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Turbocharging Mini Engines

The ERA Turbo was a nice mini saloon with smart wheels interior and dash, a sexy body kit and a 1275 metro turbo engine setup but with a side mounted radiator EXPENSIVE NEW and USED.

Here in the UK the "quick and dirty" method to make a mini turbo is to transplant a MG Metro Turbo engine transmission and fuel/turbo/ecu setup into a standard mini, bulkhead and cooling/fuelling modifications are needed but the end result would be the fraction of the cost of an ERA (but not as nice).

Turbo, mods required for fitting

Fit a MG Metro Turbo engine. You'll need to modify the bulk head. Cost ~100-300 pounds. Buy an old metro and scrap it yourself. You'll get the decent brakes then too.

Turbo conversion

Avonbar (see any Mini world mag) do a box with instructions which you fit into the bulkhead. (35ish UKP) Go and buy a metro turbo with no MOT This will give you most of the parts you need. You will need to use the Fuel system (including fuel pump) of the metro turbo as This is a little special (Have you got Dave Vizard's book called 'tuning the A series engine' ? If not buy it.

You will need a huge amount of cooling 4 core radiator minimum I Also suggest you flip front your mini. The Metro turbo only has 95bhp as standard which is a bit poor. If you Drop the CR Down to about 8:1 (the standard Metro turbo has a CR of 9.4:1)

You can up to boost from 4psi to 10psi+. Which will put the power up to about 110bhp. Watch out though as the gearbox will have a drastically reduced life time above about 95ftlb of torque (100bhpish) If you want to keep the reliability then you will need straight cut drop gears. If you want more than 110bhp then I suggest you modify the cylinder head as per Dave Vizard.

Cam choice is important for reducing lag; Kent and Avonbar do 'turbo' cams which claim to reduce lag.

Lastly the turbo charger used on the metro turbo is too big for the size of engine. This gives a very 'laggy' engine response you can get the Turbo modified to be capable of less boost (this wouldn't be a problem with and A series as you would not really want more than about 14psi anyway) but have a turbo that comes up allot on boost quicker (lower revs and better throttle response.)

If you want more than 125bhp with reliability, you will need a straight cut gearbox as well as the drop gears mini spares do a replacement gear set for approx 600ukp + drop gears.

Ditch the ECU without any other mods and you get the same boost as standard in the midrange (up to aboput 4500 I think) and then less boost than standard from there on up.

There are two ways to ditch the ECU one is to replace the wastegate actuator with a 7.5psi one (standard is 4.5psi) this gives you the same boost as you normally get at high revs all the way through the rev range (ie 3psi more boost in the mid range). The other is to replace the ECU controlled boost modulator with an adjustable bleed valve which you trim to give 7.5psi peak boost. Either way you get the same boost at high revs and extra boost in the mid range.

If all you do is leave off the ECU when you install a turbo from a Metro Turbo, then you will loose power.

This is due to the waste gate being set at 4.5psi, and the ECU modulating the signal to the waste gate, and fooling it into thinking there is less boost there than there actually is.

So, with the ECU, you get 7.5psi boost at high revs, and 4.5psi boost in the mid rev range, this is to stop you ripping your gearbox apart with the huge midrange torque that is produced.

Without the ECU, and with everything else standard, you would only ever get up to 4.5psi boost right across the rev range.

If you remove the ECU and run with a 7.5psi waste gate, then you would get this all through the rev range. So you would need to strengthen up the gearbox, and the most likely thing that will go would be the diff, so a comp dif pin would be needed.

See also Boost Modulator Info

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