N54 8hp cut outs during upshifts

[Maksym]

Hi. Since ive swaped gearbox to 8hp I’m trying to adjust engine at wot and gearbox. After few fast up shifts at 70-100% pedal jb4 shows me failsafe overbost. Or If set higher than 80 boost reduction during shifts engine have problem to build fast boost.
I’m looking for a solution like is in n55 with 8hp
During up shifts there is a cutout and burble sound allowing gearbox to change gear without slip and strange behaviour. Is it possible to set some stuff in msd81 ?

 

[Boorda]

Hi. Since ive swaped gearbox to 8hp I’m trying to adjust engine at wot and gearbox. After few fast up shifts at 70-100% pedal jb4 shows me failsafe overbost. Or If set higher than 80 boost reduction during shifts engine have problem to build fast boost.
I’m looking for a solution like is in n55 with 8hp
During up shifts there is a cutout and burble sound allowing gearbox to change gear without slip and strange behaviour. Is it possible to set some stuff in msd81 ?

Just curious, what TCU controller route did you take, xHP flash, HTC, Turbolamik?

 

[Maksym]

Non from above. Ive use oem bmw tcu

 

[Boorda]

Non from above. Ive use oem bmw tcu

Interesting, I didn't know this was an option. Haven't looked into OEM TCU on 8HP for a bit but last time I did I remember it being locked.

Not to hijack your thread, but who, or how, were you able to get it unlocked? Or is this only an issue with newer 8HP gearboxes?
Mine is a 2016 - ZF8HP70X.

Sorry I don't have a real answer for your question, I'm going the Turbolamik route.

 

[SLOWESTN54]

Interesting, I didn't know this was an option. Haven't looked into OEM TCU on 8HP for a bit but last time I did I remember it being locked.

Not to hijack your thread, but who, or how, were you able to get it unlocked? Or is this only an issue with newer 8HP gearboxes?
Mine is a 2016 - ZF8HP70X.

Sorry I don't have a real answer for your question, I'm going the Turbolamik route.

I assume he's using CANTCU

 

[Maksym]

Unlocked you mean isn clear ?. It was only block that ive got during swap.

 

[Boorda]

Unlocked you mean isn clear ?. It was only block that ive got during swap.

What I mean is the TCU from my understanding is VIN Locked and there were issues with flashing it directly.
But like I said, it's been a while since I did any research on that and I'm sure someone has figured it all out by now.

 

[Maksym]

Yea. Propertool in my case mini acdp,3 min and tcu unlocked

 

[MR-KRAKA]

Yea. Propertool in my case mini acdp,3 min and tcu unlocked

Are you running xhp on it? I’m assuming you’re running a BEF for the JB4? You can PM me if you’d like I’ve been running CANTCU 8HP45X since beta and have a few things that can help. MSD81?

 

[SLOWESTN54]

Are you running xhp on it? I’m assuming you’re running a BEF for the JB4? You can PM me if you’d like I’ve been running CANTCU 8HP45X since beta and have a few things that can help. MSD81?

with that setup at what power level would the transmission start to slip

 

[MR-KRAKA]

with that setup at what power level would the transmission start to slip

I’m right around 600whp and 1000’s of pulls deep on this one I got used with 120k on it. The 8HP45 is nearly identical to the 8HP50 mechanically used in all the B58’s. I’m sure there’s much more documented about the limitations in that circle.

 

[Boorda]

with that setup at what power level would the transmission start to slip

Just to add to MR-KRAKA's response, torque is really what you need to pay attention to in regards to specking your limit on a transmission, not HP. The last two numbers of the transmission model indicate the manufacture's designed torque spec. You add a 0 (zero) to it and that's the torque designation in Newton-Meters. So, in the case of the ZF8HP45 (BMW Model Number GA8HP45) this would be 450Nm or 332 ft-lb. Keep in mind that this is not the actual limit rate, in the engineering would there is usually a 1.5x to 2.5x safety factor built in. That's why you see people pushing more torque than the designation and not blowing the gearbox up. But the wear on the transmission will defiantly happen faster as you pass the designed torque spec.

So here is a list of common 8HP swaps you can do for the N54, N55, and S55. Some require a little more work than others and-or additional components like an aftermarket TCU or adapter plate, so research what options are available. Controlling the 8HP is the biggest hurdle and there are a few routes to go, some with limitations.

I'll try to update the table as I come across additional info...

Gearbox	Rated Torque	Mating Engines	Notes
ZF8HP45	450 Nm (332 ft-lb)	N55
ZF8HP45X	450 Nm (332 ft-lb)	N55	AWD
ZF8HP50	500 Nm (369 ft-lb)	N55, B58	Gen 2 8HP (Supersedes the 45)
ZF8HP50X	500 Nm (369 ft-lb)	N55, B58	Gen 2 8HP (Supersedes the 45), AWD
ZF8HP51	510 Nm (376 ft-lb)	B58	Supra gearbox
ZF8HP70	700 Nm (516 ft-lb)	N57	Diesel gearbox, requires notching bell housing to clear starter
ZF8HP70X	700 Nm (516 ft-lb)	N57	Diesel gearbox, requires notching bell housing to clear starter, AWD
ZF8HP75X	750 Nm (553 ft-lb)	?	Not sure about this one, but it may be possible. Found on X5M I think.

Hope this is helpful.