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Today i ordered a FlyinMiata supercharger kit with the standard ECU reflash, extremely excited!

Q - I have the 4.1 final gear ratio in my MX5, can anyone comment on this ratio mated with the supercharger? I still have the standard 3.7 in the garage but FlyinMiata want to buy it but i am having second thoughts on selling because of the supercharger. The gears are already pretty short. I sit at 2900rpm @ 100kms. First gear is very quick but i can't imagine how quick it's going to be with the charger.

It's not cheap to get it swapped again ($800~), can anyone comment?

Cheers

I can tell you that a turbo NB with a 4.1 ratio is not exactly what I would call "fun", especially in city driving.

You spend more time changing gears than pretty much anything else.

3.9 was the recommended ratio and alot of the SP owners have already gone down that path (or about to have the 3.9 ratio installed in their cars)

Word of mouth from NC owners is that they have seen improvements in race times with the 4.1 over the 3.9.

Unsure if it helps, but its relevant info

you can't compare final gear ratios between the NC and NB8B because they have different gearboxes with different gearing.
but even if they ran the same gearbox the engine characteristics between an SP and a supercharged NC would be quite different, so it's not a fair comparison.

FWIW, i would leave the diff as standard for now and change it if you don't like it down the track. if it ain't broke...

If you're tracking the car I'd be looking at where you might need to change gears with the different diffs on each circuit and go for the best compromise.
Remember that with the blower you won't want to rev it as hard to keep stresses down..and I don't think the std FI Dynotronics tune gives a rev limit increase
For road the 3.7 will be perfect with the extra grunt available.

BTW there will be, very soon, a facility in NSW doing the Dynotronics tunes,according to rumours, you might be able to negotiate having the tune done there rather than the extended process of sending yours over to the US. It'll also allow you to get the usual (in the US) free tweaks after logging or a dyno session to get the tune perfect for your car.

Oh and if you're selling that diff...let me know!

Thanks for all the replies. I prob won't track the car, maybe some fun gymkhana etc days, not sure yet.

The 4.1 is already in the car, so it's a matter of swapping it out for the 3.7 if preferred. I can tell you now that with an NA setup, the 4.1 is perfect. The car feels a heap faster, much more so than a full exhaust and intake. So for an NA, id strongly recommend it.

Decided i will let the 3.7 go to FM, if i need to chase up another one i will. It shouldn't be that hard because most people will want to swap in Australia for a 4.1

A lot of the guys from America running the SC are still using the 4.1 so see how it go's. Fingers crossed it will be all well and good.

If it breaks - Hello OS Giken superlock.

zombie on this forum has a Cosworth supercharged NC. Maybe ask him and see what he has done.

Hey Dean,

Please make sure to keep us informed on the progress, with installation, costs, ecu etc.
I've also got a NC with 4.1 and have been thinking about this.

cheers
Neil

Looking forward to seeing the install pics.

Finally finished the install. Just need to put the front back together and i am ready to run it in.

Started it up and let it run for about 5-10 mins. Everything seems fine, although the the thermostat didn't open but the thermo fans were on, im hoping it opens when i drive it.

A few issues were present whilst installing, take note if you are thinking of installing.

-the aus MX5 has the brake booster on the driver side, the us mx5 has it on the passenger side. This means that you need to get a longer hose than the one they provide (cant remember what hose its called off the top of my head)

-The intercooler/heat exchanger reservoir cannot fit where they tell you to mount it because of the brake booster. The only place i found you can mount it (didn't try that hard, was limited on hose) is where the washer bottle is. So goodbye washer jets until i find a small replacement of some sort.

That's all i can think of off the top of my head

Cheers

Awesome ! Photos and videos until we can see it in the flesh !

MX52NV might still have some cowl washer bottles for sale.

Been driving around all weekend, it's fantastic. Fuel isn't affected as much as i thought either. Car is pretty damn quick if i don't say so myself, pulls effortlessly in any gear.

It's running really well, But the rev hunting is back again when it's cold. Seems to jump from 500 rpm to 800rpm really rapidly, like it's fighting not to stall. It only really happens when i have the clutch in and apply the brake as well? Possibly vacuum leak?

Any ideas?

Okibi wrote:MX52NV might still have some cowl washer bottles for sale.

Pretty sure they were for the NAs & NBs so probably won't suit the NC

^ yeah it is only for NA/NB

i gave the MAF a clean, seemed to fix the problem but then after filling up with fuel tonight it started doing it again. Fuel filter maybe?