Road and Track tested a solstice and it turned 7.4 seconds to 60 and a 15.8 in the 1/4 mile. Both of these are slower than what i thought the 2.4 SS would do. The test conditions were 74 degrees and only 15% humidity too. So, apparently the 2.4 with vvt is not much faster than the 2.2. The Solstice also has an extra gear and a higher rear end ratio. So, whats the deal here? If these numbers are true, that means the 2.4 SS cobalt must only be just a tad faster than the 2.2 liter cobalts. I would guess over 8 to 60 and in the 16s for the 1/4. Maybe RandT only used 87 in it and it needed to be broken in yet or something. Also now that i think about it, the solstice is supposed to have a few more hp too, and it weighs about the same as the cobalt.

 

well thats disapointing! BUt a few considerations should be taking into account.

1. Broken in---like you mentioned. Most magazine test cars are not fully broken in and cars get quicker when they are broken in.

2. Road and Track: They usually get the worst times of all the magazines.

So the sky is not falling.....yet. Lets see what Car and Driver can do.

I am starting to open up my 2.4L SS and am very imprerssed with how much faster it feels then the 2.2L. Hopefully this will hold true when I take it to the track in 5 days!

 

I bet that once properly broken in and with some practice a Cobalt SS coupe will be pulling the same numbers as these. And the solstice doesn't have an extra gear over the manual cobalt; the only transmission offered for the Solstice this model year is a 5-speed manual.

 

Howdy,

I'm from over at the solsticeforum.com, thought I'd go looking for what our fellow 2.4L ECOTEC VVT brothers and sisters were doing with our engine. Been lurking for a bit reading over things, thought I'd make my first post about a topic I'm pretty familiar with.

The various magazines are getting 0-60 times of 6.9 to 7.4 seconds with the Solstice. Official Pontiac time is 7.2s though.

There are a couple major differences between the cars too that would impact like comparisons with this engine.

• Doing a quick search I couldn't find the Cobalt Coupe coefficient of drag but I found the ION RL to be .32. Comparitively the Solstice being a convertible Roadster with a blunt nose is easily in the .40 to .45 range. This much larger CD is going to cause the engine to have to work a good bit harder to overcome the aerodynamic drag created by it's shape.
• The Coupe SS stock has only 17" wheels compared to the Solstice which has 18" wheels. That extra 1" does add up very quickly when you're trying to overcome rotationial inertia. A basic formula is I=1/2mR^2, so if you've just increased R and also moved the m variable farther from the center you've greatly impacted performance for 0-60 times now.
• The gearing is different between both cars also causing variations in 0-60 times too.
  • Cobalt SS Coupe (5M)
    Transmission gear ratio (1st) 3.58 (2nd) 2.02 (3rd) 1.35 (4th) .98 (5th) .69
  • Solstice (5M)
    Transmission gear ratio (1st) 3.75 (2nd) 2.26 (3rd) 1.37 (4th) 1.00 (5th) .73

I saw some question in various places on octane too. The engine is designed to run opimaly with 91+ octane. However the engine is also designed to run perfectly fine on 87 octane too. Currently the Solstice is the only one that "Recommends" the primary use of 91+, but even it will work without causing pinging on 87 octane. Of course the Solstice gets a small power loss, but it's also the highest rated of the engine line at 177 HP & 166 lbs-ft of Torque.

I know we're defintely looking forward to performance parts for this engine as well.

 

solstice tranny swap?

 

welcome to the forums. Excellent points you made. I love the 2.4L Ecotec----really smooth engine. I just hope a few mods come out for it.

 

We love ya for the extreme technical stuff, but I still say the SS MIGHT BE only a couple tenths faster. Looking at your gear ratio comparo, the Solstice is better geared for 1/4 racing. The SS looks to have taller gears= lazier acceleration. Plus, ther Solstice has 7hp and 3 tq more than SS.

 

Well if your talking about taking the tranny out of the solstice and putting it in the cobalt then that wont work since the cobalt is front drive and the solstice is rear drive.

 

Thanks for the data brentil. You are right about the drag. Car & Driver lists it as .44 Cd which is not very good. Weight is about the same for both cars. Here is their data:

PONTIAC SOLSTICE
Vehicle type: front-engine, rear-wheel-drive, 2-passenger, 2-door roadster

Price as tested: $24,675

Price and option breakdown: base Pontiac Solstice (includes $575 freight), $19,995; A/C, $960; Power package (includes power windows, locks, and mirrors, and keyless entry), $625; Premium package (includes leather seats and leather-wrapped shift knob and steering wheel with audio controls), $590; in-dash 6-CD changer, $495; polished wheels, $495; Convenience package (includes cruise control, fog lamps, and driver-information center), $465; anti-lock brakes, $400; Monsoon 7-speaker stereo, $395; limited-slip differential, $195; floor mats, $60

Major standard accessories: tilting steering wheel, rear defroster

Sound system: Pontiac AM-FM radio/CD changer, 7 speakers

ENGINE
Type: inline-4, aluminum block and head
Bore x stroke: 3.46 x 3.86 in, 88.0 x 98.0mm
Displacement: 145 cu in, 2384cc
Compression ratio: 10.4:1
Fuel-delivery system: port injection
Valve gear: chain-driven double overhead cams, 4 valves per cylinder, hydraulic lifters, variable intake- and exhaust-valve timing
Power (SAE net): 177 bhp @ 6600 rpm
Torque (SAE net): 166 lb-ft @ 4800 rpm
Redline: 6900 rpm

DRIVETRAIN
Transmission: 5-speed manual
Final-drive ratio: 3.91:1, limited slip
Gear - Ratio - Mph/1000 rpm - Max test speed
I - 3.75 - 5.2 - 36 mph (6900 rpm)
II - 2.26 - 8.6 - 60 mph (6900 rpm)
III - 1.37 - 14.3 - 98 mph (6900 rpm)
IV - 1.00 - 19.5 - 123 mph (6300 rpm)
V - 0.73 - 26.7 - 110 mph (4100 rpm)

DIMENSIONS
Wheelbase: 95.1 in
Track, front/rear: 60.7/61.5 in
Length/width/height: 157.2/71.3/50.1 in
Ground clearance: 3.6 in
Drag area, Cd (0.44) x frontal area (21.5 sq ft): 9.5 sq ft
Curb weight: 2888 lb
Weight distribution, F/R: 52.5/47.5%
Curb weight per horsepower: 16.3 lb
Fuel capacity: 13.8 gal

CHASSIS/BODY
Type: unit construction
Body material: welded steel stampings and hydroformed steel

INTERIOR
SAE volume, front seat: 50 cu ft
luggage: 4 cu ft
Front-seat adjustments: fore-and-aft, seatback angle
Restraint systems, front: manual 3-point belts, driver and passenger front airbags

SUSPENSION
Front: ind, unequal-length control arms, coil springs, anti-roll bar
Rear: ind, unequal-length control arms, toe-control link, coil springs, anti-roll bar

STEERING
Type: rack-and-pinion with hydraulic power assist
Steering ratio: 16.4:1
Turns lock-to-lock: 2.7
Turning circle curb-to-curb: 35.1 ft

BRAKES
Type: hydraulic with vacuum power assist and anti-lock control
Front: 11.7 x 1.0-in vented disc
Rear: 10.9 x 0.5-in disc

WHEELS AND TIRES
Wheel size/type: 8.0 x 18 in/cast aluminum
Tires: Goodyear Eagle RS-A, P245/45R-18 96V
Test inflation pressures, F/R: 29/29 psi
Spare: none

C/D TEST RESULTS
ACCELERATION: Seconds
Zero to 30 mph: 2.3
40 mph: 3.7
50 mph: 5.3
60 mph: 7.2
70 mph: 10.1
80 mph: 13.1
90 mph: 16.8
100 mph: 22.2
110 mph: 31.6
Street start, 5-60 mph: 8.0
Top-gear acceleration, 30-50 mph: 14.2
50-70 mph: 14.1
Standing 1/4-mile: 15.8 sec @ 87 mph
Top speed (drag limited): 123 mph
BRAKING
70-0 mph @ impending lockup: 165 ft

HANDLING
Roadholding, 300-ft-dia skidpad: 0.88 g
Understeer: minimal moderate excessive

FUEL ECONOMY
EPA city driving: 20 mpg
EPA highway driving: 28 mpg
C/D-observed: 16 mpg

INTERIOR SOUND LEVEL
Idle: 53 dBA
Full-throttle acceleration: 79 dBA
70-mph cruising: 73 dBA


Full review here: http://www.caranddriver.com/article....&page_number=1

* Of note to all you people is that C&D says the turbocharged version will have 250HP. I seriously doubt that engine would find it's way into a FWD Cobalt SS. That is way too much power. I suspect that this may be used in the AWD Cobalt if that ever becomes a reality. I'm sure the 2.0L Cobalt SS is here to stay for quite a while as is! Other than GM re-styling it in 2008 that is!

 

Good find, mi6.....R&T got same numbers on their test. I pretty sure the Ss has 3.91:1 gear ratio as well.

 

3.94s for the SS

 

Question: What's the redline on all of your Cobalt SS's? As stated above the Solstice is 6900 RPM, but some of our speculation on why the Solstice has some more power and lower fuel economy also had to do with a higher RL then the other cars using the 2.4L VVT engine as a base.

Currently we know there will be a Turbocharged ECOTEC, but besides that we don't have any solid specifications. We're hoping for some teaser info at SEMA, but more then likely the official information will be released at NAIAS06. Pretty much all the sources are reporting 250HP+ as the output value. It'll be in the Sky RL and Solstice GXP at least.

I'd talked about it over at the other forums before, and I think it would make sense for GM to migrate to this engine for the various other ECOTEC powered cars in place of the 2.0L Supercharged LSJ. Even if they dind't use the Solstice GXP's tuned version they could easily offer a detuned ~230HP engine to compete with the SRT-4 (as long as it still exists that is, been reading rumors of its demise soon at C&G and GMI). Most people in the younger generation also seem to desire Turbocharged systems over Supercharged systems, but that's an entire other can of worms. It would also let GM compate against the PT Cruiser with it's higher powered Turbocharged versions with a sweet HHR.

The AWD Cobalt is also another item I've discussed at length too before. I personally view GM as currently greatly lacking a presence in the realm of WRC. Yeah GM owns part of Subaru, but most people don't know that, and I'd rather see a Cobalt entry to compete with the WRX-STi and EVOs. If GM's pushing 250HP+ on this engine now in prototype development, I'm pretty confident they can go much higher once the platform has matured some as well.

 

I didn't find the redline but I found the Fuel Shutoff values. With the difference in redline and fuel shutoff being 100 RPM I would then sumize the Cobalt 2.4L VVT redlines at 6800 RPM or lower.
Awesome source of GM information.
http://media.gm.com/us/powertrain/en...g%20trans.html


Cobalt SS 2.4L VVT dyno plot
http://media.gm.com/us/powertrain/en...let_Cobalt.pdf

Solstice 2.4L VVT dyno plot
http://media.gm.com/us/powertrain/en...c_Solstice.pdf

Those are flywheel dynos of course using the new SAE standards. Meaning the 177HP or 171HP it's rated at now could be considered as being higher compared to older cars and companies not using the new SAE standard. The old standard let you dyno an engine with componenets missing and even allowed use of componenets that would not be on the final version. Like superlight flywheels, underdrive pulleys, removal of all accesories, etc. All new GM motors from now on will use this rating system. Some of them already are, like the 2.4L VVT and the LS7. I wouldn't be suprised if the LSJ was too and that's why it dynos whp so close to its rated value.

 

the ss i test drove has to redline near 7000 id guess in the 6800 to 7000

since most of us that have driven a cobalt or ion , we know the stock tach sucks ass at reading actual rpm when accelerating under full throttle

 

Did my math wrong. 6800 - 100 != 6800. What I meant was 6700 RPM or lower for the redline since the fuel shutoff is at 6800 RPM. Raising the redline along with more performance tuned ECU probably account for the 6HP and 3 lbs-ft more then the Cobalt. Would also help explain the much lower MPG values too.

 

Our fuel shut off is 7000rpm.....I know, I hit it by mistake. Redline is 6750, but orange line is 6500

The cobalt IS recommended to use 91+ octane right in the owners manual.

And our rim/tires 205 17 will be a lot better in a straight line then the solstice 245 18's

 

Yup, exactly. Wait to see what happens to Honda engines once they start to have to use the new standard.

 

Funny how Honda hasn't readily adopted the new standard, then seem to be putting it off

Seems as if the Japanese manufacturers have something to hide - so far only Toyota has started to rate their vehicles with the new standard. The results haven't been pretty either, the Camry lost 30HP in the switch, which is an inexcuseable amount. It just proves that they've been overrating all this time, but nobody ever found out because Camry buyers aren't the type to take their car to the dyno

Many of the GM vehicles actually raised their HP ratings with the new system, the new Z06, for example, went from 500HP to 505HP SAEC. GM has been honest with their ratings, unlike the Japanese, which have been spoofing their numbers for some time now.

If a manufacturer grossly overstates about their power ratings, what makes people think they're not lying about other things??

 

Uhh reason 1 why its slower....driveshaft...its got more drivetrain loss thant he SS does...the bigger rims and drag coeffeciant are not enough to make a big difference in acceleration or max speed untill over 100 mph.

 

Good to know since the GM documents say 6800 RPM. But we all know GM doesn't necisarily keep all these documents exactly up to date or even correct when up to date.

 

lol, like how GM doesn't even have the 2.4l SS listed on its site yet!

 

Members this week just passed their first 1000 miles on Solstices. We're waiting to get some dyno charts from a couple of them. I'm defintely looking forward to comparinig them to a Cobalt SS 2.4L to see how much we really loose compared to you all. I haven't seen any yet, but are there any Cobalt dyno graphs out yet from people going to local shops to test it out?

 

Not for a 2.4. There is a dyno day for my car club coming up soon, I think I get two pulls. I want to wait until at least 5000KM to dyno it, but maybe I'll make it there sooner.

 

They've got it on the 2006 engine section, but in their infinite wisdom they put the 2.4L engine under the normal car even though they call it an SS.

 

don't worry its still an SS. Info is on the US site but not Canada---except it is in the Pontiuac Pursuit section.


As for dynos:

http://media.gm.com/us/powertrain/en...html#chevrolet

Okay there are fly wheel dynos but interesting nonetheless.

And its LOSE not loose! (as in my pants are too loose) sorry pet peeve that no one on the msg board can spell a simple word!