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MG ZR ZS ZT Technical - 1.4 or 1.8 engine ?

The latest Rover45 with 1.4 16v engine has been given a good write up in a current French magazine.If it develops as much as 103 hp,one would expect the 1.8 to produce more than the actual 117.
Is the latter being deliberately kept down in order to minimise risk of HG failure? If not,how much more could it produce on an equivalent level of tune to the 1.4?
antoine

The MG TF has a 1.8 K-series engine with a 135PS engine. I think it has different cams which helps increase the output.
Matthew Semple

If this has no problems of HGFs,wonder why it is not used in the saloons?
antoine

Antoine
The 95 on Rover 400s were sold as 4dr or 5dr, and continue as this with current 45s. However, previously the 5dr was badged 200, whilst the 4 dr saloons were 400. But when the current 25 was first launched in 95, it was meant to replace the ageing Metro (100), but because sales were so good of the 100, it was kept on for another 3 or 3 yrs until early 1998. So instead of calling the 25 a 100, it was then called the 200, which meant that the 5dr became the 400 (perhaps this should have been 300 but BMW might have complained!).

The point of all this is that the 5drs were always sold as a lower spec car compared to the 4dr saloons, and thus the 1.6 was the smallest engine available in the 4dr range, and probably because the weight of the 4dr saloon would have made it too heavy for the 1.4 engine. Also the 5dr hatches are more popular especially to the budget concious family buyer so a 1.4 would have been welcomed in this sector, but not in a saloon. The typical saloon buyer was likely to want a little more prestige so a 1.4 probably wouldn't have sold well.

The 1.1 and 1.4 8valves were excellent engines when launched and used in the 100/200 range, and it was only ever designed for a maximum of 1.4 capacity if I recall. But the use of damp (combination of wet and dry) cylinder liners was partly responsible for the extra capacity. Although now at a maximum 1.8, the BTCC MG ZS WSR team were using a 2.0L K series this season which was remarkably reliable and gave them a definite advantage over the previous season's 2.0L KV6 engine.

As to why the 1.8L only gives 120 bhp over the 1.4L 103bhp, I think this is partly due to the way the capacity increase occurs and whether an increase in capacity comes from larger cylinder diametres or from an extended crank/piston stroke.

HTH
Martin ZT

Interesting stuff Martin:

>>The 1.1 and 1.4 8 valves were excellent engines <<

Can confirm that! Drove my teenage son's 37,000 mile (60,000km) Rover Metro 1.1C (C=carb?) last night. It's surpringly quick and as smooth as a turbine. It felt much more powerful than you'd expect from a mere 1.1 litre. The little car flies. However, he has plans to put a 1.4 multi point (MPi) in it. This will give in excess of 100 ps (bhp).... Having driven the car in it's present 1.1C state, I have to say why bother...... get another 1.4 Rover Metro MPi instead.... :)

The ZS 120+ now has 11,000 miles and that 1.8 16v engine also has turbine like qualities which I admire... the coolant level has not moved a millimetre in the 17 months we've had it..... which is nice.

On a recent trip to France, high cruising speeds were sustained with five adults and much heavy luggage on board. This engine has freed up nicely since new but I still detect some tightness. This almost certainly means there is further engine improvement to come. We shall see.
MGJohn

What is the best bet then to get more power(without affecting reliability), out of the 4Cyl K series?
135 HP as in the TF
or xxx HP as in the 2 litre version
(or does the latter have too high a fuel consumption?)
antoine

The 1.4 is an absolute honey of the engine. I agree, on first appraisal, it is surprising that there is so little difference in power between it and the 1.8. However, the manner in which the engine gives that power is quite different: the 1.8 has sheds more torque - not surprising, given the much increased stroke and bore of that engine over the 1.4.

The other thing to consider here is the head design: the 1.8 uses the same head as the 1.4 - therefore the 1.8 is actually somewhat restricted by its port design. If you look at the VVC head - the head designed specifically for the 1.8 - then 160 is easily and reliably achievable.

180bhp is reliably achievable from a normally aspirated 1.8K.

The question regarding the 2.0K cannot be answered as yet: the production engine has yet to hit the streets...

A bit more detail regarding the K-series as applied to the MGF/TF can be found here: http://www.mgf.ultimatemg.com/group2/engines/index.htm
Rob Bell

To complete the picture,how does the 1.6 engine fit into all this please?
antoine

It's effectively a short stroke 1.8 Antoine. Same 80mm bore, and 79mm (IIRC) stroke.

These 'big bore' engines have what has been termed a 'damp liner' - half wet liner, half dry liner - easier to see the expanded engine schematics to see what I mean.
Rob Bell

Rover Metro 1.1C (C=carb?)

The C model was the base model that replaced the City name used in the Austin Metro.
Matthew Semple

This thread was discussed between 29/10/2004 and 18/11/2004

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