Thoughts on aftermarket air filter kits...

[clubhead]

Some of you would have read of my negative dyno experience after switching to a Evo Highflow intake. I've talked to several people locally to find out the reason. Finally, I got to speak to a rather prominant local racer/tuner today and what he said started to make a whole lot of sense. I don't think it's totally new as I believed I've read it somewhere before. Anyway, here goes :

- In all combustion engine, cylinders fire in sequence
- Hence, air is drawn into the cylinder in 'pulses' (Intake) and waste gases expelled in 'pulses' (exhaust) as well
- The piping length and diameter for the intake are designed with this intake flow in mind. Apparently, a longer intake route will result in higher torque at lower rpm. That's why some top end cars uses variable length intake routes
- Because air is drawn in 'pulses', the resonance chamber along the stock intake piping acts as a 'reserve' air tank to ensure sufficient intake air volume during peak 'pulses'
- Hence, rather than causing obstruction, the resonance chamber actually assist in boosting torque along the low/mid range

What do you guys think? I recalled reading a few posts where the major tuners from Europe (Techart, Gemballa, etc) does not replace the stock airbox or piping but just the filter element. I guess the stock piping along with its resonance chamber and heat shielding are very effective as it is.

So the big question is whether an ECU retune will resolve this issue ie. higher bhp/torque throughout rpm range with EVO intake kit (in my case) with ECU retune compared to stock intake with ECU retune.

I guess there's no concrete way to find out except to do another series of before/after dyno runs My intention now is to get a GIAC program for BOTH the EVO Highflow and stock intake kit. And then do dyno runs to compare... I wonder if GIAC will sell them both to me for US$1k or do I need to pay US$1k for each program. GIAC has a Flashloader that I can use to switch in between programs. This will certainly save me the hassle to send my ECU back for re-programming each time I wanna change it.

Having said all the above, it doesn't mean the exhaust manifold are very efficient on our cars. These are not equal length manifold and are manufactured with cost in mind. They also do not have a central merge collector where the manifold piping meets. As exhaust gases are expelled in 'pulses', there is a scavenging effect. Meaning for example, as the exhaust gas travel out of cylinder 1, the gases from cylinder 2 (assuming it's the next cylinder to fire) will just be ready to exit. The 'momentum' created by the gas from cylinder 1 will help 'pull' the gas from cylinder 2. Hope someone understands me here. So I think replacing the exhaust manifold and cats on our cars will definitely yield positive results across the rpm range, as shown in my previous dyno reports.

Ok, somebody say something

[Lux]

Your post makes sense. Only thing is, what you're talking about usually refers to the intake manifold after the throttle body...not the intake before. For example, BMW tightened up the intake runners for '96 and on E36 M3's to achieve more torque down low. This sacrificed some top end power vs. the '95 M3 which had slightly larger runners. Plenty of owners have swapped intake manifolds and dynos do show this.

Throw the stock box back in and dyno. If you regain your power and the a/f is good, there's no need for a GIAC.


.

[FUHRIUS]

first off, as with many aftermarket tuners who appear to overpromise and underdeliver, I think dyno shops are part of the problem here too. most dyno's aren't very high quality to begin with, their results vary, and there's no way simulate real airflow into a car at speed on a dyno, unless you in one of these hug wind tunnel-room jobbies. So, I'm not a big fan of being a slave to the local dyno shop.

second, I can really only tell you what I feel, and after test driving about 6 or 7 boxster s's of '00, '01, and '02 varieties, I can tell you that whatever TechArt did to my car (remember, I bought it used with the stuff already installed) they did a nice job of it...this car kicks prety good (and it's not just the exhaust noise 'fooling' me into thinking I'm going faster...though it does sound so sweeet!). And not necessarily in a 0-whatever acceleration test, and not necessarily proven out on authoritative-looking charts off some freakin' dyno machine, but in real world driving conditions.
Look, I think we all bought these cars for the mix of engineering science and qualitative magic...from the looks, to the sounds, to the feel, etc, etc. And I believe these cars have an organic element that is not easily re-engineered. So, while removing pre-cats and expanding throttle bodies seems obvious, and less restrictive exhaust and headers is probably the same, I'm just not convinced the EVO or anyone else can lay claim to a better understanding of what makes our sensual little beasts tick than the boys (or fraus, if you will) at Porsche do.
So, for me, as I drop the car the 3rd gear and get on the throttle to move into the fast lane and the my sweet six starts singing to me as it's curvy body coaxes swirling air in to meet it'sw new partner in the dance called combustion, I'm thinking....what the hell does this have to do with being strapped to an dyno in some dude's shop...and why do we keep trying to outhink the porsche guys who draw on 50 years of passion and knowledge in this area.
Poetic BS? maybe. but as Sheryl Crow aptly points out: "It's not about getting what you want, it's about wanting what you got."

And btw, the $7k techart kit that was installed on this car (that's the actual receipt and includes labor) included: new cat-back exhaust, pre-cat delete, new headers, new ECU, expanded throttle body, and a new air filter...but NO change to the air intake otherwise..oh, except for the add'l 'scoops' on the exterior, which I can't believe are anything other than cosmetic, despite their marketing stuff.

For what it's worth.

I can't believe I just wrote all that...must be friday...someone get me out here...I gotta go for a drive!!!!

[Brucelee]

I have installed several K and N filters in my day. Subjectively, they didn't do spit to make my cars any faster.

Looked OK though!

[Adam]

I agree with furious. Some things just shouldn't be messed with on the car. Porsche spends Millions of dollars every year on R&D and has much more tuning experience than EVO or most other boutique companies. With that being said, there are areas which could be improved because Porsche does have to meet certain price points or regulations ie: headers and cats.

[Fletcher]

After speaking to Rob at scargo last summer about his intake much of what he said made sense. I know they try and mimic the expansion chamber by the throttle body and use multi size/shaped tubing for the intake. Evo by the way now uses the oem expansion chamber at the throttle body, so this is obviously one of the good design areas. I know from modding many cars (last one was a Mini Cooper S) that a well designed intake can give some power increase at the expense of noise. In some cases ECU reflash is needed to take full advantage of this. Rob at scargo also made this clear to me.
That being said the Euro tuners largely use BMC filters and that's all. A slight increase in flow to complement higher exhaust flow is probably in order but by itself is probably a wash. Many subjects claim to feel an increase in performance with the evo. In the real world maybe they do (most get the ecu done at some point). Can a dyno duplicate a real road experience, maybe half way. This could explain some of what clubhead has seen with his dyno results. The lack of true air flow is the biggest difference (around engine and into engine intake). Fans just cannot duplicate rolling down the road especially at higher speeds. Is it a waste of money....who knows. Sure, before and after dyno runs can tell alot but don't deliver the whole picture (a graph based on third or fouth gear full acceleration run, usefull but not tell all). And dyno's differ like you cannot believe. Mustang dyno's are much less likely to show a few h.p. while a dynojet can show 1-2 h.p. on it's graph easliy. Maybe there is more to be said for the fanny dyno after all. It is tuned for your car and experience after all isn't it. I am sure we will see more dyno plot's soon for intakes like the evo and scargo and I may well buy one at some point. Whether I will dyno or not is VERY debatable in my own mind. For every subjective fanny dyno that is out of calibration, there is at least one real dyno's that has issues of it's own (lack of high power fan's, corrected h.p?, .not to mention the typist behind the keyboard...no offense intended). They are all just tools and need to be put in there proper place in our minds.
"The truth is out there" Mulder said. It's just that every case may present a slightly different truth.

[Adam]

Originally Posted by Fletcher

That being said the Euro tuners largely use BMC filters and that's all..

Looks like I made the right choice on this one. This is the only mod I have on my car so far and well worth the 70 bucks.

[clubhead]

Fletcher, while talking to Scargo, did you enquire about the oversize throttle body? I'm thinking of doing that down the line but as our cars are using drive-by-wire throttle, my mechanic says removing it is not as straight forward as unplugging it out. There're some calibration to be done...

[clubhead]

Originally Posted by Lux

Throw the stock box back in and dyno. If you regain your power and the a/f is good, there's no need for a GIAC.
.

Hmmm.... I'm still tempted to get the GIAC and see what gains I can get out of it. US$795 is not that bad. But eventually, I will put the stock airbox back and use a BMC filter to see the difference...

[Adam]

I don't think you will be disappointed with the GIAC club. I looked over their website thoroughly and they seem to be on the ball. It looks like they did their homework and test their products under alot scrutiny before they sell them. I liked the chip at 1,200 bucks but I really like it at 795. Is this a limited offer or a permanent price cut?

[clubhead]

Originally Posted by Adam

I liked the chip at 1,200 bucks but I really like it at 795. Is this a limited offer or a permanent price cut?

It seemed like a permanent price cut to me when I spoke to them yesterday. It's apparently because in the past, a new chip needs to be soldered onto our ECU. But now, it's just going through a FlashLoader to 'flash' the new program in. But I mistakenly thought it was a flash program all along...

[Brucelee]

"End of the day, I'm convinced not everything stock and engineered by Porsche is the best. Unfortunately, like it or not, there are people out there who subscribe to this. There are parts that can be improved upon. It's a matter of finding out the 'right' replacement that will gain bhp/torque.
Edit/Delete Message"

The issue seems to be one of cost/benefit analysis. In other words, how much time and money does one spend to gain some HP, which we hope is usable HP.

If someone says, hey, spend 500 bucks for 20 HP, that sound really good to me.

If someone says, spend $5000 for 20 HP, well, that sound really lousy to me.

If I spend money and get nothing, well now I am really mad! :dance: