Anyone done this combo? I wonder if this would be a reliable way to go as I have heard that the bored 2.5L becomes unreliable. Would this combo yeild more performance than a 3L with the long stroke crank? Seems like it would because you would be able to rev. How about using a 2.7L block, are these better than the 2.5L? Anyone have any experience with the above?

 

Using a 3.0L block with 2.5L crank is the same as a 2.7L engine (MY89 944NA).
The 2.7L and 3.0L blocks (basically the same) are a great base for an engine. The problem is finding low compression pistons for turbocharging.

The 2.7L block will not make more HP/TQ than a 3.0L.

You can use a 2.7L NA head or modify the 951 or 944NA (2.5L) head to match the 3.0L block. The 3.0L block has a larger bore. Also the water inlet on the 3.0L does not match the one on the 2.5L head.

The 2.7L head works fine, just need to replace valves, springs with ones that are suitable for turbo application.

 

Can the 2.7L block be bored out to work with the new Mahle pistons that can be used in the 3L engine? If so then will it have the same reliability issues assosiated with boring out the 2.5?

 

The bore size of the 2.7L and 3.0L (stock blocks) is the same 104mm.

 

So this could be the solution to boring a 2.5L and not have the over bore problems which I dont know is a fact but have heard several times. I guess Rage will let us know.
Fast951, in your experience which route would you take. A 3L, a 2.7L bored out to? or a bored 2.5 to a 2.8L. This would be for a street/ track car.
I dont have the experience you do or some of the other guys on this list but think that keeping the stroke the same and going larger on the bore would let me get high RPM so better acceleration. In other words, at the end of the quartermile the bored motor would be ahead, not that this is a quartermile car but you know what I mean.