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Discussion Starter #1
I think I may have found a plausable head swap for the Nord engine. The Miata head (I used a 1.8L but I believe that the 1.6 is the same size) is very close size wise.

Length wise the head studs are perfectly spaced compared to the Alfa, and width wise, they seem to be about 1mm closer. I think drilling the holes in the Miata head 1mm oversize might do the trick. It was so close I was able to slide the Miata head 1/2 of the way down the Alfa studs before It became stuck. When I relive the head gasket to fit on the Alfa block I will know how the combustion chambers match up.

The cooling passages match up fairly well, some reliving of the Alfa block would provide better flow.

The pressure oil passages are way off, and I would just plug them on both the block and head, and run external hoses.

The only one that posses a threat are the drain back passages. They are the circular holes on the passanger side of the head gasket that are paired with the head bolt holes (in the picture the front of the gasket is to the right). You may be able to plug the holes in the head and run some external hoses to the drain back passages at the ends of the block or the oil pan directly, This part requires more thought. I believe Huyandi uses a BP Mazda based engine with a head that can fit a Miata with drasticly different drain back, this could be a better alternative.

The Miata uses a 83.5mm bore to the Alfa's 84, Miata pistons are commonly available in 84 and 84.5mm oversizes. They have a smaller pin, so a small ID bushing could be fitted to the Alfa rod, as far a piston height, I have no clue, that will need to be looked into, worst case scenario, custom pistons. There are two different compression heights for Miata pistons from the factory.

I have not compared these parts closely yet so these are just ideas, but a Miata crank pulley could be fitted to the Alfa crank, but this may hamper the distrbutor and oil pump drives. Alfa cam sprockets could be fitted to the Miata cams. In either case you will need to cover the front part of the head as it is not covered as the Alfa, and a tensioner will be needed.

I do not know if I am going to be able to pursue this swap, but I thought I would share what I have found so far.

A great resource on Miata heads can be found here:
http://members.aol.com/solomiata/MX5Engine.html

From his site is this:
http://members.aol.com/solomiata2/BPHeadCompare.jpg
A cutaway of two different Miata heads, both fit the same except intake manifolds, and both are 4 valve heads. It is obvious they are much better than the Nord or Twin Spark.

If anyone wants to colaborate on investigating this, I am willing.
 

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how are you going to address the difference between a timing chain and a timing belt?
 

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Hi!
If you are going to do all that reengineering work to get a belt driven engine, I think would be easy to go the Pedrazzani Brothers way.... they developed a Formula3 TS engine belt driven....

Anyway, its an amazing project!!!

Best regards
 

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Other then going where no man has gone before (reason enough) what would be the benifits of doing such a swap?

Increased HP?

Cheaper performance parts?
 

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Discussion Starter #9
Increased power pretty much. The larger displacement of the alfa engine combined with the 4 valve head of the miata, miatas are commonly stroked to alfa-like dimensions. Yes it would be easy to swap a miata engine into an alfa, especially since it is front engine rear wheel drive (might be shifter issues), I would argue that the alfa block, and probably transmission are lighter than a miata's. The next logical step is why not use a better all aluminium engine like a ecotec, duratec, or honda s2000.

For the cam drives I would use a miata crank pulley on the alfa crank or alfa cam cogs on the miata cams.

Honestly, I do not have much time to chase after this, and was hoping someone way want to follow through with the idea. I may take the unassembled engine I have an fit the pulleys or cogs and work with the oil drain back system, but I am not sure I am even going to have an alfa romeo car to try it out in when it is done.

As far as the F3 belt drive, id rather have the required parts down to a pair of keyed bushing for the miata cams or something along that line. Imagine if all it took to make the engine work was a front guard for the head, a new timing chain (might even be able to reuse alfa's) a pair of keyed bushings, small end rod bushings, some hose, drill bits, and two pipe taps. Everything else would be mazda or alfa made.

Maybe I will modify one block and head as a proof, and then sell it off to someone who can run it.
 

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Discussion Starter #10
I can not say that the idea was not sparked by me wanting to do something different, but that spark was a while ago, and I have only now laid my hands on a miata head. I also have a half done scratch built car and an unrelated shell of a high power 1.5L v6 vying for my attention (I can not wait to begin work on the V6, but I do not have the funds at this time).
 

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The Miata head looks pretty tall. How does that compare to the Nord and TS height?

Regards,
Lawrence
 

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Discussion Starter #14
how is this little project coming along?
It is happily sitting in my craw space waiting for time,money, and space to do it. The miata head was loaned to me (I need to get my own to do the slight modifications to). Once I have a decent shop, I can set up my dyno and maybe get the thing to run!
 

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so do the bores and the cylinder head line up right? looks like this could be a great avenue for some power! :)
 

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Discussion Starter #16
so do the bores and the cylinder head line up right? looks like this could be a great avenue for some power! :)
Yes, the only thing that does not match up perfectly is the oil pressure supply, oil drain, and cam drives, but they are not as hard as they sound.
 

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Discussion Starter #18
I have not done a thing. I have had some discussions with a few friends on different ways to cheaply modify cam drive systems, but that is about it. If anyone wants to give it a try I am up for telling them everything I have come up with so far, but I have not built anything. When there is time I may pick up where I left off, but there are many other things that are more important at the moment (like getting my formula vee ready and selling my spider).
 

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This is interesting :cool:. I did compare a Mazda BP head gasket with a FIAT 2ltr HG, but to no avail.
Don't the later model engines chain driven cams?
 
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