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

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