Is this as unusual as I think it to be?

[humbucker]

I'm about to put the proverbial pen to paper and write about a car equipped with a heavily tuned C20NE block mated to a Z20LET cylinder head. That's a new one on me!

[James McGrath]

Well they are both family II engines so I suppose it was always possible.
Probably would have been more sensible to start with the Z20LET in the first place though.

[Envoy CDX]

Don't see why not if they are the same sort of size. I've seen people using 8v blocks for c20XE and c20let's builds with some mods.

[Robsey]

Judging by that comment Gary,

Z-Let should only be a more advanced electronically controlled version of a C-Let.

So Yup, why not..?

[humbucker]

I think the SEH, NE, XE, LET blocks share the same casting, it's just the internals (crank, rods, pistons etc.) that are different. The guy's rationale for using a Z20LET head when switching to 16-valve power was that there are a lot of them about, whereas XE and C20LET heads are getting a bit long in the tooth now, and he needs reliability for drag racing.

800bhp of Family II joy!

[humbucker]

Probably would have been more sensible to start with the Z20LET in the first place though.

I think I'm right in saying that the Z20LET/LEH blocks are weaker than their predecessors due to wider open waterways that are designed to help cooling. Effectively, this reduces the thickness of the casting, making them prone to cracking under pressure. It is this that has resulted in almost every LEH feature car that I've written about being equipped with wedges/inserts in the waterways that are intended to prevent catastrophe. The downside to this measure is that the wedges then put additional pressure on the cylinders. This is probably a moot point on engines of less than 800bhp(!), but I can see why the stronger eight-valve block was appealing when pulling together this particular engine. Interesting stuff.