Bigger Turbos

Once you get a taste of that boost you always want more, and that leads us into the next discussion and that is turbo upgrades.

150-180 HP factory cars come  equipped with a k03/s turbo thats a bit small for the displacement of the engine and the result is bottlenecking in the exhaust manifold / turbo hot side. K03 hybrid / K04 (001 / 015) hybrid turbos offer a bolt-on upgrade for the k03 and allow you to run the “stock style” exhaust configuration. Also, the cooling and oil lines remain the same keeping the installation straightforward. The downside of using a “OE Style” turbo is the limitation of options for going bigger down the road, small frame turbos have an inherent boost spike that can cause engine damage without forged connecting rods or a very mild tune. Small frame turbos are limited on the top end due to the choke point, make excessive heat and limit topside power.

210-240 Hp factory cars have a much larger turbo stock then the 150-180hp cars, and have the ability to push the 300Hp mark with the use of e85 or water / meth injection. Again, the rods are the weak point and should be upgraded while chasing power on a smaller frame turbo. Hybrid K04-02X turbos are decent in size and make 400+ Hp with a good hybrid, forged rods and safe tune. The larger k04 and hybrid offer a lot more than the smaller turbos, better flowing exhaust manifold and hot side.

T25 flange turbos such as the smaller gt28 and gt25 turbos pack a punch, spool quickly and can hold decent top end power. Normally you'll see a log style manifold with a internally wastegated turbo, the setup is a good option for a streetcar that gives a good bump in power (over a stock turbo) while still keeping that low-end power used for daily driving. Forged rods are recommended especially if you want to max the turbo out. Also, something I have personally experienced with gt28 turbos in general is boost creep when trying to control boost over 15 psi or so and requiring the use of an external wastegate to properly manage boost control.

T3 flange turbos offer a large range of options from gt28-gt35 and beyond. T04E, GT30 /GTX30, Hy35, 58/58 are some of my favorite turbo options for the 1.8t as they make power on top side and do not have that low end torque spike allowing you to push the stock bottom end safely on the 1.8t to 400+ Hp with low risk of engine damage. Low end lag is the saving grace with the larger turbos as the power is made gradually and peak power is made in the 5000rpm+ range reducing stress on the connecting rods. If you want to make a highway killer and/or do not mind some low end lag you may want to consider going with a t3 framed turbo. A t3 turbo also gives you the option to make more power in the future with your current turbo. Example: gtx3076 on pump gas at 20 psi should be around 350-370 wheel horsepower and safe for a stock engine. Next year 480-500 horsepower at 32psi after mild engine build, upgraded clutch and fueling.