Right, onwards..
Engine in, was time to fit a bunch of the front end up and get on with rebuilding the bodywork - I wanted to make sure all the pannels lined up OK and do all the jiggling and adjusting now while the car was 1/2 painted, to hopefully reduce the amount of fiddling later on
First up a couple of details - plugs made for the bits of the inlet manifold I wouldn't be using anymore..
And installed with cleaned-up slightly ported throttle body
You will notice I'm using the standard plastic inlet and single throttle, whereas in some of the pictures I had a set of 6 throttles fitted - these are from an M3
I used the opportunity while the engine was out to mock-up an inlet manifold/adapter for a guy that allows fittment of these throttles and an adapter linkage to suit the standard cable throttle, however I didn't really need the top end on this car. It also requires a different ECU, etc., and so for the time being I've not gone this route
Referring back to the BHP / KG limits of the Kumho BMWRDC regs I don't think I'll need multi throttles, hence sticking with this standard set-up
This is an inlet manifold from the M50B25 engine, which is from the earlier (1992-1995/6) 325i. This was a smaller capacity engine, and so had a "proper" manifold - the M52B28 (from the 328i) had a restricted manifold which gave good torque, but really strangles the top end - this manifold swap is worth about 15bhp, and with a remap to support it maintains torque..
Example of the two manifolds together - M50 left, M52 right
You can see the runners are significantly smaller cross section, lengths are about the same, resulting in better low down torque but less top end. Again this was to gap the 328i vs. the M3, but also to keep the engine just under 200bhp, which seems like it was a car tax (company car (BIK), road tax (VED), or purchase tax (VAT) I'm not sure) in Germany.. most of the 2.5-3.0 litre german cars of that era are right around 190-195bhp
I also installed an M3 (3.2 evo) oil filter housing - this has a thermostat in it, and inlet/outlet ports for an oil cooler (the 328i didn't have this)
Front "clip" drilled and dimpled, then test-fitted
Front wings fitted - these were fit-up to figure out the alignment, etc before everything got painted
Oil cooler mountings welded onto the front cross member piece, and mounted - it was a bit tricky to fit the oil cooler "the right way up" so fitted it upside down with the plan of bleeding it before fitting
And bonnet on - the intent is the oil cooler will sit right behind the front grills
For the oil cooler plumbing, I installed the following..
Tee piece between the oil filter housing and the return line from the oil cooler. This routes to the firewall
Its fitted to this line because that port is effectively seeing oil pressure all the time
A line to/from the cooler, the line away from the cooler has a near zero rated (about 0.1psi) check-valve installed, so it only flows back to the engine
This was done with the oil cooler the "right way up" and I don't have a picture at this stage but will post one later in the process
This gives you an idea how it looks the wrong way up!
Then inside the car, this happened! (shown here not in its final location)
An Accusump is basically a big (1.5litre i think) piston accumulator with an adjustable nitrogen pre-charge. You set the pre-charge so it gives you a decent volume (around 1 litre) of oil at full oil pressure. The accumulator is tee-d into the oil system downstream of the oil pump such that it supplies oil pressure when the pump can not.. Think of it as a 1/2 way house between a standard oiling set-up and a dry sump system. There's a choice of "nothing", a fancy electric solenoid valve that comes on/off with ignition, and a clunky big manual ball valve (I went with the latter)
The logic is as follows - the thermostat is effectively a shuttle valve, either opening the pump to the engine but closed to the cooler when cold, or open to the cooler but closed to the engine when hot..
When cold
PUMP -- ___ ---- ENGINE
.......:.........:
.......:.........:-- ACCUSUMP
.......[COOLER]
When hot
PUMP --- ][ --- ENGINE
........:.......:
........:.......:-- ACCUSUMP
.......[COOLER]
PLEASE IGNORE THE ..........'s I had to include them to make the formatting work!
This gives full flow through the cooler when hot
The return line is always open to the engine/accusump though, so is always subject to engine oil pressure (just not always flow)
The installation I've gone with is to have..
FILTER HOUSING --- COOLER --- CHECK VALVE --- TEE to ACCUSUMP and FILTER HOUSING
So before starting the engine you open the ball valve, wait a few seconds then start the engine. The accusump will provide pressurised oil to the top end of the engine before starting
When cold, the accusump operates on the engine side and cannot effect the cooler because of the check valve
When hot, the same situation exists but the cooler is in-play (however cannot see pressure from the accusump)
The check valve effectively prevents the accusump being able to drain through the oil pump in situations where the oil pump can not create pressure - this doesn't work when the engine is cold, but not planning on any creating any oil starvation situations when the engine is cold anyway
Before turning the engine off, you close the ball valve, and it sits there ready to go for the next time
This is also a going time to point out another upgrade - I actually fitted an E36 M3 Evo sump and dual pick-up oil pump when I rebuilt the engine and forgot to mention it!
This should prevent any starvation anyway (fore-aft) so its really only cornering.. I didn't baffle the sump because a) its a ball ache, b) the only people who sell a kit thats ready to go are in the US and wouldn't ship to a colleague for suitcase-importation or to the UK! c) its not really a 100% fix anyway.. The Accusump isn't either because its a limited volume, however its capable of maintaining about 30psi for 20 ish seconds as its set-up which is pretty good!
The other advantage of the "check valve" set-up I have, is the oil pressure switch is acting on the outlet of the pump.. So if it fails, I have a big-bad warning light on the dash, and effectively 20 ish seconds notice WITH oil pressure from the Accusump, but nothing from the pump.. Hopefully its a decent insurance
This accusump has some relevant heritage - it was from a mondeo super-touring car.. I was a bit worried my BMW might "reject the transplant" due to the donor being the opposition but so far so good
All cleaned-up and ready for the next stage!