Are all 2.5 engines the same? I am looking to purchase a good used engine for a 1988 944 I recently purchased with a rod knock. Wondering if all model years are inter changable -thanks

 

Not all 2.5 engines are the same...

There are 8v (NA and turbo) and then 16v 944S motors.

The NA 8v engines have minute differences, but as far as swapping goes, they're basically interchangeable. If you were to throw in a 16v engine you would have some wiring work to do (different Motronic setup) but mechanically it all bolts up.

 

This is the standard 16V engine. The original engine has a bad rod knock , and I was going to pull oil pan and take a look , but I do think its has damaged crank,

 

sorry I meant to type 8V

 

Luckily 8v cranks are easy to get for cheap (< $100). A good-to-go entire engine is around $500-1000 average for an NA 8v, depending on location and condition.

You should measure the crank, they're pretty tough and maybe it's still in spec.

 

yes I plan to check it first. I do also have a '84 engine that I have had a couple years that broke a timing belt - I took head off and #1 cyl has a couple score marks, but I am pretty sure crank is fine, would it be better to just rebuild this knocking engine?

 

The '88 actually had higher compression than previous years, so you will lose a few horsepower if you go with an earlier engine. They only thing unique about it is the pistons, so at least save those if you decide to scrap the engine. If you are really lucky they will be the correct tolerance group and you can put them in the '84 engine.

 

The NA engines are all "interchangeable", but there are slight difference in the year ranges, including cylinder wall thickness, forged vs cast connecting rods, oil pan size and oil capacity, windage covers on balance shafts, timing belt tensioners, and, as noted before the '88 has slightly higher compression (different pistons). There are also difference with the DMEs and AFMs which help the later engines make a little more power.

an '89 engine is a 2.7, due to a larger bore and has a different head. But, it is also compatible with all of the mounting points and will bolt in.

 

So the higher compression in the '88 2.5 is due to piston shape AND crankshaft? Also are all 2.5 rods cast and 2.5 turbo's forged?

 

The '88's higher compression is due to piston only. '83 and some '84 cranks were cross drilled - all the rest are the same.

Early NAs had forged rods, the rest of the NAs have cast rods, the turbos have forged rods - all interchangeable.

 

Thanks for all the info!!, sounds like i should just rebuild this one, unless I find a reasonable '88 engine in good shape.

 

...also some 1989 model TURBO cars (250hp models) were given regular cast rods...Porsche was trying to cut costs and use up what was on the shelf by then.

 

Interesting!

 

If your interested, I have an 87 2.5 with 91k miles that is complete for $600, comes with fuel rail, injectors, intake, belt covers, oil cooler, and engine mounts.

I can put it on a pallet if you want to arrange shipping.

 

Hi Fiily, that sounds like a good deal. I am having the car towed to my home this weekend and I want to pull the oil pan, and investigate what damage has been done first, probably be a few weeks, but if I need a engine, I would be interested. Do you have any idea what shipping might be? my zip is 28204 - thanks!