[kingsley]

I've always believed that induciton kits are generally a BAD THING because they suck in hot engine bay air rather than nice cool outside air.

However, I see that Abbey Motorsport recommend them as one of the first upgrades. I've seen people here talk favourably about Abbey so what gives? Surely it's bad to suck in hot air from the engine bay? I know you've got a big intercooler but it's not a good start, surely?

 

[DCD]

Its very bad fot a naturally aspirated car...but for a turbo not so much. The air gets sucked in through the turbos and gets heated anyways before being cooled through the intercooler.....

 

[kingsley]

Hi,

I can see that if you have a nice large intercooler then it is not so bad because this will get rid of most of the heat for you.

Do people here find, then, that they can get much more power with the induction kits? Can the factory air box not be modified to give good flow? (I've not ever seen one so I don't know what they are like - I don't have a Skyline yet, just looking into it).

If you can suck COOL air with the same ease of air flow that an induction kit provides then surely this must be even better still. Has anyone tried this?

 

[Shin]

Hi

Hi,

Getting initially hot air is not good for performance.
Even the intercooler make the air cool, but if the original air is hot, the effectiveness would be bad.
Furthermore, we'd better to consider about maintenance of the filters.
Do you clean your filters frequently enough?

Yours,
Shin

 

[ph1]

This is something that I allways wondered, so my tuner and I decided to test my new engine before installing my "apexi super induction kit"..

outcome, 350kw (470hp) at the wheels, at 22psi (1.4bar) on a dyno dynamics dyno, using the std airbox with a panel k&n filter

result, my unused apexi kit is now for sale

 

[Josewick]

Something i have come acrossed now.. I have a k&N element in my GTST. At the moment, I have run it without the top half of the box since i have found that the induction section from the box ( the long oval / rectangular area) is pretty small. Also there is a seperately section that is placed directly "under the bonnet when the bonnet is shut" .I had a good look and found that the bonnet has blocked the whole section of it anyway hence "no real" cold air can be sucked. If I just run it as it is now with no top half of the box, the whole sucktional area will be the area of the filter "much bigger than before".. You will hear a great sucktion noise too.

 

[DCD]

My intake air temperature has never really varied after changing from factory air box to HKS PF. This is measured after the intercooler.

I chage my filters every 2500-3000 Kms.

 

[Andy T]

Induction kits

Well, I can only comment on the experience I had with my last car, an Evo 5, as the Skyline already had the HKS filters on it when I got it. I originally fitted a Ralliart air box to it, which effectively was a foam filter in a sandwich plate that made the air box bigger. I subsequently on Ralliart UK's (Now Extreme Autos) advice fitted the HKS Super Power Flow, which gave another 11 BHP. As discussed, there are pros and cons for both. I would think that as you run more boost however, the Induction kit type will generally give better flow, depending on material and regular maintenence.

Andy.

 

[kingsley]

How about leading a 3 inch diameter pipe from the inlet of each turbo to somewhere behind the bumper (is there room?) and have the cone filters on the end down there in the colder air stream?

DCD - interesting. The intercooler must be pretty good then!

I do wonder though:

• if charge temps after the intercooler aren't really much different, then the air mass flow must also be the same
• as we know, hot (engine bay) air is less dense and so a unit volume contains a lower mass of air than the same unit volume of cooler ambient air
• the above two points being true ... if drawing in hot air, the turbochargers must now have to work harder to maintain the same boost and power levels when compared to drawing in cold air, and thus have to spin faster ... ?
• assuming that the turbos now have to spin faster to achieve given levels of boost, is lag increased and longevity decreased?
• if the above point is true, the difference (ie how much faster it has to spin) may be small or may be large (not sure of the calculation for this one, maybe it varies from one compressor to another)

What does everyone think?

 

[DCD]

Don't know about that line of thought. After fitting free flowing filters I noticed less lag, quicker response, and a better overall preformance.
I think the main factor about aftermarket filters is tha actual quality of filtration compared to paper panel iems. There is alway a trade off...but since I don't live in a dusty climate I believe I'm not risking much. Every time I replace filters they are squeaky clean inside and dirty on the outside...meaning that the dirt that needs to be filtrated is being filtrated.

I'm still running a stock intercooler. Intake temp is always around 3 degrees higher than outside temperature. The intake temperature only rises to higher leves when sitting in traffic. Once you get going it all gets back to normal. The exact thing happened when using the stock airbox.

 

[kingsley]

Hi, I guess the standard air box is very restrictive then! The resulting turbo inlet vacuum must reduce the density of the air entering the turbos more than the heat of the engine bay.

A 1.5psi vacuum in the air box would be roughly equivalent (air density wise) to drawing in 50 degree C air instead of 20 degree C air. Has anyone done any vacuum measurements on the outlet of the std airbox or am I just rather sadder than everybody else?

 

[Andy T]

DCD- I think you hit the nail on the head with this one; Surely the whole point is that these filters work better because they do exactly that. I mean it's like fitting a carbon part in lieu of a steel one. Because the material is lighter / stronger / better then less of it can be used to achieve the same result in say strength terms. With these filters, it surely follows that because they absorb better, less material can be used, meaning the air has less material to pass through, and therefore can get on it's way better? I would assume that there is a point (presumably governed by the intake size) where the ambient temp under the bonnet does start to decrease the effectiveness in comparison to a standard air box. I would have to say though that with the Evo, I experienced the same benefits as you did.

 

[alex h]

AFTERMARKET POD FILTERS DO NOT FILTER OUT PARTICALS AS WELL AS OEM UNITS.

HKS Foam Filters are pants IMO. Engines that use them show more wear and tear than those that use stock filters.

From what little I know the best idea would be a large panel filter from, say, K&N panel filter (as they are proven to be good) inside a custom box with a direct feed from a NACA duct in the bonnet.

 

[Scott]

ph1,

You should of dyno'd it with the Apex'i and seen the difference.

Kingsley,

Your getting a little over concerned.
Once the car starts to move this hot air is purged by cool air.
You'll only be breathing in hot air while stationary, and you don't need power for that.
Also the GT-R intercooler being in front of a condensor and the rad
resists heat soak, and so isn't effected so much by standing around getting hot.

Check out the Technical section from the GT-R Home page.
There is an article I wrote about the pro's and con's of Air Induction.:smokin:

 

[kingsley]

Scott - cool (no pun intended).

I'm fairly good with the theory but I don't yet know the practical when applied to Skylines. Thanks everyone for your answers.

 

[Mycroft]

if you go to site posted below, fellow soarer owner peter has done all the work with figures to back it up, we all run these (well nearly all) and the pick-up/fuel economy is just superb.

http://www.users.bigpond.com/pgscott/BFIDIY.html