Mabotech M520H – Round 1


Recently I swapped out my IS38+ for the Mabotech M520H turbocharger.

Mabotech M520H Turbocharger
Mabotech M520H Turbocharger

I already had the Eurodyne Powertap Cable and Eurodyne tunes, so leveraging Mabotech for the tuning of their M520H turbo made sense since they support the Eurodyne tuning platform.

No other significant changes were made to the GTI when I swapped to the M520H turbo, which significantly means the fueling is still “stock” with the exception of an aftermarket HPA high-pressure fuel pump that I installed in 2020 during IS38 custom tuning.


The first tuning effort went straight to using E30 and the first couple of revisions were focused on refining the fuel trims for the Ethanol fraction of the fuel mixture.

M520H E30 tuning fuel trims

Next, a couple of revisions were made so that the Eurodyne ECU tune would operate more smoothly with my customized Stratified TCU tune.

With the groundwork complete attention turned to increasing boost pressure to see what level of pressure the fuel system could support:

(Green lines are my IS38 E30 tune; Purple lines are the M520H E30 tune)

M520H Round 1 Injection Times
M520H Round 1 Injection Times vs IS38 E30 Tune

After about six (6) revisions we arrived at the boost curve shown below:

Mabotech M520H Round 1 Boost Curve
Mabotech M520H Round 1 Boost Curve

I did a series of ten pulls with this tune revision to record acceleration data to process using the Virtual Dyno application:

M520H Round 1 Virtual Dyno
M520H Round 1 Virtual Dyno

Peak wheel horsepower for each pull was then extracted to calculate an average:

Mabotech M520H Round 1 Virtual Dyno Estimated Peak WHP
Mabotech M520H Round 1 Virtual Dyno Estimated Peak WHP

Average and Median calculations are 403 WHP.

Side road:

I was interested in trying to simulate an IS38 boost curve with the goal of producing a compressor outlet air temperature that is similar to an IS38. The reason is that if I want to compare intercooler performance when using the M520H with the data I recorded with the IS38 it would be important to have similar air temperatures leaving the compressor.

Frank at Mabotech made a couple more revisions to create the boost curve shown below:

Mabotech M520H Round 1 - IS38-Like Boost Curve
Mabotech M520H Round 1 – IS38-Like Boost Curve

The compressor outlet air temperature with this boost curve is shown below:

Mabotech M520H Round 1 "IS38 Boost Curve" Turbo Discharge Temperature
Mabotech M520H Round 1 “IS38 Boost Curve” Turbo Discharge Temperature

The M520H compressor outlet temperature is roughly 30-40 degrees Fahrenheit lower than the IS38+ turbocharger. A sample of the IS38 outlet air temperature is shown below.

Shuenk IS38+ Turbocharger Outlet Air Temperature
Shuenk IS38+ Turbocharger Outlet Air Temperature

While the temperatures are not drastically different, there’s enough of a difference that I don’t think I’ll be able to fairly compare intercooler performance from the use of the IS38 turbocharger to what is recorded while using the M520H turbocharger.

Mabotech M520H Next Steps:

Tuning progressed very quickly during this first round. It was not uncommon for Mabotech to have a tune revision available for me the same day I sent them data logs.

With fuel supply the current limitation on pushing more boost I’m looking into upgrading the low-pressure fuel pump along with adding multi-port fuel injection.

This will include shipping my candidate fuel injectors to Mabotech for them to perform a flow test to ensure the balance and quantity of fuel delivery are acceptable for the next round of tuning.

Mabotech Fuel Injector Flow Test


7 thoughts on “Mabotech M520H – Round 1”

  1. Nice choice. Bi cooler set ups seem like a great alternative if u don’t want to compromise safety by having to chop things up for a very large fmic

    1. It would be interesting to see how a bicooler and aftermarket stock location stack up with the larger FMICs that require modifying the front crash bar.
      Mabotech Race Bicooler

  2. I agree but I definitely would ask for logs from folks that already compromised the crash bar. I wouldn’t want mine compromised at all! That’s just me tho

    1. DBV2 and Mabotech both offer an alternative crash bar, so the OEM bar could be removed for testing and then be reinstalled without needing to be modified.

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