Intake plenum and 911 throttle body

[Ben006]

I just reset the ECU, we'll see how it does tomorrow.

I tested the intake at up to 240F, but I measured only 150F after a drive, so it should be good from a temperature point of view

[Ben006]

Hi !
Just did 55miles today on my daily commute, and everything worked fine !

I only did one pull WOT, and yes, it feels more powerful even on the first gear (1st gear pull are usually not showing great improvement due to flywheel inertia).

The intake sound changed too ! louder at any speed when you put your foot down !
I wanted to make a video at home, but my neighbours were there trying to rent their condo, therefor I couldn't rev the engine, it would have looked bad !

I'll try with the dashcam if I don't forget it.

Also, I found a better way to measure the effectiveness of the modification.
Taking acceleration measurement is hard because you have to repeat the exact same procedure each time.

So instead, I'll use my OBDII scanner to get MAF readings.
What we want with the plenum is better airflow at WOT, and it's easy to see it with the scan tool.
We'll see if there is an improvement over stock, or it's just the noise that makes me feel that.
I just have to do pulls from 1000rpm to 7200rpm in any gear to compare.
As long as the weather conditions are the same: Today 29°C and 55% of humidity.

Ben

[epapp]

Would love to see some OBD MAF information with pulls and steady state driving

[Ben006]

It's around 20g/s calculated MAF if I remember.

I just did another pull on an empty back road, and yes, it definitely pulls more after 4500rpm.
It red 210.5g/s.

But looking at the data, max RPM says 6762, I might need to hold the throttle longer...


Next week I'll take the plenum out to inspect it. I'm pretty sure it will be OK, but I have to, to collect data with the stock plenum.

If someone has a S model with the 3.2L (or bigger ?) and wants to try it and tell me how it feels on a bigger engine (I have the 2.7L, and I think the difference will be bigger with the 3.2L !), and also collect some data if he can, tell me

Ben

[steved0x]

I did some pulls a while back before and after doing my UDP and found a couple things.

The first was that (at least with my Bluetooth odbii reader) I was only getting updates once a second, useless for counting time to make pulls from x rpm to y rpm. I then used durametric which can read many times a second. Still not conclusive, probably due to many factors, grade of road, temp, and who knows what else still felt more powerful.

I think your idea of measuring a specific metric like air flow at WOT has a better chance fir a meaningful result. Or if you were able to do multiple before and after runs on the same day, same temps, etc.

There is a good thread on rennlist somewhere about doing pulls with a durametric that may be helpful and I will try. They focused on pulls in 3rd which did not get a person too high into the triple digits.

Good luck and looking forward to reading more.

I have got a cold air intake I picked up with a trailer I bought, while unsure of the various benefits it does come with the makings of a new intake tube that may be useful to folks doing this mod, look for it in the for sale in the next week or two.

[Ben006]

We have a new wireless 10 000$ scan tool at school, I'll try to borrow it and do some pull with it, it has a really high frame rate.

My tool is fast enough though

I did another pull earlier, red 198.5g/s, but it was a first gear pull, and it was really hot outside.

I'll do more

Is it a cold air intake for boxster or a random one ?

[steved0x]

Specifically for Boxster. I can take a picture tomorrow at lunch if desired and try to get a brand/model.

[Ben006]

Good, you might be able to sell it easily

Well, I have a good and two bad news ...

The first bad news is I had to remove the plenum, to check it.
My cel went off on my way to school this morning, nothing bad, the well known P1128 and P1130 codes. I had a vacuum leak on the AOS to plenum hose.
Because the plenum is a prototype, this part is not as good as it can be (I will use another method to connect it on the next prototype).
Also, I saw that it collapses at idle, nothing bad, just 2 or 3 millimeters (3/32").
The vacuum is around 8inHg at idle and it pulls everything together (just look at the whole intake system when you step on the throttle and you'll see it moving from the variation of pressure).
That's why the by pass tube is ridged, prevent it from deformation that would cause the valve to bind.
The stock plenum is made from a material stiffer than mine, and the boss where the two parts of the molding are bonded increases its rigidity further more.

Then comes the second bad news... I have to make another prototype ! A better one.
But that takes money... and, I don't have money to spend on that at the time :/
So unless someone's willing to be a guinea pig and have a prototype for the price of a printing ...
I think the plenum is still safe to use, but I want to inspect it first (it's full of oil... from the AOS).

Then the good news !
The bigger TB does make more power !

After installing the stock plenum back in during break at school (I had it in a bag in the car for safety !), I plugged the scan tool back, and got some readings.
And it does show less flow and way less manifold pressure at WOT, which shows that the bigger TB and plenum is in fact freer flowing and have the potential for more power.

My butt dyno also noticed the low end torque was back below 4000rpm with the stock plenum, but the engine chokes past 6500rpm and had less top end.

I'll try to get more datas, but the IPD numbers are believable from what I've saw !

So now, back the computer to make a stiffer design ! (A wedge would stiffen it enough... just saying ^^)

Ben

[Ben006]

Hi !
Turns out the cel wasn't caused by the plenum, but the O2 sensors, as it came back today, but just the P1128.
Since it's affecting only one bank and the car runs fine, I guess it's just the sensor (they are 13 years old now !).

So, guess what ? plenum is going back in as soon as I can
I still designed a new one, and I think you'll like it !

I'm getting used to the software:



Ben

[Ben006]

Hi !
So, nobody wants to try it on his 3.2 (or bigger) ?


turns out the check engine light was in fact the O2 sensor

I'm still working on the new, stiffer version, but the current one works.

So If you want to give it a try, I'll send you everything (plenum, TB, intake tube and hoses for the AOS connection), as long as you're collecting some data and sending it back to me after you're done playing with it !

Ben

[mavis.d]

I could be interested, what's involved?

[Ben006]

You might be a few hours late, I might have found someone with a 3.2

I'll still PM you with the details tomorrow... now I need sleep !

thank you !

Ben

[Ben006]

Here is the last version, with stiffening ribbons.
The Y shape plus the stiffening bits should prevent any sort of collapsing !
It is also few mm shorter, which should make things easier for the intake tube.






The new AOS connections:


Here you can see the larger radius between the stock and mine.


I've put it back on the car this afternoon for one more test.
You immediately notice the noise change.

Ben

[BRAN]

Originally Posted by BRAN

Awesome project

My IPD intake plenum package should arrive soon, breathe baby breathe ...

It is installed, finally: "Not cheap, but good investment"...noticeably more "umpf" through all ranges... pulls & sounds better = more smiles per gallon

[Ben006]

Even at low rpm ?

Now that I've tried mine I totally believe IPD numbers !

[BRAN]

Originally Posted by Ben006

Even at low rpm ?

Now that I've tried mine I totally believe IPD numbers !

Yes. Although I have to drive a bit more (and probably getting used to the stronger pull and therefor won't be able to tell the difference more precisely), I can already say...pulls better all the way, >3500rpm even better.
As my 986 is desnorkeled, the air intake sounds even a bit (not obnoxiously) louder now. Guess I have to balance that out with a valve PSE now

I was skeptical at first, not anymore!

[Ben006]

Good, thank you for the feedback !

[pkp4911]

Originally Posted by Ben006

Hi !
So, nobody wants to try it on his 3.2 (or bigger) ?


turns out the check engine light was in fact the O2 sensor

I'm still working on the new, stiffer version, but the current one works.

So If you want to give it a try, I'll send you everything (plenum, TB, intake tube and hoses for the AOS connection), as long as you're collecting some data and sending it back to me after you're done playing with it !

Ben

I'm happy to give you feedback. Doing a 3.6 swap into my 986 S. Both 2003. Let me know!

Sent from my SAMSUNG-SM-G900A using Tapatalk

[pkp4911]

I'm still available if you want a 3.6 involved.

Sent from my SAMSUNG-SM-G900A using Tapatalk

[winter.k]

Hey Ben, This is great work. Very cool.

What type of plastic and process are you using for 3D printing? Do you have any interest in sharing your CAD so that some of us can have them made any try it out?