MHD Power Level vs BM3 Torque by Gear / Boost Limiter

[parametric]

Hi guys,

I’m trying to optimize an OTS-only pump-gas setup around the actual knock limit of the fuel, rather than just running the strongest available map and letting timing corrections manage it.

The setup is B58TU, stock turbo, stock fuel system, catless downpipe, running Korean premium pump gas. I don’t want to rely on ethanol blends or WMI for the normal setup.

I know one obvious option is simply to move to an OTS map designed for lower fuel quality, but what I’m really interested in is fine-tuning the output/load within the same general OTS calibration, so I can stay as close as possible to the fuel’s real limit without unnecessary timing corrections.

My goal is the highest clean and repeatable output, with minimal systematic timing correction and good consistency in hot/high-DA conditions.

The three methods I’m comparing are:

• MHD+ Power Level: 100 / 95 / 90%
• BM3 Torque by Gear
• BM3 Max Boost Limiter

The main question is:

When fuel quality is the limiting factor, which method gives the cleanest and most adaptive way to fine-tune engine load without simply dropping to a lower-octane map?

For MHD, when Power Level is reduced, does it mainly reduce requested torque/load while still letting the DME calculate boost normally?

For BM3, is Torque by Gear the closer equivalent, or is Max Boost Limiter the better tool for this purpose?

I’m especially interested in how BM3 Torque by Gear actually reduces torque. Does it mainly lower load, boost and cylinder filling, or can a meaningful part of the reduction still come from throttle closure or ignition retard depending on conditions?

I’m a little hesitant to rely only on a fixed boost cap, because the same boost pressure can represent a different actual cylinder load depending on temperature, altitude and air density.

Has anyone directly compared these methods and logged things like:

• timing and cylinder corrections
• requested/actual load
• boost target vs actual
• throttle / WGDC
• IAT / EGT
• acceleration and repeatability

I’d especially like to hear from people who have tested BM3 vs MHD on B58 pump-gas setups in hot or high-DA conditions.

Any direct logs or tuner experience would be very useful.

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[Hasan]

When fuel quality is the limiting factor, which method gives the cleanest and most adaptive way to fine-tune engine load without simply dropping to a lower-octane map?

When fuel quality is the limiting factor, you should use a lower octane map. That would give you the optimum and cleanest operation.

You post is quite self contradictory.