LS7 Pontiac Solstice-tested (photos)

[jetsetter]

We knew it would be fast. We promised you, dear readers, that it would be fast. And ya know what? It's fast. Damn fast.

The HOT ROD Solstice was borne out of the hot-rodding tradition of the engine swap. Stick the biggest, nastiest engine you can in the smallest, lightest car, and go destroy everything else on the street. The combo plate with the new Pontiac Solstice and the unbelievable 505hp, 427ci small-block LS7 from the Corvette Z06 was just too tasty a meal to pass on, so HOT ROD conspired with GM Performance Division to figure out how to cook it. We showed you most of the build details in the last two issues of the magazine, but it all boils down to this month, when we put it on the ground, cinch the harnesses, mash the throttle, and give it the torture test.

When the car was nothing more than an idea, we bench-raced a few goals that would be difficult, but not impossible, to meet. We wanted it to run 10s. It should pull more than 1 g on the skidpad without resorting to slicks. It should go through the testing-standard 600-foot slalom faster than any production car. And it should out-stop everything short of an IndyCar. The HOT ROD Solstice delivered, and how. But first let's recap what this car is.

The Solstice competes in the marketplace primarily with the Mazda Miata, and it does so very well. The stock engine is an Ecotec four-cylinder, and the chassis is set up to be sports-car tight but still comfortable for the average consumer. Those with a need for more speed can opt for the GXP Solstice that for '07 adds a turbo and stiffer suspension. And if you're looking to go road racing or autocrossing, the Club Sport Z0K option is nearly track-ready and currently available. An LS7 is, of course, not an option, but that didn't stop us.

Working closely with GM Performance Division, we stripped a base Solstice down to a bare chassis and took measurements to determine what was necessary to stuff a Gen IV small-block into the car. It was surprisingly easy to make everything fit, but we went to extra lengths to make sure this car was as perfectly balanced and engineered as it could be. We're a long way from the days of slapped-together V-8 Vegas, and especially since GM was involved, this car had to be done right. The GM engineers used sophisticated math data to determine many things, such as how to build the exhaust to allow maximum ground clearance and how to set up the suspension for optimum handling with the altered weight-distribution the finished car would have. The entire project involved much more than just shoehorning in a small-block and calling it a day. The end result is a very well engineered car that works as designed and has few, if any, compromises.

The engine is a stock LS7 (which you can order as a crate engine from GM Performance Parts), but we added a GM Hot cam, a set of tri-Y headers, and a complete exhaust system with Burns mufflers. The final dyno numbers were 585 hp and 540 lb-ft of torque. Backing it is a T56 six-speed from the Chevy SSR pickup, and the rear differential is the stock Getrag independent centersection with Cadillac STS-V 3.23:1 gears and a Corvette Z06 clutch pack.

The suspension hangs on essentially stock Solstice components but uses top-of-the-line parts, such as Ohlins coilover shocks and big Brembo brakes. The suspension calibration is another area where GM's engineering expertise shined through, as the car was good right out of the box and needed only fine-tuning when it hit the test track. A stock Solstice weighs just under 3,000 pounds, and the drivetrain swap added about 700 pounds to our car's girth, so a lot of thought went into a weight-loss program. The Jenny Craig solution was many carbon-fiber body panels, plenty of lightening holes drilled where there were no structural issues, and the removal of anything that was deemed not absolutely necessary. The stereo still works though! The final, ready-to-run weight came in at a shocking 2,880 pounds split 52/48 front to rear.

After some shakedown time at Firebird Raceway in Phoenix with GM Performance Division's Mark Stielow, the Solstice was ready to be instrumented and documented. Firebird allowed us to do all the testing in one place, as it provided a quarter-mile dragstrip with lots of runoff room, a skidpad, and an area to set up a 600-foot slalom and a 60-0 braking test. All of the test data were collected with a highly accurate V-Box, which uses GPS data to precisely log time, speed, and distance.

The skidpad was the first test. Any production car that generates more than .90 g on a 600-foot skidpad is considered a very well-handling car. Numbers higher than 1 full g are reserved for big-money exotics, purpose-built cars, and full-tilt race cars. Motor Trend's comparison test of an '06 Z06 Corvette and an '05 Porsche 911 Carrera S delivered .95 g for both cars. On Michelin PS II treaded tires, the HOT ROD Solstice generated 1.05 g.

"The Solstice felt very neutral and controllable on the skidpad, and it was easy to get it into a slight tail-out attitude for the best max lat numbers," Stielow said.

After the skidpad, we tested the braking. We knew those big Brembos in the sub-3,000-pound car would halt it in a hurry, and man did they ever. Entry into the supercar 60-0-mph braking club is usually earned at 110 feet, but the Solstice kicked that number's butt with a 60-0 distance of a mere 95.62 feet. Without the seatbelts, it would literally throw you through the windshield.

"I put the car into a full ABS brake stop, and it was very straight and predictable," Stielow remarked. "Even with extended track use, the brakes didn't experience any fade. The brake system inspires confidence because it's very easy to modulate."

Next up was the slalom, where we ran the car through seven pylons spaced 100 feet apart for a total start-to-finish distance of 600 feet. This is a standard test that measures transient handling ability-it's more of a real-world situation than what you get on a skidpad. Any car that goes through the slalom over 70 mph is a hero-the HOT ROD Solstice did it at 74.9 mph.

"The Solstice handles great, and the short wheelbase and smaller track width really aid in the transition," Stielow said. "Because the car is so lightweight, it's very nimble and tossable in the slalom."

And now for what most hot rodders really want to know-what did it run in the quarter-mile? It ran 10.99 at 133 mph. It met our goal of breaking into the 10s, but anybody who's been around drag racing realizes that 133 mph is a ton of speed for only a 10.99 e.t. That trap speed shows an e.t. potential of about 10.30. But the HOT ROD Solstice was designed to be an all-around performance car that had to meet a variety of goals, with handling and braking being just as important as quarter-mile performance. Its tight suspension does not allow the ultimate weight-transfer characteristics that a car needs on the dragstrip, and the hugeness of the rear brakes didn't allow us to run drag slicks. The tires were 315/30R19 BFGoodrich Drag Radials mounted to billet aluminum wheels, and we didn't even put skinnies on the front. We did, however, loosen the rebound on the front shocks to help weight transfer. Other than that, it ran on the dragstrip how it ran on the skidpad.

That means the car annihilated the tires on the launch and spun them through three gears, as indicated by the e.t. and a 1.88-second 60-foot time-decent for street tires, lame for anything on slicks. If we could put some wrinkle-wall slicks or some taller drag radials on the rear and some lightweight skinnies on the front, it's reasonable we could achieve a low-10. Throw a 100-shot of juice to it, and we may have a 9-second car on our hands. How fun would that be?

But how is it to drive? The car went straight from the factory to the shop to be converted into a V-8 car, so it hasn't even been licensed yet, which means we didn't get to drive it on a public road. Firebird's surface is racetrack smooth, so we have no experience yet on bumpy roads. The car is obviously pretty stiff, so it won't ride like a Cadillac, but how many hot rods or Pro Touring cars do?

Sitting behind the wheel, the experience is just like a stock Solstice, mostly because it is. The only things that tell you there's more going on here are the Sparco seats, the five-point harnesses, and the full rollcage, which was designed to make ingress and egress easy and provide plenty of head room. There's nothing worse than being in a race car and having your helmet constantly clanging against the upper rollcage bar. That's not a problem here, so driving without a helmet won't give you a concussion over every bump. A fire extinguisher mounted to the rear bulkhead between the seats also hints at the car's purpose.

Turning the key lights the engine with a roar. That heavenly bellow is the first thing you notice, followed quickly by the lopey idle the engine settles into, courtesy of the big cam. The car is in no way quiet, but it sounds so sweet when you blip the throttle. The six-speed and clutch feel about the same as they do in a Corvette or an SSR, which is to say the Solstice is an easy car to drive. But stepping on the throttle turns it into a whole 'nother animal-one that will bite your arm off and eat it in front of you if you're not careful. It'll break the tires loose in any of the first three gears at any speed.

The cornering forces are equally brutal and will drain your brain out of your ears, but all you have to do is put more pressure on the right pedal, and the tail steps out nicely. With such a short wheelbase we expected the car to be twitchy, but it's very controllable, very tossable, and easy to drive fast. And if you have it pointed straight when you stand on the gas, the acceleration will blur your vision once the tires get a hook. It feels as fast as it is.

Tens is quick for any street/strip car, but a 10-second car that can also humiliate Eurotrash exotics in the twisties and do it for 100,000 miles is just flat amazing. To everyone who worked on the HOT ROD Solstice, we give you a standing ovation.

We can't wait to start racking up some street miles on this thing. After all, it's just now broken in!

POWERTRAIN

Engine: It's an LS7 engine that's completely stock with the exception of a GM Hot cam and custom tri-Y headers. The front accessory drive came from a Cadillac CTS-V, and the radiator is a Griffin-built four-core aluminum unit that measures 22.6 inches wide and 17.4 inches tall.
Power: It made 585 hp and 540 lb-ft of torque.
Transmission: The Solstice transmission wouldn't hold up to the LS7, so it was substituted with a T56 six-speed from a Chevy SSR pickup. The gear ratios are First: 2.66:1, Second: 1.78:1, Third: 1.3:1, Fourth: 1:1, Fifth: 0.79:1, Sixth: 0.63:1.
Rearend: The centersection is from a Cadillac CTS-V and has 3.23:1 gears, a Z06 clutch pack, and a CTS-V T2 cooling kit.

CHASSIS

Frame: The stock Solstice structure was lightened and strengthened at the same time, as contradictory as that sounds.
Suspension: The front and rear control arms are stock, but the shocks are Ohlins four-way adjustable units and the springs are from Hyperco (350 lb/in in front and 200 lb/in in back). Custom-bent sway bars measure 33 mm (front) and 24 mm (rear).
Brakes: Big Brembos have four- piston calipers and two-piece vented and slotted discs, 355x32 mm in front and 365x28 mm in back.
Wheels/tires: Custom 19x9 and 19x10 CCW wheels wear Michelin Pilot II tires, 265/35R19 front and 305/30R19 rear. On the strip, the rears are swapped for 315/30R19 BFGoodrich Drag Radials on 19x11 CCW wheels.

STYLE

Body: Stock-appearing panels were constructed of carbon fiber for weight savings. The front and rear fasciae were also modified for aerodynamic improvements. It was all constructed by Specter Werkes. The carbon-fiber top is from the SCCA Solstice SSB racing program.
Paint: The paint is DuPont Super Red, but we call it HOT ROD Red.
Interior: The dash, gauges, and controls are all stock Solstice, but the seats are EVO 2s from Sparco, the harnesses (also from Sparco) have cam-lock buckles, and there's a custom-fabricated rollcage that allows for maximum interior space. In the trunk is an ATL 12-gallon fuel cell, made to work with the stock filler neck, and an Optima YellowTop battery.

VEHICLE SPECIFICATIONS

Wheelbase: 2,420 mm
Track (f/r): 1,533 / 1,566 mm
Mass (curb): 2,861 pounds
Weight distribution (% front): 52

SUSPENSION SETTINGS RECOMMENDED BY PERFORMANCE DIVISION

Front camber: -1.2 degrees
Front caster: +7.50 degrees
Front toe: +0.1 degree sum
Rear camber: -1.5 degrees
Rear toe: +0.1 degree sum
Jounce travel: 72 mm front and rear with two passengers on board

The V-Box Data

0-60 mph 3.32 sec

0-100 mph 6.58 sec

60-foot time 1.88 sec

0-100-0 mph 10.30 sec

11/44-mile time 10.99 sec

11/44-mile speed 133.25 mph

60-0 braking 95.62 feet

Max. lat on Michelin PSII 1.05 g

Speed Time
0 mph 0.00 sec

10 mph 0.30 sec

20 mph 0.82 sec

30 mph 1.50 sec

40 mph 1.99 sec

50 mph 2.53 sec

60 mph 3.32 sec

70 mph 3.98 sec

80 mph 4.67 sec

90 mph 5.64 sec

100 mph 6.58 sec

110 mph 7.62 sec

120 mph 8.97 sec

130 mph 10.54 sec

140 mph 12.19 sec


http://www.hotrod.com/projectbuild/h...est/index.html

We tested the LS7 crate motor in the Feb. '06 issue, and it made 519 SAE-rated horsepower out of the box. With 1 3/4-inch
headers and the GM Hot cam, it cranked out 600 hp at 6,800 rpm and 526 lb-ft from 4,800 to 5,200. As installed in the HOT ROD
Solstice, with tri-Y headers and full exhaust tucked under the car, it makes 585 hp and 540 lb-ft.


A 15-gallon ATL fuel cell replaces the stock tank, and it ate up all the luggage room, so we finished it with a nice aluminum panel.
Look closely and you can see the lightening holes drilled in the hatch hinges.


The rollcage was designed for maximum interior space, so the bars all have compound curves in
them. Most of the interior panels were also custom-made (some in plastic and some in carbon fiber)
to look stock but fit with the cage.


Note how tightly the exhaust fits under the car. It's all 3-inch stainless steel tubing, and the 95dB
circle track-style mufflers are from Burns Stainless.


The Firebird dragstrip had not been sprayed with VHT, which certainly didn't help our launches. The Solstice was impossible to
launch without wheelspin, and it spun the tires through three gears on every pass.


Custom billet wheels were made to mount the 315/30R19 BFG Drag Radials. The tires were aired to 17 psi.


The car has almost perfectly neutral balance, so it went through the slalom at a very fast 74.9 mph.


On Michelin PS II treaded road-race tires, the Solstice blistered the skidpad with 1.05g lateral acceleration. Front tires are
265/35R19s on 18x9 wheels, and the rears are 305/30R19s on 19x10 wheels.


You can order a hardtop for the Solstice through any GM dealer. Ours was a flyweight carbon-fiber top that is available for the
Club Sport Solstice racers we talked about last month.

[zenkidori]

Very very cool stuff. I was excited to see this project get started in Hot Rod. I like how the magazine no longer snugs smaller more nimble cars(way back in the day they covered stuff like british roadsters and italian sportscars too).

[BlaRo]

That is so hot.

[BlitzR]

looks bloody fun too drive.

[teletubby-warrior]

It's finally finished!

[NAIDANAC A]

Theres a hardtop for a Solstce....Does that mean a Sky too? B/c my dad wants one. I LOVE THOSE CARS.

[matt_shaw]

I WANT ONE!!!

[zenkidori]

Originally Posted by NAIDANAC A

Theres a hardtop for a Solstce....Does that mean a Sky too? B/c my dad wants one. I LOVE THOSE CARS.

Yeah, there are hardtops available thru thier motorsports catalogs. I want a Sky redline with a hard top soooooooooo bad.

[jayjaya29]

Wow, thats crazy awesome. Kinda like the Miata with a Vette engine stuffed into it. Nice!

[jayhawk]

Monster.

[epp_b]

FanTAStic! Quite a supercar-slayer...wait, no, it is a supercar! Just awesome...

[patrick10]

i dont care what you guys say about polished rims, it looks hot as hell. but if it were me, it would definitely be slammed

[Wizegui]

Yum just imagine the sound and performance. Would this make the LS7 Solstice faster than the Corvette since its in a smaller body?

[ESPNSTI]

Fantastic.
I wonder how much they've spent on it? (including the stock car)
$70k? $80k?

[bartboy9891]

can't argue with the figures the looks on the other hand can be improved
want to see this done to the Sky for an all round winner though

[NAIDANAC A]

Ya I vote sky too. I wonder how long until GM puts a V8 in it stock? That would sell.

[youngwarrior]

looks like GM payed for this going by the "go buy a corvette instead of bringing money to us" statement.

Ultima GTR will eat all those cars for even less money.

[jetsetter]

Originally Posted by youngwarrior

looks like GM payed for this going by the "go buy a corvette instead of bringing money to us" statement.

Ultima GTR will eat all those cars for even less money.

Why do you even bother posting anymore?

[youngwarrior]

Originally Posted by jetsetter

Why do you even bother posting anymore?

I cant stand the attempt at hidden marketing. Theyre pulling the wool over average peoples eyes that nothing comes close to the Z06 when it comes to bang for buck.

[jetsetter]

Originally Posted by youngwarrior

I cant stand the attempt at hidden marketing. Theyre pulling the wool over average peoples eyes that nothing comes close to the Z06 when it comes to bang for buck.

The Ultima GTR comes from the factory without an engine at $89,000.