POWER DOWN

THE IN­TER­CON­TI­NEN­TAL PER­FOR­MANCE BAT­TLE RE­SUMES WITH THE TWO BAD­DEST BRUTES AROUND

Motor Trend - - Contents - Randy Pobst

2019 Chevro­let Corvette ZR1 vs. 2018 Porsche 911 GT2 RS The in­ter­con­ti­nen­tal per­for­mance bat­tle re­sumes with the bad­dest brutes around.

Do you ever won­der where this is all go­ing to end? More power, big­ger wings, bet­ter aero, fat­ter tires. Re­mem­ber when the ’90s Porsche 911 Turbo and Chevro­let Corvette ZR1 hit 400 horse­power? We thought we were all go­ing to die. Yet now we’re close to dou­bling that. What hath the de­mon seed of tech­nol­ogy wrought?

With such ex­is­ten­tial the­o­riz­ing in mind, we present the ever-ris­ing top of the up­ward spi­ral: the 2019 Chevro­let Corvette ZR1 with ZTK pack­age and the 2018 Porsche GT2 RS Weis­sach Edi­tion.

As a re­sult of my long rac­ing ca­reer and in­tro­duc­tion to the in­ner work­ings of Porsche Motorsport when I had a fac­tory con­tract, plus my 10 sea­sons of track test­ing with Mo­tor Trend, I have fol­lowed first­hand with in­ter­est and won­der the twists and turns of this steady pro­gres­sion of tech­nol­ogy and per­for­mance.

Th­ese su­per­cars are the high­est evo­lu­tion of their own long lin­eages and make claim to be­ing at the top of the afore­men­tioned spi­ral in the en­tire ma­jor au­tomaker uni­verse, as well.

Let’s start with the ZR1, be­cause ’Murica! Today’s ’Vette is the last of the C7 gen­er­a­tion, cre­ated di­rectly out of the C6, trac­ing its his­tory back to the 2005 model year. The stan­dard en­gine then was the 6.0-liter LS2, rated at 400 hp, later up­ping to 430 with the 6.2-liter LS3. In re­sponse to the ever-swelling out­put of its Amer­i­can V-10 ri­val Dodge Viper, the C6 ZR1 fired a ma­jor salvo in the dyno wars with its 638-horse su­per­charged Blowerun­der-glass (with see-through hood bulge). A cou­ple years later came the Z06, with 650 horses and a strong ten­dency to over­heat—both the en­gine’s vi­tal flu­ids and the in­take air temps—when driven at pro speeds on track (some­thing I dis­cov­ered on my first three laps at a Road At­lanta press day). This track-ori­ented model was sim­ply not ready for prime time, though it’s true that more con­ser­va­tive own­ers were able to suc­cess­fully track their Z06s at a milder pace.

This leads us to the lat­est ZR1 and its top-dawg 755-hp LT5. The chal­lenge for the Corvette team was to si­mul­ta­ne­ously im­prove the speed and the cool­ing of the Z06/Z07 we know and love. Tough task, be­cause those two goals pull the nee­dle in op­po­site di­rec­tions. More power equals more heat. To ad­dress this, five new ra­di­a­tors have been added, re­sult­ing in far bet­ter cool­ing. On track, temps still get warm, but dur­ing my time at the wheel, the nee­dles never speared the red zones.

Com­pare that to the Porsche GT2 RS. Right up front, it’s more than twice as much moolah—if you can find one to buy. But it’s also a new pin­na­cle in the long and bril­liant his­tory of the 911. For 15 years, I was up to my ears rac­ing them. I started rac­ing just as the wa­ter-cooled cars were com­ing to mar­ket. With far su­pe­rior con­trol of en­gine tem­per­a­tures and four­valves-per-cylin­der breath­ing, the 996 made far more power than the ven­er­a­ble fan-and-fin-cooled flat-sixes.

But a funny thing hap­pened. Af­ter years of work­ing so hard to re­duce the fa­mous over­steer­ing ten­den­cies of the rear-en­gine 911—cul­mi­nat­ing with my now sec­ond-fa­vorite 911 chas­sis to drive, the 993—the over­steer was back. The 996 was twitchy and loose and dicey. New gen­er­a­tion, back to the draw­ing board. I raced with both ver­sions on my teams at Alex Job Rac­ing and with Greg For­dahl Mo­tor­sports in the early 2000s, and I saw how the old 993 RSR would kill the

new 911 GT3 R in the cor­ners with sta­ble, us­able grip but get smoked down the straights by the newer car’s four-valve urge and slick, low-drag aero.

Why the his­tory les­son? To ex­plain why I’m so ex­cited about the new GT2 RS. It’s the first 911 since 1999 that truly takes ad­van­tage of its rear­ward weight dis­tri­bu­tion and turns its co­pi­ous torque into ac­cel­er­a­tion. It’s my hope that this will be the new par­a­digm.

The GT2 RS makes more power than any fac­tory 911 be­fore it. “Big deal,” you say. “We’ve had 911 Tur­bos for years, and they’ve been grad­u­ally evolv­ing through 400, 500, 600 horse­power, and they’re fine. Noth­ing new.” Wrong, Bratwurst Breath. This most-po­tent-ever 911 is two-wheel drive. The real magic of this ma­chine is its abil­ity to send 553 lb-ft of torque (214 more than the awe­some GT3) to just the rear tires and turn it into ac­cel­er­a­tion—not wheel­spin and tire smoke—with­out the added com­plex­ity and weight of all-wheel drive.

That prodi­gious power pro­pels the GT2 RS for­ward, not side­ways in a drift­ing burnout (un­less your name is Jethro Bov­ing­don). This first-or­der pri­or­ity of a win­ning racer in this ul­ti­mate per­for­mance street car earns my re­spect and ad­mi­ra­tion. OK, and love. (I’m con­fi­dent enough in my mas­culin­ity to ex­press those four let­ters to­ward a rel­a­tively inan­i­mate ob­ject.)

With such de­vo­tions spo­ken, let’s see what hap­pens when we let slip the dogs of war.

The Corvette’s great tech­no­log­i­cal step for­ward is the way it never lost out­put from the boosted LT5 V-8. Un­like its pre­de­ces­sor, this ZR1 pulled hard the whole ses­sion. Credit this ad­vance­ment to the 52 per­cent larger Ea­ton supercharger and more ef­fi­cient in­ter­cool­ers. How­ever, the 755 horses in the ZR1 never seemed to quite pull like those of the GT2 RS and oth­ers in the 700 Club dur­ing our Best Driver’s Car test­ing—both in the quar­ter mile and at the top end.

At our World’s Great­est Drag Race, I had the un­mit­i­gated plea­sure to floor both cars down Van­den­berg Air Force Base’s pris­tine 3-mile-long land­ing strip to achieve my own per­sonal land speed record of 200-plus in the GT2 RS. By com­par­i­son, the ’Vette lagged be­hind, time af­ter time, even with­out the ZTK pack­age’s high wing. With sim­i­lar top speed claims, what gives? I can only re­port faith­fully what mine eyes have seen and hy­poth­e­size that the in­ter­cool­ing is per­haps still not enough to keep up, be­cause in­ter­net dyno tests do seem to sup­port the 755-hp es­ti­mate.

Hot-lap­ping at Weathertech Race­way La­guna Seca showed sim­i­lar re­sults on the front straight. The GT2 RS reached a heady 149.0 mph, but the ZR1 made only 141.6. All of that can­not be ex­plained away with a bet­ter cor­ner exit. That’s sim­ply too big a spread. Some of those Chevy horses weren’t pulling their weight.

But enough about straight-line fury. What hap­pens when the wheel is cranked into Turn 1? In my world, the gods live

Enough about straight-line fury. What hap­pens when the wheel is cranked into Turn 1? In my world, the gods live in the cor­ners.

in the cor­ners any­way (al­though I must ad­mit, even straight ahead gets in­ter­est­ing once you’ve crossed the dou­ble cen­tury). At La­guna, Turn 1 is a gen­tle left bend over a rise. It’s been an easy flat in nearly ev­ery car I’ve driven there over the years—un­til the big-hit­ter street cars started ap­proach­ing 140 over that crest. They’d get light, even get some fifth-gear wheel­spin, and track far right in a hurry. The bend is a gen­uine cor­ner at those ve­loc­i­ties, with a late apex, and straight­en­ing up the steer­ing be­comes a ne­ces­sity to re­main on the pave­ment. Ten years ago, the last-gen ZR1 was the first car that forced my right foot to feather back, for fear of dis­as­ter on the land­ing.

Well, this year the ZR1 once again achieved the high­est Corvette speed ever over that yump, but it stuck the land­ing eas­ily. The ZTK aero proved ef­fec­tive there and at sev­eral other fast cor­ners around the cir­cuit. It’s not race car lev­els of down­force, but it’s sig­nif­i­cant for a street ma­chine. Un­usu­ally, the higher the cor­ner speed, the bet­ter be­haved the ZR1. On track, most cars are the other way around: Faster means dicier. When I set the lap record at Road At­lanta in the new ZR1 on a Chevy press day, the car was sta­ble and hooked up in the high-speed Turn 12 and drop­ping into the esses, which is crit­i­cal to a quick time there. I mean re­ally well be­haved.

This leads us to the Corvette’s great down­fall: low-speed trac­tion—which is also the rea­son for the his­tory les­son. When power was un­der 500, the chas­sis could han­dle it, but as the Z-se­ries cars pushed it over 600—and with the ZR1 now crest­ing 750—the rear sus­pen­sion is over­whelmed. High-pow­ered ’Vettes are di­a­bol­i­cally prone to snap power over­steer in the lower gears. The won­der­ful ad­di­tional ponies in the ZR1 make it even worse.

True story: I kicked out the ZR1’S tail on a de­serted side street, and it ripped the wheel from my hands so hard I rein­jured a torn ro­ta­tor cuff. Brutal. In th­ese cars, the driver had best leave the mul­ti­mode trac­tion and sta­bil­ity con­trols ac­ti­vated.

This han­dling is­sue is noth­ing new. Chevy has never solved the peren­nial prob­lem of the rear sus­pen­sion not putting power down well or the gen­eral fright-in­spir­ing twitch­i­ness of the rear end. It frus­trates me, and it holds the ’Vette back from its far greater ul­ti­mate po­ten­tial. The un­ruly and un­trust­wor­thy rear grip makes the car a wild ride in first through third gears, which means in most cor­ners. The Mo­tor Trend note­book is rife with ed­i­tor re­marks about it. It’s a thrill and an adren­a­line rush, sure, but not ex­actly for the right rea­sons (fear and ter­ror be­ing cul­prits cited by some pretty vet­eran scribes).

The Z06 was al­ways a wrestling match to drive at the limit on track, and the ad­di­tional 100 horse­power makes it even more so, ex­cept that the ZR1 is much im­proved at high speeds. The sit­u­a­tion re­minds me a lot of the Viper: It’s al­ways been a real hand­ful, and its en­gi­neers seemed to just ac­cept it as part of the car’s mas­cu­line per­son­al­ity—un­til they mirac­u­lously, com­pletely cured it

with the ACR model in the last year of pro­duc­tion.

Would that Team Corvette could have fin­ished with the same flour­ish. The arm­chair en­gi­neer in me sug­gests rear ge­om­e­try; per­haps it has too much anti-squat. The rea­son? I’ve tried all man­ner of fac­tory shock set­tings, year by year, and none seem to cure it. It can help, though. For the Z06/7 and the Grand Sport, I rec­om­mend plac­ing the sus­pen­sion set­tings to Sport rather than Track. Yet the ZR1’S damp­ing pack­age feels softer on all set­tings than the Z06’s, es­pe­cially in Race shock mode. It’s great for com­fort but still doesn’t tame that ner­vous twitch. Some driv­ers, es­pe­cially tal­ented ones, ac­tu­ally pre­fer a twitchy turn-in, so per­haps Corvette’s dy­nam­ics team likes it this way. But I don’t. Like I said in my Twit­ter war re­gard­ing the pre-acr Viper a cou­ple years back, bad­han­dling cars scare me. I don’t want to work that hard, and in a well-bal­anced sports car, I don’t have to.

Not all my venom is di­rected at Chevro­let, though, which means it’s time for my of­fi­cial Porsche Motorsport rant. I spent a lot of time on track in 996 ver­sions of the 911, and it was al­ways a chal­lenge to get good trac­tion ac­cel­er­at­ing out of a turn. Our archri­val BMW seemed to be as good or bet­ter, but with a front en­gine. That didn’t make sense. But I felt the 911’s tail want­ing to snap loose if I wasn’t care­ful about the throt­tle. In­ter­est­ingly, it seemed like the more racy the 911, the worse it be­haved, es­pe­cially in the last eight years. The Mo­tor­sports depart­ment seemed to like pointy over­steer.

But why? My hy­poth­e­sis: Per­haps their Werks fahrers—young su­per­stars who grew up kart­ing—do their test-driv­ing. Karts have a solid axle, no dif­fer­en­tial. If the driver doesn’t kick it side­ways, it un­der­steers like crazy.

I fig­ure the Werks­fahrers bring this psy­chol­ogy over to the big cars, be­cause that’s just how they felt. At least, that’s how the fac­tory cars felt when I raced them. For years, I’ve felt that the ba­sic street Porsches were the best-bal­anced and that the closer it got to Porsche Motorsport, the worse the cars han­dled and the more they over­steered. Some con­sider that sporty, lively. I con­sider it un­nec­es­sary. Three re­cent cars with which I am in­ti­mate—the 911 GT Amer­ica for the IMSA Gtd-class a few years ago and the 991-era GT3 Cup cars, both the 991.1 and the cur­rent 991.2—were dif­fi­cult to drive fast. They were dicey, quite spinnable, and spooky. Not what a cus­tomer-racer needs.

En­ter Frank Wal­liser, the rel­a­tively re­cent head of Porsche Motorsport, with whom I credit the great suc­cess of the GT2 RS. With this new-gen street-le­gal racer, I see a real change in chas­sis be­hav­ior, one I’ve never be­fore seen in a mod­ern-era 911. Sta­bil­ity. Trac­tion. Grip. Power to the ground. A real, pos­i­tive omen for the Motorsport cars of the fu­ture.

The GT2 RS was my per­sonal choice for Best Driver’s Car (sorry, Lam­borgh­ini). Sta­ble and con­fi­dence-in­spir­ing yet with pre­cise steer­ing re­sponse even un­der full throt­tle, a tough com­bi­na­tion to achieve with rear weight bias. Bal­ance. I ar­gued hard for it, but my col­leagues had not ex­pe­ri­enced the sub­lime plea­sure of driv­ing it on a vel­vet-smooth race­track, where I found it did every­thing so right. It felt as if a heav­enly beam of light had shone down upon it, en­dow­ing it with magical pow­ers.

My col­leagues drove it on Route 198, a civil­ian road with real-world un­du­la­tions and un­pre­dictable pave­ment. Many of the edi­tors drove it in Sport Plus mode, as did I. Stiff. Far too stiff for that road, be­yond the range of the Porsche Ac­tive Sus­pen­sion Man­age­ment (PASM) to ab­sorb. Those con­di­tions caused the car to leap about a bit and in­sti­gated the ABS to a dis­con­cert­ing ex­treme. Just a punch of a but­ton into Nor­mal mode could have saved the day. (Some edi­tors noted the same con­di­tions, to a lesser ex­tent, in Nor­mal mode, as well.) For­give us, for we knew not yet what we did.

Part of the value in the GT2 RS comes from so­phis­ti­cated sys­tems like PASM, rear-wheel steer­ing, dy­namic en­gine mounts, Porsche Torque Vec­tor­ing, and Porsche Sta­bil­ity Man­age­ment. Yet it’s more than that. Th­ese aids have been tuned with great fi­nesse. The lat­est GT3 RS has the same sys­tems, yet it’s ner­vous on cor­ner en­try. (Shall we blame the karters again?) That car was

The Corvette ZR1’S Pi­lot Sport Cup 2 tires are spe­cial, but to the seat of my pants, the GT2 Rs-spec rub­ber has raised the bar.

a dis­ap­point­ment to me; al­though nearly ev­ery com­po­nent was made more track­o­ri­ented from the GT3, the bal­ance was lost. That was my con­cern here, and my joy to dis­cover. This is the best-ever 911.

In brak­ing, I have bragged that Corvettes have world-class ca­pa­bil­ity, and al­though brak­ing is still very strong, the pedal feel has gone soft in all six cars I’ve driven on track. I don’t no­tice it on the street, but that firm, in­stant re­sponse I en­joyed now feels “like step­ping on a wet sponge,” ac­cord­ing to the test­ing notes of one of our edi­tors. The Porsche? Per­fect. Im­me­di­ate, lin­ear, and record-short dis­tances in our test­ing.

And tires. Al­though both cars have Miche­lin Pi­lot Sport Cup 2s, each is tuned to its own spec, and we at MT have rec­og­nized the ’Vette’s rub­ber as some­thing spe­cial. But to the seat of my pants, th­ese lat­est Porsche GT2 RS R–spec SC2S have spi­raled up the bar. I still re­mem­ber BDC La­guna Turn 2, lap one for the record. As I cranked the wheel to­ward that late apex, I ex­claimed aloud, “Gr­rrrrip!” and the Ra­cepak soft­ware con­firmed the sen­ti­ment a split-sec­ond later.

To com­pare the ZR1 and the GT2 RS, start with the price. The Corvette’s $131,000 can look so cheap! Be­yond that, the Porsche is a clear win­ner in ev­ery cat­e­gory save one: machismo. The Corvette wins that stare­down, with the right badass tat­toos on big bi­ceps and a sharp goa­tee over a pressed but­ton-down and a per­fect com­plex­ion. It’s strong and loud and de­mand­ing, mak­ing proud and strik­ing en­trances and rau­cous ex­its. To the con­trary, the strictly busi­ness Porsche wins on com­pe­tence and ex­e­cu­tion. Next to the ’Vette, it’s un­der­stated.

What I see in the Corvette ZR1 is po­ten­tial; what I feel is frus­tra­tion. The car is out­ra­geously good at so much and comes tan­ta­liz­ingly close to pro­vid­ing su­per­car per­for­mance. Just find the se­cret to calm­ing that hy­per­ac­tive rear end in the lower gears, switch back to the Z06 brake pedal, and you’re there, Chevro­let, at a rel­a­tively bar­gain-base­ment price for per­for­mance, com­plete with your own mus­cu­lar, ex­tro­verted style.

As for you, Herr Dok­tor Wal­liser, con­grat­u­la­tions to you and your GT2 RS team, for a mag­nif­i­cent driv­ing cre­ation. It’s the best all-round per­for­mance au­to­mo­bile I’ve had the plea­sure to ex­pe­ri­ence—one that in­spires pas­sion and de­sire in this en­thu­si­ast like no other. n

STRENGTHS Randy Pobst came to trust the Corvette’s amaz­ing brakes, and he could rely on the 911’s as­tound­ing cor­ner­ing grip.

BIG WING Chevro­let says the Corvette ZR1 ZTK aero pack­age pro­duces 950 pounds of down­force at its top speed of 212 mph.

IN­TE­RI­ORS The Corvette pos­sesses a cer­tain de­sign flam­boy­ance, whereas the 911 is but­toned-down and fo­cused on the busi­ness at hand.

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