powdrhound

I was at my race shop and had a 997GT2 oil scavenge pump / vacuum pump installed on the car. I am extremely happy with this conversion as there is a huge improvement in brake pedal feel compared to the stock 996TT/GT2/GT3 stock vacuum set up. I have been running the complete 997GT3 RS 380/350 brake system on my car for the last 3 years including the 997GT3 brake master cylinder. Even though my brake pedal has been very firm compared to the previous 350/350 set up, it still did not quite have the same feel as a 997GT3. One of my gripes has been the fact that sometimes when I would transition very quickly from full throttle to max braking, my brakes would not have quite the bite they normally have and braking would require a lot of pedal effort. Basically, what was happening was insufficient vacuum and would manifest itself on very hot days when the air is naturally thinner. I am also at a 5000'+ elevation where the air is even thinner with density altitudes in the summer approaching 10000'. I went over this with the owner of my race shop and it was decided to install the 997GT2 vacuum pump. On the 997GT2/GT3/TT, Porsche installed a separate vacuum pump which is piggybacked onto the drivers side exhaust cam oil pump. On the 996GT2/GT3/TT, brake vacuum is tapped of the throttle body. I am assuming that Porsche added the vacuum pump to improve brake feel and consistency and remedy the shortcoming of the 996 brake system.

The conversion is a direct swap. The exhaust cam oil scavenge pump is removed and replaced with the 997GT2 oil/vacuum pump. The stock 997GT2 vacuum line is routed from the pump and plugged into the stock 996 vacuum line which is just left of the F-hose. It is a direct plug in as the connectors are identical. All that is left is to remove the stock vacuum line that connects to the check valve at the throttle body. We installed a rubber vacuum cap on the stock nipple of the check valve at the throttle body. You also need to install a small rubber vacuum cap on the nipple that goes to the exhaust bypass flap in the 997 cars (you can see the capped off nipple in the third picture). The vacuum caps can be sourced from NAPA. Total time of the swap was about 3 hours start to finish with everything essentially plug and play.

The result of the conversion is profound and makes the brakes feel identical to those of the 997GT cars. Pedal firmness is drastically improved along with improved modulation. This is a huge improvement especially for those that track their cars but it even makes a noticeable improvement in normal street driving. I can see why Porsche decided to go this route on the 997GT/TT cars. For those looking to maximize their brakes, this is a worth while upgrade.

996TT/GT2/GT3 EXHAUST CAM OIL PUMP


997GT2 PUMP EXHAUST CAM OIL/VACUUM PUMP


997GT2 VACUUM LINE

z06801

Cool upgrade! If I tracked the turbo more I would have to do something with the brakes for sure, Seems like your getting your car really sorted out.
Btw do you run NASA with Chris that has the TT3 red m3 at High Plains?
He came out to Miller for our last event and his car was really fast for a TT3.
How do your lap times compare?

powdrhound

I have run with a red M3 at HPR. I am not sure if it's the one you are referring to but it's a red fully gutted race prepped M3. If I recall correctly and it's the car I'm thinking of, my car is slightly faster. I have not run NASA TT but would like to in the near future. It looks like a lot of fun. Based on the NASA record times published for HPR, my car would break the NASA TT1 and TTU lap records both of which are held by an ACR Viper at 1:55.26 and 1:55.87. I have run numerous documented 1:55s with my personal best at 1:55:17 as seen in the lap video below verified by HLT. This was on DOT tires, Kumho V710s. Sticker slicks would good for another 1-2 seconds at HPR. I am not sure what the rules are for the various TT classifications with regards to the use of tires. HPR is a track that generally favors lighter more nimble cars. I'd love to run Miller where you can really use the HP of our cars.

High Plains Raceway (HPR) - full course

z06801

That track looks fun for sure! I bet that is the car. He seemed like a really nice guy as well. Nice work on the laps. You would have fun running TT, should give it a try.

pete95zhn

How much?

powdrhound

The retail on the pump is roughly $1250 and the vacuum line $150.

pete95zhn

Thanks!

In Europe:
99710702272 Z TANDEMPUMPE ZYL.1-3 1.167,15 €
99710503670 Z UNTERDRUCKLEITUNG 141,04 € (not the part# in PDF-PET)

Ever thought about electric vacuum pump?

powdrhound

Those are the correct part numbers. This is the pump that is used on the 997GT2/GT2RS/TT. Porsche also has a GT3 version of this pump which has a different part number but externally looks the same. I can only figure the gearing is different to account for the higher engine redline of the GT3.

I have not entertained an electric pump. Porsche did their homework on this so I see no need to reinvent the wheel.

To update this, I put over 80 hard track miles in 90F+ heat on the car today. The brakes performed flawlessly. Very solid pedal and totally repeatable over a 25min session. I'm thrilled with this upgrade..

pete95zhn

Found just a new pump from evilbay for €500,- ...lucky me... =)

powdrhound

Nice find. Make sure it's the whole tandem pump as I believe you can also buy just the vacuum pump separate of the scavenge oil pump.

pete95zhn

It was the complete assy.

pete95zhn

No, it was not... But on the contrary to this:

Originally Posted by powdrhound
Nice find. Make sure it's the whole tandem pump as I believe you can also buy just the vacuum pump separate of the scavenge oil pump.

It was the scavenge oil pump without the vacuum pump. New pump, never installed, but where is the vacuum pump? Pic was nicely taken from the underside and seller confirmed the part number. Why on earth it's always British sellers on ebay I have similar problems with?? It's now returned, let's see if I get my money back.

powdrhound

Sorry to hear that Pete. Looks like one of those cases where it was too good to be true. I suspected that when you said you found it for 500 Euro. The whole assembly new from Porsche should be 1300-1400 Euro including the vacuum line which is obviously listed as a separate part number.

split71

Great post, this was one thing I noticed in my recent purchase. I have a 996 GT3 (350MM) setup up front. The pedal is ok, that's the best I can describe it. It just doesn't have the bite that my M5 had. My first thought was, well maybe I need a GT3 master cylinder/brake booster setup for the added pistons in the calipers and pressure from brake fluid. I may give this a shot down the road as I would like to track the car eventually.

powdrhound

I have both. The 7GT3 master cylinder gives you a harder pedal and the 7GT2 vacuum pump gives you a sharper biting point... I believe these are the two items that make the brakes feel so much better on the 7GT2/GT3/TT cars compared to the 996 predecessors.