Which intake manifold to use for turbo 1.8?
 

Hi, first post here. I have a '90 Miata that I picked up a few weeks ago. It's a ton of fun (+/- a few lbs.) but of course needs to be faster. I am in the process of planning a turbo setup for it.

So far I have accumulated a nearly complete 1.8 motor -- it's only missing the intake manifold, and a Megasquirt II. (I figured if I am going to the effort of building a turbo motor I might as well start with the 1.8. It was cheap and it came with a transmission which may come in handy...)

I am thinking that the VICS intake manifold from a 99 would be an interesting choice. I can control it with the MS2 easily enough. Any thoughts on the advantages of using the variable intake manifold with a turbo setup? This would be in conjunction with a 1996 head and block. Right now I am thinking of running at 1-1.5 bar boost, probably with stronger rods but stock pistons.

Thanks for any input pro or con.

The vertical port positions are different on a 96 vs 99 head and therefore you will need to either find a 99 head or weld a new flange on the VICS intake manifold to make it work.

99 head, and begi intake mani.

Ah, ok, didn't realize the 99 head was that much different. I guess I need to find one of those or just pick up a cheap 94-97 IM.

Will the later VVT heads bolt up to a '96 block? That might be interesting...

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Notice: This post complies with the OMG - READ THIS FAST (ORTF) Act of 08.

Yes. The heads themselves are all mechanically interchangeable across the 1.8 engine blocks, though the IM is slightly different between '99-'00 and '01+. Installing an early NB head onto an NA 1.8 block has been a very popular upgrade for quite some time, in fact.

Truthfully, if it were my car, I'd aim for a non-VVT NB head. At this point, VVT control via MS is purely theoretical, whereas VICS has been pretty well proven out. The '99-'00 head has essentially the same improved port geometry as the later VVT head, however from a control standpoint it'll be a simpler retrofit.