Stock airbox intake flow (pics)
 

During my research on a custom intake, i never did see a pic of the stock airbox opened. I heard how restrictive it was and wanted to see it for myself. It does look turbulent, as the air takes multiple turns before going through the maf.


http://986forum.com/forums/uploads02...1556789224.jpg
http://986forum.com/forums/uploads02...1556789197.jpg
http://986forum.com/forums/uploads02...1556789178.jpg

Stock airbox sucks and is barely adequate for 2.5l.

Thanks for posting this. A picture is worth 1000 words! Always wondered what one looked like on the inside.

Forgot to ask...so what’s your design for a custom intake look like?

Put in a 987 air box.

http://986forum.com/forums/performance-technical-chat/32074-987-v-986-air-box.html

http://986forum.com/forums/437845-post182.html

Gotta be something easier than doing that. Watched a few you tubes including Newart’s and man what a pain.

before it was figured out that the 987 airbox fit in the 986, i tried one of those carbon dynamic airboxes (cda) and just not enough room in there. about the only other valid solution i've seen is i think the fabspeed 987 solution that put an air filter in the gap between the rear quarter panel and the engine bay.

Sure, if you don't want cold air induction.

Gotta agree with the King on this one. I’ve seen a couple of the fabspeed design mock up’s in our cars. Cleaner design, leaves A LOT more working room in the engine bay and it’s still a true cold air intake. Much easier than squeezing 10 lbs in a 5 lb bag.

You will get more air with the kit FabSpeed offers, but it's not a cold air induction kit like the 987 air box is. For $400, not worth it to me.

https://www.fabspeed.com/porsche-986-boxster-evoms-v-flow-air-intake-system/

The 987 air box fits perfectly fine in the 986, you just have to move some stuff out of the way to get it in there. Is it easy to install, nope, but IMO, well worth the time and effort.

:cool:

sorry, i wasn't referring the 'hot' air intake, but this guy ...

https://soulpp.com/product/porsche-987-1-cayman-boxster-pcs-innovations-high-flow-intake/

edit to add the fabspeed version ...

https://www.fabspeed.com/porsche-987-2-boxster-cayman-competition-air-intake/

Why in the world would you install that on a 987? As for the first link saying it will block water from getting into the system, I find that hard to believe, but possibly manageable on a 987, but on a 986? Also the claim of 12 whp gain on a 987 I find hard to believe.

The $800 lol FabSpeed kit doesn't even address the water issue, but they do say it's for competition.

They are interesting, would be much easier to install, but I'll stick with my 987 air box. It works perfect.

Holy balls!
$400 for a couple pieces of tubing?!?!

...and $800 for basically the exact same thing from FS?
That is laughably stupid! :D

But don’t forget... you get a “permanent” oiled air filter and a cool mounting plate too!:eek:

I have to agree that the 987 box is much better than the stock setup for sure. And you’d have to be an idiot or a billionaire to buy $400 - $800 worth of plastic/rubber tubing. However, I still see a lot of merit in the design. It’s simple, free flowing, utilizes a space that is protected from engine heat and readily available, lighter, etc. What I struggle with are the water entrainment issues. On most of my other cars the intakes are located in the front grill and direct the air (more or less) straight back to the throttle body in a very short distance. On the Boxster, while some water may enter the air duct, it would still have to get through a filter and travel you heck of a long way before reaching our throttle body. What am I missing?

well, $800 is stupid, but $400 not so much. you do a 987 airbox it will cost you $200 or so with txes and shipping, at which point you have to do a bunch of fabrication (time = $) and buy couplers, joiners, elbows, hose clamps, etc. i mean, the gas for the multiple trips to the post office/hardware store adds up, you know?

the water issue is a red herring. one guy on planet 9 installed one and drove it in a torrential rain and saturated the filter. became a big deal, impacted sales, so now vendors are trying to mitigate it. with my 987 air box, and the trimming i have done to the filter hanger, etc., there is a clear shot from my filter to the great outdoors (rain and all) and never had an issue.

otherwise, it is easy to fabricate and there is a how-to on this forum. a piece of lexan cut into a trapezoidal shape, a cone filter, and some silicone/couplers.

my review of it was this: resistance to airflow caused by the air filter is proportional to area; the larger the filter surface area the better (hence why the 987 air box is such an improvement over the 986 unit). measuring the inside of my fender well, there was no way i was going to fit a filter as big as the one in the 987 airbox.

Just as a point of reference, I'm looking to revise the air intake for my 03 Boxster S. The Evo product looks pretty nice and would be easier to install. The 987 airbox makes sense, but is a bear to install. The price for either is about the same. For the 987 pieces, Ebay has them all, but it looks to be about $400 total, the airbox, tubes, throttle body and plenum. In my mind, the only reason to do either the Evo or 987 is to get the 74mm TB and greater airflow.

As to whether one or the other is a "true" cold air intake, the Evo looks to be sealed around its perimeter, and the 987 box is self contained. Both draw from the same source. Is one significantly warmer than the other? Dyno charts for both are about the same. Fabspeed published dyno runs for incrementally modified 986s. Eventually they ended up at the Evo airbox, full exhaust system and their ECU tune. I believe the final increase was 27-30 hp above base.

If you think that EVO air box is sealed, you're sadly mistaken. You are correct, if you're going to do the air box, you should do the full intake system, including the larger throttle body and intake pipping. I would say on a 986 3.2 engine, just doing that you're looking at around 18 HP gain. I don't have a tune on my car, but with my mods, I'm getting around a 30 HP increase.

Your 987 air filter is much larger and would not be saturated by water as easily as the smaller air filter on that $400 kit, plus the 987 air box has the filter inside the air box and not sitting right in the smaller vent area of a 986 like the $400 kit. I waited 2 years to clean my K&N air filter and when I pulled it out, there was plenty off clean area on the filter as to not starve the engine for air. After cleaning it, I didn't even notice a difference. There are trade offs going either way, if you never drive in the rain, then that $400 kit would be a decent upgrade, but if you want the best all around air box for the 986, put in the 987 air box. Yes it's more labor intensive, but worth it IMO. I'm still scratching my head why anyone would put the $400 kit on a 987.

I would have went 987 airbox but the difficulty in fitting one in swayed me away.

I'm still working on my new setup but for now its an aluminum airbox with a cone filter inside, a snorkel attached on the outlet, fed to the side vent. I cut off the snorkel piece on the stock airbox and used it as a block off plate and used foam tape to seal any possible gaps.

So far I've been seeing 20F above ambient(60F average days) in city and 5-10F on hwy.

http://986forum.com/forums/uploads02...1556943773.jpg

My mods now are 3 inch intake tubing(airbox inlet/outlet is 4inch) 997 throttle body and plenum. Headers and catback.

Just thought Id throw a wrench into this old thread :)

https://www.youtube.com/watch?v=l1Volf_rp_I

https://www.fabspeed.com/porsche-986-boxster-competition-air-intake-system/

That basically looks like the EVO intake Fabspeed used to sell, only now more expensive. It still doesn't seal the engine bay from the filter section. That rubber on the top edge is below where the top cover will be, it will never seal like that. Why can't they just make it a sealed box with some kind of air tight door to service the filter? Why does it have to cost so much? I mean really $500 for a piece of metal, a foot of plastic tube and a cone filter.

I agree the price is quite outrageous.

As for sealing, I dont think its a problem. If you find it doesnt seat well, you could add foam or something else under the rubber seal to make it tighter.

But, honestly, to me it just demonstrates all the naysayers saying you NEED a stock airbox to make power are saying nonsense.

There is nothing magical about their design. And the M96 works just like 100% of all engines out there. Less restriction = more power.

They show considerable gains on that dyno. Now, on the other hand, I'm sure you wont get that in all conditions. Especially on a hot day when things are heat soaked.

I can build one like that, only thing is to find a MAF flange for 986/996 MAF sensor to weld on a suitable aluminium pipe.

EZ-PZ....

https://shop.advanceautoparts.com/p/spectre-mass-air-flow-sensor-adapter-87051/11430025-p?c3ch=PLA&c3nid=11430025-P&adtype=pla_with_promotion&product_channel=online &store_code=&gclid=CjwKCAiAhJTyBRAvEiwAln2qB3I459S o1fmiJ8C87j9N4NnnrZZOKqzM7L05jwpSLgje1VT4aKsCthoCx 4MQAvD_BwE&gclsrc=aw.ds

You can get MAF housings cheap. Bolt on plastic configuration, or the aluminum like above.

It's easy to overthink this stuff and get sucked into the marketing hype vortex.

Back in 2005 there was a lot of independent dyno testing going on to compare different intake airbox designs. The airbox should do 2 things well: Let plenty of cold air in while keeping the hot air and bad stuff out. As I recall these were the basic results after a LOT of testing:

Stock 986 airbox worked fine on a 2.5L

987 airbox added 1-2hp primarily on 3.2L models

Cone style EVO filter inside the engine compartment lost 2-3hp due to higher intake temps, and rapid oiling of the MAF sensor caused the engine to run poorly. It was discontinued.

Boxster Spec Race cars all run stock 986 box and (I think) stock paper filters.

Did no one test a well sealed paper cone filter?

Just seems like they abandoned half way through.

Boxster aren't the only IC engines on the planet, principles of physics and engineering arent different in the M96 universe, unless I'm mistaken.

There is a reason that ITBs are the best nor NA engines, if you manage the air fuel right.
The most direct route is the best.

It just seems like everyone who abandoned just didn't build a well sealed unit to keep hot air out.

No one built a well sealed cone style paper filter so no, none tested. What is your attraction to the cone style specifically? Do you think it flows significantly more air than a pleated filter in an airbox designed and tested extensively at the Porsche R&D facility? Have you actually flow tested this yourself or do you rely completely on marketing claims? I suspect that the Porsche R&D testing is 100x more sophisticated than any aftermarket air filter company. What does Porsche use for their winning factory team GT3 Cup cars at 24hr Le Mans and 24hr Daytona? Check it out yourself.

Show me some hard independent data and we can have a conversation about which filter types measurably improve intake flow rates. Bisimoto did about the most extensive independent flow testing and he did not find significant improvement on the Boxster. Test results were within the margin for error (1-2hp) on his dyno for a given day.

There are applications for a cone style air filter and Bisi uses 2 on his completely custom 850hp Twin Turbo 911. They were an obvious choice because the turbos hang off the back of the car and need to be cleaned often being fully exposed to road grime. He has now gone fully electric with a 650hp Porsche 935. Fun guy and he lives about 20 minutes from my house. We see him often at events.

https://www.youtube.com/watch?v=-4HVBx1TmGE

You're almost right. Or shall I say, half right.

I've been contending since I joined the Porsche world that there is no magic. These motors will respond to improvements, just like any other.
But here's the caveat: make sure you're really improving.

Why are ITB's the choice for many extreme- performance applications? Not because the most direct route is the best, as you stated, but rather because they are best at delivering large volumes of air at high velocity in a meter-able fashion. A difference with a distinction.

ITB's are not always better. They become a favored choice when traditional (cheaper) methods can't provide enough air for a motor's specific volume at rpm. But up until that point, they offer little (or no) benefit.

In other words: can your 986 engine in standard trim use more air than the OEM intake can provide? Tests show the answer is clearly "NO". And there's where the Porsche "magic" (which isn't magic at all) happens: that 986 intake was designed well enough that you need to modify other things before you'll see a need for an improved intake. This isn't your LS Camaro, trying to breathe through a tiny slot in a plastic can, with a spring loaded flap blocking it.

Start with the exhaust. Get it to breathe better there, then maybe a hi flow air filter can help. Then increase the size of the TB, and you will want to increase the size of the intake feeding it. But just throwing on an intake that can feed more air than the motor can use isn't going to help it.

And then there's the risk of introducing hot air while you're at it.



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Hi May!

All that makes sense.

What about gutting the 986 aitbox internals... removing any internal mufflers... bends... twists... and turns? In other words... mitigating the internal turbulance caused by the twists and turns? Would have to remove the airbox... cut it open... take a Dremel or something to it... seal it back up... reinstall.

I'm curious.

I know Porsche engineers ran the numbers... but I'd like your opinion. :cheers:

Thanks!

I 100% agree, that an intake by itself, wont give you much.
Exhaust, plenum, throttle body, etc.. are necessary to actually benefit.

And we are agreed as well that heat management is key. Its obvious by the placement and closed nature of our engine bay that, its not enough to just throw in a filter with more direct intake route.

There just seems to be this contention that there is no way to make more power than stock box, which I just cant believe from experience.

Nah, you're right. I think where things get lost is the real cost:benefit. Take my 5.7 hemi: Its pretty easy to add a CAI and swap a tune and find 20hp. Hell you can find 12-15 with the CAI-alone.
But with the m96 in the boxster, you need to spend large dollars on multiple modifications to see the same sorts of increases.

On mine, I've done headers, de-cat, by-pass valves, 78mm tb, 987 airbox and intake with the EVO filter and riser , lwfw, udp, and a tune. Yeah.... add that up in your head. Haha. I bet I've found maybe 5HP on top. (Though I've fattened the curve a bunch). I haven't had it on a dyno, but I've got a lot of years on the "butt-dyno".

Why'd I do it then?
Can't help myself. I modify, therefore I am. It's what I do. It's the bigger part of the fun of an enthusiast-car, to me. I've got some mods I don't like much, and next year I'll change them.

I think ya just have to be realistic about what you may find, and to many / most people the cost: benefit to modifying the M96 in the boxster just isn't there.

Fun fact: i'd probably get more performance increase by going on a diet and dropping 30lbs. Hahaha

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There's 60HP right there. :dance:

Indeed, Im in that same boat :)

Installed Sparco Chrono Road seats, as my stock seats where torn appart and wanted something to hold me better.

However, to fit my fat a$$ I probably ended up with heavier seats than stock, or at the least no weight loss...

They look good though :)

As for the rest, you are right, people assume because you get massive intake gains on some cars, you will get it on others.

I agree with "I modify, therefore I am!" :)

It takes every inch of my soul not to tinker with my winter car, but so far, so good.

Me too!! We should get a group of members and do a "Biggest Loser: 986 Edition"! :D

The whole point of modding a car is to measurably increase performance and that is tougher on a Porsche because those crazy Germans already did a pretty good job. Just bolting on sexy parts won't get it done. We need independent measurement and verification to separate legit gains from the BS, and get beyond the marketing hype which is pretty rampant.

All of this 986 stuff was tested extensively about 20 years ago and the results were interesting and often disappointing. Aftermarket products failed to meet their claimed HP improvements across the board. Fabspeed makes sexy products and their exhaust is arguably the best looking and best sounding of all aftermarket exhausts. They claimed a 22hp bolt-on gain but independent testing showed the stock exhaust actually made more power with a fatter torque curve. They claimed a 15hp gain with the EVO intake but independent testing showed -3hp and higher intake temps.

Underdrive pulley- Verified 3-5hp gain to the wheels across the RPM range by reducing parasitic drag.

Weight loss- Verified improvements in acceleration, braking, and cornering.

Plenum- Combined with TB, exhaust, and custom software tuning- 10-15hp depending on model with more improvement on the 3.2L.

Airbox- 987 box performed the best gaining 1-2hp on 3.2L

If we are serious about improving performance we need to do the math, and before and after testing to confirm that gains are real and not just marketing BS.

In an earlier life, we used to hot rod Ford, Chevy, and Honda motors to race at the drag strip and off road. Detroit mfg tolerances were pretty loose then with a lot of internal friction and you could make 30hp verified simply with a balance and blueprint, getting everything up to the engineering specs. Add a real intake manifold, Holley carb and custom exhaust instead of those stamped things from Detroit and there might be another 30hp verified as we allowed all that displacement to measurably breathe better. Porsche doesn't miss much, tolerances are a lot tighter, and we have to get more creative to squeeze more power from these well-tuned little mills.

Tuning is fun as long as you independently measure and verify gains along the way. This requires regular visits to a fairly precise dyno. Trusting aftermarket marketing hype is a fools errand and leads to disappointment.

These guys did a pretty good study on Boxster tuning and they did significant before and after testing along the way. A few interesting findings: They did not find improvements with an underdrive pulley as many other's have seen and verified. Also the stage 1 ECU remap caused the power to be down 10 hp vs the stock ECU tune on their modded car with a rich AFR. A custom dyno tune would probably deliver more juice if they got the AFR really dialed in.
https://www.youtube.com/watch?v=kja5LSsUT_g

I'll put this here instead of a new thread as it is somewhat applicable. Care to comment on my plans on a 2.5 base? I'm thinking maybe +10 whp?

- Underdrive pully - check.

- Lightened flywheel/clutch? - In a nutshell, Raby said the 2.5 could handle this the best. Is there such a thing as a lightened dual mass flywheel?

- Weight loss- -367 lbs. (2,455) so far. Goal around 2,350, including weight added back on (structural stiffening and body work/aero).

- TB, software?, exhaust (headers, 2 cats, no mufflers (for weight loss) - still need the headers. Will I need 2.5 specific headers? Would Pedro's system work adequately with the semi-custom software? Alternatives; rolling dyno plus? I'm looking for a broad range torque improvement, not 6700 rpm hp. This is more of an auto-x/street car than track - built for fun and don't care about being class competitive.

- Manual steering.

- Re-working of body/drag but I'll leave this alone for now but it will reduce the hp required to go x mph.

Weight loss and UD pulley are a slam dunk. Intake/exhaust/DME software are a moving target and best done together with a custom dyno tune. I don't see much benefit in any off-the-shelf flash unless it gets further tuned to your specific car and mods. Everything needs to work well together and then you can find some hidden HP.

A lightweight flywheel was on my brother's 2.5L car while mine retained the dual mass. It definitely spooled up faster and was a little quirkier to drive around town. We never dyno'd B/A this change and we noticed no difference in lap times. He was usually a bit quicker on tight tracks and I was quicker on more open tracks, always within a few tenths.

The only benefit to me for manual steering is a little weight loss. The PS pump is very reliable once the UD pulley is installed.

Good luck and test/verify as you go!

For manual steering, is anything needed to be done to the rack, or just remove the pump and lines?