Jeff I don't think anyone is arguing that the Rover 2.25l petrol engine isn't built to last. I think every pro mechanic who first opens one up remarks about how seriously overbuilt the engine is. And I agree that with proper maintenance the engine will keep running long past the point where others won't even start.Originally Posted by Jeff Aronson
My personal beef was that the engine is not powerful enough to be safe pushing a 109 Dormobile in traffic when everything around you had 2X to 3.5X the power. I personally went to a higher power engine for safety in some of the places I drive and I hate failed climbs because the engine just grinds to a stop.
The Series gearbox was considered quite robust and advanced when it was first used by Rover in 1932. The design has undergone a number of upgrades since then and the box seemed a good match for a topless 80 inch SI with its 1.6L petrol engine.
But with the SII the body got a lot heavier, especially the 109 stationwagons. The 2.25L engine was a decent power increase over the original 1.6L engine. Rover uprated the gearbox a few times. Early gearboxes tend to break lay shafts and main shafts at the circlip groove positions. Late 2A lay shafts without the circlip groove are stronger than the early ones. By the D suffix the SII box got about as robust as it was going to get. But even then it is reliable for only up to about 120 HP and 160 lbft of torque.
As you say it is plenty good for a Series 2.25l engine and even a 2.5L upgrade and at 200/300 tdi stretches it close to its reliable limit.
I agree completely that a stock 2.25L engine with stock LR gearbox all with genuine LR parts is a reasonably reliable combination that if treated properly and well maintained can last for many many miles. Uprated rear axles would really help though. If this is the performance envelope you feel comfortable with and have access to genuine parts then it is a good solution.
However, Rover has been happily discontinuing genuine parts for Series rigs and the aftermarket parts available for SII gearboxes are proving to be substandard. Too many people are rebuilding gearboxes these days and having aftermarket component failure within a year of heavy use. I think that's why so many people are looking for alternatives to a Series gearbox these last few years.
As for your 18-19 mpg [highway driving at 60 mph] figure, I'm guessing it is a little high unless you are running an 88 with spare on bonnet, no roof rack, a Weber one barrel out of the box and possibly a soft top. Oh and you are driving 100% petrol and are below 3000 feet. Add good street tyres and that is about as good as it gets. A lot of the time a Weber right out of the box is a little under jetted. Have you had a sniffer put up the pipe & got an air:fuel ratio test?
Alcohol gas blends alway decrease mileage from 100% pure petrol.
I agree the thread's starter has got some issues going on with 12 MPG IF HE IS TALKING HIGHWAY MILES ONLY. I think 12 MPG COMBINED highway and city is fairly common for most people. I think most Series rigs get between 14 and 17 MPG highway depending upon their configuration, weight, tyres and state of tune. Those claiming 20-22 MPG highway are likely figuring imperial gallons or running real lean and cruising for a bruising in the form of burnt valves or a hole in a piston.
If you are happy with the performance of a 2.25L engine, don't over stress your drive train and have a source of 100% genuine parts, I agree the stock drive train is good and reliable. Except for the 10 spline rear axles. You will never get me to say good things about them other than they make good pry bars. But 12 MPG combined mileage is pretty much ball park for a stock Series rig.
Some of us look for more and I think that is what this thread is all about.
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