Connecting Rod Set For 2.4L Conversion

Product Ref: ENG225Z


Many club members will be aware that our associates, LMB in Belgium, used to offer a 2.4 litre conversion for the 2 litre engine.  Amongst the large quantity of spares that was bought from LMB by the Club (in 2018) were some new crankshafts and associated conrods of the type that were used in these engines, and we have been reviewing the best way to offer these to members.

 Although the Club does offer many parts with improved specifications compared with the originals, these improvements are mainly aimed at reliability and durability, and we do not generally offer to members parts (apart from lightly improved camshafts) that are aimed at getting more power out of the engine.  There are widely differing views about the uprating of Lagonda engines, and most people who pursue this path have their own individual ideas and requirements. Moreover, the engineering skills required, and the technical risks and liabilities that are involved, mean that the Club has always steered clear of offering components for major engine upgrades.

 However there are a number of these 2.4 litre engines around, and, as far as we are aware, their owners are happy with them, so we have decided that we should find a way to utilise these special parts that we have acquired.

 The uprating of these engines by LMB involved a lot more than just a capacity increase (we understand that the bore is increased to 76mm and the stroke to 130mm, giving, in fact, 2.36 litres), which itself requires significant modifications to the crankcase and cylinder head, as well as a new crankshaft, rods and pistons.  Much uprated camshafts were normally fitted, which required the bearings to be bored out, and the valve gear (incl. rockers) was modified and uprated as well.  Twin SUs are assumed (HV3).  Rebuilding the engine invariably requires a number of other replacement parts in addition, depending upon its initial condition.

 We understand that the power output of these '2.4' engines was at least 100 bhp at 4,000 rpm, and that there is at least one supercharged engine in existence which develops even more.

 So this is not just a matter of fitting another crank and rods, but it involves a great deal of  skilled work if the full results are to be achieved.  Of course it is possible to take a more gentle approach, with much less modification. This could mean just increasing the stroke (to improve the low-end torque), together with a modest increase in compression ratio and improved (but not aggressive) camshafts. This would not require changes to the cylinder head or to the valve gear, and the engine would operate within its normal range of r.p.m. (or slightly less).  For a member who is anyway undertaking a comprehensive rebuild of his engine, the extra cost of this may be acceptable, and the need for specialised knowledge would be less.

 However, it would be good for members to be able to have a full uprating, so we have discussed all this in depth with LMB, who have the detailed knowledge and the necessary skills to do this work.  Arising from this, we are pleased to say that LMB are willing to offer this full uprating service to any member who is interested. Owing to the amount of work required (which would carry their guarantee), the total cost of this conversion is unlikely to be less than €25,000, and this will depend upon the initial condition of the engine and upon the degree of uprating required.  Interested members should contact Ronald Albers at LMB ([email protected]).

Therefore we are offering members the choice between a DIY approach, simply acquiring the crankshaft and rods from the Club (£3,500 for the set), which would carry no guarantee; or a full-house approach, with a rebuild by LMB, carrying their guarantee.

One needs to bear in mind that the power of an engine is largely a function of three things  -  b.m.e.p., piston area, and r.p.m.; lengthening the stroke (to a first-order effect) just lowers the r.p.m. at which peak power is developed; it does not increase the power, despite the increase in capacity.

In uprating the engine, members should also consider the impact of this on the rest of the car.  The 2 litre clutch is a weak point, and the fitting of a 'Borg and Beck' conversion might be a wise move.  Needless to say, the brakes will also need to be in tip-top condition.

Follow the link below for the corresponding crankshaft:

Please contact the club directly if you wish to purchase the discounted set of connecting rods and crankshaft, priced at £3500.