Heavy's calibration seems to be dialed in because cutting races out on a RWD conversion is a 9.5.

 

Not the answer I was expecting from a board sponsor, but regardless I thought the 997 GT3 is 82mm not the 996???

 

Board Sponsor, Human, keyboard commando... I dont feel like arguing with someone on page 5. The 997GT3 TB is a 82mm. The CayenneTT is a 78mm. The 996TT is a 76mm.

 

So not to sound like an idiot but is the 2 mm really worth it?

 

Its not 2mm, its an overall surface area change that when the math gods calculate, it is an improvement. As you see from page 2 or 3, the dyno shows it is worth it. The reason we do not use the 82mm TB is you LOSE a ton of lower end power.

 

Dan.

It all depends what year model GT3 you are referring to. The latest GT3's throttle bodies are 82 mm. I believe earlier ones (not sure what year) they were using 78 mm's. I know the throttle body sizing was changed at some point. The measurement is done at the location where the throttle body shaft goes through the throttle body.

It is not unusual for Porsche to use different dimensions on different parts on different year models for the same motor.

I have no idea what the different sizes for the different year model Cayenne's are or if they are even different.

 

Dan,

Not sure about the math gods ........... you are correct in that diameter and surface area is different. However, it comes down to designing everything to match the air flow.

If 82mm by itself was to "lose a ton of power," how do you account for the fact that we are running six 48mm throttle bodies (or a total of 288 mm) and making a ton of power and unreal response?

I just don't want people getting the wrong impression of the mechanics involved.

 

I am referring to the 997 GT3 and the 04-07 Cayenne Turbo.

 

True, this is why sport bikes make so much power, individual throttle body on each cylinder with velocity stacks. You can tune the length on each cylinder according where you want to make power.

 

This is exactly why I was confused I thought we were talking about 996.

Thanks Chad for the clarification!

 

911GT700,

You always have to be very careful when mixing Porsche products. About five years ago we were experimenting with GT3 heads. Everyone knows there are three diameter sizes ..... one for GT3 Street, one for GT3 Cup and one for GT3 RSR. What many people didn't know is there is also three different tappets (as far as I have seen) and the valve stem length for each valve (street, Cup and RSR) is a different length.

I learned this the hard way and had to have my valves custom made twice as the first time they were too short and I didn't want to use caps.

 

You are absolutely correct!
There is a lot of misleading information out there.

 

I have a Cayenne tt 2008 Throttle body with 82mm....it works with my ecu

now I am searching for a ipd plenum that support this diameter...my intake system (y-pipe) is from speed tech and great enough for this 82mm throttle body...

attached the pic from a oem 996tt tb and the Cayenne tt 2008 82mm

 

Dan did you ever get a chance to run this back to back with an IPD piece? Do you have any dynos with an IPD piece vs stock?

 

If I sit here and put down another product, it does not benefit us. Someone told me 1 time the members will dictate what is good and what is not. Unfortunately the old Pepsi vs Coke thing is frowned upon by IB.

Based upon the tests, the quality, the sales, and the price, the Agency Power TB/Plenum kit is a NO BRAINER!