Bulkhead - to cut or not to cut?
Turbo Mini Forums

Hi guys,

Whilst I'm in the process of overhauling my mini, I've got a little bored of replacing one rusty panel, only to move round to the next hole to find it's actually a lot bigger than I first thought!

So as a very welcome distraction, I've decided to start acquiring parts to build a turbo engine to replace my 100bhp 1380 lump.

I've spent the last couple of days looking around the forum, there's a whole wealth of information, but having done a few searches there are some basic-ish questions that I'd like to get opinions on.

- The most powerful and developed engines all seem to be 1293cc, not many people seem to turbo a 1380cc block. I'm presuming this is partially because people don't want to risk having less material between cylinders? So would people advise me not to take on turbo'ing my 1380 block?

- By not cutting the bulkhead and fitting a box, would I be restricting turbo options and ease of fit? I know about what Mirage can do, basically fitting any sensible size turbo to a custom manifold, but I've got a full cage to go in so the strength isn't so much of an issue to me. I'd rather not cut the bulkhead, but if it'll end up saving me a couple of hundred quid and make fitting the engine and reaching parts on the backside of the engine whilst in situ a lot easier, I'd definitely consider it.


If it will help you answer my questions, I'm looking to get 150+ bhp from the engine, and it'll be for a road car.

Thanks in advance for your thoughts!

Rebuilding a 1992 mini...will be finished in 2019

A turbo'd 1380 will be fine.

Having a bulkead box does not really give more room to work than not having one.

Personally I'd rather spend a few hundred squid on a manifold than cut the bulkhead; and have done.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Do the mirage manifolds flow much better than the std style manifolds used when the bulkhead is cut? As if they perform better that'll probably settle the argument for me

Rebuilding a 1992 mini...will be finished in 2019

As a non-turbo manifold the mirage (or sinilar) would be pretty crap, but as a turbo manifold they are no restriction to power.

Flow when using a turbo is all about the turbine size and design.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Cool, I'll have to see if any mirage manifolds come up for sale on here, depending on my choice of turbo unit, which I'll be researching next! I'm happy with N/A but turbos are completely new to me

Rebuilding a 1992 mini...will be finished in 2019