ock in the qood ol' doys, tuninq wossimple. YoJ po*ed the heod, ttt'ot.hudthe'monifolds ond the ports, ond.whqcked in o lumpy com. A quicke of corb iets ond o re-curved diznt ondchonoe of corb iets ond o

you'J produced'oodles ofzry

you' J produced.'ood les of power without

full monoqement svstem qoes one sfep further.ln odditioi to this 'iqnitio"n mop' there will be o'fuel mop' which tells the computer how muchfuel to iniect under o qiven sei of conditions.

Fuel ond oduonce Equired wil l chonqewhen you olter the oirflow chqrocteristiis of theenqine - bv fittlnq o performonce com, for

"^Jrplu. So the fomputer will be using the

wrong volues, ond the engine won't run right.Worse still, there ore now'odoptive'

monoqement systems which 'leorn' obout theenginJ they' re tontrolling, ond groduollyodiust themselves to qet the best oui of it -

beorino in mind thot"enoines will differ due tonorrol'production tolerlnces. Put o differentcom in one of these enqines ond the computerwill recognise o differeice, but ossume thot thedifferencE is becouse one of more of iis sensorshos siorted to molfunction. lt'll therefor:e runthe enoine usinq volues i t hos previously leorntto be obout riqF'i which won'i do ot oll.'

So it's cleor"thot if you fit o different comprofile, you need to qlter the ignition qnd/orluellinq mops used bv the monooement system.Whicliis why Piper ond Superch-ips hove gottogether, to ofter. complete pockoges,benefitinq from their experience inp"rfor*o"n.e coms ond're-progrommed enginemonoqement chips, respectively.

To iheck out ttre'combinotion of o chip ondcom, we tried the Piper/Superchips pockog.on o Mk3 WV Golf GTI used by MorkHororeoves. our tome timinq mon lromDot[n. Aport from o tosty it of Borbet wheelswropped in Pirelli PZeros, the cor woscompletely stondord.

This wosn't iust q motter of fittinq the bits,thouoh. becouse Piper don't yet do-o com forthe MkS 2-litre enqine. so Piper's TechnicolDirector John Cro6b brouqhitheir Mk2 Golfcom ond hoped it would fi't ond be somewhereneor the riqht profile. And of course therewosn't o SJperchip mopped for the com, sowe hod to siort wiih the stondord Mk3 GolfSuperchip ond olter the mop to suit.

ruinini driveobility.lfls not so eosy ony more. Most cors now

run some sort of enqine monoqement system tokeep control of spofts ond fuelling,.onJ o,soon os vou stori chonoinq the mechonics ofhow the Lngine works,"the"mops used by themonoqement system will be wronq.

Mois? Well'we exploined somE of this ocouple of issues bock (see Fost Cortogrophy,Fasi Cor November), but let's iust recop.

As we've exploined before, o,moppediqnition system stores o set of volues - o mop -

o"f iqnition odvonce. The system hos enqinedotl inputs (usuolly sp""Jond lood) frimwhich ii con decide on the right volue to use. A

ffi

New Piper cam wastimed in using'OT' marks on the

pvlley and cam box, which give theTDC position,

slightly (usuolly by 4-8degrees, moybe less otsrrgnfly lusuoily by -udegrees, moybe.less otcertoin points in the rev ronge) ond richens the

Superchips used their emulotor system sothey i:ould olter the mop, ond topp6d into theoutpul from the cor's lombdo sensor to monitorthe fuel l inq.

First we"ron the cor usino the emulotor withthe doto from the stondord"Golf Superchip.This normolly. increoses.ignit ion odvonce'

mixture where neededSuperchips' Jomie Turvey ron the cor up on

the rollinq iood to check the fuellino.monitorin"q exhoust CO ond the ouiout fromthe lombd"o sensor. Bosicollv the fuellinq wosobout right, thouoh ot idle (*h"r" the cim hostoo mucf, overlop"ond isn'tiill ing the cylindersvery efficientlv) the mixture *os"prouin'o tooric6. To correct this the fuel mop'wos chonged

to reduce the omount of fueliniected. This olso hod the sideeffect of reducino idle emissions.

At wide openThronle theionition needed odvoncino sliohtlvo"t the top ond the bottom-of tlie

'

rev ronqe. while in the middle itneeded-reto rd i ng sl ightly wherethe com wos ooerotino of its best.At port throttle'o littleless odvoncewos needed in the low ond midronoes to ovoid the onset ofpin[ ' inq. But beor in mind thot ol lihit *o"t bosed on the volues in the

Managemenl system revealed - the'chip'is the smaller of the two blackobiects al the bottom left of theboard.

Superchip, not the stqndord Golfmop, so in oll cqses the engine wos