L20b withh z22 internals

[Kingcab]

I've red up on alot of different builds with these 2 motors. I have a l20b I'm running right now with 1mm over bore and a w58 stock head. I have 2 z22 motors sitting here one out of a 83 720 other one out of an 83 200sx. I was wondering if I could use the pistons cranks and rods for a build that would be worth it with any combination of what I have laying around. It's a daily driver/ drift motor so I'm looking for more horses and reliability but I'm not scared to tear into any of it 

[Hix1985]

I would use the Z22 motor and put the W58 head on that, also witch timing cover.  That would be more power  and easier then switching everything over.

[datzenmike]

You would have to measure to be sure absolutely sure but the later Z22 on the 200zx has longer 149.5mm rods and shorter pin heights than the earlier 145.9mm ones. That's if you really care about rod/stroke ratios. All truck and 200sx rods up to December '81 build dates were the shorter variety.

 

I would look for a U67 head to avoid the round exhaust ports and the metal liners in them. I would take the valves out and cut the liners and remove them. A round port header will be hard to find I think, but a U67 will take the earlier square port L16/18 cast iron header. But either head will give you 9.84 if mounted on a Z22 block.

 

 

 

I would definitely mount a Z22 head gasket and mark the cylinder holes on the L head of choice, then grind away the metal where it's closest to the intake and exhaust. This opens opand removes the shrouding that reduces flow in these areas and improves breathing. This would work on the W58 as well. Make sure you don't make the opening larger that the gasket metal fire ring. It must remain completely pinched between the head and the block. You have lots of compression to play with so removal won't drop the compression excessively.... and you can always plane the head to assure levelness. I would also port the two runners to increase flow. After all you are pulling an extra 10% more air through them.

 

Here's what I did on my U67 head that's on my larger Z24 engine.

 

 

You will need the Z22 head gasket and compare to the L series one and open up any missing cooling passages. You can cut the front off the L series gasket and graft to the Z22 gasket  to match the L front timing cover.... but I mounted my L head on the Z24 timing cover and it covers well enough. I added a small fillet of JB weld on the corner of the cam opening below the fuel pump, just to be safe but it does seal. You can't use the front two bolts between the head and the timing cover but a little gasket sealer will do. After all it only seals in fumes and a bit of oil spray and nothing serious.

 

 

 You can relocate the Z22 dip stick to the starter side or simply check the oil when the engine is cold. ?

[Kingcab]

Why would I cut the metal liner on the w58 exactly? And what's the difference in the square ports vs round ports. 

[datzenmike]

The metal liners do not help the exhaust flow. It's debatable if it hinders, but if it's no help, common sense would say to loose them and grind away the bumps that hold them away from the walls.  The liners are thin steel with minimal contact with the ports that would transfer heat away. To do this there are several bumps in the wall to hold it out and away. This allows the steel to heat up glowing hot and help burn off unburned fuel. To make this happen air is pumped into the exhaust manifold through individual tubes for each port.. 

 

A 1.5" diameter circle fits inside a 1.5" square. The square ports are definitely larger than the round ones, specially with the liners in place. If you remove the liners it would be closer to the U67. You can run a square port header on a round port head but not recommended the other way around. 

 

Either head is going to be flowing 200cc more through it than it was designed for on the 2 liter engine, so every effort should be made to maximize the flow in and out.

 

 

I definitely would use a Z22 block rather than over boring the current L20B. Keep the L20B and use the W58 head or look for a U67.  If measured, and theZ22 bores are out of spec (tapered or oval) go to the largest over size piston and ring for the most displacement. If you can find a good set of KA24E (89mm) pistons they will fit and work on that truck Z22 and produce a 2.3 liter engine.