[KappaMan]

http://www.solsticeforum.com/forum/showpost.php?p=205767&postcount=1

VERY IMPRESSIVE - torque like an electric motor, comes on like a freight train... torque curve as flat as a southwestern desert mesa... 260 horsepower... MMMMmmmmMMmmMMmmmmmm....

 

[brentil]

It's oh so pretty. Makes me want a GXP all over again.

 

[SkyBaby]

i gotta start shopping around to make mine faster...... what work to be done.... look, look, look..... ugh...... i can do it..... SOUNDS SWEET!!!! SkyBaby-07

 

[nighttripper]

i gotta start shopping around to make mine faster...... what work to be done.... look, look, look..... ugh...... i can do it..... SOUNDS SWEET!!!! SkyBaby-07

Don't need to go fast to look good:thumbs:

 

[skywatcher]

It's oh so pretty. Makes me want a GXP all over again.

Hope to not hijack, but not a car tech and curious.
I pulled up corresponding the base Solstice plot and it's nowhere near as "clean".
I think I understand the implications of the GXP data.
Can you car guys educate the rest of us on the comparison between the two?

The Ecotec 2.4 I-4 is much choppier, shows a dropout at 3k rpms,and declines beyond 5k.
Is this engine, gearing, all of the above?

What would we feel between the two?

edit. adding link to Soltice plot
http://media.gm.com/us/powertrain/e...y/Ecotec/2006_Ecotec_LE5_Pontiac_Solstice.pdf

 

[SkyBaby]

Don't need to go fast to look good:thumbs:

need all the help i can get .... SkyBaby-07

 

[LS2 MN6]

Hope to not hijack, but not a car tech and curious.
I pulled up corresponding the base Solstice plot and it's nowhere near as "clean".
I think I understand the implications of the GXP data.
Can you car guys educate the rest of us on the comparison between the two?

The Ecotec 2.4 I-4 is much choppier, shows a dropout at 3k rpms,and declines beyond 5k.
Is this engine, gearing, all of the above?

What would we feel between the two?

edit. adding link to Soltice plot
http://media.gm.com/us/powertrain/en/product_services/HPT%20Library/Ecotec/2006_Ecotec_LE5_Pontiac_Solstice.pdf

The Engine Curve is raw power coming out of the Crank so gearing is not invovled. Also HP is a function of Torque specifically HP = Torque X RPM / 5252, which is why HP and Torque always cross at 5252. I think the reason this one is good is that Torque reaches it's peak Quickly and then stays there. Meaning the faster the engine spins the more power you get.

 

[RickKappa]

Hope to not hijack, but not a car tech and curious.
I pulled up corresponding the base Solstice plot and it's nowhere near as "clean".
I think I understand the implications of the GXP data.
Can you car guys educate the rest of us on the comparison between the two?

The Ecotec 2.4 I-4 is much choppier, shows a dropout at 3k rpms,and declines beyond 5k.
Is this engine, gearing, all of the above?

What would we feel between the two?

edit. adding link to Soltice plot
http://media.gm.com/us/powertrain/e...y/Ecotec/2006_Ecotec_LE5_Pontiac_Solstice.pdf

Pretty much what DuSpinnst said. When you say, "The Ecotec 2.4 I-4 is much...," I assume you mean the base engine in the Solstice/Sky now and not the turbocharged one? If so, here is a quick synopsis.

The Solstice GXP / Sky Redline engine is a modified, reinforced, direct-injected, turbocharged version of the engine that is in them now. The turbocharger takes the force of the exhaust to spin an impeller. This impeller is connected by a shaft to another impeller which will also spin due to exhaust gas flowing out; however, this side has no contact with the exhaust. This side instead is connected to your air intake. As the impeller spins, it forces air to come in faster than what it would normally. A car at normal acceleration and cruising speed has vacuum in the intake manifold (measured in the English system as inHg (inches of mercury)). This means that there is less air pressure in the manifold than the ambient, atmospheric pressure. When you are at wide-open throttle (WOT) and just stomping on the gas, the vacuum is near if not gone and equals the ambient air pressure (0inHg). The turbo however goes beyond ambient air pressure and creates pressure (in the English system, it’s psi (pounds per square inch)) that we call “boost.” With more air, you can add more fuel, and with a denser air/fuel mixture, an engine can get higher VE (volumetric efficiency) which not only offsets, but goes beyond offsetting the negatives of having a slower burning gas (you need premium in forced inducted cars, higher the octane the slower it burns) and a lower compression ratio which is normally required for a car with forced induction.

What you will feel is your ass being sunk into the seat as if it were Mustang GT or Camaro Z28 (stop me if I am going a little too far with that) off of a four-cylinder engine. It’ll pull hard at any RPM as long as there is not a lot of turbo lag which is the time the turbo needs to spool up when accelerating to create boost.

 

[skywatcher]

DuSpinnst & RickKappa.
Thank you for sharing your knowledge.
It took a few reads and some poking around on the web, but think I got it.
I think I see now why the plot is cause for pause.

 

[Delnari]

That's how you put engineering talk into a drivers language. :thumbs:

 

[skywatcher]

That's how you put engineering talk into a drivers language. :thumbs:

Well, what the hell. I'm actually learning car stuff on a car forum.
One thing which keeps popping into my head, but assume is handled by engineering.

What about heat?
With more burn, we get more heat?
Will the engine reach a point where it's heat soaked to a point where fuel burn efficiencies change?
I'd assume engine management s/w adjusts as needed for burn, but is heat buildup to a level where
thermal conditions become any sort of limiting factor?
Don't think I'm quite nailing the crux of the question, but see mention
of the turbo engine as reinforced and the plot makes me picture thermal stresses.
How do you mitigate, and where's the wall?

 

[brentil]

In essence yes since you're introducing a new high rpm item that's being driven by heated exhaust gases the engine bay can heat up to higher heats sooner. However I'm pretty sure the car layout is designed to handle this, along with various other items like oil coolers and such to help eliminate the extra heat being created by the system. The air compressed by the Turbocharger is passed through a intercooler which drops the temp of the air being compressed greatly prior to it entering the engine. Also the Direct Injection technology helps for far more efficient fuel delivery which allows a powerful system like this to be far less knock prone because of the way it's delivered and burned compared to normal fuel injection.

 

[Nemesis]

I know that my MR2 Turbo had an intercooler, which was basically a miniturized radiotor dedicated specifically to the turbo. This allowed all forced air to be super cooled as well. So the radiator cooled the regular air/fuel mix, and the intercooler cooled the forced air. I am assuming the RL has an intercooler, this also explains why the turbo needs more air space on the GXP facia then on the solstice facia. I believe the GXP has either a larger radiator in the front, utilizes the larger airspace, or uses an intercooler place inthe front airdam to cool the air. The easiest way to explain the intercooler would be to see one for yourself. Do a yahoo search for the Mazdaspeed Miata, one of it's styling cues was the intercooler monted infront of the radiator which could be seen from any front pic of the car. One person had mentioned turbo lag previously as a possible issue with this car. I experienced turbo lag with the MR2 Turbo I had, because the turbo spooled at 3k RPM. With this car showing 260ftlbs of torque at 2.5k I think it is safe to say that lag will not be a serious issue. I can't remember the last time I saw that much torque on a modern car, at that low of an rpm. Specially from a 4 cyclinder engine. The MR2 Turbo had 200lbs of torque nd 200hp out of the same size engine, and it was a fast little car. I would imagine this will be a great little car.

 

[brentil]

What you will feel is your ass being sunk into the seat as if it were Mustang GT or Camaro Z28 (stop me if I am going a little too far with that) off of a four-cylinder engine. It’ll pull hard at any RPM as long as there is not a lot of turbo lag which is the time the turbo needs to spool up when accelerating to create boost.

If you read the tech documentation about this turbo it's some sort of special twin vain design, and GM goes on and on about low lag times, quick spooling, etc.

2006 Mustang GT - 3,483/300HP = 11.61 lbs/HP
2002 Camaro Z28 - 3,433/310HP = 11.07 lbs/HP

2007 Solstice GXP - 2950/260 = 11.35 lbs/HP

I really have no clue what the GXP weight is, that's just a guestimate. The GXP will have some slight benefits over either though. Sport traction control mode, and Goodyear Eagle F1 GS2 tires.

 

[Delnari]

You have a good point about heat soak being a potential problem. Turbochargers do produce more engine bay heat then superchargers. The turbo impeller turns over 100,000 rpms at speed. This friction does generate high oil temps and without an added oil cooler the engine oil would break down and fail to protect the bearings. This is why a factory turbo engine tends to be stronger in duty-cycle than an aftermarket. The engineers take these temperatures and stresses into account when designing them. That's why it was pretty amazing to some of us that GM is running more than 20 lbs of boost in this engine. Typically, you would not see this much pressure from a factory turbo engine. The science is getting better for of us.

 

[brentil]

I know that my MR2 Turbo had an intercooler, which was basically a miniturized radiotor dedicated specifically to the turbo. This allowed all forced air to be super cooled as well. So the radiator cooled the regular air/fuel mix, and the intercooler cooled the forced air. I am assuming the RL has an intercooler, this also explains why the turbo needs more air space on the GXP facia then on the solstice facia. I believe the GXP has either a larger radiator in the front, utilizes the larger airspace, or uses an intercooler place inthe front airdam to cool the air. The easiest way to explain the intercooler would be to see one for yourself. Do a yahoo search for the Mazdaspeed Miata, one of it's styling cues was the intercooler monted infront of the radiator which could be seen from any front pic of the car. One person had mentioned turbo lag previously as a possible issue with this car. I experienced turbo lag with the MR2 Turbo I had, because the turbo spooled at 3k RPM. With this car showing 260ftlbs of torque at 2.5k I think it is safe to say that lag will not be a serious issue. I can't remember the last time I saw that much torque on a modern car, at that low of an rpm. Specially from a 4 cyclinder engine. The MR2 Turbo had 200lbs of torque nd 200hp out of the same size engine, and it was a fast little car. I would imagine this will be a great little car.

Yup, it's an intercooler down front.

Heck, this car is making 250 lbs-ft at 1500 RPM, its freakin amazing.

 

[KappaMan]

...
Heck, this car is making 250 lbs-ft at 1500 RPM, its freakin amazing.

Yum...

 

[SlidinSky]

why is it they keep turbo charging the 2.0 and not the 2.4? Is it the compression ratio? and do you think they will make aftmarket parts for the 2.4?

 

[LS2 MN6]

why is it they keep turbo charging the 2.0 and not the 2.4? Is it the compression ratio? and do you think they will make aftmarket parts for the 2.4?

It's typically easier to turbocharge smaller displacement engines. The 2.4 also has a ridiculous compression ratio.

 

[brentil]

why is it they keep turbo charging the 2.0 and not the 2.4? Is it the compression ratio? and do you think they will make aftmarket parts for the 2.4?

Actually the LNF IS the 2.4L engine with the displacement decreased to permit safer functioning under boost. In the GM documentation they say they're both the same block with the VVT. The LNF builds on top of the LE5 by adding SIDI technology as well.