Kia Stinger 2.0T G4KL - G25-550 Full Setup Introduction

[Bugra demir]

Hello everyone,

My car is a 2018 Kia Stinger 2.0T (G4KL engine), and I’ve been working on a detailed performance build for a while now. My goal was to create a setup that is both daily drivable and performance-oriented, while maintaining durability and safety. Here’s my current mod list:

Engine & Performance Modifications:

• Garrett G25-550 Twin Scroll turbo
• 44mm GFB external wastegate
• GFB G-Force III electronic boost controller
• 11-liter custom intercooler
• Full straight 70mm chrome exhaust system (including downpipe)
• K&N 5060 open air intake filter
• Snow Performance 2.5 methanol injection kit
• 1-liter oil catch can
• HKS high-performance spark plugs
• SCORCHER High-Performance ignition coils
• ARP CA625+ cylinder head studs
• Cometic reinforced cylinder head gasket
• N75 upgraded high-flow injectors
• N75 upgraded high-pressure fuel pump (HPFP)
• N75 Tuning custom ECU software

Target Figures:

• 20 PSI boost pressure
• Safe AFR and methanol ratios aiming for 350-400hp

While building this setup, I’ve carefully considered the limits of the stock internals, as well as cooling, fueling, and overall engine safety.


Now I’d like to ask you guys:


What are the generally accepted safe power and torque limits for the Kia Stinger 2.0T (G4KL) engine with stock internals?

I’m especially interested in hearing your experiences and opinions regarding long-term reliability in the 350-400hp range.





Thanks in advance!

 

[Snicklefritz]

Very few 2.0L modified powertrains on the forum. Your list is the most extensive that I have seen. I have a 2.0L as well, bone stock. But the subject interests me. You are questing for well over 50% increased HP. That would be the equivalent of boosting the 365 HP V6 to 500-572 HP, which is a lot, but I think it is fairly common. And we don't get blown engine reports very much. So, your probably "safe". Ah hah.

 

[Bugra demir]

Thank you, you’re absolutely right. My actual goal is not to exceed 50% over stock power. My ideal target is more like a 35-40% increase. So, I’m aiming for around 360 HP. I believe this level can be achieved while keeping it suitable for daily use and maintaining thermal and mechanical loads under control without risking engine longevity.





To support this, I’m planning to stay within safe limits with a more efficient turbo choice (such as the G25-550), a high-capacity intercooler, methanol injection to cool intake air and reduce knock risk, and by reinforcing the fuel system. My main goal is not exaggerated “dyno records,” but rather a sustainable and reliable power increase.

 

[Death]

Excited to follow this as a fellow 2.0 enjoyer.

 

[Snicklefritz]

Garrett G25-550 Twin Scroll turbo

Ima curious if you can tell a significant difference in reduced turbo lag and increased torque with this upgrade over OE twin scroll?

 

[Thomby]

I think ~400 horsepower from a modern 2.0, with aftermarket cooling & turbo, is very reasonable. Mercedes has been selling the A45/CLA45 with those numbers stock for years, and tons of Evo, WRX, and DSM guys have done it over the past couple decades.

 

[Bugra demir]

I think ~400 horsepower from a modern 2.0, with aftermarket cooling & turbo, is very reasonable. Mercedes has been selling the A45/CLA45 with those numbers stock for years, and tons of Evo, WRX, and DSM guys have done it over the past couple decades.

Even though methanol injection helps, I don’t think the stock internal engine components can reliably handle 400 horsepower for a long period. In collaboration with N75, we’ll be testing to find out the maximum and safest power we can achieve. I’ll be sharing all the data with you as we progress.”

 

[Bugra demir]

Hello everyone,

We’re slowly approaching the end of the project. Currently, the injectors, methanol kit, and electronic boost controller have not yet been installed. I’ve completed the break-in process with the car in this condition. Next week, the missing components will be installed, and I’ll upload the final tune.

For now, I’m using a base map provided by N75, designed for the 15 PSI spring in the wastegate, and I’m quite satisfied with it. Since the engine is freshly built, I’ve only done one pull so far, which I’m sharing with you here. Once everything is fully set up, I’ll do another pull and share the results again.

 

[Snicklefritz]

Nice update. Looking forward to the rest.

Meanwhile, in the interim, I have had my stock high pressure fuel pump and valve cover gasket replaced. Fuel pump was a TSB from December 2023, which I responded to, and KIA did the software update and declared my high pressure fuel pump good to go. A year and a half later, that was no longer the case.

Both were replaced under warranty.

Have you checked your high pressure fuel pump as KIA recommended?

 

[Bugra demir]

Nice update. Looking forward to the rest.

Meanwhile, in the interim, I have had my stock high pressure fuel pump and valve cover gasket replaced. Fuel pump was a TSB from December 2023, which I responded to, and KIA did the software update and declared my high pressure fuel pump good to go. A year and a half later, that was no longer the case.

Both were replaced under warranty.

Have you checked your high pressure fuel pump as KIA recommended?

Yes, I replaced the stock high pressure fuel pump with a high-flow upgraded one from N75. It’s been working great so far.