Stock air box

[Suprash]

Let's just put things in perspective and get a few facts into the mix.

 

First off, an aftermarket induction kit will certainly have a lower pressure drop across it than the standard airbox. I havn't done any real world measurements to back that up, but I reckon its a near on dead cert. Taking that fact insolation, aftermarket air filter are "better" than stock. No-one quote me out of context on that, though

 

The pressure dorp across a restriction will increase the more you try to flow air through it. Think of it like when you give yourself a love bite with the vacuum cleaner (everone does this, right?) Put it on low suck and you get a small hicky. Now, switch it to high and even though you've still got the same nozzle pressed on the same neck (hence the same air restriction, geometrically speaking) you get a BIG hicky. This is because the greater airflow causes a much bigger depression acorss the restriction. Generally speaking, any restriction will have a pressure / flow characteristic where the pressure drop increases with airflow.

 

Now, it was mentioned earlier that an induction kit was fine for the TT but "strangles" the NA. If you relate the above to the engine bay then you can see that this cannot possibly be the case, assuming that the NA airbox and filter are the same as the TT. The TT airbox can flow 6500RPM's worth of boosted air into the plenum, which is a hell of a lot more air than that going past the filter without the pressure drop becoming an issue. If the TT induction system can do this then it should be no problem for the NA. Because there is no boost pressure, the air flowing past the filter is less, so the pressure drop will be lower.

 

As for the issue with heat, its going to be a tricky one to bottom out without someone doing accurate charge temp measurements for aftermarket versus stock, but I rationalise it like this:

 

An intercooler won't refrigerate the induction air. Maybe it will knock off 5 degrees or so? Underbonnet temperatures can run nearly into three figures, so the potential difference between sucking air from outside to sucking it from the inside has got to be a benefit. Possibly a difficult one to actually quanitfy, especially when you consider that the TT will heat up the air with its turbo (even with an intercooler) whereas the NA will be using air at the same temp as whereever it sucks it from.

 

In the absence of proper measurements I can't justify putting an induction kit on an NA, because:

1) The stock airbox is good for the TT, so it should be more than good for the NA already bacause of the lower airflows.

2) Induction air at ambient temp has got to be better than air at underbonnet temps.

 

I think the big single guys fit induction kits because they dont have a lot of choice - and at the volumes of air they are flowing then the stock airbox might start to become a seriousl restriction. I still reckon that the reason you see so many tuned cars with induction kits is simply because "its what everyone else does".

 

I'd like to see some proper measurements done so that we can make a more informed decision, one way or the other.

 

Good right up Digsy, albeit a little over my head in places lol.....but Im still not totally convinced And Im also not agreeing with the fact that a NA is strangled by the standard air box, I dont believe that, my challenge is purely on heatsoak.

 

Sure having an enclosed air box with feed supplies should be a more benificial setup, but again, we're all talking theory, just like Blitz is, but how much of a difference is there when on the move, especially if your cone filter was boxed in with a cold feed supply, I mean theoretically its not far off the design of the standard air box then is it ??

 

I agree some cone filters are questionbable, and Nic made some good points.....

 

Im not going to sway one way or the other until any side can actually prove one way or the other, until then its a argument of theories in my eyes.

 

:cool:

[JohnA]

I've done pressure drop measurements all across the induction path, timings, the lot.

Have been through this bullshite debate dozens of times, I even created my website to cover such issues in more depth.

 

Sorry, but I can't afford to waste more energy preaching that noiz airflow

 

Hopefully Digsy is happy to continue...

[blitz supra]

Just to throw another reason into the debate about which is the better 'choice' - FILTRATION.

 

The filter element in the stock airbox, has a greater filtration area, compared to most pod filters.

 

Also the quality of the filter elements used on some aftermarket pod filters is questionable. Plus the location of a pod filter means it is more exposed, in comparison to a sealed airbox.

 

The reduction in filtration will allow more particles into the engine, which will subsequently lead to greater engine wear.

 

This old article was an attempt to test the performance of a number of aftermarket pod filters.

 

http://mkiv.com/techarticles/filters_test/2/index.html

 

Good point Nic

The HKS green mushroom filter is apparantley one of the worst filters for filteration, there is a test on one of the Supra sites and it shows how bad it is,

 

That is on the list to replace, but as i got my HKS kit brand new i thought it a bit of a waste to immediatley change the cone,

 

Would be interesting if there were any test info on the Apexi Cone as a comparision to the HKS in regards of filteration quality

 

Original when i took delivery of the car it had a HKS ELEMENT, in the stock box ,

 

This was really poor and i was only getting 15mpg around town!! when i took the element out it fell to peices in my hands, although looked fairly new

[JohnA]

Just a quick supra-specific note here: When I compared the APEXi induction wonder (paper element) with the stock panel, it had almost 1/5 of the active area. 1050cm2 vs 5000cm2

Shocking.

 

Air pre-heating came as a bonus.

[Suprash]

I've done pressure drop measurements all across the induction path, timings, the lot.

Have been through this bullshite debate dozens of times, I even created my website to cover such issues in more depth.

 

Sorry, but I can't afford to waste more energy preaching that noiz airflow

 

Hopefully Digsy is happy to continue...

 

Sorry dude, but I dont spend all of my time on here so wasnt aware of what you had done or read about it, was just discussing things in this thread. If you dont wish to get 'into' it again, then dont......... :cool: