810maxima

Sorry to post a link to a thread but I posted in General Discussions and maybe should have been here. Had a question specific to the L24E. Thanks.

https://maxima.org/forums/general-ma...der-bores.html

gen1

Yes. The stock L24E block has the cylinders notched on the exhaust valve side of each cylinder. Uses a maxima version of the N47 head.

Check the cylinder bore in the specs compared to stock L28. I wouldn't think that the L28 block would need the notches.

810maxima

Thanks for the reply. Yes, I think the bore for the L28 will handle it, some people think the bore for the 240Z L24 will too. One of the reasons I posted. Maybe Nissan was unshrouding the valve for better flow.

Are you in the States? Apparently Nissan did different things for US versus Non-US models.

The odd thing is that the 260Z L26 cylinder head has the same valve sizes, with the L24 bore size in the block, but the bores aren't notched. Of course, the cylinder head combustion chamber is a different design.

Thanks again. This is one of those weird things that pops up with little discussion about it. The notches I've seen pictures of from Europe and Australia are pretty deep.

810maxima

Just discovered that some or all of the L26's used in the 260Z's also had notched bores. They have the same valve sizes as the L24E head.

Not really sure why Nissan notched the bores but it seems clear that it was a factory operation.

Thanks again for the reply.

CMax03

iTrader: (3)

pickup this book it's a priceless tool for any ole school Nissan L-series engine enthusist:

810maxima

Thanks for the suggestion. I do have that book, along with Monroe's How To Rebuild and Wick's Restore books.

I've seen the section in the Modify book about how one must notch the bores for unshrouding to get more power. But his comment is about modifying factory issue bores. My question was about what Nissan did to the stock bores at the factory.

I was just looking for confirmation that Nissan did notch the bores on the L24E. It looks like they did, along with all or some of the L26 bores. If they did it for unshrouding the valves, they did a pretty crude job of it. Flow-wise, the straight edges of the notch will create turbulence and could be better. But, maybe turbulence is good for what Nissan wanted. Or maybe the effect they got was good enough.

I appreciate the reference. It was pretty close.