Merc M45/M62 Supercharger Build

Today has been a day of taking yesterday's discussions with Dan and James (BOFI partners in crime) about our ideal supercharger setups, and implementing them.

We have two options for designing a supercharger system, based on the way that we drive the supercharger.
The first option is to run the supercharger in line with the PAS and aircon (if present) using a 4 rib pulley.
The second option is to run the supercharger on a separate track, using a crank overlay and a 6 rip tensioner.

Whatever route we choose, we will need to address the way that the PAS etc is tensioned. The easiest way is to lock it into position with a Trackdog style tensioner bracket, which would be simple with the 4 rib setup. The 6 rib setup will require the way that the PAS is tensioned to be redesigned so that we can get the charger lower and further forward without fouling the standard bracketry.

When it comes to designing a bracket, it appeared that our main constraint was positioning the charger far enough forward to reach the track. Especially with the M62 which has no nose, and somewhat with the M45, which appeared to have a short nose. More on that in a moment.

Another consideration is the factory mounts of the Merc M45 protrude far enough to be annoying. When the supercharger is positioned with the outlet a 90deg, one of the lugs fouls the exhaust manifold. We want this to work with aftermarket manifolds, so it's quite a risk when the Merc charger is about 2" wider than one from a mini.

So, mounting the charger far enough forwards...

It looked like we didn't have a lot of nose to play with, as the standard pulley sits quite close to the body of the charger.

Please excuse the potato photos, I had left the big camera indoors...



But pulling it off revealed that there was quite a bit hiding under there. If we redesign a pulley, we can make the most of the available nose, as per the picture below.



This gave us the room to push the charger backwards, and inwards towards the head. At this point, you can see our two mounting options.

Either horizontally, if we redesign the PAS tensioner mechanism, although here we're holding it a little far out to clear it.



Or at an angle, which is what the rest of the post will focus on.



There is oodles of room without a strut brace in there, but were going to need to be clever about maximising the space available. The charger just tucks over the manifold lovely, but getting a second throttle body under the brace might prove a challenge. I guess we'll find out soon enough!

So the first thing to do was figure out how we're going to mount this thing at a jaunty angle.

We took some 3mm steel, ran a grinder down its length and folded it into position. We then cut out where the standard headshield mounts to, and drilled holes for it to bolt to the manifold.



Mint.

I wasn't able to get photos of all of the next steps, so I'll try to fill you in.

With the first fold in position, we added a second that brought the plate up to where the engine hoist bracket normally lives. Then we bent the top of the bracket back down around 120deg. At this point I'm hoping our engineering company can fold at such a mad angle!

The problem at this stage was that we had folded the sheet too low, meaning we couldn't get the bolt into the head. We cut along its length, and added about an inch in height, giving us plenty of room.

We thought it would be a good idea to join all four holes of the supercharger together, believing it would create the mount inherently stronger when we triangulate the bracket back to the block.



It's definitely unnecessary though, as the supercharger will form the link between the brackets to make it more than strong enough.

With the charger in place, there is probably too much room between it and the manifold. I didn't get chance to measure it, but I'd guess there's probably over an inch of wiggle room.



Here you can get a better idea of the folds we have used. The third bolt in the manifold is probably unnecessary, as we'll triangulate the bottom of the supercharger down to the block.



Leigh

Looks good, if you're aiming at the M62 then stick with 6 rib and an auto tensioner.

Russell

Really interested to see how this goes, it's the long term plan for mine

6 rib setup, but thinking about it, that's the Mini charger so slightly different to the above.
We ended up rotating it 45 degrees to get it clearing the underside of the bonnet and shortening a TRLane outlet to get it low enough.

The reality of these setups is they are limited ... ironically because they get too hot. No intercooler means you have to faff around with a 5th injector and water injection if you want to make any decent power ... it's an interesting engineering project but not really worth the effort

Russell

I didn't realise it was on an Exocet, awesome!

Do you know how fast you're spinning the charger? I have a PAS pump in the garage I might look to see if we can remove the pulley from. I personally run without PAS, but as we would like to offer the finished product as a kit we need to take that into consideration. Which is why the initial idea was an overlay on the crank and a third track, to keep everything else stock and as 'simple' as possible - only the S/C pulley to remove.