IPD Plenum - best performance mod?

[PaulE]

Originally Posted by michaelpetersen3

Hi Paul, I really like the idea of the direct connect dyno. It takes one more variable (wheel rolling resistance) out of the equation. Should give you more consistent results. Im pulling 79HP/L on my 3.2. You should be able to pull 285HP from your 3.6 w/ exhaust work, maybe 290/295HP if you eliminate rolling resistance. BTW, if you want to see the details on my exhaust mods and dyno results, I posted a vid several years ago here: https://youtu.be/MdCQg2tJFYg.

Thanks for the video Michael. Interesting that the Max Flow mufflers actually make a little more HP than the Super Cup ones! I've already got those same Fabspeed headers with 200 cell catalysts, so if I get the itch for more power, replacing my CircuitWerks mid pipes and stock muffler would be the next step.

[michaelpetersen3]

Nice work Ike. Your idea is similar to how Porsche runs their GT4 Cayman race cars... dual intakes running to the rear window vents.

Only potential downside of your design is the intake temps. Have you read the temps in the trunk during normal operation?

Solid work!

[ike84]

Originally Posted by michaelpetersen3

Nice work Ike. Your idea is similar to how Porsche runs their GT4 Cayman race cars... dual intakes running to the rear window vents.



Only potential downside of your design is the intake temps. Have you read the temps in the trunk during normal operation?



Solid work!

Thanks for the props!

The intake temps are an issue with the rad expansion tank in there. Here's a chart from this morning. Ambient temp was 78deg. These measurements are from the OEM IAT sensor. You can see a pretty quick climb, this was start to finish on a 13 min drive. I should have charted water temps too but they never exceeded 185. More work to be done! Maybe I'll go ahead and install the water air intercoolers now lol.

Another subjective thing I can say about the performance difference is how freely the engine revs now in neutral. My very first reaction after I pushed my tune was shock over the difference there.



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[fabioan]

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[NotthatJake]

Originally Posted by tommy583

I have a 98 with the 2.5 motor. I already installed the larger throttle body from a 996. I think the T on the 2.5 is the same size as the 3.4 T in the 996. It bolted right up. The throttle body from the 2.5 is the same OD as the 3.4 TB, the ID is the only difference. So what i'm saying is I'm not sure if the IDP would make a difference on my car or not. I'm pretty sure it wouldn't make an $800 difference. Maybe on a 2.7 of 3.2 it would?

Can you help me know where you found your larger throttle body? I can’t find the correct one and don’t have a part number to reference. I have the ipd plenum but can’t find the cable throttle body needed to bolt up to it.

[PeterBleakney]

I'll add my 2 cents here. I have a 2001 Boxster S with a Fabspeed catback exhaust and a "mystery" tune that came with the car when I bought it 8 years ago. I only know it was tuned because the local Porsche dealer said it was not factory. I bought the intake kit from ESC (IDP plenum, 74mm TB and hose) and "though" I felt more midrange punch. Granted, the throttle response feels sharper but numbers don't lie. According to the dyno, I lost a few hp and lb-ft. A gigantic waste of money it seems.

[The Radium King]

NECRO thread, but i'll take a shot.

all the info is in the provided dynos, but i do not think they have been interpreted properly.

first of all, there are three passes - stock, exhaust, exhaust+intake. both exhaust and exhaust+intake improve over stock throughout the curve.

exhaust+intake also has higher peak torque and HP over just exhaust (ie at higher rpm) however exhaust looks to have much more midrange over exhaust+intake. they say it's not the peak power that matters but rather total area under the curve. but that depends on how you drive - keep it over 5k rpms and exhaust+intake is outperforming everything else.

further, exhaust was performed with a tune while stock and exhaust+intake were not. this becomes very obvious when looking at the afr curves at the bottom of the dyno - exhaust runs leaner and for longer compared to either stock or exhaust+intake. ie, the tune looks to run an afr of 12.5 vs 12 when the ecu transitions to open loop. apply the same tune to stock and exhaust+intake and i think you will see exhaust loose the midrange advantage. until then it's an apples to oranges comparison.

[BrakeExpert]

is the 987 plenum 3D printed yet?

[Nitro V8]

There is some great info and discussion in this long running thread.
From everything I have read here, elsewhere and my own findings I conclude the following.
On the intake side the biggest restriction is the standard airbox which has a tortuous and choked path for the airflow.
Replace with a 987 airbox or some other sealed system and that should help.
As for a larger throttle body and plenum, all I have read does not lead me to believe these are of any benefit and indeed seem to result in a power loss low down in the rev range.
Why is this? Well my thoughts are as follows.
From what I understand the electronic throttle body works by receiving a single from the DME that dictates how much it needs to open based on throttle position, load, engine speed etc.
If you have a larger throttle body then it just opens less (once it has calibrated it self).
As the throttle body is a larger diameter then although the air mass flow is the same as the standard smaller one the air velocity slows down which results in reduced cylinder fill at lower revs hence lower torque/power.
I know the intake neck after the plenum is unchanged so the air velocity in theory could return to normal but it won’t as it has decelerated too much to be clawed back in time.
When the revs climb the air velocity increases sufficiently to overcome this deficit and full cylinder fill is again achieved and possibly a small hp gain at very high revs.
Just my thoughts.

[Newsguy]

Nitro, I think you may be right, but…
I know a tech very close to one of the major engine rebuilding firms.
He has an early 4.0 rebuild in a 996. I’ve ridden in the car and it runs pretty well. He says he has modified nothing. No tune (or bigger intake AFAIK.)
It would seem the ECM is able to adapt pretty well.

[fokker2003]

Although this thread is old, I'd like to contribute my two cents:

First of all (since it's my area of ​​expertise), I did the electronics, tuning the DME. I had several problems until I finally found the correct timing adjustment because the car was backfiring terribly when it reached 5000 RPM. But in the end, after several tests, I managed to adjust it.
To be honest, I didn't notice much of a difference, but I wasn't expecting much more; used to modifying turbocharged engines, all naturally aspirated ones seem underpowered to me.

Next, I installed a BMC air filter, and this time I did notice a small change, which I imagine was a result of the combination of both modifications.

The next step was installing an IPD plenum along with a larger throttle body. Once again, a slight improvement, but nothing spectacular.

The next step was the exhaust manifold, in this case from FVD Brombacher, and at this point, the change was truly remarkable.

With all this, I did a new stage tuning and again noticed small changes.

I have to say that before I bought this car, the right cylinder head was replaced at a Porsche center, and they broke the lambda connector in the wiring harness. I didn't want to solder them because it's a highband probe and they pick up the reference signal from the cable, which would occasionally cause an error. So, I opted to disable both lambda sensors.

Also, it always passes emissions inspections very closed, which is why I've kept the original catalytic converters.

One curious thing I noticed was that during a service, the air filter was dirty. I didn't have time to clean, dry, oil, etc., so I opted to install a Bosch one.
There was a significant loss of performance and engine noise. A few weeks later, I reinstalled the BMC, and the car was like a rocket again.

In summary:

Just tuning the electronics doesn't give the expected results. Just tuning the intake doesn't either.

If you want to notice a difference, you have to modify everything; that's how I think you achieve the ideal balance.

On the dyno, my car originally produced 253 hp. At this point, it's producing 289 hp, but my goal has always been torque.

In fact, I'm currently waiting for the arrival of a lightweight flywheel from AASCO and a clutch from SACHS Performance; that's my next upgrade.

[redpepperracing]

Originally Posted by fokker2003

Although this thread is old, I'd like to contribute my two cents:

First of all (since it's my area of ​​expertise), I did the electronics, tuning the DME.

Can you elaborate on your process of tuning the DME? I'm just at the point of trying to do it, I am able to extract the stock bin from my ECU, but I am stuck at how to modify the fuel and ignition tables.

Thanks for any insight!

Tom

[fokker2003]

Hi Tom, sure.

What is your sw number?

[redpepperracing]

Originally Posted by fokker2003

Hi Tom, sure.

What is your sw number?

Sorry, what is the sw number? Treat me like a 5 year old...

[fokker2003]

Originally Posted by redpepperracing

Sorry, what is the sw number? Treat me like a 5 year old...

What tool are you going to use for read maps?

And what software are you going to use to modify the file?

To modify a file read from an ECU, you first need to define the maps you're interested in.

To do this, it's crucial to know the software and the upgrade software, as this allows you to know exactly which maps the ECU uses.

Also, many (paid) software programs allow you to purchase a template that precisely defines the maps that control engine management. Be careful with this because there are good templates and bad ones.

For reference, my car uses an intake air management map (QS) which, in turn, has 11 submaps; it's a 10x16 map (rows x columns).

What I mean is that if you open a complete eeprom file read from an ECU, you get a 512kb hexadecimal jumble (in this case, since the DMEs of the 986 usually have an AM29f400BT, in a more modern car you can find files of up to 9 megabytes).

It's very important to be clear about which bits you're modifying, otherwise the results can be disastrous.

I imagine you're familiar with WinOls. It's an editing software that allows you to load a template (DAMOS) from any source and modify the file. Be careful with this too; there are some very good and well-intentioned people who create it, but again, you have to trust that the DAMOS file is good, with the potential consequences that this can entail.

I prefer reliable software, like Alientech, Dimsport, etc.

They prepare good templates that are a very good starting point, and from there you can start testing and even create your own maps to improve the template.

Even so, as some users have already mentioned, these engines aren't easy to tune; you have to be very careful and precise.

I'm going to start a new thread because, if people are interested, there's a lot to discuss, and I can provide a how-to guide on how to safely read and write the files and give you a guide on how to modify them. I can also review your modifications before you write them.

Link to this post:

https://986forum.com/forums/performance-technical-chat/87685-i-want-modify-electronics-my-car-how-do-without-dying-attempt.html

[The Radium King]

to be clear - fokker has a 2004 which runs a 7.8 dme and pepper has a 2000 which runs a 7.2.

the 7.8 is very open source and easy to program. lots of info out in the wild for the 7.8.

there is not a lot out there for the 7.2. porsche keeps this info very proprietary so what is known has been reverse engineered by people dumping the ecu and trying to extrapolate what all the little bits and bytes mean. that takes a lot of work and those that have done it (softronic, etc.) keep that info close (a) to get some return on investment, and (b) so it doesn't become obvious that even the pros haven't cracked the entire ecu (ie, iirc most of the pro tunes you can get for the 7.2 play with fuelling and rpm limit but nothing touches the timing).

so good luck. there are other (older) threads here by people who have attempted, but none that have fully succeeded. the 7.2 wasn't around that long so not a lot of incentive to invest the time. one of the work-arounds is piggyback ecus (or even a potentiometer connected to the maf signal) to fool the dme into fueling differently.