I understand that the brains make a big difference (i.e., headache) when doing an enqine swap from one year 928 to another....but are there ANY straight across engine changes that can be made without having to change all the wiring and brains? What about an engine/brain change without messing with the wiring, it that possible? Or are we better off sticking to the same model year engine that came with our cars?

Harvey
928S

 

The US brains, sensors, motors, etc 981-84 are the same. Except that the 83-84 have more displacement.

All of the 78-79 are the same.

The Euro 78-83, including the S are apperently bolt in, excepting the exauste. They also don't use a computer so other than upgradeing the fuel pumps, and exauste, they will just about drop into the US cars up to 84.

 

Porsche made many changes in the 928 over the 1977 - 1995 production span. Some were major changes made at model year changes, some were more subtle and were made "when ever they deemed it necessary." It takes a lot of digging to understand the changes and how they may effect body wiring. Some changes may not have been documented at all!

US model year (MY) 80 - 84 shared the same L-Jetronic injection system. However, per Pet 5, MY 80 - 82 share the same L-Jet brain (928.618.106.01) and MY 83 - 84 are a different P/N (928.618.106.04). The MAF for 80 - 81 are the same (928.606.121.01), but there is a different P/N for MY 82 – 84 (928.606.121.02). So even changing from a 4.5 to 4.7-liter motor (not much to gain from that) would require changing the electronics.

The US MY 85 - 86 went a 32-valve engine and moved to LH injection, 25 pin units. A 25 pin EZF spark digital controller (with vacuum connection) was added. The L and LH-Jetronic fuel injection controllers are completely different and are not interchangeable.

The S4 and newer cars use 35-pin LH and EZK spark control (with knock detect). There are different versions of both modules that accommodate calibration changes for specific models and model years, improved diagnostics, etc. So even if all the modules have the same number of pins, you should ensure that replacement modules have the proper calibration for your MY 928.

Euro engines are also different. CIS was retained through until MY 83. For MY 84 – 86, the LH and EZF modules are 25-pin but have different calibration and no lambda input.

In conclusion, to swap later "generation" engines into earlier model 928s, all these electronic items (and many more mechanical items) must be taken into consideration. My suggestion, buy the year 928 you can afford and LIVE WITH IT or be prepared to undertake a MAJOR endeavor!

 

928.618.106.04 L-Jet brain supercedes the (80?) 81-84 brain. Same with the AFM.

I understand you can swap the bottom end of a 5.0 L 85-86 into the 16V cars for more grunt.

 

Incorrect,

The 1980 car has the special L-jet brain. The 1981-84 L-jet brains are the same.

1980's control brain is 928 618 106 01
1981-84 928 618 106 01

I belive this is because of the location of the air injecton port ahead of the cat, but I'm not 100% sure.