Cracked cylinder head getting repaired & improved

[jaekormtb]

Back in May I found the dreaded oil-in-coolant, followed by coolant-in oil. I got the engine out of the car and the heads off, and away they went to Len Hoffman in Georgia. He confirmed yesterday that I've got a crack in the 1-3 head. He's doing the repair along  with some other maintenance items and port/polish. The lifters and fuel injectors are also away for service. I'm aiming to have my 996 back on the road in the spring, running better than brand new with a bit more umph from the head work. Anyone else had work like this done? Just wondering what to be looking forward to.

[JFP in PA]

You need to tread carefully when modifying the ports on these heads.  Cleaning up and port matching is always useful, but beyond that is the realm that requires considerable experience, expertise, and some significant equipment, like a cylinder head  flow bench.  When most people think of head porting, they envision enlarging the ports and runners, and then buffing them to a mirror like finish; only problem is that bigger is not always better in this area, and quite often the best final runner finish is somewhat textured.  Unfortunately, the only way to determine what is optimum is to basically ruin a set or two of heads testing various configurations and then verifying the actual flow improvement on the flow bench at various cam lifts to determine what is going to allow the heads to move the most air.  Along the way, this process will also identify when the modifications have gone "over center" and the flow performance starts to drop off, which would require welding up the heads and starting over.  Once the desired combination is identified, its technical specs are then fed to a CNC machine so that the profile can be reproduced accurately on customer's heads whenever it is needed.

 

I know Len's shop has done a lot of work in this area on air cooled engines, so I would suspect he also has some background with the water cooled as well.

[Randy Remington]

Your in good hands with Len. He did my heads last year due to a 1-3 crack. I can't tell you about the added umph just from the head work since I also sent my cases LN Engineering to go from the 3.4 to 3.8. But I can tell you he thinks the 996 heads are almost piece of art and only does minor grinds. You'll see no smooth, polished ports. Porsche's like turbulent air. Hope you have fun with your build.

[jaekormtb]

Wow, bump to 3.8! what kind of increase did that deliver?? 

[Kim]

I had the dreaded intermix due to a cracked head. Jake Raby did the repairs for me, and I've been very happy with the results.

[jaekormtb]

Got my heads back from Hoffman automotive yesterday. Wow, they look great! Unfortunately, there are a lot of "while you've got it apart" items that I want to tackle, so it may be spring 2017 before she's on the road again. I'll keep posting here as things come together. 

[Ahsai]

Len rocks! I He's THE M96/97 head specialist in the US!