1972 Rover P6 2300TC - Saab B234 Turbo

I've been doing a little more research on exhaust manifolds and turbo's. The manifold I made to fit the T25 was quickly thrown together to get the engine to fit int he bay of the P6, all done before the engine was fitted so I really didn't know properly how much space was available. Now I've just fitted the overly big Garrett T04 with twin scroll exhaust housing, I can really feel the engine is more responsive over the T25 in the low-mid rpm range. Obviously the way in which I've bolted the big Garrett on is a temporary bodge to see if it's the way forward, so now I'm looking forward

Doing a bit of digging, apparently joining cylinders 1+4 and 2+3 into a divided T3 flange should help spool up the twin scroll turbo



I'm now in the position where I can take very specific dimensions of the head to turbo flanges and the space available allowing for reaching in to actually fit it and other related maintenance jobs, and hopefully make a much better flowing manifold

So RRG15 prep became a disaster, the Megasquirt was my biggest concern but that seems to be running really well now. That left the over-sized turbo not spooling, and as it's a bit rough and knocked about I decided to have a little fun with it...











The housing has been cut back by about an inch and plated in with 5mm steel.

Obviously the next job is the testdrive...



.... and it blew an oilseal out of the head emptying half the sump

At least I now know the puffs of smoke out of the exhaust are clearly the crankcase pressurising! I'm now in the process of making a new oil breather seperator with a dedicated oil return to the sump and a second rocker cover breather port, this should hopefully cure the breathing issues.

Of course the other issue was that the turbo was still not spooling early enough, so that should be an easy fix too





My spare Eaton M62 supercharger fits nicely just there!





I need to make the drive snout, mounting plate, fit some idler pulleys for the longer auxiliary belt, and plumb the supercharger and idle bypass systems in place between the intercooler and throttle body, then another test drive

Really I'd like to mount the supercharger below the inlet manifold, and I'm also making serious considerations into fitting a Saab B234 engine at a later date

If your thinking about compound charging you need a mass air flow input so it knows the difference between pressure from supercharger and combined from both .

I enjoyed the time I spent building my system and it would take too long to go through all the issues but the fact is that the solution to lag etc it to buy a modern ball bearing turbo sized to suit what you want to achieve . The only advantage the twin charge had was a little more torque from 2500-3200

Preaching to the choir mate , I would put the throttle in front of the charger and spray water / meth into the blower case to keep it cool . Blower bypass doesn't need to be very large this way and the bov just goes in the usual place .
If you can find a way to open the bypass once it reached a couple of psi over the sc output you could let the turbo do the heavy lifting but as I said you need a mass air measure to deal with the transition from compound pressure to pure turbo which I couldn't do with the t5 trionic being speed density and the later t7 being maf based I went with a new fangled ball bearing blower . Never got bored of the noises it used to make though

There is just enough room to remove the top half of the inlet manifold and mount the supercharger directly to that







I've measured the crank pulley at 140mm diameter, and have a choice of two suitable pulleys to adapt to the Eaton nose of 50mm and 63mm, giving pulley ratios of approx 2.75 and 2.2. Going by this the 50mm pulley would be more likely to overspeed the M62 and bake the air going in. Using rough generic calculations the Eaton M62 with a 63mm pulley should be able to produce 10-15psi which is right on the top side of what I want to hit with it

With regards to your oil seal/breather issue, I have been through this. You might already be using it but on the exhaust side of the block there is what looks like a fuel pump blanking plate probably from the blocks B series days, this is a good place to make a crankcase breather and as you already say an oil return from the catch tank to the sump. Hope this is of some help.
Fascinating project

Inlet manifold now mostly welded together, enough for a proper test fit of the supercharger















Yep, that's gonna sit a little proud of the bonnet!

I've started on a plan to 'fix' the engine meltingly high intake temps....

So far I've ordered a Jaguar chargecooler from a V8, the idea to make an adapter or re-weld the port flange to attach to the Rover manifold. The hope is that the 4 ports roughly align and also the top of the chargecooler gives a reasonable equal distribution of air. I intend to fit the throttle body direct to the elbow on the chargecooler after the supercharger



After a little more rough research I've also ordered a water pump assembly from a BMW Mini, it's mounted externally to the Mini engine, is a complete unit and is cheap secondhand! The idea is to mount it somewhere on my engine to flow the water round the chargecooler and heat exchanger. I have no idea how the variable flow rate of an engine driven water pump will compare to the expensive oem electric water pumps, be fun finding out either way!



That leaves searching for a suitable heat exchanger that will fit in the engine bay, probably below the intercooler at the front and then how to control the heat when there is little to no airflow when stationary or at slow speeds? I guess a small header tank will also be needed somewhere in the engine bay too, and a water temp gauge to monitor the performance and heatsoak.