Diamond port headers on square port head...

[Mycarispurty]

Good idea? Yay or nay. I think I recall in my years of being into Zs, a thread on Zcar I think a long while back how it was no big deal putting round ports on squares, and vice versa. However that's been years ago and my mind may be a little foggy and may be recalling it wrong. Anyone with experience care to expound on diamonds on squares? The used header is only $50, so might be worth it, but I don't know.

[ozconnection]

Round port head to round port header= good.

 

Round port head to square port header= good.

 

Square port head to square port header= good.

 

Square port head to round port header= not so good, but maybe saying its 'bad' is not entirely correct either.

 

From my experiences, this is how it is!

 

Cheers.

[dirty white boy]

i'm about to do the same thing (i think).

 

round port head to square header.

 

which gasket should i use? round or square?

 

thanks

[johnc]

Here's a thought... buy the right header!

[Mycarispurty]

I didn't buy the wrong header. There is a person with 1 used that I'm picking a motor up from, and figured if it fit then I'd pick it up.

[ozconnection]

i'm about to do the same thing (i think).

 

round port head to square header.

 

which gasket should i use? round or square?

 

thanks

 

Here in Australia, we never got round port heads until late......on some of our EFI R30 Skylines we got the N47 round port head. But as a consequence of their late arrival and very limited demand, round port headers were never offered here.

 

When I bought one of those heads and used it on an L28 I had, I had no option but to use the square port gasket. Round port gaskets didn't exist then either down here. (What Nissan would sell you would be a gasket with the exhaust ports cut out and the sides angled, a bit like a diamond shape.) The square port gasket worked well and didn't leak at all.

 

There is talk about a phenomenon called 'anti-reversion' and some guys actually build headers to take advantage of this. I think that by using a square header on a round port head can mimic this. I have no hard evidence for you but the theory seems to hold up when you look at the parts. It certainly didn't drop any power when I used this setup.

 

Cheers.