Is there a diffrence between a 89 928S4 and a 87 928 S4 engine?
Or is it a straight swap?

 

Not sure about plugs because the '89 engine would have electronics that drive the digital dash, vs the 87/88 cars are full analog dash. I am sure someone has done it at some point and will chime in, but mechanically they should be the same anyway. Always comes down to the crazy electronics in cars it seems.

 

Slight differences in piston and rod, but it is a straight swap. May be some other very minor changes that won't affect the swap.

 

Doc, how are the sensor plug ins? All common between those? I would think it is just what they drive on the other end (digital dash or analog sensor device) that is different but same plugs and harness anyway...

 

The actual engine (think longblock) should swap straight across.....the harness might be different since the 89 has digital dash and I think the exhaust temp monitoring? 89's also had the thicker head castings....

 

As far as the LH harness part #'s go, '87-88 are the same, '89, '90, '91-'93 and '94-95 are all different.


The exhaust temp sensors were added to cylinders 4+8 in 89-90, and 3+7 from 91+. I assume the 94-95 change is for the dynamic kickdown stuff.

Not sure why 89 and 90 are different.

 

Big change in the heads also, they went to the thick boss heads by 89, which is a good thing.

 

The hardware on the motors is mostly the same except for the EGTs has has been mentioned. The harnesses are not plug and play between the two motors. '89 has the IMS relay connection on the LH harness, plus the EGTs. The plug and sender for the Temp-I is different. The oil pressure sender and connector is different too IIRC.

The rear fuel connection is different between early '87s and '89 at the fuel cooler on the fire wall. If it's an early '87 you'll have to mix and match parts to make it work.

 

You guys are GOOD.

 

I think the OP want to make sure the block are interchangable. They are. As long as the harness in the car is in tact, you shouldn't have any issues. They only thing you need to be aware of is the 89 will have Ehaust Gas Temp sensors (one for each side). The '87 does not use these. So if you're putting a '89 into an '87, no worries. But if the '87 is going into the '89, then you need to pull the EGT sensors and put them on the '87. Simple swap - no issues. Everything else is effectively the same.

 

The 89 up implemented a safe drive home mode. The exhaust monitors connect to the relay on the control panel. When sensing a difference the relay shuts down the gas to one bank of the engine. This allows you to drive the car home or to the shop safely. The 85-88 did not have this fail safe mode. When they shut down one bank due to a bad coil wire for an example. This means raw gas is continually dumped into a very hot and unhappy car. Drive too long and the car can catch on fire.

This is a good upgrade to make if you are upgrading to a newer engine.

 

Small clarification: the relay shuts down the gas to 1-4-6-7 or 2-3-5-8.

 

The Ignition Monitoring System kills the injection on four cylinders so the cats don't overheat and set the car on fire. It is NOT a "keep driving until it is convenient to do something" system. Driving on four cylinders can break the driveshaft, among other things...

 

Thanks Guys, U Guys are good.

 

And retrofitted to 3+7 to 89-90 as of 91.

Basically the difference is, the 89 rules