NC1 vs NC2 Engine advice

Technical Area Engine, Transmission, Exhaust etc
1

Hi you mx5 lunatics

I’m in the process of acquiring parts to rebuild my NC1 2.0. I have been toying with the idea of trying and upgrade the internals of the NC1 with parts from the NC2. I have done some research, and I found that you can’t just replace the pistons with the NC2 version, but you will have to have the NC2 crank as well. Looking on the parts diagram, cranks and pistons are different part numbers. Will I get away with buying the crank and pistons or is it worth buying a used NC2 engine? I will be rebuilding that too, but from a cost prospective, what would you do? A used NC2 engine is over £1000, and the pistons and crank + all of the other bits is about £1500.

My goal? I think 250+ hp with a supercharger. I had my NC1 for 6 years now and I have slowly upgrade things on it, engine is bone stock and drinking oil. I will be slowly building up to that power figure, but since I’ll have my engine apart, I want to do it right.

What would you do?

2

You can change pistons & rods in the NC1 motor to the later NC2 ones.

NC1 has heat fitted wrist pins ( the rod and piston need to be purchased as an assembly )

NC2 has floating wrist pins retained by circlips ( you can buy rods and pistons separately )

Some of the engine reconditioners fit the NC2 rods and pistons in to the NC1 engine.

However - if your quest is big power - the NC2 engine has a forged crank and forged rods to make the bottom end stronger.

When you consider that a forged crank is appx £900
NC2 rods are appx £125 each
NC2 pistons are appx £90 each

Starting your refurb with an NC2 motors it probably more cost effective.

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3

Take you NC1 engine out, take it apart and work out why it was using oil. If its just the piston rings and all is within spec, then rebuild it.

Put your supercharger on it and enjoy. If you happen to blow it up (unlikely at those power numbers), then you can put a different engine in.

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4

There is some discussion with the engine guy for the MX that says the reason the forged stuff was included in the NC2 and on was about smoothing the engine: not that the NC1 was weak. Sure, forged stuff is more cool and may be stronger but are you the guy to break the NC1?

5

I thought the general consensus is that a good solid and well maintained engine will withstand 250hp no problems whatsoever. People like bbr, flying miata and fab9 all offer bolt on kits with no internal work required. I went with a late model as I intend to turbo the car eventually and the forged bottom end and the fact that it’s newer with lower mileage all added up to a good starting point.

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