R&R 944na

[Cocacolakidd]

Hello All,
I have been a Porsche (H2O cool) for the past 25 years. I traded my old 924na for a new 924Turbo back in the day, wow did it go. Mostly now I have been driving the 944's. I now own a 85.5 944na that I'm about to R&R the motor (that's a start, other upgrades also). My question now is whether I can go with a 3 liter crank, and boring on the 2.5 liter block - Or to go with a complete 3 liter motor. Keep in mind that all internals will be forged (crank, rods, and pistons on the 2.5 or the 3). Also I intend to add a supercharger to the soup (8:1 forged pistons, etc.). I'm hoping to get away with a Turbo brain to control this setup. I would love to be able to stick with my original block, but all new internals, head (lots of work done), new & better manifold, high profile cam - etc., etc.

Any advise on crank to use, rods, etc.

Thanks guys, Ed. (AKA: Cocacolakidd)

[JivenJim]

You can do any of above. Since it sounds like you beefed up internals maybe the Supercharger Kit would be the easiest way to get some extra Pony's. Topics been done alot so if you search on any of these topics in this forum, you will finds lots of long threads.

[Cocacolakidd]

Thanks for the info. I will continue to search for other threads on R&R'ing the motor...Good to hear that the 3 liter crank will fit my 2.5 na block. Now to do more searches to find specs on the rod length, piston size, etc.

Again thanks, Ed.

[Cocacolakidd]

Hello,

Well after doing more research I'm finding that a complete 3Liter motor will be less work, and about the same amount of cost as rebuilding a 2.5 Liter to be a 3 Liter. So this part of a project somewhat evens out. What I am finding out though is, it's going to be real hard to beat the dual over head cam, and thus 4 valves per cylinder of the 3 liter head. True the valves are smaller (Not by much though), but when two intake valves are added it's much more valve area available. Even by reworking a 2.5 Liter head for it's greatest flow (i.e. bigger valves, full porting, bowl matching, enlarging, and polishing exhaust runners). If one does the same to a 3 Liter head, the air flow is far, far above the 2.5 Liter head. So even though I would have loved to have kept the 2.5 Liter motor looking stock/OEM from the outside, it looks as if the 3 Liter Head wins out.

I'm somewhat of a Porsche purist, otherwise the cheapest cost, and most horsepower is won by the Renegade Hybrid kit. Thus with a 6.6 Liter all alloy Chevy motor would put this little 944 in orbit. That does not sound as much fun to me though, and then it's not a pure Porsche either.

I wish I would have started to search , and read all of the threads available a year ago. Thus I would have many answers to what are the pitfalls and weaknesses of the DOHC, and 4 Valves.

I certainly do appreciate all of the information I have found, and replies given on this board.

Thanks, Ed.