NA8 or NB8A: which manifold would you use?

madjak · Postby **madjak** » Wed Aug 10, 2016 2:17 pm

You could get a NA8 manifold extrusion honed. I've heard to brings up the peformance significantly. I have no idea how much it costs though... I'm guessing not cheap.

If its for a street car then use whatever you have and be happy. The stock NA8 manifold was good enough for 180whp for me. The Honda manifold picked up lots of upper midrange power which tells me the larger runners removed a decent airflow restriction. Running them on a 140whp engine I doubt the difference would be as much.

If you really want a flat top I can mill the top off my spare NA8 manifold for you. Could even make a small indent so the spanners can't fall off.

mx5002 · Postby **mx5002** » Wed Aug 10, 2016 10:49 pm

Sent you a pm Manga.

manga_blue · Postby **manga_blue** » Fri Aug 12, 2016 12:40 am

NA8 inlet manifold adaptor plate fastened and port matched to NB8A head. No going back now ...

Postby **orx626** » Sat Aug 13, 2016 9:48 pm

This is one I did a few years ago.

manga_blue · Postby **manga_blue** » Sat Aug 13, 2016 10:01 pm

It looks beautiful, Danny - almost too good to be hidden under the flanges - and a better design than the one I used.. How did it perform with an NA8 manifold?

Postby **orx626** » Sat Aug 13, 2016 10:15 pm

manga_blue wrote:It looks beautiful, Danny - almost too good to be hidden under the flanges - and a better design than the one I used.. How did it perform with an NA8 manifold?

It released a few more ponies in the top end on both a standard and modified NB8A BP engine.

manga_blue · Postby **manga_blue** » Sat Aug 13, 2016 10:30 pm

That's good to know, thanks. PM me if you've got a fuel rail for that.

Postby **orx626** » Sat Aug 13, 2016 10:34 pm

manga_blue wrote:That's good to know, thanks. PM me if you've got a fuel rail for that.

Standard fuel rail was used.

manga_blue · Postby **manga_blue** » Sat Aug 13, 2016 10:57 pm

I have a standard NA8 rail. It won't fit. They changed the positions of the 3 rail mounts on the heads relative to where the injector tops need to sit. NB8A mounts sit 1.5mm lower and 9.9mm further out to the right than they did on an NA8 - basically a long way out. It requires an NB8A rail (as your pic shows), or maybe alternatively an NB8B.

Postby **orx626** » Sat Aug 13, 2016 11:00 pm

manga_blue wrote:I have a standard NA8 rail. It won't fit. They changed the positions of the 3 rail mounts on the heads relative to where the injector tops need to sit. NB8A mounts sit 1.5mm lower and 9.9mm further out to the right than they did on an NA8 - basically a long way out. It requires an NB8A rail, or maybe also an NB8B.

Yes, you'll need an NB8A fuel rail.