Hello from UK
Turbo Mini Forums

Hello everyone

Come from a background of family owning various Minis and Metros over the years, with turbocharging the A-Series being of particular interest to dabble in at some point.

Was also told the forum would be able to help regarding a query on the reliable road-going output limits the 1275cc Turbo engines are capable of, both with and without an intercooler as well as without factoring in the limitations of the 4-speed in-sump transmission on both the ERA Mini Turbo and MG Metro Turbo (let’s assume for the sake of argument the issue has been remedied beforehand to focus on the query itself).

Have read claims elsewhere of the naturally aspirated 1275cc reliable output limits ranging from 110-120 hp before further modifications are needed to go higher, with the following article making a similar claim regarding the 1275cc Turbo in the MG Metro Turbo with as much as 120-130 hp being easily attainable during development before being dialed back in order to preserve the life of the gearbox though was wondering if users can verify the 120-130 hp claim? https://www.aronline.co.uk/cars/austin/metr...h-october-2004/

Additionally heard the actual figure for both the ERA Mini and MG Turbo being around 100 hp stock rather than the quoted 94 hp figure.

At the other end of the spectrum, what is the most power owners have extracted from the A-Series Turbo in 1275-1380cc+ form? And say hypothetically BL gone in an earlier more RMR-like (instead of RM 4WD) direction for its Metro-derived Group B challenger (being a Metro 4R2 Turbo rather than a Metro 6R4), with extensive development could it at least in terms of power have realistically been competitive against the 158+ hp 1.4 Renault 5 Turbo (that in rally spec was putting out 178 hp up to as much as 345 hp)?

Regards

MM

Welcome! Mine's a Midget not a mini, but it's road legal and makes 205 bhp at the flywheel plus about 70 bhp of NOS on the strip. Others have reached around 250 bhp without NOS and still street legal.

'Where does the engine go?'

Thanks. So there is some truth to the idea of 120-130 hp being very feasible for a 1275cc Turbo had a suitable 5 speed gearbox been found for the Mini and Metro.

The ERA couldn't have run anymore boost feasilbly without an intercooler, however an overly busy engine bay and the needs for longevity prevented that. There are plenty of peeps on here running 150+ bhp with ease on better turbos. No real need for a 5 speed box as most of them don't have 5th as an overdrive/long ratio. It's still usuall 1:1.

In the case of the ERA and taking into consideration the busy engine bay, what would have been a comfortable output for the car in road going form?

Am not after too much power for it to be a handful, just a usable output that is more than standard yet still within the limits of what the both engine and car are capable of coping.

Edited by MM on 4th Sep, 2020.

150BHP is great/usuable for a road going car.
A 150 BHP engine can be made reliable and built for sensible money without the need for swanky components, just the right selection of suitable parts.
Reliabilty lies in the build quality and ensuring that timing, fuelling and charge cooling all have been addressed for example using mappable ignition such as mega jolt over a distributer, using a suitable size and placed intercooler then having everything set/mapped on the rollers.
As for transmission, depending on power a well built standard box with straight cut drops can be adequate for lower power outputs, or straight cut or Minispares uprated helical gear sets for greater outputs.
Final drives as Im sure your aware can be tweaked by either swapping the crown and pinions or/as well as changing drop gear ratios to suit the intended use of the car.
Shane