993 Faq Frequently Asked Questions about the Porsche 1994-1997 993


993TT short shifter pic

Filed under: Turbo — Jeff 993TT @ 10:56 pm

Image that shows how the transmission tunnel needs to be modified to allow for short shifter install.


Turbo Modifications

Filed under: Links,Turbo — Jeff 993TT @ 10:31 pm

Here is an excellent site on how to modify your turbo:

993 Twin Turbo Mods


Oil Change on a Turbo

Filed under: Do It Yourself (DIY),Turbo — Jeff 993TT @ 7:50 pm

In addition to Robin’s information for an oil change on a NA (normally aspirated ) 993, I’ve created some additional specific for Turbo cars.



Smoking exhaust on startup ( TT cars )

Filed under: Engine,Turbo — Jeff 993TT @ 11:07 pm

If your car starts smoking upon startup and DOES NOT go away after a seconds, you make have a different problem.

Usually, smoke starts pouring out of the left side ( driver’s side ) exhaust. White billowly clouds behind your exotic sports car. Not a good sight.

Most owners notice this after an oil change which included changing the oil filters.

Here are the symptoms:

a) Smoking on left side tailpipe ( driver’s side )

b) Small drips of oil under the right turbo ( passenger side )

c) Excessive oil in the turbo intake pipes

d) Excessive oil in the intercooler ( there should just be a very light film of oil in there. )

e) No other driveability problems, ie getting full 0.8 bar boost, etc.

f) Strong oil smell when the car is idleing or turned off after running it.

Usually, smoke in one side of the exhaust points to points to a bad turbo seal. These seals are like piston seals and DO NOT degrade over time. The normal lifespan for turbos ( which have NOT been abused or hot shutdown’d ) is about 75K miles. If you have a low mileage TT, I would not suspect faulty turbos just yet.

Here are the diagnostic procedures:

a) Drain both turbo oil tanks. You should get the same amount of oil in each. If they are drastically different, then you may have a bad turbo seal. If they are pretty much the same, then you should keep looking. Your turbos are probably fine.

b) Do another oil change. But this time, verify, I mean VERIFY that the engine oil filer ( the small one ) part number ends in 03. There was a TSB about older filters not working properly. There is a check valve in the filter which is VERY sensitive to how tightly the filter is screwed on. Follow the service manuals which state to HAND TIGHTEN, then do another full turn with the wrench. If you don’t tighten it sufficiently, then the check valve will not make contact to the engine nipple.

c) Do not overfill the engine. Fill it to the lowest twisted mark on the dipstick.

d) Use 15w50 Mobil1 oil. I can’t confirm that this really does anything, but the two times I’ve used 0w40, my smoking returned.

e) Clean out your turbo intake hoses and intercooler for any residual oil. Even if you fix the problem by using the correct oil filter or tightening it correctly, you will still see smoke if there is oil in these 2 areas.

Following these procedures, I’m smoke free. Even the smoke puff on startup is gone. However, usually, after I do another oil change, I will get smoking/oil drips again. I can never seem to get the oil level just right and habitually overfill it. DOH. The oil level is VERY SENSITIVE, DO NOT OVERFILL!

I’ve helped over 15+ TT owners fix their smoking problems with these procedures. If you’ve done all these and you still have problems and can confirm that your turbo are still good ( via the oil level of the turbo oil tanks ), then there is another solution.

Andial in Santa Ana, CA ( southern California ) sells modified turbo oil lines to prevent the oil from collecting in the turbo. They are specially modified and bent oil lines which replace the current ones.

You may be asking why is the problem happening in the first place? It appears that the turbos are lower than the crankcase. So gravity will pull the oil down and it will pool in the turbos. That is why the system of check valves is so important. That is also why using the Andial solution should work too. It just raises the oil line so that gravity will not automatically drain the oil from the crankcase to the turbo. In the 996 turbos, they have check valves in the oil lines to address this issue. Not sure why they did not design the 993 the same way.


How do electronic boost controllers work?

Filed under: Exhaust,Turbo — Jeff 993TT @ 9:54 am

A wastegate is a valve that regulates the boost in our cars. It does this by opening at a preset setting and allows exhaust gas to bypass the turbo out to the atmosphere (either through a muffler or directly out.). This keeps the turbo from spinning faster, therefore keeping the boost at the preset setting.

Speaking strictly of external wastegates, most, maybe all, wastegates, electronically controlled or manually controlled have a mechanical spring in them. When you install a 1bar boost spring in the wastegate, the turbo will not produce anything more than 1 bar of boost. Since it is a mechanical device, as the pressure on the spring increases, it begins to open the wastegate, so by about .5bar, the wastegate is starting to open even though it has not yet reached full 1 bar boost. This causes some degree of inefficency as the boost does not build as fast as it could by keeping the wastegate closed until 1bar. Additionally, a manual wastegate, although set with a 1 bar boost spring, may tend to fall off in the upper gears and may only allow .8 or .9bar.

An electronically controlled wastegate, uses engine vaccuum/boost pressure to assist the spring tension and keep the wastegate closed until its preset setting. Take the above example of 1bar. An electronic controller can usually handle about 150% of the spring rate, so if you install a .7bar boost spring, the controller can be set to control from .7bar up to about 1.05bar of boost. Once the electronic controller senses 1bar, it will release the spring and the wastegate will open and it will regulate it exactly at 1bar assuming it was programmed properly. You can also usually change the setting on the fly. If for instance, you wanted less boost while driving in the rain, you could set it to .7bar with the touch of a button.



Cat bypass pipes

Filed under: Exhaust,Turbo — Jeff 993TT @ 6:08 pm

Catalytic converts convert the incomplete burning of gasoline products into more environmentally friendly products.

But as with any filter, it will reduce air flow, which reduces power. Environmentally ethics aside, I will share my experiences with them.

For a NA car, the effects will be much less notacable than a turbo. That is because on a turbo car, the most exhaust gasses which are expelled means more forced air into the engine.

Popular manufactures are Cargraphics and FVD. Cost is about $2500 for a turbo car.

How to purchase a TT

Filed under: Purchasing a used 993,Turbo — Jeff 993TT @ 6:06 pm

Buying a turbo has some extra things to look out for. There were several model year variances as well to keep in mind.

Please follow this link to this excellent buying guide for 993 Turbos: 993 Twin Turbo Mods


Auxilary Oil cooler

Filed under: Engine,Turbo — Jeff 993TT @ 5:56 pm

Reducing engine temperature is essential to engine longevity and should be considered when adding modifications to increase horsepower. This is especially important for modified TT cars and cars which are tracked frequently.

Most high end synthetics will provide protection up to 310 degrees F, however, power loss will start as low as 210 degrees F. ( Just above the 8 o’clock mark on the oil temperature gauge )

Here are some popular options:

a) Turbo S oil cooler ($800) – Standard on the 430 HP Turbo S cars. Adequate for modifcations up to 430 HP.
Advantages: Factory parts, retains A/C function, easy DIY installation.
Disadvantages: Relatively small surface area, limited cooling benefit.

b) Cargraphics GT Oil Cooler ( $1500 ) – Good for heavily modded cars (> 440 HP) and cars that are tracked very hard. The Cargraphic unit is installed next to the A/C condensor.
Advantages: Argueable the best oil cooler on the market. Over 3 times the surface area of the Turbo S oil cooler. Retains A/C function. Since it sits next to the A/C, turning on the A/C acutally increases oil cooling function.
Disadvantages: A little more difficult to install than the Turbo S cooler. Possible slight loss of A/C function on hot days.

c) Cargraphics Oil Cooler ( $1000 ) – This is two turbo S coolers, one on each side. I don’t have any information on this.

d) Modified piggyback existing oil cooler ($900) – This is a custom job with custom plumbing. Martin mentioned there are some shops in Los Angeles that do this. You can find more information about that here: Rennlist Discussion Forums: 2nd oil cooler

e) RSR oil cooler – This is installed in place of the AC condensor. Obviously, you will not hav A/C operation anymore. You can contact Rennsport Systems for more information.

You choice will depend on your car type ( NA vs TT ), your expected driving and expected ambient temperatures. For NA cars, the Turbo S cooler is usually more than adequate. For TT cars, the Turbo S or Cargrahic units would be more suitable options.

Both the Cargraphics and Turbo S auxiliary oil coolers can be ordered from Carnewal.com and Rennsport Systems.

All these options mentioned are passive cooling. The car needs to be moving before it actually does anything ( with the possible exception of turning on the A/C with the Cargraphics unit installed ). If you are stuck in traffic or at a standstill, I’d recommend that you install the oil cooler fan switch. This turns on your existing oil cooler fan on when you are stopped.


Fuel pressure regulator

Filed under: Fuel system,Turbo — Jeff 993TT @ 5:20 pm

On TT cars, the fuel pressure regulator should be upgraded if your engine produces over 430 horsepower to keep up with the increased HP and boost levels.

Options include adjustable regulators and the Porsche Motorsports 5 bar regulator. It is NOT recommended to modify the existing fuel pressure regulator.

The Porsche Motorsports 5 bar fuel pressure regulator can be ordered from Schatz Motorsport


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