How to do a before and after of Plenum

Ok I ordered the plenum today. There are over 20 orders for the group buy. Any suggestions on how to do a before and after test without a Dyno? Or should I just trust the seat of my Pants?

A seat of your pants test is probably more accurate, satisfying and will help you more easily justify your investment.

Make a few runs at a drag strip before and after. If that's not practical you can set up a course on a road that sees very little traffic. Use an object for a "start" and another for a "finish". The distance between these points should be long enough that you can measure time with a stop watch or speed at the second marker with a GPS. You should make several runs and record the results. I would recommend trying different things such as approaching the first marker in 4th gear at 30 MPH and when even with it accelerating as rapidly as possible and if necessary shifting at 7k into the next gear and having a passenger measuring speed and time. Try different speeds and possibly different distances. If doing several runs the same, the results should be very close. Keep track and compare results. Make sure you record and wind and temperatures, humidity etc. as these can make a difference. Have fun!

Steve, I'm part of the group buy also. I have a G-tech performance meter. I have previously measured my 0-60 and 1/4 mile times. I plan on doing it again after the plenum to see the difference. You might see if you can borrow one from a fellow Rennlister in your area.

Thanks for the ideas. I just remembered I have a first generation G-tech in a box somewhere. Maybe I can figure out how to employ it to do a test. I don't want to do 0-60 or quarter mile type test because the start off the line introduces to many variances. Maybe I can use a rolling test from 60 to 80 or something I can do on the hyway that would be semi legal.

are you serious? or perhaps superhuman? the difference is going to be in the tenths of a second, if not the thousandsths and to have a 'normal' human being so heavily involved in such a test is a sure fire guarantee that the inputs are not consistent. And as you are suggesting two humans be involved.......

Just do a run w a buddy side by side in same gears wo the Plenum. See the results. Then do a run same scenerio w the Plenum and see the results. If its pulling alot more then I would say its a good investment

Nothing like a good old fashioned before and after dyno test.

The only porblem I have with the dyno is $$$. The G-tech test is free (unless you get caught doing the 1/4 mile run) and with a tiptronic the times are fairly consistent.

To prove absolutely nothing!

so are we all agreed then? Dynos are a waste of time and trying to prove this without a dyno is ridiculous Sorted!

This: and this: Have the same parents?

After installing them on, drive the car hard, it takes a few miles before the ecu recognizes the mod. Drive it like you stole it, then you will notice that your mid range power has increased and its a lot more smoother on the throttle and better response. You will get a lot of negative feed back on this forum and just like any new product, when they get a chance to try one out they will look back and say damn, wish I new better. There are a lot of heels, but there is nothing we can do about them. They just have to try if for themselves to learn. Best mods for more power as old school mods, intake dosent do anyting it the throttle body and intake sucks, basically its like a bottle neck, you want as much air in the engine, but the engine can only take so much in.

Hey - don't forget to put on that K&N air filter for even more performance improvements! Michael

HA! Actually, plenum replacements aren't new, not even for Porsche. The problem for me is that the same quality part I see for Mustangs are $169 vs our $765. This one for the 996 is the only applications I've seen that has no recommendation of changing the thottle body as well.

What would be even more useful is a good DIY on how to change this out. I know I have purchased one and will do it myself once it arrives to Germany. Hopefully before then other will post the best method of doing this and make my life easier.

It's true that the ECU does remap based on mass air flow, but I often think the "wait for the re-map" talk is more of a delay tactic, so that in case we don't notice a difference right away, we can convince ourselves over a longer period of time. Anyway, your advice to drive your car really fast, then you'll notice that your car is faster, sounds about right. Having a preconceived notion that "you will notice that your mid range power has increased" is not really consistent with the scientific method.

Dosent take a scientist to figure out that better airflow gives more power. Since our engines combust with fuel and air, more air means more combustion. Better combustion give more power. If you are local, or if anyone is in the so cal area and would want to take a ride in my car, ill be willing to give them a ride. This is a no brainer, just like a T-intersection on the street, with this type of intersection, traffic is slowed down and cars cannot keep their momentum, with a Y-intersection, people can keep their speed.

The major difference between these 2 plenums is the modified one has a wedge in the center (with holes no less) vs. the stock one that is a T intersection. If it was that simple, why do you think that Porsche has not come this design in the first place. Also why is the design not patented if it is so revolutionary? Call me a skeptic, but I have seen these things come and go for last 40 years just waiting for a newbie to "discover" it and take the bait. The soCal speed scene has had this sort of stuff out there since my dad was hot rodding in the 50's. Lastly $1K for a Y shaped tube that is the same size as the one it replaces? And it uses the same throttle body? No increase in airflow here my friend. The target market must be newbies with more money than sense. (a sizable market it seems ) BTW, the holes in the center of the device are essentially whistles that will give the car that "power howl". We all know that if it sounds faster, it must be faster!

How big are the intake valve openings in these cars anyway.... wouldnt these be the most restrictive part of this system..? .... Even if they are the size of a quarter, the lift can be that high... can it ? "This is a no brainer, just like a T-intersection on the street, with this type of intersection, traffic is slowed down and cars cannot keep their momentum, with a Y-intersection, people can keep their speed." If the valves are smaller than the plenum doesnt this T-intersection then have a toll booth with stop barriers right after it ?

I think there is good reason to be skeptical. However I bought one any way. If you think about how a boxer engine like ours works. First the air goes left then it has to go right there also may be some backflow at various rpm combinations. My thinking is that this plenum design will decouple this effect. I might be having a pipe dream. I like empirical solutions in a computer design age. It may be the only way to find that hidden power! I don't own a K & N no more power there. They are consider green if you give a hoot.

Hmmm with all these airflow restrictions I wonder why our cars are running after all!

would one consider a high flow will be a better deal if restricted air flow is the culprit to our lost in power or the lack of?????

It is pretty obvious that you two have all the power you can handle.