thing using sophisticated equipment. Your best bet is to source HR air boxes and put a decent panel air filter in them. That will probably outperform most intakes you can find and it will be most cost effective. Larger or shorter tubing may not necessarily be better. My main point is that you don't have the equipment to make that determination so stick with what you know works very well. Good luck.