RPM TECH­NIK CAYMAN CSR

Well cho­sen mods from RPM Tech­nik turn the Cayman 981 into a mid-en­gined mas­ter­piece

911 Porsche World - - This month -

Much has been writ­ten about the in­flated val­ues of Cayman GT4S and the yawn­ing gap be­tween this highly evolved halo model and the rest of the range. One could sit and rage about the in­jus­tice of this, mut­ter­ing darkly about dealer al­lo­ca­tions and flip­pers cash­ing in on yet an­other over-hyped, lim­it­ed­sup­ply Porsche.

Or, like Buck­ing­hamshire-based RPM Tech­nik, you could take a more pos­i­tive, proac­tive view and in­stead con­sider it an op­por­tu­nity. Be­cause in Man Maths terms the c. £40,000 gap be­tween the re­spec­tive used val­ues of a 981 Cayman S and the start­ing price of a lowmileage GT4 at your lo­cal Porsche Cen­tre gives you a big ball­park for play­ing with some up­grades to make the for­mer into some­thing akin to the lat­ter. Or pos­si­bly even bet­ter.

The fis­cally pru­dent would prob­a­bly point out at the end of it you’ll never make your money back on mods whereas the GT4 will al­ways be a GT4 and main­tain its value ac­cord­ingly. But we’ll leave that to those with the liq­uid­ity to pay £80,000-plus up­front or spend more time ob­sess­ing over resid­u­als than be­hind the wheel. Be­cause as a pure driv­ing ma­chine this new Cayman CSR is one wicked lit­tle car.

There’s a good chance you’re al­ready aware of RPM’S CSR pro­gramme, the con­cept in­tro­duced with a 986 Boxster be­fore spawn­ing 996 and 997 ver­sions for 911 own­ers. All are sub­tly dif­fer­ent but the ba­sic premise has stayed the same, CSR brand­ing the um­brella for a pack­age of me­chan­i­cal and styling mod­i­fi­ca­tions in­tended to make the cars faster, fo­cused and – most of all – more fun for the dis­cern­ing driver. So it’s less about big power, at­ten­tion seek­ing aero or other un­nec­es­sary bling. And more about high­qual­ity sus­pen­sion, im­prov­ing the range and re­sponse of the en­gines and then mak­ing some sen­si­ble weight-sav­ing on ar­eas that mat­ter to han­dling, like wheels, tyres and brakes. The goal is a more fo­cused Porsche you can en­joy both on the road and track with­out be­ing overly com­pro­mised on ei­ther.

The mod­i­fi­ca­tions can be bought piece­meal ac­cord­ing to taste, need and

bud­get. Or they can be added as a com­plete pack­age to a base car to qual­ify as a full CSR model, sub­tly branded and liv­er­ied up ac­cord­ingly. And that’s what we have here, cour­tesy of one gen­er­ous RPM cus­tomer and his fully kit­ted out Cayman CSR. “

The devil in a makeover like this lies in the de­tail. Start­ing with the en­gine it gets Kline head­ers, high-flow air fil­ters and a Cobb Ac­cess­port re-map with a handy dash-mounted in­ter­face for get­ting a sense of what it’s do­ing. RPM tech­ni­cal di­rec­tor and all-round en­gine guru Ol­lie Pre­ston ad­mits there is still work to do per­fect­ing the map but the gains are al­ready sig­nif­i­cant, a rough con­ver­sion of the at-hub dyno read­ings trans­lat­ing to around 350ps [345bhp] and a frac­tion un­der 300lb ft, up from the stock fig­ures of 325ps [321bhp] and 273lb ft.

While the im­proved breath­ing ob­vi­ously helps, the bulk of the im­prove­ment comes from the map­ping, Ol­lie shocked to find the fac­tory map doesn’t nec­es­sar­ily trans­late foot to the floor on the pedal to full throt­tle at the en­gine. Porsche will have its rea­sons for this, the stock set-up seek­ing to iron out flat spots and de­liver its power smoothly rather than go all-out for max­i­mum per­for­mance. Suf­fice to say on the CSR when you de­mand full throt­tle that’s ex­actly what you get.

A light­weight clutch and fly­wheel are fit­ted to im­prove re­sponse but the real killer fea­ture is the re­duced fi­nal drive cour­tesy of a new crown wheel and pin­ion, this drop­ping from the 3.89:1 of the stan­dard set-up to a racier 4.125:1. Mean­while a Wave­trac torque-sens­ing dif­fer­en­tial – as de­vel­oped for pre­vi­ous CSR con­ver­sions – puts it all to the road.

Chas­sis work is ex­ten­sive, the key points be­ing Oh­lins Road & Track coilovers, mul­ti­po­si­tion GT4 anti-roll bars and a heav­ily up­graded brak­ing sys­tem based around six­pot ARP front calipers and tour­ing car spec float­ing ro­tors. These are housed within light­weight 19-inch HRE wheels run­ning Miche­lin Pi­lot Sport Cup 2 tyres, the com­bi­na­tion of parts sav­ing at least a kilo per corner.

Vis­ual mod­i­fi­ca­tions are sub­tle but sig­nif­i­cant, the most no­tice­able change

When you de­mand full throt­tle, that’s ex­actly what you get

be­yond the new wheels be­ing the switch to a GT4 front bumper with its in­creased breath­ing and big­ger split­ter. There’s also a GT4 dif­fuser and a small rear wing fixed into its raised po­si­tion, these all fac­tory parts adapted by RPM and com­bin­ing to give the CSR an un­der­stated but pur­pose­ful stance all of its own. In the cabin there are some neat touches, plas­tic trim parts colour coded to the ex­te­rior paint a nod to the GT4 while this par­tic­u­lar car is also fit­ted with full Schroth har­nesses in ad­di­tion to the ex­ist­ing in­er­tia reel belts. In­cor­po­rat­ing them ac­tu­ally proved a sig­nif­i­cant chal­lenge, RPM us­ing GT4 har­ness mounts on the bulk­head but fab­ri­cat­ing steel plates to adapt ex­ist­ing seat fix­ings to take the waist and crotch belts. Ol­lie takes par­tic­u­lar pride in this be­ing achieved with­out the need to drill the chas­sis or make any ir­re­versible mod­i­fi­ca­tions that would pre­vent the car be­ing re­turned to stock if re­quired.

First im­pres­sion head­ing out of RPM’S Buck­ing­hamshire base is how smooth and quiet the en­gine is. This is de­lib­er­ate, the owner stick­ing with the stan­dard sys­tem so as to keep within track day noise lim­its. It’s an in­ter­est­ing con­trast with the ag­gres­sive set-up of the chas­sis, the bumpy lo­cal Broads re­veal­ing a de­gree of ag­i­ta­tion to the ride and sen­si­tiv­ity to cam­bers you don’t get in a stan­dard S.

It’s not un­duly harsh though, the trade­mark Oh­lins flow giv­ing a pil­lowy sense of plush­ness even with the stiffer springs and re­duced wheel travel and

noth­ing like as brit­tle as the pas­sive Sport chas­sis op­tion of­fered by Porsche on reg­u­lar Cay­mans. As much as any­thing this par­tic­u­lar set-up again re­flects the tastes of the owner, who Ol­lie de­scribes as a ded­i­cated track day driver will­ing to ac­cept a lit­tle more harsh­ness in re­turn for im­proved cir­cuit per­for­mance. Harsh­ness that can eas­ily be di­alled out on the Oh­lins ad­justers if you want a more road­bi­ased set-up.

Joy of joys there’s real in­cen­tive to use all of the avail­able gears too, the short-shift mech­a­nism im­prov­ing the al­ready pos­i­tive move­ment of the stubby shifter. With its re­duced in­er­tia, im­proved breath­ing and beefier power de­liv­ery the en­gine has the nee­dle on the rev counter fair whip­ping its way round the dial, the off-cam lethargy you get in the stan­dard car negated by both the in­creased torque and the lower gear­ing. As such throt­tle re­sponse is far sharper, the en­gine happy to pull from 3000–4000rpm in any gear but hap­pier still in the up­per reaches of the range. That no­tice­able step-change in tone and fe­roc­ity now lies be­yond 6000rpm, which could be frus­trat­ing and peaky on the road were it not for the ex­panded mid-range and im­proved re­sponse.

On twisty B-roads this more of­ten than not means you’re slot­ting to and fro be­tween third and fourth, which is a much faster and more pleas­ant mo­tion than go­ing cross-gate be­tween sec­ond and third as you would be in the con­ven­tion­ally geared car. Or, in­deed, a GT4. Even fifth and sixth have the flex­i­bil­ity for mak­ing more re­laxed progress, the lower fi­nal drive mean­ing the shift in­di­ca­tor is con­stantly nag­ging you to shift up, even at a re­laxed mo­tor­way cruise and show­ing just 3000rpm or so. Where a long-geared stan­dard car might need a down­shift to squirt into a gap or even deal with a slight gra­di­ent you now have re­sponse to leave it in gear.

The op­po­site is true when you’re mak­ing more spir­ited progress on a back road but with a driv­e­train as re­spon­sive as this it’s hardly a chore, the com­bi­na­tion of the shifter’s short throw, the lack of in­er­tia in the en­gine and the snappy re­sponse of the clutch en­cour­ag­ing fast, pre­cise shifts and re­ward­ing ac­cu­rate rev-match­ing and fancy foot­work. Shifts that would be re­dun­dant with the stan­dard gear­ing now be­come an in­dul­gence you can en­joy purely for the

Joy of joys there’s a real in­cen­tive to use all of the avail­able gears

sake of it. Which is ex­actly what an en­thu­si­ast’s car should de­liver.

On the road this all adds up to a richly in­ter­ac­tive and im­mer­sive driv­ing ex­pe­ri­ence. Com­pared with a GT4 the CSR main­tains the stan­dard Cayman’s sense of agility and com­pact size, the sense of flow ar­guably more en­ter­tain­ing in this en­vi­ron­ment than the more se­ri­ous and locked-down feel of the fac­tory spe­cial. At the same time it un­locks some of that abil­ity re­alised by the GT4 and proves how the stan­dard Cayman S is, if any­thing, a lit­tle con­strained by its fac­tory set­tings.

Can the CSR match a GT4 on the track though? Our venue is Longcross prov­ing ground rather than a ded­i­cated race cir­cuit, the short but chal­leng­ing ‘Snake’ section ac­tu­ally more like a B-road. One with the ad­van­tage of be­ing able to use all the avail­able width with no fear of any­thing com­ing the other way!

A greasy, win­try sur­face and Cup 2 tyres fo­cus the at­ten­tion some­what, the slightly fat­ter side­walls on the 19-inch wheels more vis­ually ap­peal­ing than rubber band tyres on the 20s worn by many stock 981s. Cups can be a lit­tle alarm­ing on stand­ing wa­ter but in these con­di­tions they’re bal­anced and pre­dictable, the lim­its low but eas­ily read and the car giv­ing you op­tions ga­lore on how to take the cor­ners.

In this set-up there’s still a de­gree of front-end push if you bar­rel into the cor­ners too quickly and no amount of power can over­come it. Trailed brakes to keep the nose tight or a lift to tuck it in are all you need though and, once set­tled, you can get hard on the throt­tle and fully ex­ploit the more mus­cu­lar power de­liv­ery the re­vised gear­ing and ex­tra grunt pro­vide. There’s no need to wait for it to come on cam, the in­creased mid-range urge mean­ing the Wave­trac diff can as­sert it­self and ro­tate the car into the turn on the throt­tle.

It does so more softly than the plated dif­fer­en­tial used by the GT4 and the CSR is def­i­nitely less spiky in its on-limit be­hav­iour. But such is the nat­u­ral bal­ance of the Cayman you’re con­fi­dent play­ing with cor­ner­ing lines and slid­ing it around, safe in the knowl­edge it’s not go­ing to bite you or do any­thing too un­ex­pected. Ol­lie ad­mits they have ex­per­i­mented with a plated diff

CAYMAN CSR New boy Dan get­ting RPM’S Cayman CSR out of shape. Way to go! And there he is at the wheel (be­low) in a shirt that seems to have come from Ti­pler’s wardrobe!

In­te­rior gets colour coded styling touches, CSR badg­ing. Seats are Porsche’s hard­backed, tilt­ing buck­ets

RPM CSR looks very ‘GT4’ which is no sur­prise given that it uses the GT4 front and rear apron, split­ter and dif­fuser

Schroth har­nesses for track day work, while stan­dard in­er­tia belts are re­tained for con­ve­nience and road use. Right: Light­weight bat­tery CAYMAN CSR

CSR looks just right in mono­chrome black and white. Rear spoiler is set in the up po­si­tion. Stance is set on Oh­lins Road & Track coilovers

Be­low left: It’s a man­ual, nat­u­rally. Not to utilise one of Porsche’s best ever gear­boxes in a driv­ers’ car like this, would be a trav­esty!

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