Entertaining the Pedro intake mod...
 

http://986forum.com/forums/uploads02...1513035922.jpg

1998 Boxster.

The piece/connection in the yellow circle.

What purpose does it serve? And... what would be the workaround if installing that Pedro intake mod... or something similar? How would that be bypassed, as it wasn't mentioned in the Pedro instructions.

Thank you.

Its my understanding that its a resonator that cuts down on intake "noise". Pedro's modification replaces the whole pipe that this is connected to with a piece of straight 3" PVC pipe. I plan to do Pedro's modification this winter.

The resonator is at the near corner of the pipe before the throttle body. You can see it 6 o clock position of the photo.

The pipe/tube/line/hose in the yellow circle, I believe, isn't capped off. It's leading under the manifold.

Are you telling me there's 2 resonators?

Thank you.

Red is the resonator.

Anyone?http://986forum.com/forums/uploads02...1513041219.jpg

No idea what that is but it doesn't look stock to me. I've had two '98's and the area in yellow is where the MAF sensor was located. I don't see it on your car.

No, maf would be at 10 o’clock from the yellow circle.

http://986forum.com/forums/uploads02...1513042573.jpg

Blue is the MAF.

tipronic i bet. provides addnl vacuum.

Yes. I have the Tiptronic. But, vacuum?

You're right..I didn't look close enough!

sure, why not. where does it go? if you follow it, it is connected to ... the vacuum system. really, although it is a big tube (it gets small at the other end, however) there couldn’t be any airflow in it as it is after the maf, so that air has been metered. tiptronic needs more vacuum than a manual car for all the geewhizzery on it, so porsche added an additional vacuum source. the air rushing down the main tube creates a bit of a venturi effect on as it passes over the opening of your mystery tube, and creates some more vacuum.

here’s a link to a similar thread ...

http://986forum.com/forums/performance-technical-chat/56336-whats-function-venturi-tube-tiptronic-2.html

A bit of a side discussion... In very simple terms a resonator (that extra appendage looks like an extra resonator) increases the volume of air in the intake tube without making it flow farther. In doing so it acts as a buffer for the vacuum.
In more precise language:
https://itstillruns.com/air-intake-resonator-do-12156112.html

Deeper still is the discussion of intake runner length. A few years ago I was swapping an SUV engine into a small car and noted the SUV had a much longer intake. In simple terms, length mainly effects where the torque peaks in the power curve. Longer tubes make the torque peak sooner:
https://mechanics.stackexchange.com/questions/25236/how-does-intake-manifold-runner-length-effect-the-power-curve-of-a-car

Then there's the 2000 and later M96 engines with the cross tube and resonance flap that can spread the torque peak across a wider range:

Thank you. I find a lot of value in your posts and responses.

That hose coming off the intake tube... in the yellow circle...

You can see that the intake tube wasn't modified for that hose to attach. The hose attaches to the tube, held with the hose clamp. The photo I took a couple months back... and haven't returned to the engine to see exactly where did the hose lead under the intake manifold.

Because the intake tube wasn't modified... I'm turning to the Pros: The forum members.

Thank you.

The parts catalog (PET) has 5 variations of intake tubing by year/model. Yours looks like is the stock tube for a 1999 and earlier Tiptronic. Here's the parts diagram (M249 is the option code for Tip.):
http://986forum.com/forums/uploads02...1513093933.jpg

Thank you. Just found it and wanted to report. You beat me to it.

It is the "Throttle Valve Tube". I read what generally it does. Seems necessary.

So... it came with the Tiptronic. I'll assume, unless otherwise corrected, that the manual tran arrived absent that pipe.

Does that mean that the Pedro mod won't happen on the Tip, or only with some additional fabrication to accommodate that valve tube?

Finally, if you know, what exact function is that valve tube providing?

Thank you.

sometimes i wonder why i bother to reply to posts ...

It takes a team. The Captain sets the course. The bridge staff works out the details. Everyone has a role.

Well done as usual. :cheers:

Because you are awesome.

My comments were intended to expand the conversation, not diminish yours.
:cheers:

This "sometimes"... how often is that? Were you being facetious?

You've ~2,000 posts to your credit. Obviously you've answered every imaginable inquiry. However, aside from sharing with me that the tube provides vacuum... actually, there is no aside. Me thinks that in those ~2,000 posts of yours lies the answer to my inquiry:

What purpose does that vacuum serve on the 98 Boxster? Further, to further massage your intellect, what changed after 1999 that rendered that line absent? What method did Porsche employ in later models to achieve the same result enjoyed on the 97/98/98 models? What was the workaround?

:cool:

Did I stump the pros? Nothing?

I am curious if anyone has any experience with this mod. Pedro states that it is really only for improved sound.

Most any of the mods done here will have little affect on the HP or Torque without an accompanying change to the computer mappings to take advantage of improved flow etc.

However some mods lead to faster response, improved sound, better functioning etc so it depends what your goals are when you consider an "Improvement".

Like Pedro said, improved sound in case desnorkling does not get you the sound you are looking for.

Don't think the juice will be worth the squeeze...

But if it makes you happy then go for it!

Good luck :)

Vacuum is commonly used as a switching mechanism vs. relays and solenoids.

None of us are here to "massage our intellect". We're here to share our knowledge and passion for Boxster's.

There wasn't much point in responding to these rhetorical questions. Your question was answered - you'll need to find a way for the Pedro exhaust to provide vacuum to the Tip transmission.

Thank you for the response. That would explain something I read along the lines of at a certain point a valve opens/closes, associated with the throttle.

With all due respect, I employed the 'massage the intellect' as my choice of words because it appeared that no one was responding to the original actual inquiry. It appeared that no one had an answer to my inquiry(s). In the future I'll tone down the vernacular to mitigate misconceptions, and to provide balance.

My other questions weren't rhetorical. I'm quite curious, now having been bitten by the Porsche bug. I've an eye on future Porsches, and for something that might seem innocuous, that vacuum line for example, I'm interested in learning about the progression. The improvement. That would be a general discussion and, last I checked, this is the forum for it. The BMWs I mastered the same way, and it was learning from people with many, many posts and lots of bruised-knuckle experience. People like you, likely. So, thank you.

:cool:

If it doesn't do anything other than increase noise, why bother? Do you want your Porsche to sound like a ricer with a cheap CAI?:barf:

There are mods that will improve your car's performance that are easy and (relatively) cheap, like an under drive pulley or a spin on oil filter kit. Or even a magnetic drain plug.

"Cool Prius!"

- Nobody

You haven't seen my Prius.

How many extra bhp does the magnetic drain plug give? ;)

On your car, 264hp.

That’s how many horses you will prevent from leaving the stable if your engine grenades due to metal in the oil. An ounce of prevention...

Yes. A ricer. I'm looking at fart-can pipes on eBay, too. 2 footers straight out the back, 6 inch cans. 26HP gain.

That under-drive pulley I've looked at... but read somewhere that there's a small piece that has to be ground down in order for that pulley to fit. Is that correct? I've the pulley on my Pelican wishlist... but have held of purchasing it until I know it'll just bolt on... no extra shimming.

The spin on filter in on that list, too.

AOS is next on the list of parts I'm hoarding, for in the spring I'll replace the AOS, plugs, tubes, water pump, thermostat, etc.

Cheers!

http://986forum.com/forums/uploads02...1513451978.jpg

Yes, a portion of the boss on the engine case needs to be ground down a bit in order to install the under drive pulley. Full removal of the boss isn't recommended as the boss might need to be used at a later date to hold the engine at TDC for repairs.

The installation recommendation is to only remove enough of the boss to clear the UDP while still retaining enough of the boss for future use.

This thread has relevant information and discussion. Do a search on "under drive pulley" and you'll find that this subject has been well discussed.

http://986forum.com/forums/performance-technical-chat/23645-installed-raby-under-drive-pulley.html

If you are considering tracking your car, then I would highly recommend a UDP. Not for the HP gain, which may or may not exist, but just to play nice with your peripherals, especially your PS pump. :eek:

For me I did the UDP for ps reasons as mentioned above, and imaginary or not, it felt like a nice little bump in power, especially in 1st and 2nd.

At least 15.

Thank you. Read the material... the boss... makes sense.

Cheers.