which intake manifold has bigger runners?

[z_boi]

Ok. Im in the prosess of port matchin my intake manifold and was lookin at the runner inner diameters on my 280z's manifold. My friend has a 83 280zx and we've had his intake off b4. He compared it to a different manifold (not sure wat car it came from, maybe a maxima?) and his manifold had larger runners. Im not exactly sure of it but i tink it does. So i compared mine to the other manifold and it was the same size.

So my question is basicly, does the 280zx intake manifold have larger bore runners than the one on my 77 280z?

And another question is, does anyone know if it would be better to use the 280zx manifold because it has a different design? which design is better?

[z_boi]

ok, so i dont need to know n e more because i decided to just use mine.

Now im tryin to figure out wats the best way to port out and polish the runners. I want to at least polish it( smooth out the insides). Any suggestions?

[hls30.com]

There are a bunch of ways to smooth the casting. A coarse and properly sized wire brush on a flex-shaft will do a good bit of the work if you go slow enough, and have a strong enough motor driving it. Then follow that with normal grit wheels in smaller and smaller grits.

Sending it of to have it extrude honed will probably do the best job because the polishing is done in the direction of flow which also minimizes the turbulence of the features that are left by the process(read that "great job, big $").

Will

[Bleach]

FYI:

Datsun 810/Maxima: 1977-84 was a fuel injected L24

it would make sense that those manifolds might be slightly smaller diameter inside.

As far as I know all L28's have the same size runners in the manifold. The late 280ZX had the main "log" of the manifold neck down slightly near the back of the engine. I don't know if that hurts performance at all.

A little bit of turbulance is good for an intake. You want the air to pick up the mixture of fuel and dispurse it well. Even on head porting, it is always said to not polish the intake ports, just open them up. Port and polish only the exhaust ports.