Hey folks, I've been doing some reading about various L-block engine heads (using this site as a resource), and I've just got a quick question for someone who wants to answer.

If I've read and understood this correctly, my '76 should have the N42 head (if it's as stock as I'm assuming it is), which means it has square exhaust ports, the same as the the P90(A) heads... so in theory, would that mean at some point down the road (forgive the pun) I could bolt on a ZX turbo exhaust without having to replace the N42 head?

Link me up if it's been done (that'd be great). :squareeye

I believe the N42 does have the square exhaust ports, and the N47 has the round exhaust ports with the exhaust liners.

If the ZX turbo exhaust has square ports (like the P90/P90A should have), then it should be a direct bolt up.

The turbo exaust leads to a turbo then a down pipe from the turbo. Unless you are looking at using an N42 for a turbo the exaust manifold/hearder from a ZX turbo is useless. If you are turboing then you should be o.k. with the N42. I know that people use the NA square port header on the P90 so in reverse it should work.

The turbo exaust leads to a turbo then a down pipe from the turbo. Unless you are looking at using an N42 for a turbo the exaust manifold/hearder from a ZX turbo is useless. If you are turboing then you should be o.k. with the N42. I know that people use the NA square port header on the P90 so in reverse it should work.

Actually yeah, that's what I was aiming at doing in the future (distant future probably): a turbo upgrade...

I also have a question about the N47 head... The Z-history timeline in my Haynes manual says that in 1977 "modifications" were made to the engine to increase total power to 170 hp, does this have anything to do with the N47 head vs. the N42?