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To get the most out of decent cams you would need to upgrade at least your fueling system, ie a fuel controller

These guys have been the best value so far and after several emails they are very knowledgeable. They produce each \"stage\" to the maximum that each is meant to achieve.

Prices are quite cheap when compared with the dozens of makers out there.

http://www.integralcams.com/

Anyone who suggests that HKS264deg cams will not work on a stock NA6 without ECU augmentation is speaking rubbish.

You do not need to adjust your fuelling when you fit camshafts, and you will get a gain on otherwise stock engines.

BUT

You will get better gains if you have made other changes to the engine. The changes commonly include improved intake, extractors/exhaust, improved pistons, head porting, and may go as far as ECU augmentation although on an NA6 without turbo that is usually to REMOVE fuel and advance the timing.

A couple of words of warning....
Camshafts with a duration greater than 264deg start to need engine mods to work optimally. A 264deg cam works best in the approximate range of 3500-7000rpm. The next common duration is 272, and this does start to lose bottom end and works best in the range of 4000-8000rpm. This means your peak power actually happens past the stock rev limiter.
and
The lift of camshafts on the MX5 is limited without head modifications. This website explains it better http://www.maruhamotors.co.jp/miata/parts/na8fcam.html.

Hi Adam, I've fitted JUn 272's 9mm lift, and peak power with the stock plenum is 7200 according to Rick Shaw as at today's tune with the stock intake and Microtech MT8.

I understand there is always merit to do things properly. But I'm curious now. 1 day I'd love to go down this route too. But unfortunately for me its way off.

However since we are discussing fuelling & revlimiters.

If we are saying a 272 deg cam can work on the standard computer. The reason I'd assume you get a stand alone ECU is because peak power is a 7200 but rev limiter comes in at around that.

so if you then went & changed the 4.00Mhz crystal in the standard ECU to increase the reving to say 8000 rpm & fiddled with the spring in the AFM to adjust the fueling.......would this be plausible or way to dodgy?

Plausibly dodgy

Get em Stefan... We'll work out the rest along the way :p

StanTheMan wrote:
so if you then went & changed the 4.00Mhz crystal in the standard ECU to increase the reving to say 8000 rpm & fiddled with the spring in the AFM to adjust the fueling.......would this be plausible or way to dodgy?

Fairly dodgy. It would probably run, the problem is that you have almost no control over the shape of the fuel curve, and no control at all over teh ignition timing map (which will be the more important one).

Slammer, thanks for that.....interesting fact on your peak power.

I think I might need to consider finding some 272s.