Engine Replacement Advice

[Smallblock454]

Hello Carlos,

if your car is an AT car, it's easier to use an AT engine, because if you buy an MT engine some things have to be replaced and transferred from the AT to the MT engine. But it's no rocket science.

If you're talking about 2003 i don't know if it's a 252 or a 260 HP engine.

Over here in Germany the 2003 986S cars had the 260 HP engine.

The 2003 / 2004 engines (228 / 260 HP / 266 HP) have a much better adjustment system for the camshafts that works without chain ramps. I would prefer these engines in general.

The later engines from 987 cars won't fit without ECU and other adaptions. What can fit is an engine from a 987S 280 3.2 car. But these are rare and were only built in 2005 (think it's the 2006 US model).

The later on 987 3.4 engines have a different IMSB that can't be changed without disassembling the engine.

AT engines can't be overreved that easy, because the AT electronic prevents that. MT engines can be overreved easily. Overreving can cause problems. Maybe that is why the workshop has asked for an AT engine.

In general all types of M96 986 engines can be used, but if you don't use exactly the same engine type you have to adapt wiring harness, ECU and / or ECU / TCU software… Emissions can also be a problem.

Easiest to install is to use the exact same engine that was used in your car.

Because the engine is toast, just think of other options like B4, V6 or V8 engines. OK, maybe this is not the easy way, but to me personally this would be a nice challenge. Over here in Germany it's very very complicated to do these kind of conversions because of law regulations. But in the US it seems to be much easier to get it street legal.

Regards, Markus

[jsceash]

I've done most of this so here is what I found.

I run a 2003 Boxster that has a 2004 Boxster S motor from an auto trans. 2 cooling hoses needed swapped, 1 t vacuum connector was transferred. I used the original 2003 harness. You will need to transfer the harness. Your harness will stay with your car.

If you decide to use a 2005 or 2006 motor it will work. Again you will need to keep your cooling hose T's your wiring harness and the vacuum T that connects to the transmission. The driver side head bank 2 cylinders 4,5,6 has a different scavenge pump. Take it out and use yours if it is OK.

The flywheel or tourque converter bolt up the same the bolts are the only difference. The manual or automatic trans bolt the same and the bolts are the same.

[itsnotanova]

I wouldn't get hung up on if the used motor is an auto or manual. It's hardly any trouble switching everything over from one motor to the next. Heck I recommend replacing all the vacuum hoses while you have the engine out anyway.