Ever wondered what it was like to build a 996TT

Ever wondered what it was like to build a 996TT ?

This is a post I put over on the 996TT board. Thought you would like see the contrast to the other motors. I thought I would share with you the typical day in an engine build. Not many people have dove into the TTs motors for several reasons. One I think because most are still under warranty. The need will arise sooner than later. There are some natural wear items and as the HP goes up so should the insurance policies. AKA, rods, studs etc. Everything has a purpose and a goal in mind. The one thing unlike the motors from years past is the 996TT motor is old and new technology combined. When that happens there is always a different way of doing things. This means a battery of tools that is required. We have always been able to slip by on the old stuff with very little mandatory tools. If you plan on building a 996TT motor be prepared to spend 3-4K in tools alone. This is if you already have the equipment for the older motors. I will out line as I go along the newer procedures and things that require a different tool. Removing the motor is not any more difficult than any 993TT motor. More wires, more lines, more weight and coolant. Be prepared for one heck of a mess. I rarely make a mess, all bets are off on these motors. Even for me. The amount of crap on the top of these motors is amazing. The maze of lines, additions and supports is staggering. The 993TT is nothing. It will take you a day if you are familiar with them just to clear the motor to the long block. Keep a keen eye out for the order that you removed things. If you go to assemble and do not reverse the order you will spend the next 2 days trying to figure out how in the heck the lines went under all the crap. I will post pictures of the motor on the table when I find what I did with them. Once you have cleared the motor of the intake etc then you can start into the meat of the motor. You will remove the valve covers to expose the cams.

Notice the mess of coolant and oil draining, even 3 days later! The next step is to remove tensioners, holders and cams. You will want to invest in the manuals. If you do not follow the order you run the risk of damaging the cams and or sprockets.

Notice the center of the top tappets. There are two sections to these tappets. The center section and the out edges. As computer deems necessary based on load, TPS, RPM etc the cams will switch from 3mm lift to 10 mm lift. If you look at the picture above you will notice the 3 sections to each lobe. This is the equivalent of 2 cams in one. The sections of the tappet will drop out exposing the desired section to achieve a specific lift. At the same time the cams are also advancing from the sprocket on the nose of the intake cams. It is a very elaborate system that relies on oil to act as a hydraulic coupler. This is what activates and moves these items. Never use anything other than the weight the factory recommends. The next step is to remove the housing and remove the cylinder assembly. These items will simply pulloff exposing the pistons and head studs only. From here the motor splits like any other 911 case. The 14 case studs and a nut. The outer bolts and the case splits in half exposing the crank,oil pump intermediate shaft and chains.

This picture shows the original pump compared to the new GTIIIR pump to be installed. Notice the second pick up on the bottom. The new pump goes in without modification to the case. If you use high performance rods you WILL need to profile the pump 20 thousands. Notice the red ink on the installed GTIIIR pump. This is the profiling area. If you don’t profile the pump expect to be back in there. The rods will hit the pump as the big end passes on the stroke.

The newest gig from Porsche is a clear silicone that sets in 10 minutes. I am not and never have been a fan of silicone in any Porsche motor. I cleaned the case halves with a soft wire brush, steamed the cases then applied loctite 574 to the case halves. Notice the case through bolts on the lower channels. These are now sealed with O rings and the case has a beveled edge to seat the rings down when the case halves are closed. Also never forget the orings on the oil pump. For those of you reading, notice the oil pump bolts? Next is the assembly of the head studs. I have chosen to go with an updated heavy duty version. These are not available from Porsche. These are aircraft strength and quality. Notice the coating.

Once the head studs are installed and set to 150mm from spigot you can preassemble and set the cylinder assembly. This is were things get very different from the past. In the older motors each cylinder was separate and assembly could be done in any order. In the new setup there is no way to install the pistons of you do not follow the order and have the special tools. You will want to press the liners out of the block and install new seals. I replaced the old style rubber ones on the liner with Viton, while the others remain a different compound. The liners must be pressed in. Keep in mind for final assembly the center liner has to be pressed in on the car with the special tools. I will post those tomorrow. For those that think you can buck the system and do it without. Forget it. Not happening. I promise. BTDT.

This is the cylinder assembly with the center liner out.

This is a liner out of the block. Notice the updated seal.

Install the base gasket.

Number 2 and 5 preset ready for the cylinder assembly to be placed on.

I will continue with more pictures tomorrow. I don’t want to bore anyone. I do however want to share a few more things. I had mentioned premature wear on the thrust bearing and on the intermediate shaft thrust. The picture here shows at 40K miles the brass is visible on the thrust collar. Odd to say the least.

Here are a few of the cam tools need for the cams. Special holders and wrenches.

Heads, cam housing, cylinder assembly, valve covers and more. I have a high pressure steamer that will clean anything. Notice no cosmline on this motor.

Ok, time for more pics… We talked about the pressing in and out of the liners. Below is a picture of the procedure for pressing it out. I use a hydraulic press to do this. Notice part of the Porsche tool in the liner.

The next picture show the liners on the outer cylinders

and the factory spacer tool behind the cylinder block

. This is a picture of one of the two circlip tools you will need. There is an art to using these and making them help rather than hurt. Install it wrong and the circlip will pop off and roll into the newly sealed case. You guess it, hope you are good at fishing.

Next is the picture of the piston being compressed in the

ring and supported by the Porsche OEM tool.

There are other ways to do this procedure, but to be honest the OEM tool keeps it simple. You will not loose time by continuously slipping past the rings. One of the interesting things about the 996TT pistons that is unlike any Porsche piston from the past is the second ring land. The groove has a dowel as seen in the picture that prevents the ring from spinning in the cylinder. When reringing the piston I highly recommend you place the oil scraper ring away from the bottom of the cylinder. This will prevent unnecessary smoking from time to time.

Once the cylinder assembly is installed on the spacers you will need one of these. Once again this is about an 800.00 tool.

Here is the tool installed and live at work.

This picture shows the headgasket. When installing notice the orientation. There is a face of the gasket. The gasket is a three part gasket riveted together. There is only one way to install this.

Here are the heads back on the motor and torques to spec.

One nice upgrade is the use of the older style chain housing gaskets. The 993 style has about a .5mm more rubber on it than its newer brother for the 996TT. The gasket on the left is the 993 version, the gasket on the right is the 996TT gasket. They are interchangeable. I also suggest this to the chain tensioner gaskets.

Ok gang, here is the meat of the motor. The whole system comes together through the heads and cams. There are a few pictures I left out previously so I will back track a bit and show those. Below is a picture of the old style 993 chain housing gaskets. The right side only will need to be profiled to move around the cylinder block. A little file will do the trick.

Once you have the head on, the gaskets and the chain housing you can then set the cam assembly and the gasket. Notice the lettering on the gasket. There is an orinetaion to the gaskets, They are embossed on one side and different on the other. The EGR ports run through these and are sealed specficly based on shape by the seal. Any seal in the car that is sandwiched will say “top” which mean you should have this on the front .

Cam housing installed.

Next install chain ramps and bolts. Notice that the bolts are all the same size but one. On each chain housing there is a short bolt. This bolt goes on the outer most section of the chain housing. If you try to use the longer ones the bolt will bottom out and in crease the risk of cracking or popping a hole in the chain housing.

Next install the tappet. Each one should have been marked prior to disassembly and be bank specific. The tappets can only go in one way and must be lightly oiled. Per Porsche do not oil the cam journals. Note the pin on the lower right hand corner of the tappet to guide the unit in and prevent spinning.

Next is to ready the cams. Oil the lobs and press the oil tubes on the end. There is a tube for the left and right banks to accommodate the offset from the right to left bank. Much like the older cam sprocket issue. The oil tube on the left is for banks 1-3 and the one on the right is for 4-6. There are rings as pictured below that must be pressed on to the nose of the cam. This is done by hand and without tools.

Cam end with ring

Inlet Cam with tube pressed on.

Pre lube the cam jornels and cam saddles.

Insert cam saddles. Take care in observing the order of the saddle to the housing. Each saddle is marked or hand engraved from the factory. Match the face of the number with the number on the saddle. Tighten per Porsches specs at a half turn each in the correct order then tighten 9.5 Ft Lbs. The order is important here. If you screw up here you will destroy the cam on start up.

Cams in saddles. One note. Before you place the inlet cam on and secure the saddles make sure that the chain is over the top of the cam. Once the cam is in the saddle rotate the left bank so that 1 intake and exhaust lobe face one another. One 4-6 make sure they are opposite and go away from one another. The picture below is cylinder 1.

If not the chain sprocket and chain can not be put on. Once the cam is tighten down you may put the inlet sprocket on and the exhaust sprocket in. Only hand tighten the bolts at this time. The left and right exhaust sprockets are different and are market on the face Left sprocket “links” I think is left in german.

Right sprocket. Notice the offset

Next set tension on the chains by inserting the factory

tension tool.

Set the unit tension until the first mark just disappears

Next setup a dial gauge to mark true TPC. The point of this is to watch the gauge as you come up on TDC. When that happens the gauge will briefly stop moving. There is a point where the gauge will swing up then come back down when the piston comes back down. That spot in between the two is TDC. The plunger is extended down on to the top of the piston.

Set factory cam tool for left and right on the back of the cam. Note the order in which it is bolted up.

Making sure you are on TDC and insert the tool in the back of the cam. The tool will only go in one way. If it will not slightly rotate came until it slips in via the nut built into the cam.

Do this both with the inlet and exhaust.

Turn center of the inlet sprockets to the left stop and lock inlet and exhaust cams while using the holder tools 22 ft lbs. Remove the tools from the end of the cams and lock the top inlet bolt by rotating 170 Degrees. The bottom sprocket will be rotated 90 degrees. Remove tools and rotate 720 degrees and check TDC. Insert factory cam tool and confirm timing is still correct for left bank. Rotate engine 360 degrees and duplicate order to the right bank.

Looks like where we started….

There are various sensor and solenoids that will need to be reinstalled. Below is the solenoid that adjusts the oil pressure to the variocam. This is the upper sprocket that will lock in and out causing the car to jump 25 degrees on mechanical cam timing.

It housing location is on top of the cam housing. Install a new oring and seat. I always recommend a little silicone paste, not glue around the o’rings.

Next is the tappet locking solenoid. This is the unit that allows oil pressure to flow to allow the tappets in to change profile from 3 to 10mm lift.

Its installed location is in the middle of the valve cover.

. Also in the in the scope of sensors is the hall effect sensor. The intake cam has a wheel located on it that allows the car’s ECU to count where the cam is location wise. This used with various other sensors will establish the ability to run sequential fuel injection.

Knock sensors placed in location on top of the cylinder bank

Next reinstall the water pipes under the cylinder head. Once again use new orings.

Next you will want to install the front support for the hydraulic pump and alternator. You may want to install water pipes that are on the inlet of the cylinder assembly at the same time.

Sure hope you took the time to look at the original routing of the lines. This is not the easiest thing to recall. Route the lines to the slave cylinder so that the runners on the left bank catch and hold the lines. Go over the oil filter console and under and around to the pump. There a few clips along the way. If you are doing it right then the lines should hit the clips. I suggest the factory manuals for routing or detail drawings/pictures.

Install the fuel line to the fuel cooler in the manner you see below. It has to be this direction in order to fit.

Next install the water lines that run to the pump and console. These become brittle with heat so careful.

Next prep and install gasket and injector blocks.

Install new orings and clips and install injectors and rails.

Notice the fuel line in the rear of the rail. That runs to the front of the right rail. Install these as well as the rear line from the FPR to the fuel cooler.

At this point double check all your hose clamps and install the air pump lines from the switch over valve to the left injector block runner. Now lay the harness in the general location. Once again it is obvious ( to me at least) what Porsche has in mind. There are only a few clips here and there. If you have it right you will hit them without stress. If you don’t then you will know it.

This is where my nice clean looking motor goes to hell.

Reconnect all the sensors and wires to their locations. Once completed reinstall the oil tank and lines. Then the air smog pump. You must install the tank first.

Install turbos and turbo vent lines. Next prep the spark plugs with anti-seize on the threads

Install the plugs.

Torque plugs to 22ft lbs.

Next install coil packs and torque to 7.5 ft lbs

Reinstall heat shield

Now ready the clutch and tranny and install in the car. I probably will not follow the rest of the in car install. If anyone has any questions please let me know.

Stephen Kaspar

ImagineAuto Inc

PCA National Tech Advisor, 75-Present 911 Turbo, TT, GT2