Tii Engine Performance Upgrades

This is a very common question asked about the Tii engine, so I’m going to share one asked that fits the discussion.

I have a euro 73,74 tii engine with the larger 9.5 pistons and newly rebuilt pump and injectors. Was wondering what it would take to get 160, 180hp from this motor? And would the pump need modifications as well ? Would it be drivable ? What would such an upgrade cost? Appreciate any opinions and experiences.

For a 30-50hp increase, there are several things that could be done to increase your engine’s performance with and without pump modifications.

There are several approaches to doing this. Answering this without making it a “how to” article on the subject which has been done in 100 different ways over the years, let’s cover specifically what you said.

What would it take? Would the Pump Need Modifications?

Horsepower improvements from 160-180 hp without changing the pump:

  • Increase your displacement with larger pistons up to 2.2 liters
  • Increase the torque with a longer stroke, using the E30 M3/S14 crank
  • And then improving the exhaust system to a larger diameter free flowing system

Horsepower improvements from 160-180 hp that require modifying the pump’s fuel delivery curves

  • Increased induction and air intake by using multiple throttle bodies or larger bore throttle body in addition to the modifications listed above.
Alpina Throttle Bodies

A word of caution about Tii engines It’s important to note that a different camshaft other than stock has proven to create more problems than it helps. Historically, BMW used the same camshaft lift and duration from the 1600 1 bbl Solex all the way to the 170hp 2002 turbo.

Would it be drivable?

There are many 2002’s on the road with engine performance modifications in the horsepower range you mentioned, but not using the base of the Tii fuel system to do it.

With different cam, head improvements, bore and displacement changes, stroke changes and dual side draft Weber 40s or 45s carbs instead. It’s possible to have a drivable car, and making the assumptions that how much fuel you consume is directly related to how often you keep the accelerator pedal on the floor 🙂

What would it cost?

As a rule of thumb,  as costs go, an engine with these kind of modifications could easily cost one half to twice as much as the cost of rebuilding the engine in stock condition.

Last update: 2007-01-03 21:26
Author: tiiregister

Tii Air Filters

Q. How many air filters are installed in a 1972 BMW 2002 Tii and in which direction are they installed, with the open ends of the filters facing the spouts on both ens of the unit or facing in towards the center of the canister. Thanks Burt

There are (2) identical elements, both are open toward the center of the housing. Clean air enters the snorkles, passes thru the elements and enters the throttle body.

Engine view with airbox

Last update: 2009-04-13 17:23
Author: Jim Gerock

How to identify a 2002tii exhaust manifold

How to identify a 2002tii exhaust manifold

We are asked many times how to identify a 2002tii exhaust manifold. There seems to be several for sale which appear similar but are not.  For example:

What is the difference between the exhaust manifolds fitted to tii’s and standard 2002’s? Were the original castings the same or was there a difference in the casting? Also, have the manifolds changed; i.e., are new replacement manifolds the same as those originally fitted to tii’s? Currently, the tii exhaust manifold seems to be the only manifold available through Mobile Tradition (excluding the thermal reactor which is also available – for $2000!). What’s up with that? -Jerry

The good news is that adding the tii manifold to any BMW 2002 engine will improve the performance in terms of gas mileage and horsepower because of better flow.  The original manifolds, especially the 1975-1976 models were restrictive to meet early EPA pollution standards and eventually warp the head due to the extreme heat produced by them compared to the original design.

When you place the old style and any 2002tii manifolds side by side, it is easy to tell the differences. As the saying goes, a picture is worth 1,000 words.

Click the photo to see the full resolution photo.

Tii Exhaust - Click to view

Noisy timing chain adjustment

Does your engine make a lot of noise from the passenger side of the car. It’s a “grrrr” type noise just above idle, not a clank. If you listen closely with the hood up, what you may be hearing is the timing chain rattling because it’s not receiving enough pressure from the tensioner.

Normally this involves bleeding the piston properly, which is not documented very well.

This step takes about an hour, a ¼ ratchet with 10mm socket and small extensions, two new gaskets for the upper timing cover and some RTV silicone sealant, along with a quart of the oil you are currently using.

The procedure is the same whether the engine is new or already broke in. Only step 3 is different because the reservoir is shaped to be level when the engine is at it’s normal mounting procedure and you must compensate for that.

Steps to a quieter timing chain are as follows:

  1. Remove the valve cover completely
  2. Remove the upper timing cover, which is the cover in front of the timing chain gear
  3. If the engine is out of the car, move the engine so that it is approximately in its normal tilted position with the bottom of the oil pan horizontal.
  4. Carefully remove the timing chain tensioner piston cover. The spring and piston will come out unexpectedly so be careful and be ready to catch the pieces. Note the position of the spring, it only goes in one direction!
  5. Inspect the piston and clean it carefully with either kerosene or a carb cleaner. If it’s totally clean you should be able to shake it up and down and hear the ball bearing inside it rattle.
  6. Insert either a cleaned or new tensioner piston into hole so that the tab on the tension rail sits in the slot on the end of the tensioner. This normally with the tabs on the piston turned horizontally because the slot runs vertically on the tensioner rail.
  7. Next insert the spring, washer and threaded plug. then tighten one complete turn of the threads, just enough to hold it to the lower timing cover.
  8. Pour oil down the inside edge of the cam sprocket cover to fill the tensioner oil reservoir. This can easily be done with a syringe or an old fashioned oil can because it won’t take but a small amount to fill it to the top.
  9. Now with your fingers on the tensioner rail, force of the tensioner spring, then release the rail. Repeat until oil is moving out of the threads on the back of the tensioner piston cover on the lower timing cover.
  10. Secure the timing chain tensioner piston cover
  11. Continue step 9 again until the tensioner rail quits moving or is very difficult to move.
  12. It might be necessary to refill the oil reservoir to completely bleed the tensioner.
  13. Before reassembly, ensure the reservoir is full and that all gasket material of the upper timing cover has been removed and replaced
  14. Put a dab of RTV silicone sealer in the crack between the head and upper timing cover. This is a spot for oil leaks to occur over time.
  15. Tighten everything back up.
  16. Start the car and let the engine warm up
  17. You can now blip the throttle several times and the chain noise should be gone or will go away after a few more blips of the throttle.

Now enjoy how quiet your engine really is!

Last update: 2007-01-02 11:32
Author: Keith K