Period Reports

THE LAYSTALL-LUCAS CYLINDER HEAD

A High-Performance Light Alloy Head for M.G.s

the extra urge, and some slip took place  at  the  getaway and on chang- ing gear.  Stronger clutch springs are readibly available, and would be well worth having.

    The actual changing of the heads was  done  inside  an  hour  and half, or 1¾ hours if one includes warming up and   checking  valve   clearances. In   order  to  accommodate   the specially shaped ports, the Laystall- Lucas head is somewhat wider than the standard article. The regular manifolds  and  gaskets  go straight on, however, and any normally com- petent owner could do the work himself.   The  M.G.  engine  is  very

accessible, so the job is quite straightforward.

    I   also   used   the   M.G.   as my normal hack for a few days, and the improvement  in   performance was most marked.    Although the maxi- mum speed is considerably aug- mented, it is the better acceleration in the middle ranges that one notices most  in  everyday  driving.    I used 80   octane   fuel,   on which the unit was remarkably flexible.   I  am  told that the high commpression-ratio does not preclude the use of pool petrol, but as branded spirit will soon be available everywhere,   I  did  not bother to verify this.

for ”Stage II” tune, and these are included  in the price of  £48.   It  is cast  in  RR  50  aluminium  alloy, which  not  only  eases  all  the heat-  flow problems, but saves 16 lbs. of weight.   The main feature, however, is the scientific proportioning of the ports and head shape, which greatly increases the air flow, as the accom‐ panying graphs show. The technical side  of  the  project  is  the work of John Lucas,  who  has  put the speed into many of our fastest engines.

    On the bench a b.h.p. increase of some 20 per cent is recorded, by simply changing cylinder heads, and making no other alterations to the engine.   Bench  tests  are  all  very well,  but  it  is  road  behaviour that really counts.   Accordingly, I took over  a  TD  type  M.G.  recently,  to see  if  the  theoretical  advantages were  obtained  in  practice.

    It will be observed that, in the data panel, performance figures are given for the car in standard form and with the Laystall-Lucas head fitted.   These results were secured at the M.I.R.A. proving ground, and were electrically timed.   It will be realized that the length of run avail- able did not allow the ultimate maximum speed to be developed, but the figures are strictly compar- able.

    Having tried both heads with the standard 1¼-in. S.U. carburetters, the new head was finally fitted with 1½-in. instruments. Although the engine felt considerably livelier at the top end of the revolution range, the times recorded were not enor- mously better. This was simply be- cause   the   clutch   disliked   handling

COMPARISON: John Bolster, Basil de Mattos (Laystall's), John Lucas, Martin Burgess (W.H.M. Burgess, Ltd.), and Ronald Goldberg compare the standard M.G. TD cylinder head on the scales with the light alloy Laystall-Lucas unit.

to  welcome  this  new  compenent with  open  arms.   Where  the cylinders have been over-bored to contain a piston-swept volume approaching 1½ litres, the head will give a compression ratio around 10½ to 1.   Still higher figures are possible if domed pistons are employed, and 1½-in. carburetters  would  certainly be desireable for such work.  The weight-saving conferred by the light- alloy head will be appreciated by competition drivers.

    Pause,     then,     you     sports-car

    During my test, freezing tempera- tures were experienced most of the time, and I did not even cover the bonnet with a rug at night. Never- theless,   starting  was  rapid  and  cer-

is  ”ready  tuned“,  so  to  speak,  and no  work  is  entailed  apart  from fitting.

    On  the  other  hand,  the gentry who race M.G. engineered cars are sure

owners,  before  you  cross  swords with  an  innocent-looking  M.G.  It may have a Laystall-Lucas cylinder head  under  its  bonnet, and you will be in for a rude awakening!

JOHN V. BOLSTER.   

tain every morning. The fuel con- sumption  worked out at 28 m.p.g., but  as  this  included  the  flat-out

timed runs,  I would  say  that  a  full 30 m.p.g. could be relied upon for ordinary journeys.

    This head is applicable to the TB, TC, TD and 1 ¼-litre saloon model M.G.s, also the new Wolseley 4/44 though twin carburetters and mani- folds  must,  of  course,  be  obtained for  the  two  latter  cars.   It repre- sents a remarkably cheap way of augmenting   the  performance,   for  it

Component     Tested:    Laystall-Lucas Cylinder   Head,   tested   on   TD   type M.G. car.  Price U.K. £48, or £50 including fitting.

Material: RR  50  aluminium  alloy,  with valve inserts.

Valves:  36   mm.   inlet,   and   34   mm. exhaust valves, with 150 lb. springs.

Rocker   Gear:   Standard   rockers   and   all other fitments.

Compression   Ratio: 9.3 to 1.

Performance:   20   per   cent.   power increase.

Test   Results:   Standing   figures   are   for last   100   ft.   of  ¼ mile.   Flying  figures are for last 100 ft. of 1,400 yds.
Standard Iron Head, 1 ¼-in. S.U. car- buretters, standing, 58.14 m.p.h.; flying, 70.79   m.p.h.    Laystall-Lucas    Head, 1¼-in. S.U. carburetters, standing, 63.17 m.p.h.;   flying,   75.45   m.p.h.  Laystall- Lucas Head, 1½-in. S.U. carburetters, standing,   63.76   m.p.h.;   flying,   76.52 m.p.h.   Electrical   timing,   all    figures are   mean   of   runs    in   both   directions.