Motor was out recently to upgrade my Clutch so decided to add the Agency Power Big Mouth TB Dan just started offering. Dan as usual is a pleasure to deal with.

Couple of notes on the install. I can't imagine doing it with the motor in the car. Would be next to impossible. Overall the unit is nice. One of the time-serts of the four that allows you to bolt the stock Cayenne TB to the new T pipe on mine was not threaded property. And you cannot just run a threading tool into it to clean it up. Not sure why the designer bothered with time-serts. For future production runs would suggest just tapping the housing, this is just not like a Cylinder head that if for some reason it was over tightened you would be screwed. Then is plenty of room for longer bolts with nuts and would even be easier and less expensive to produce. Anyway sorted that out and doubt it will be a big issue on other kits.

I tried to show in the pictures below the area of the install that was difficult. The larger T pipe had some interference with the aluminum piece that connects the lower part of the intake plenum runners. This piece is a factory piece that blocks off the lower opening normally meant for the normally aspirated cars, to balance the airflow in the Intake Manifolds. For the turbo charged 996's this opening is blocked off by a cast aluminum piece that is connected with two hose clamps on each side and a connecting rod between them. The larger T pipe hits this rod and can not be rotated down to level with the Y-pipe. This rod needs to be either ground down to allow clearance, or it needs to be loosened on both sides and rotated out of the way. (not easy to get to) would be next to impossible with the motor still in the car. I ended up grinding a relief in mine to get the clearance needed.

Next of the three tubes on top of the T that are for the crankcase breather etc, one of them is significantly smaller than the factory hose that connects to it. Some flare in the ends of those tube would really help, these tube must hold boost, they are on the boost side of the check valves.

Once in place the distance between the factory Y-pipe and the Cayenne throttle body opening is les than 1/2". The silicone hose step up hose that was supplied that connects the two must be shorteded significantly. Once cut down to half of its size, barely, and I mean barely, clamps the two together. The Cayenne TB is held too far forward due to the thickness of the TB itself, and the mating surface on new T pipe. I know the length of the bottom "leg" of the T looks like it is about as short as you can get it because of the welds. Not sure if it can be made shorter in length here but any shortening here would help greatly. The factory Y-pipe cannot be shortened either because there is a fitting on it just a very short distance from the hose clamp area.

All installed now but was not smooth. That being said, they car is running very nicely and no sign of leaks yet but I have not run it hard, or done a smoke leak test yet. Drivability is very nice, if not better than before. Looking forward to doing some dyno runs and will keep you posted on the results.

Should be an interesting test because my car has some modest mods, and my intake is all stock except for this new Big Mouth addition. So with all of the factory intake and intercooler known restrictions this should tell us if just changing the TB and T-Pipe to a bigger one makes any difference with the rest of the intake system stock. I have a baseline dyno on our Dynojet before the mod, and no other mods have been done since. The temp here in Nashville is colder than when I ran on the dyno last, and the SAE correction factor for cold air is not as linear as it is for normally aspirated cars. So the correction will not be completely accurate, but still will be interesting.

Mods on my car now are simply GT28 hybrids (old style not Alphas), RPI 3" exhaust, Meth Inj (30 meth/70 water), 93 octane gas, EPL tune, 1.3 bar, factory ECU boost control. Car previously made 558 RWHP (drive shaft disconnected) on our Dynojet 248. My guess it that the stock intake and intercoolers will severly limit the benefits, but would like to see it one piece at a time....

Will be dynoing in the next week or two and post results.

 

Good stuff! Thanks for the thread and pics!

 

One thing i forgot to mention is how nice the new T plenum was. Piece of art....wish I could have kept it on my desk. I just happen to like cool aluminum fab work. Fitment issues were minor, first timer to hopefully help others spot what they need to do without the trial and error.

 

subscribed

 

great post can't wait to see the dyno!

 

Did you dyno yet?

 

Will Dyno next week. Need to put my exhaust back to exactly how it was last time I dynoed to make sure even comparison. The exhuast I was using had a Cat honeycomb that came unwelded and it lodged itself at 45 degrees on one side. Had to send it off to the manufacturer and they are fixing under warrantly. Supposed to be shipped back to me this week. So I do not want to dyno with different exhaust. Will post results as soon as I can.

 

Just got done putting mine in, ill post up my experience when the car is all wrapped up and running

I concur on the timeserts sucking comment

 

Easy fix. Order another one for your desk. High HP papers holder!

 

Weird that I agree

 

I past on the concerns about the nut inserts and was told... "since the flange is aluminum and the bolt is steel, with only 4 threads, they were concerned people would strip them out." So they did a steel nut insert.

 

logical, I removed the timesert on the lower right and used a nut and bolt to hold it in, 2 were fine 1 had to have the planets align correctly to thread but it went in fine

ill post pictures later on, its 100% possible to do it in the car though, without much hassle

 

Thanks for the write up. (going to attempt this with a lowered motor)

May I ask what was done to resolve the small tube to OEM hose issue?
And about how many mm thickness and length was the relief grind on the alum rod?
(Dan, with the big mouth T/TB and AP Ypipe combo, will the relief be necessary?)

TIA

 

I just turned to dog bone further back, didnt need to cut anything fit in just fine actually faced further down then it needed to be, theres plenty of room without having to cut it