A long long time ago far far away I had tested a plenum with the stock throttle body on my car with mods consisting of an exhaust and ECU flash as seen here. The plenum made torque and horsepower but lost up top. After retesting and reinstalling as well as questioning the issue, no further improvements could be had. Almost a year later I now have GT3076 turbos on my car and I want to continue to maximize the potential of the car and improve inefficiencies. I learned that the Porsche intake manifold system works off of engine pulses so the airflow pattern of the plenum is not important as improving the restriction of the airflow. You can only get as much airflow into a system as the smallest opening. So I took it old school...

For those older then me, you just bored out the throttle body. For those my age, we took our first tuner car and purchased one of those JG throttle bodies for more air. Wouldnt you know, it made a difference. The same is true for the Porsche 997 Turbo. The more air flow you can get it whether on the stock VTG turbos or on my GT3076 monster, the better performance you will get. So we went to work.

First thing needed here was a bigger throttle body. Imagine the cost to make one from scratch . So we spec'd the Cayenne TT throttle body which will work with the 997 Turbo drive by wire system. Because the Cayenne TT part comes in at 78mm, it will not bolt up to the stock plenum. This is where Agency Power comes into play. Our fabrication department had this CNC machined flange designed and built with a inner cut for a rubber o-ring. We then used aluminum tube the same size as the throttle body to make the T-Plenum. A straight piece of aluminum with fittings was welded to the back side of it to accomondate the factory hoses.

The factory part inlet is only 76mm which gives the overall surface area about a 3% increase which is quite alot of volume. Because of the increased air flow, we will be retuning the car to get a before and after dyno run. Softronic is about to release a new product exclusively through Vivid Racing so you 997TT owners will not have to take your ECU out .

Anyways stay tuned for the testing and leave your input.

 

still da man, dan!

 

Thanks bud. I hope to get some good feedback from these tests.

 

You have stated that the increase in SURFACE AREA between a 76mm & 78mm diameter is about a 3% increase but that is WRONG.

The difference in diameters is about 3% but the increase in SURFACE AREA is a funtion of radius squared and in this case is aprox. a 5.1% increase in SURFACE AREA.

The ratio between what you think you have achieved and what you really have is an error of about 170%.

I hope the test results you report are more accurate than your math skills.

 

"Hey go easy on him, he missed that day in school"
"which day, math?"
"yep"

 

Slowcart your a troll. All your posts have to do with IPD and hating Softronic. Anyone look his previous posts up.

 

Laugh Out Loud ! *troll*

 

Looks good. Looking forward to see how the testing goes

 

Great project dan...You should really bring your 997TT into high-9s..Lol...

 

I did not call you any names so why are you so defensive and respond by calling me names, shouldn't you be representing your self and your company in a more professional manner?

I did not mention IPD or Softronics in my previous post in this thread so just based on that fact we can see that your statement that all my posts have to do with IPD and Softronics is wrong.

My previous post was attempt to point out to you that you did not display enough math skills to show that you know what you were talking about and the worst part is you don't seem to know what I'm talking about even after I gave you the solution to your error.

It seems like you are starting your project without any respect for the importance of even simple math and unless you get help your errors will only multiply.

Good luck on your project it looks like your going to need a ton of it.

 

I don't think you can post a new idea and just expect everyone to drink the Kool-Aid. I personally don't know whether or not your idea will lead to measurable improvements but it is interesting nonetheless.

The cross-sectional area, not surface area, is what you are improving. As mentioned, the formula for cross-sectional area is pi*r^2. The 76mm inlet would have a cross-sectional area of 4537mm^2 and the 78mm inlet would have a cross-sectional area of 4778 mm^2, so Slowcart is correct to state the difference is 5.1%. He is correct and calling him a troll is not productive in promoting a constructive discussion.

I think the altered flow dynamics are really difficult to predict. The internal surface areas of the throttle bodies are difficult to calculate without sophisticated modeling. It will be interesting to see if there is a significant improvement measurable on the dyno. It might be worthwhile to test the stock and replacement parts on a flow bench to see the differences before the install since the 997TT is a pretty difficult car to dyno.

Going off topic, one thing that nobody really talks about is whether or not any of the dyno results for our cars has any statistical significance whatsoever. We see all of these smoothed dyno plots, but it is just about impossible to exactly match conditions. The statistical significance (or my suspected lack of) would be interesting to look at if someone had lots of dyno data.

I sincerely wish you good luck (and good results) with the project. I am still learning, so if I missed the point please let me know.

 

What is being done here has been done for over eight years now. It has been done by boring throttle bodies and using larger throttle bodies that are compatible with the 996tt throttle by wire. Some have used larger TB's and then bored them. I know of at least four that will work. Some use a larger throttle body and then also bore them. We utilize a 90 mm throttle body on KA. Just as important to the larger TB is the flow design of the splitter which is the part immediately following the TB. Without flow numbers for this part you really don't know anything.

So what Vivid has done is not new nor the largest single throttle body available for our applications. Now if they have a significantly better price for a workable enlarged TB ..... that is a different story. This is also not to say the biggest is always the best. The flow of all parts need to be in balance.

Now let's address the flow. Slowcart is correct about the 5.1 percent ....... to a point. This is in theory ..... in a perfect world. Two things significantly affect the flow of the individual part. Volume (where slowcart is correct) and the actual surface, ie curves, surface texture and coatings that reduce friction. If a manufacture really wants to prove his part he must have it flowed on a flow bench at a specific pressure (usually 25 or 28 psi) along with utilizing air horns. Any other claimed numbers are a kind to bench racing. Not criticizing anyone ..... just a fact.

I might also point out, slapping on a single part and saying the part produces X hp is really meaningless. The part may be designed to produce X amount of flow, however that does not mean the part is the weak "flow" link so to say. All parts of the motor must be designed for a certain minimum flow. If you do not do it this way, when you replace a certain item, that is the weak flow link, all you are doing is making another item the weak flow link.

A example could be the above Vivid part. Vivid may have tested "his" motor and obtained a 3% increase. That could mean a part that possible should have obtain 5.1% only got 3% because something else on this motor became the new weak link flow wise. This could mean the TB is too large or Vivid needs to discover where the new weak flow link is. The motor is definitely not blueprinted and flow engineered ..... anyone proceeding like this is guessing. Which unfortunately is what the majority of people playing with their cars do.

In our own tests we found torque to go up slightly while hp decreased slightly in the lower range and more so in the upper ranges. However, with some changes, especially with some head work, depending on the TB size utilized, things can be brought into balance.

From my experience, the bottom line is, the power gained from this change by itself isn't worth the cost. You have to look at what power is gained in relation to what is spent. If you do the additional costs you also need to match the TB size with the flow the all the other parts which translates into a lot of money.

Just my two cents.

One last comment, slowcart, you had some good information, however the last line of your post really was called for as it was a slight that really didn't bring anything to the table. Exchanging and correcting information is good and makes 6speed a better place for all to learn. Comments that simple bring anyone down is not so good.

 

Here are three different sizes that work.


Here is a splitter we had made years ago. Since then some one piece cast units with better flow have hit the market.

 

"Cross sectional math is hard, sometimes you think you have the formula nailed then you catch the early flight home from San Diego, and a couple of nude people jump out of your bathroom blind folded like a damn magic show and ready to burn your old math textbooks and..."

"It stops right there, and I think what my good friend Mitch is trying to say is, double check your math."

 

Mitch said "Good luck on your project it looks like your going to need a ton of it."

It is the part highlighted in red that tends to inflame. Other than that, Mitch had a valid point.