hi, first of all im a new member and wanna say hi to everyone here, im a fan of FI cars, i really want a mini S but they are quite pricey, the cobalt ss sc is affordable and i love how it looks. Anywas i have a question and it might be best suited for the RL owners or anyone who has driven the 2.0 ecotec, does anyone know if the engine when under acceleration (anytime below 3000rpm) give you the "push back against your seat" feel like how the turbo cars give you? i love that feeling in a car... the sudden surge of power, just wonderin if the 2.0 sc does that.

thanx for your help

 

I'm not a Redline owner, but generally superchargers have much better throttle response than turbocharged engines do. The S/C provides instantaneous power, whereas turbos have to spool up.

 

it is nowhere near the feeling of a turbo car, which i prefer. you have the power then and there and it builds with RPM.

i have a feeling boost is held back in lower RPMs to keep the tires from breaking loose too easily, but at around 4k rpms you really feel a boost in power compared to lower rpms (as i said, i believe this to be due to limited boost)

and about throttle response, it's perfect, a little touchy, but that's to be expected in a S/C application

 

I think many newer turbo systems are making boast at idle rpms and use a waste gate and computer help to apply/restirct boast as you accelerate. I don't think tubro lag is such an issue anymore. The supercharge is linked to Engine RPM just like a turbo is so it builds with RPM as well, it's just a matter of how the blower gets it's power to compress the air.

 

a turbo is not related to RPMs in the way that a S/C is. Superchargers are directly related to engine rpm, a turbo is only related to engine rpm in how much exhaust is put out at a certain rpm, i'm sure i've oversimplified quite a bit, but there is a huge difference

 

What he said ^^^. A turbo obviously pressurizes intake air by using pressure from the exhaust to turn a turbine. Exhaust pressure varies with RPM, but also with engine load (aka how much the throttle is opened). And since it is a turbine powered unit, it still takes some time to make significant boost. This time can be tuned down to small (nearly negligible) lag, but is not eliminated.

 

Remember, on any car whether F/I or N.A., the "push back against your seat" feeling ultimately comes from how much low-end TORQUE it puts out. Most imports lack torque, so turbocharged engines are used to to make up for this; by increasing torque substantially. For example, the N.A. 2nd Gen. Cavalier with the 3.1 L MPFI V6, though not a particularly fast car, it gives you the "push back" feeling instantly b/c of its low-end torque.

I have always like the saying that circulates around, "Horsepower sells cars, torque wins races."

 

werd

 

Exactly, exhaust gas volume is related to the RPM of the motor. The more RPM's the more exhaust gas thats being put out but the engine. Of couse the more exhaust gas the faster the turbo spins and the more air it forces into the engine so it's not linear like a supercharger. So it's a happy little circle