Mysteries of Car Engines in the days of Turbo-mania

[DGS49]

Obviously, there is something magical about turbocharged 2-liter four-cylinder engines. Everybody makes one, and most of the manufacturers seem to place engines of that size in the heart of their product planning.

Not being a mechanical engineer, I have only a rudimentary understanding of what turbocharging (and supercharging) do to make engines more powerful, and obviously the more boost can lead to more power and torque. But that just leads to more questions.

FOR EXAMPLE, GM has had a 2-liter turbo for quite a while now, It powered the Pontiac Solstice and Saturn Skye, the HHR SS, and other cars, with significant success. At the time it was rated at 260-270 hp, and having driven some of those cars, it was an amazing engine, both powerful and economical, though they never figured out how to make it sound good.

Fast forward many years, and GM is still powering a large range of cars with t-liter turbo fours from Cadillac's to Chevy's, with HP ratings that range from 237/258 in the CT4 (base) to 265/295 in the Camaro. Apparently it's the same engine.

VW has a 2 liter four-banger that is rated at 184/221 in a Tiguan, and GTI-R rated at 315 hp.

What the fuck? If the turbo-4 is capable of 300 HP, why configure it at 185?

Is it just a matter of different programming? Could a different "chip" significantly get more power out of the same engine? Is it the CFM rating of the turbo? Could a larger turbo be added to a Tiguan to improve its performance (warranty issues aside)?

Is there a goldmine of additional power available to those who are able to make simple mods to these 2-liter engines?

 

[toobfreak]

Obviously, there is something magical about turbocharged 2-liter four-cylinder engines. Everybody makes one, and most of the manufacturers seem to place engines of that size in the heart of their product planning.

Not being a mechanical engineer, I have only a rudimentary understanding of what turbocharging (and supercharging) do to make engines more powerful, and obviously the more boost can lead to more power and torque. But that just leads to more questions.

FOR EXAMPLE, GM has had a 2-liter turbo for quite a while now, It powered the Pontiac Solstice and Saturn Skye, the HHR SS, and other cars, with significant success. At the time it was rated at 260-270 hp, and having driven some of those cars, it was an amazing engine, both powerful and economical, though they never figured out how to make it sound good.

Fast forward many years, and GM is still powering a large range of cars with t-liter turbo fours from Cadillac's to Chevy's, with HP ratings that range from 237/258 in the CT4 (base) to 265/295 in the Camaro. Apparently it's the same engine.

VW has a 2 liter four-banger that is rated at 184/221 in a Tiguan, and GTI-R rated at 315 hp.

What the fuck? If the turbo-4 is capable of 300 HP, why configure it at 185?

Is it just a matter of different programming? Could a different "chip" significantly get more power out of the same engine? Is it the CFM rating of the turbo? Could a larger turbo be added to a Tiguan to improve its performance (warranty issues aside)?

Is there a goldmine of additional power available to those who are able to make simple mods to these 2-liter engines?

Turbo/supercharging merely exploits the ability to exceed the normal volumetric efficiency of an engine at normal air pressure, up to the limit that can be contained in a reasonable metal enclosure.

 

[Missourian]

This is way out of my wheelhouse.

The smallest turbo-charged engine I have experience with is 11.1 liters and it's a diesel...but the power and acceleration difference from normal operation to after blowing an air-to-air coupling boot is staggering.

We're not talking a 10 or 20 percent loss...it's more like 60 to 70 percent.

 

[Godboy]

Obviously, there is something magical about turbocharged 2-liter four-cylinder engines. Everybody makes one, and most of the manufacturers seem to place engines of that size in the heart of their product planning.

Not being a mechanical engineer, I have only a rudimentary understanding of what turbocharging (and supercharging) do to make engines more powerful, and obviously the more boost can lead to more power and torque. But that just leads to more questions.

FOR EXAMPLE, GM has had a 2-liter turbo for quite a while now, It powered the Pontiac Solstice and Saturn Skye, the HHR SS, and other cars, with significant success. At the time it was rated at 260-270 hp, and having driven some of those cars, it was an amazing engine, both powerful and economical, though they never figured out how to make it sound good.

Fast forward many years, and GM is still powering a large range of cars with t-liter turbo fours from Cadillac's to Chevy's, with HP ratings that range from 237/258 in the CT4 (base) to 265/295 in the Camaro. Apparently it's the same engine.

VW has a 2 liter four-banger that is rated at 184/221 in a Tiguan, and GTI-R rated at 315 hp.

What the fuck? If the turbo-4 is capable of 300 HP, why configure it at 185?

Is it just a matter of different programming? Could a different "chip" significantly get more power out of the same engine? Is it the CFM rating of the turbo? Could a larger turbo be added to a Tiguan to improve its performance (warranty issues aside)?

Is there a goldmine of additional power available to those who are able to make simple mods to these 2-liter engines?

They dumb them down at the factory to keep the other components in your car (detailed below) from breaking with the addition of more HP. Two cars may have the same engine, but they dont have the same components (one car is designed to handle the extra power, the other is not). There are companies that spend a tremendous amount of money to see how far they can push and tweak a motor before it blows up or the car breaks. Every turbo motor has a different aftermarket ECU tuner company for it. So like Ford has Cobb and Mountune, Honda has Hondata, etc.

As for putting a bigger turbo on it, yes, you can do that to any turbo motor, but you have to upgrade other things on the car as well or youll fuck it up. Forgive me if im oversimplifying this discussion, but there are 4 stages for turboing a car.

Stage 1 consists of an ECU tune and you also want to upgrade the air intake. You want a "cold air intake". You can usually get a stage 1 upgrade for about $500, give or take.

Stage 2 requires an exhaust system upgrade. You will also need an intercooler. At this point you also need better motor mounts because, the extra power will cause the motor to twist. Without upgraded mounts, the motor twisting will cause your car to lurch when you step on the gas, which will wreck your quarter mile times. This is the point where you also need to upgrade the brakes. Stage 2 upgrades cost around $2,000 for top quality.

Stage 3 is where it starts getting expensive. At this point you are upgrading the fuel injectors, fuel pump, bigger turbo, inlet valves, spark plugs, etc. You need an upgraded clutch and gearbox. You might even be running Ethanol now.

Stage 4 is usually only for track cars, and there is a long list of shit that you upgrade.