xHP Remap

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chrismatin
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Re: xHP Remap

Post by chrismatin »

Does anyone have xHP on an otherwise stock M135/M235?

If so, how does it perform?

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nastypoker
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Re: xHP Remap

Post by nastypoker »

ZF limit the torque in gears 3 and 6 more than others. I remember when I was playing with MHD and XHP I ended up with the limits back and changing from 3rd to 4th was like being launched in a rocket.

It is to do with the path the power takes through the clutch packs in those particular gears.
2016 M135i LCI F20

BMW M Perf LSD - M4 TS+LCA's - BBS CH-R's with 245f & 255r - B12 Pro Kit - Underbody brace - PCW Zorst - Eton/JBL sound - Powerflex sub bushes - Upgraded intercooler - MHD stage 1 + XHP stage 3 - Ceramic'd
Ralston88
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Re: xHP Remap

Post by Ralston88 »

Any concerns on this wearing out the clutch packs sooner with the increased torque? What kind of mileage have people done with the xHP?
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NISFAN
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Re: xHP Remap

Post by NISFAN »

duke 2 wrote: Wed Apr 28, 2021 12:24 pm
What's your thoughts on the torque limit issue Nisfan?

Some people suggest that even a stage 1 OTS map requires XHP as otherwise the TCU limits torque to 500nm.

Yet on the other hand, plenty of people seem to get a remap, don't touch the gearbox and have no complaints. The likes of Lichfield don't mention the need for a transmission flash.

It's a head scratcher.
To be honest I only ever had xHP on together with a BM3 map. I believe BM3 down rate the load signal going to the ZF8, artificially raising the torque limit.

I felt obliged to go for xHP for the added fluid pressure and potential clutch saving effect. Because I always drive around in manual paddle mode, I didn’t get the benefits of smoother auto operation which many report, so that is possibly a good reason to buy it. I also didn’t get hard gear changes either. They were probably 5-10% faster, hardly detectable.
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nastypoker
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Re: xHP Remap

Post by nastypoker »

Ralston88 wrote: Fri Apr 30, 2021 7:21 am Any concerns on this wearing out the clutch packs sooner with the increased torque? What kind of mileage have people done with the xHP?
If you map your engine, then XHP will help prevent extra wear on the clutches as it raises the line pressure.
2016 M135i LCI F20

BMW M Perf LSD - M4 TS+LCA's - BBS CH-R's with 245f & 255r - B12 Pro Kit - Underbody brace - PCW Zorst - Eton/JBL sound - Powerflex sub bushes - Upgraded intercooler - MHD stage 1 + XHP stage 3 - Ceramic'd
Ralston88
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Re: xHP Remap

Post by Ralston88 »

Ah, that's interesting! So in a way will help reduce wear with a Stage 1 ECU remap?
bigbruiseral
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Re: xHP Remap

Post by bigbruiseral »

nastypoker wrote: Fri Apr 30, 2021 10:26 am
Ralston88 wrote: Fri Apr 30, 2021 7:21 am Any concerns on this wearing out the clutch packs sooner with the increased torque? What kind of mileage have people done with the xHP?
Am i right in thinking that setting in XHP for cars over 600nm?
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Alex_6n2
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Re: xHP Remap

Post by Alex_6n2 »

If you run MHD or BM3 with the right settings the software deliberately calculates torque wrong (if you select "remove torque limits" in the map settings) so that the ZF8 control unit doesn't ask for a boost reduction when torque limits are breached

This gets round loss of power in 3rd/6th, however from what I've read the line pressure (and hence clamping force) in the gearbox is calculated as a product of the engine torque calculations. This makes sense.

So if you're running an MHD map with the torque limits "off" your gearbox actually just thinks you're engine is outputting less torque and calculates the wrong line pressure.

XHP say this can create microslip in the clutch. Not sure how true this is.

But then you have to remember ZF have imposed torque limits in those gears for a reason. ZF845 is probably OK to 550NM, but it's still beyond spec by nearly 25%
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