986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - Transmission Swap

Smallblock454 · 03-26-2016, 08:52 AM

Hi,

i dont't think the gear ratio is the main problem. 4.2 vs. 4.16 is not that significant. The main problem is the TCU software, because the shift process is managed by the electronic.

2.5 engine: 204 HP at 6.000 rpm / 245 Nm at 4.500 rpm
2.7 engine: 220 HP at 6.400 rpm / 260 Nm at 4.750 rpm
2.7 engine: 228 HP at 6.300 rpm / 260 Nm at 4.700 rpm

The question is if the 2.5 TCU is accepting the 2.7 AT gearbox. If yes, there won't be a bigger problem by gear ratio. But if not, than the 2.7 TCU won't fit to the 2.5 ECU, because rpms will be too high.

So for me this is not a mechanical topic, it's an electronic one.

Regards, Markus

03-26-2016, 08:52 AM	#11
Smallblock454 Registered User Join Date: Jun 2014 Location: LB, Germany Posts: 1,456	Hi, i dont't think the gear ratio is the main problem. 4.2 vs. 4.16 is not that significant. The main problem is the TCU software, because the shift process is managed by the electronic. 2.5 engine: 204 HP at 6.000 rpm / 245 Nm at 4.500 rpm 2.7 engine: 220 HP at 6.400 rpm / 260 Nm at 4.750 rpm 2.7 engine: 228 HP at 6.300 rpm / 260 Nm at 4.700 rpm The question is if the 2.5 TCU is accepting the 2.7 AT gearbox. If yes, there won't be a bigger problem by gear ratio. But if not, than the 2.7 TCU won't fit to the 2.5 ECU, because rpms will be too high. So for me this is not a mechanical topic, it's an electronic one. Regards, Markus