IS38 Rebuild Question.

[mr wrong]

Just to clear things up as I think we're getting lost in semantics. I'm going with the HPA OEM+ which only advertises an "upgraded bearing system", NOT their IS38 Hybrid which unlike the OEM+ is closer to the Vortex., and almost twice the cost.

I'm not after huge power gains rather reliability and peace of mind, otherwise I'd sell my Alltrack and get a GTI or R.

 

[ZuMBLe]

Just to clear things up as I think we're getting lost in semantics. I'm going with the HPA OEM+ which only advertises an "upgraded bearing system", NOT their IS38 Hybrid which unlike the OEM+ is closer to the Vortex., and almost twice the cost.

I'm not after huge power gains rather reliability and peace of mind, otherwise I'd sell my Alltrack and get a GTI or R.

Go with any IS38 OTS tune. Run the OEM Is12 tune for a while if you must. The airflow values for the stock tune is comically low, so you're safe.

I ran my IS20 tune with my IS38 as a base tune. You should be fine there also. Of course, better to just get the IS38 tune.

 

[mfennell]

There are a few people running EQT Vortex standard turbos on 1.8T wagens, all of them UM flex tuned with MPI and LPFP upgrades. Sure, it spools a bit later than an IS38 (can’t cheat physics with larger turbine/compressor wheels and a slightly larger A/R turbine housing) but from messaging with the owners of those cars there is plenty of torque down low, with boost building in the 2k rpm range and peaking in the mid 3k range.

To each his own, but with the gearing of a GSW/Alltrack, I'm not sure how I'd feel about "a bit later" spool than a stock is38 + IE DP. I haven't logged with the DP but I was seeing 0.5bar at 2500, 1bar at 3000, 1.4 peak with Unitronic's OTS is38 tune and the stock exhaust. I think it's a little better with the DP but I haven't logged it.

 

[J Peterman]

Fair. I think it’s safe to say the 60mm OEM downpipe wasn’t helping all that much.

Manual or DSG?

 

[jimlloyd40]

Just to clear things up as I think we're getting lost in semantics. I'm going with the HPA OEM+ which only advertises an "upgraded bearing system", NOT their IS38 Hybrid which unlike the OEM+ is closer to the Vortex., and almost twice the cost.

I'm not after huge power gains rather reliability and peace of mind, otherwise I'd sell my Alltrack and get a GTI or R.

What is the warranty on the HPA OEM + turbo? I'm guessing 12 months and 12,000 miles. If the turbo fails after that you're screwed and that's the reason I would get the FCP Euro IS38 instead. You can't beat lifetime warranty.

 

[mfennell]

Fair. I think it’s safe to say the 60mm OEM downpipe wasn’t helping all that much.

Manual or DSG?

6MT.

 

[Joe_Mama]

Just to throw another brand out there:

https://shuenk.com/IS38-for-Mk7-MQB-p303177166

People seem to love these, but I agree with @jimlloyd40. If it was me I would go with FCP for the warranty alone.

 

[joedubs]

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.

Just to echo what @ZuMBLe has already said:
- The ecu meters fuel based on calculated airmass
- It calculates that airmass based on the flow characteristics of the engine (VE).
- The only sensors it has to do that are the air pressure (PUT, MAP, and ambient) and air temp. I.e. the airmass is based on the pressure and temperature of the air entering the engine, given that the engine can flow with xx efficiency at a particular operating point.

To put it plainly - you could run a hybrid on an is12 tune and your air/fuel will be fine. When tuning for a hybrid you need to make no changes to the airmass/AFR related tables.

Where you run into issues is that the closed loop boost control is only so reactive. Proactive (open loop) wastegate duty cycle is based on modeled values given certain known characteristics of the turbine housing. Hybrids blow that up entirely. So at a certain boost pressure, the ecu won't open the wastegate the right amount and it CAN lead to overboost situations. It's really only a problem at boost levels far above the is12 efficiency range (where the gate would need to stay closed for the little turbo to keep up.)

But I'm not a pro tuner, so what do I know.

 

[GTI Jake]

Just to echo what @ZuMBLe has already said:
- The ecu meters fuel based on calculated airmass
- It calculates that airmass based on the flow characteristics of the engine (VE).
- The only sensors it has to do that are the air pressure (PUT, MAP, and ambient) and air temp. I.e. the airmass is based on the pressure and temperature of the air entering the engine, given that the engine can flow with xx efficiency at a particular operating point.

To put it plainly - you could run a hybrid on an is12 tune and your air/fuel will be fine. When tuning for a hybrid you need to make no changes to the airmass/AFR related tables.

Where you run into issues is that the closed loop boost control is only so reactive. Proactive (open loop) wastegate duty cycle is based on modeled values given certain known characteristics of the turbine housing. Hybrids blow that up entirely. So at a certain boost pressure, the ecu won't open the wastegate the right amount and it CAN lead to overboost situations. It's really only a problem at boost levels far above the is12 efficiency range (where the gate would need to stay closed for the little turbo to keep up.)

But I'm not a pro tuner, so what do I know.

Sick man, can’t wait to see your car running a hybrid on a is12 tune.

Nobody asked if your were a tuner, all I did was explain my observations of my car running obliviously lean.

 

[jimlloyd40]

Sick man, can’t wait to see your car running a hybrid on a is12 tune.

Nobody asked if your were a tuner, all I did was explain my observations of my car running obliviously lean.

Can you say EPC light and a host of other problems trying to run a hybrid turbo with an IS12 tune.

 

[ZuMBLe]

Sick man, can’t wait to see your car running a hybrid on a is12 tune.

What do you think will happen if he were to run a IS12 tune on his hybrid turbo car?

Nobody asked if your were a tuner, all I did was explain my observations of my car running obliviously lean.

Your car shouldn't run lean. Something is wrong with your setup. And what is lean really? Is it Lambda setpoint .83 and it's actual .84? Is it lambda setpoint .83 and actual .90? Do you have a log of this occurrence? Seriously trying to get to the bottom of this.

There is like no way a IS12 tune will blow up an engine on a hybrid turbo setup simply because:
A. The stock airflow tables don't command enough airmass.
B. The stock torque demand tables for IS12 drops off sharply after 4000 RPM

 

[ZuMBLe]

Can you say EPC light and a host of other problems trying to run a hybrid turbo with an IS12 tune.

If you get any EPC it will be for boost deviation. Meaning the car is not reaching boost target down low like it thinks it should. The car would not run lean etc. If we adjusted the table for how much deviation would be allowed, the EPC wouldn't happen and the turbo will eventually spool. When it spools to the target airmass that the tune calls for, the wastegate will open and bleed exhaust gas to slow the turbine. The ECU knows the airmass, and it knows the amount of fuel to add to the airmass to create the right lambda. If it's wrong for whatever reason, the wideband sensor will tell the ECU and it will instantly correct up to 35%.

This is no different than using a bike pump or shop air to pump a tire to 35 PSI. The shop air is not going to blow up the tire if you stop at 35PSI. 35 PSI is 35 PSI. That's the simplest way to put it.

 

[GTI Jake]

What do you think will happen if he were to run a IS12 tune on his hybrid turbo car?



Your car shouldn't run lean. Something is wrong with your setup. And what is lean really? Is it Lambda setpoint .83 and it's actual .84? Is it lambda setpoint .83 and actual .90? Do you have a log of this occurrence? Seriously trying to get to the bottom of this.

There is like no way a IS12 tune will blow up an engine on a hybrid turbo setup simply because:
A. The stock airflow tables don't command enough airmass.
B. The stock torque demand tables for IS12 drops off sharply after 4000 RPM

Is12 hybrid comment was making a joke of his enormous rant. As in if that’s what his suggestion for the OP is I hope that’s is plan for his personal car.

I have zero interest in this, couldn’t care less. You’re not gonna get to the bottom of anything, because I ran my car stage 2 with the is38 for literally 30 miles and that was the only time it ever went lean and popped like that.

It has 108k miles on it and traps 115mph, there’s nothing wrong with it.

 

[joedubs]

Is12 hybrid comment was making a joke of his enormous rant. As in if that’s what his suggestion for the OP is I hope that’s is plan for his personal car.

I have zero interest in this, couldn’t care less. You’re not gonna get to the bottom of anything, because I ran my car stage 2 with the is38 for literally 30 miles and that was the only time it ever went lean and popped like that.

It has 108k miles on it and traps 115mph, there’s nothing wrong with it.

It wasn't an enormous rant. It was a detailed explanation for the way the ecu actually works to meter fuel and control boost.

The ENTIRE issue with the tuning community is that nobody shares any actual information and so people are left just guessing about how things work. It keeps people going back to pro tuners, raving on the socials about how smooth their latest revision is.
That, I would be happy to rant about.

 

[Joe_Mama]

I have zero interest in this, couldn’t care less.

Maury voice: "we got the results back and it turns out... THAT was a lie!"