BRIEF HISTORY OF THE ROVER T-SERIES ENGINE

The origin of the T series goes all the way back to B series engine originally used in many popular BMC cars through out the 1960’s all the way until 1980. The B series itself was essentially a larger version of the OHV  A series engine, the efficient Weslake design of the combustion chambers within the cylinder head was retained, as was the all iron construction of the block and head. It earnt itself a good reputation as being a torquey and solid performer, especially when a 5 bearing crankshaft was designed replacing the weak 3 bearing item originally used, this also enabled longer strokes to be used with great effect.

One fault that the B series had was related to distributor wear, after high mileages the correct ignition timing would often scatter from its original setting and thus cause problems with economy and emissions.

  In the late seventies it was decided to re-engineer the B series, changes included a stronger block, different strokes, a more efficient and lighter aluminum cylinder head, and an OHC configuration with a belt driven camshaft.

  It was to be designated the O series and was intended for use in the MGB, specifically for the American market, it could use unleaded fuel with no problems, and as the distributor design was changed, the engine would stay in tune for longer and thus result in cleaner exhaust emissions.

  As it happened, MGB production was stopped and the O series never saw the light of day in that vehicle, it did however see service in the Morris Ital and Austin Ambassador in 1.7 and 2.0 litre form.

  It wasn’t until 1984 when the MG Montego was introduced that the 2.0 litre O series started to earn itself a reputation for being a strong performer with exceptional torque low in the rev range, typical of an 8v long stroke engine, it was later installed in the MG Maestro, in both cases, Lucas Hotwire fuel injection systems were used and resulted in good fuel economy and smoothness with very sharp throttle response, with an output of 115bhp @ 5500 rpm and torque in excess of 130lb ft @ 2800 rpm, these were favorable figures at the time and was more than enough to see off the competition in the shape of the Golf Gti, Ford Escort XR3i and Vauxhall Astra GTE to name but a few.

At around the same time, in anticipation of the forthcoming Rover 800 series, a more advanced version of the O series was directly developed, using a very similar bottom half but with a 16 Valve cylinder head and a more advanced ignition and fuel control system. It was very much the trend to go towards 16 valve units as they created better BHP figures, were smoother and were often more fuel efficient. Prototypes were installed in MG Maestro’s but with the longer front end of the Montego fitted, and not long after the engine was called the M Series.

Two versions were available, the single point injection and Multi point injection unit, the latter generating 140 BHP at 6100RPM and Torque very close to that of the 8v O series unit at low revs, when installed in the Rover 800 in 1986, it was a spirited performer with a surprising turn of speed and willingness to rev, unusual for the long stroke design.

Further minor alterations were made up until 1991, but not long after, another makeover turned the M series into the T series. Amongst the changes,  different engine management systems further improved performance and economy, inlet and exhaust manifold changes, different air filtration system and a more simple cambelt arrangement made the engine easier to work on and many of the earlier faults of the M series were resolved in this new version.

Fitted in 1992, just in time for the introduction of the Mk2 Rover 800 series, it was the best seller in the 800 range and was used in many other Rover applications including the Honda based 200/400 series.

Rover had one more trick up it’s sleeve, and this was the Turbo version.

Developed as a replacement high powered  engine for the faithful Honda V6 fitted to Sterling and the original MK1 Rover 800 Vitesse, it was introduced a few months after the Mk2 range appeared in 1992.

To increase the power from 136 BHP of the naturally aspirated ‘T16’,  a small Garrett T25 turbocharger was fitted running a base boost figure of just over 6psi, which was electronically regulated by ECU to 8-10psi via a boost modulator valve. Other changes included lower compression pistons, alloy intercooler, a cam sensor and different sequence to the fuel injection system.  With other minor changes, power was up to 180bhp.

As this set-up was essentially a ‘low boost’ system, lag was virtually non-existant with the quick spinning T25 turbo. It’s advantage over many turbocharged car’s is the very wide power band, with boost starting from as little as 1500RPM, you are never caught out with a ‘laggy’ moment and mid range response is exceptional.

  A year later, an even higher powered version of the T16 Turbo was introduced with 197bhp (200Ps), with a further increase in boost and different cam timing.  It was first fitted into the Rover 220 Coupe, and in this car it gave what can only be described as electrifying performance, 0-60 came up in as little as 6 seconds and would pull to 150MPH…..  Not even the Escort Cosworth could keep up with it at speeds above 110mph.

The chance for this higher powered engine to be fitted in the 800 came in 1994, when the 800 Vitesse Sport came out. With an identical engine spec to the 220 Coupe, it was not a slow car and 60 MPH could be reached in 7.3 seconds with a top speed of 143mph.

  Full engine specifications and performance figures can be seen in the Vitesse specs  section of this site.

                                                                        By Gareth Kidman.......

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