8HP Journey

[P Bateman]

I've reached a crossroad with my car where I'm considering building a forged engine and swapping out the little single turbo for a pair of decent twins.
The A340 would not handle this very well - as it's already starting to slip under heavy throttle and boost.
Rebuilding an A340 to handle 500-600 horsepower is not a cheap exercise and, even with all the fruit, it's still just an A340.

For similar money to the engine rebuilt, I have the option of swapping out the A340 for a ZF 8HP70 transmission. For those that don't know, there are many benefits to this - it can handle a significant engine power, has 8x ratios that give better torque multiplication and top speed, has numerous programmable modes - including launch control, transbrake and clutch simulation.

Doing this conversion will solve the transmission strength issues and give better usability of the power I have - so a decision has been made and I have a transmission and conversion kit enroute. Yes, increasing horsepower would be fun, but you kinda get this for free with the 8HP.
Currently, with 400hp at the wheels, the gear ratio multiplication equates to a theoretical:



Further to this, with each gear change, there is way less RPM drop, keeping the engine on song



So, the shopping list so far is:

• 8HP70 (RWD) transmission
• Turbolamik TCU + Wiring Harness
• 1UZ engine and flex plate adapter kit
• 8HP output flange to Hardy Spicer 1350 adapter
• AN fitting Oil cooler adapter

Additional to this, I will need to purchase a shifter, fabricate my own transmission mount and cross member, make some oil cooling lines, and have the tailshaft lengthened/shortened to suit. Maybe some flappy paddles too but this will all come with time.

The icing on this cake is that the chosen transmission control unit integrates well with the Haltech Elite. Furthermore, I can reclaim a number of I/O connections on the Haltech and repurpose them to run drive-by-wire throttle. This also means that cruise control is now possible too.

Updates and photos will come with each step of the conversion.

PB

 

[P Bateman]

The installation hardware arrived today, and pictures don't do this stuff justice.
The quality is exceptional and it's a shame it will be sandwiched between the engine and gearbox, out of sight.

 

[Lextreme]

That's a work of art!

 

[P Bateman]

Been doing a lot of planning and research in preparation for the install and I have to say this transmission, Turbolamik ECU and TunerPro software are impressive. The internals are built for purpose, and I can see why its rated at 700Nm. No brake bands or one-way clutches to burn up, at least 5 friction plates in each clutch and large bearings. I don't plan to push this gearbox to the limit and it's good to know its capable of addling more than I'm throwing at it.

The transmission itself has 3 internal sensors (Oil Temp, Input speed and Output speed) and, besides input from the Brake Pedal and Shifter, the only other inputs required for basic ECU operation is for the torque calculation. This can come from an aftermarket engine management system via CAN, or you can wire in your own RPM, MAP and TPS signals. It's entirely possible to run this transmission behind a carburetted engine with points ignition if you wanted to.

Shifters can be as simple as a 2-way rocker switch, or there are some stunning billet & carbon fibre shifters out there for megabucks. Most BMW CAN-based shifters are native to the software, and the harness is pre-wired for the OEM connector. I've gone with a 7-Series unit out of a wreck that will fit nicely into the console and won't look out of place.


(Photo from Youtube: Pazi88)

The number of settings and adjustments you can make in the TunerPro software are extensive and it gives you an appreciation for the work that OEMs put into making their cars perform so well. I've got both the Haltech and Turbolamik software talking to each other, and tonight I've wired up all the additional I/O in the harness.

The Haltech can take an additional 4x outputs from the Turbolamik via CAN so I've set it up for oil temp, neutral signal (for the starter inhibitor), shift program and transbrake active. Vehicle speed, gear position, torque reduction and auto blip are all hardwired, as the CAN speed is relatively slow.

To get the auto blip working, I need to install a drive-by-wire throttle too - but now that the Haltech is no longer controlling the A340 solenoids, I have enough free connections to get this working. There are several other connections that need to be juggled so there is a bit of re-wiring to be done. I'm looking forward to having cruise control in this thing too.

There system is capable of running paddle shift and a simulated clutch pedal, but this will come later. I have put the wiring in, but the focus is getting it installed and running first before going down that path.

The next job involves removing the mechatronics unit and cutting out the factory ECU (inside the transmission) with a die grinder. With that out of the way, a bridging circuit board is soldered into place and the whole thing reassembled, ready for test fitting.