MX5 BBR / Cosworth Supercharger Kit - Why Is It DIY Only ?

[V8RX7]

I've just been looking at the (lack of) Supercharger kits for the MX5 with the only one of note seeming to be the Cosworth / BBR for the NC

However I noticed it's DIY only which seems strange - anyone know why ?

I thought it was now fully sorted after it's disastrous start in life

[SmilerFTM]

Corten-Miller do what is the best (imo) forced induction option for the NC and it's a rotrex supercharger kit. I've driven one and a few turbos and it's absolutely lovely. Almost has a naturally aspirated feel to the way the power increases as you build revs.

Edited by SmilerFTM on Sunday 7th October 07:30

[V8RX7]

SmilerFTM said:

Corten-Miller do what is the best (imo) forced induction option for the NC and it's a rotrex supercharger kit. I've driven one and a few turbos and it's absolutely lovely. Almost has a naturally aspirated feel to the way the power increases as you build revs.

If you like the worst aspects of a supercharger (inefficient belt drive) and the worst aspects of a turbo (delayed non linear response) then you'd be happy with a centrifugal supercharger, it's only advantage is it's ease of packaging / fitting.

It does of course depend whether you like a large engine (I do, for an everyday car) or a VTEC type (I do, for a toy)

However IMO a PD supercharger is best for the first and a small turbo is best for the second

[doggydog33]

When I had an MX5, BBR fitted the Cosworth unit and it was great. From memory it was 234 bhp and ran a piggy back Ecu. I think Neil at BBR developed the conversion further and got rid of the need of a piggy back. They then moved on to Turbo charging with greater hp gains. I’m sure if you spoke to BBR they would give you a price to fit one but from memory there was quite a bit of work involved and ‘bang for buck’ the turbo route comes out cheaper.

Doggydog.

[SmilerFTM]

V8RX7 said:

If you like the worst aspects of a supercharger (inefficient belt drive) and the worst aspects of a turbo (delayed non linear response) then you'd be happy with a centrifugal supercharger, it's only advantage is it's ease of packaging / fitting.

It does of course depend whether you like a large engine (I do, for an everyday car) or a VTEC type (I do, for a toy)

However IMO a PD supercharger is best for the first and a small turbo is best for the second

No idea how they work, what I do know is what I felt when I drove the cars. The Rotrex unit Corten-Miller do is sublime and it was better than the turbo Blink were fitting into a NC and felt better than a BBR turbo conversion I've also been in. It wasn't long after I test drove both Blink binned the turbo conversion they were going to sell in preference of the Rotrex kit. It just keeps pulling harder the further up the rev range you go, it's a shame you can't let the engine rev higher as it felt like it wanted to keep pulling harder and harder.

[5er]

I also don't understand the finer points of difference between the boosted options, but I recently drove the Corten Miller 300 car and loved it.

Pretty sure I'll end up going for it.

[V8RX7]

5er said:

I also don't understand the finer points of difference between the boosted options, but I recently drove the Corten Miller 300 car and loved it.

The easy way is to get hold of the dyno sheets of the 3 options - rotrex, Turbo, BBR/Cosworth and the way the power comes in is clear.

EG a quick look on the CM Rotrex they don't start the dyno until 2500rpm as it's not making any power lower down - this is absolutely fine for a track car, but for a daily driven road car - not so great IME.

[SmilerFTM]

V8RX7 said:

The easy way is to get hold of the dyno sheets of the 3 options - rotrex, Turbo, BBR/Cosworth and the way the power comes in is clear.

EG a quick look on the CM Rotrex they don't start the dyno until 2500rpm as it's not making any power lower down - this is absolutely fine for a track car, but for a daily driven road car - not so great IME.

I don't use less than 3k rpm when out for a hoon on B-roads, in fact I rarely dip under 4k. 2.5k is for tootling around town and going slow on motorways and A roads. You don't need ANY power lower down

Edited by SmilerFTM on Monday 8th October 08:05

[5er]

Kinda with you there. I've no issue with using the revs. I've very much enjoyed doing so in Type Rs and M3s that I've owned.

[V8RX7]

SmilerFTM said:

I don't use less than 3k rpm when out for a hoon on B-roads, in fact I rarely dip under 4k. 2.5k is for tootling around town and going slow on motorways and A roads. You don't need ANY power lower down

As I said - it's fine for a weekend car.

Many use them as their daily and most will unfortunately find that they spend a lot of time under 3500rpm where rotrex are still making very little power.

I like going sideways with a blip of the throttle, I can do that without slipping the clutch, from idle with my PD supercharger - not relevant to many buyers but it's my favourite feature.

Edited by V8RX7 on Monday 8th October 22:58

[NailedOn]

SmilerFTM said:

Corten-Miller do what is the best (imo) forced induction option for the NC and it's a rotrex supercharger kit. I've driven one and a few turbos and it's absolutely lovely. Almost has a naturally aspirated feel to the way the power increases as you build revs.

Edited by SmilerFTM on Sunday 7th October 07:30

I like the sound of this.
What sort of price would one be, fitted?
BBR are expensive IMO.

[Nuisance]

NailedOn said:

I like the sound of this.
What sort of price would one be, fitted?
BBR are expensive IMO.

https://mx5supercharger.co.uk/