IS38 Rebuild Question.

[ZuMBLe]

Which is exactly why I'm leaning toward the HPA OEM+ turbo.

If you mainly do Alltrack things with your Alltrack, the IS38 is quite good. It's a big enough turbo to be fast when you floor it, and small enough to be spunky at part throttle. Very happy with the way my IS38 behaves when I take my Alltrack on road trips. No issues climbing up mountains at part throttle etc.

 

[mr wrong]

If you mainly do Alltrack things with your Alltrack, the IS38 is quite good. It's a big enough turbo to be fast when you floor it, and small enough to be spunky at part throttle. Very happy with the way my IS38 behaves when I take my Alltrack on road trips. No issues climbing up mountains at part throttle etc.

May I ask what tune you're running?

 

[MonkeyMD]

You can’t run a OTS tune with anything but a regular ol is38.

If you’re gonna spring for a pro tune it’s silly not to at least step up to the most popular and arguably most reliable hybrid in the industry, EQT Vortex

Yes you can. I ran an APR Is38 tune with the HPA+ turbo for a while before going custom

 

[ZuMBLe]

May I ask what tune you're running?

Custom tune. I'm sure the APR tune would yield similar results.

 

[GTI Jake]

Yes you can. I ran an APR Is38 tune with the HPA+ turbo for a while before going custom

*shouldnt

 

[ZuMBLe]

*shouldnt

Meh these cars have closed loop boost control. As long as the hardware is not of lesser quality than the tune expects, it should be fine.

 

[GTI Jake]

Meh these cars have closed loop boost control. As long as the hardware is not of lesser quality than the tune expects, it should be fine.

Flowing more air than it’s tuned for can cause a lean condition.

I stayed out of boost as much as possible driving on APR stage 2 30 miles to go reflash the Is38 after installing my turbo and even just barely coming out of vacuum it popped and back fired a few times.

Your car, do what you want, but any professional will tell you exactly what I said.

 

[Keehs360]

Flowing more air than it’s tuned for can cause a lean condition.

I stayed out of boost as much as possible driving on APR stage 2 30 miles to go reflash the Is38 after installing my turbo and even just barely coming out of vacuum it popped and back fired a few times.

Your car, do what you want, but any professional will tell you exactly what I said.

Oh he gonna learn. Hopefully his car stays healthy. But what he’s doing is definitely ill advised

 

[MonkeyMD]

Flowing more air than it’s tuned for can cause a lean condition.

I stayed out of boost as much as possible driving on APR stage 2 30 miles to go reflash the Is38 after installing my turbo and even just barely coming out of vacuum it popped and back fired a few times.

Your car, do what you want, but any professional will tell you exactly what I said.

Big difference between running an is38+ (upgraded bearings, clipped turbine) on an Is38 tune and an is38 on an Is20 tune.

Never had any lean conditions, backfire or anything.

 

[GTI Jake]

Big difference between running an is38+ (upgraded bearings, clipped turbine) on an Is38 tune and an is38 on an Is20 tune.

Never had any lean conditions, backfire or anything.

Im not up on the is38 plus, but I could’ve sworn they claim 450hp capacity which would imply a larger compressor wheel

 

[ZuMBLe]

Flowing more air than it’s tuned for can cause a lean condition.

I stayed out of boost as much as possible driving on APR stage 2 30 miles to go reflash the Is38 after installing my turbo and even just barely coming out of vacuum it popped and back fired a few times.

Your car, do what you want, but any professional will tell you exactly what I said.

That's not how it works. Your car will not have a lean condition as long as your LPFP and HPFP are working right. We have closed loop boost and closed loop fueling. The ECU is always looking at the airmass and lambda target.

For our platform, "flowing more air than it's tuned for can cause a lean condition" is simply not true. Your airflow tables would have to be completely out of wack, then you need to be so far out of wack that it exceeds what the STFT and LTFT can handle. I think the STFT can handle being off by at least 30% in their direction. That's huge.

 

[GTI Jake]

That's not how it works. Your car will not have a lean condition as long as your LPFP and HPFP are working right. We have closed loop boost and closed loop fueling. The ECU is always looking at the airmass and lambda target.

For our platform, "flowing more air than it's tuned for can cause a lean condition" is simply not true. Your airflow tables would have to be completely out of wack, then you need to be so far out of wack that it exceeds what the STFT and LTFT can handle. I think the STFT can handle being off by at least 30% in their direction. That's huge.

The is20 flows a huge amount more air than the is38 (see my above post for observed results).

The EQT Vortex flows a huge amount more air than a is38 and from my understanding the is38+ is marketed as being in the same class as the Vortex.

Again, it’s your car do what you want. You won’t find a tuner who’d recommend it though.

 

[MonkeyMD]

Im not up on the is38 plus, but I could’ve sworn they claim 450hp capacity which would imply a larger compressor wheel

Gotcha. They have 2 different turbos, an IS38+ which is what I described and the HPA450 which is a hybrid like the Vortex. That one would need a custom tune.

 

[ZuMBLe]

The is20 flows a huge amount more air than the is38 (see my above post for observed results).

The EQT Vortex flows a huge amount more air than a is38 and from my understanding the is38+ is marketed as being in the same class as the Vortex.

Again, it’s your car do what you want. You won’t find a tuner who’d recommend it though.

Without getting too far in to the weeds. The factory calibration (and APR) are torque targeting. That means they target a specific airflow number. You slap a IS38 in and it will still flow the same because it's programmed to reach an airflow number. That's why torque tuned cars show less boost when it's colder and more boost when it's hot. Nothing really dangerous will happen.

 

[MeltedSolid]

Logs are useful. Having run an IS20 on an IS12 tune for a while (back before IS20 tunes were even released), I never had any lean issues (until the transmission swap, but that is a whole different issue), and was still running at the apr super rich 11.5-12 afr consistently.