BMW BTCC Inspired Track car

[smallspeed]

So, couple of weeks past, transport re-borrowed/hired, and this was the scene my neighbours were met with..



..they hated me anyway, the green did nothing to cool the flames!
The plan (discussed with the painter, and his idea) was to paint doors/boot and the bodyshell on the inside, plus paint the engine bay. Then I could do all the "big stuff", bring it back to him and he could paint the outside and touch up any damage. Given the limited space I had to work in this made a lot of sense to me, and so thats what happened!
Without wishing to waste any time, I dragged it down the driveway and popped it back into the security (and dryness) of the garage















Couple of tarty bits - the plan is to make these from Carbon Fibre one day (similar to the actual racing cars) but for now I put some stickers over them and put them back in the car

Fuel pump covers in progress:



Pump covers/side covers complete:



And in:







There are a few runs and things in the paint inside the car, but apparently this was a B***ARD to paint (which I can well imagine) and so the plan was to leave them and block out / touch-up later
Overall I was super-happy with the paintwork - both the colour and the finish, given i did all the prep, and especially given the price! I think most full-car paint jobs cost more in sandpaper and masking tape than this did

[911hillclimber]

Any chance of the painters contact details please.
No probs if you don't want to divulge.
Thinking next summer to re-paint my 911.
Graham.

[smallspeed]

You have pm

[911hillclimber]

Got it and thank you very much.

Graham.

[smallspeed]

Car back in the garage, next step was to get the engine and trans back in place..
The steering column took a bit of a polishing, plus the rubber "donut" between the two halves was replaced with a delrin spacer to tighten things up a bit - turned on the lathe and drilled



Also polished up the heat shield - this protects the lower-arm rear bush from the exhaust. These are a weak point on most BMW's and so these bushed had previously been replaced with off-set powerflex black bushes
The offset bushes allows you to effectively rotate the bush and give a bit more camber



Then basically put the box on the engine, and put the whole lot back in! Unfortunately my race-mechanic neighbour had emigrated to Canada between engine out and engine in, hence was doing this on my own..
Got finished just before dark..

Before:



After:



NOTE: I used the following method to do this on my own..

1) pick engine up using huge engine crane and load levelling/tilting beam
2) fit and centre clutch, etc
3) pick-up gearbox under one arm and fit to engine
4) put a few bolts in with your free hand to hold it all together
5) fit remaining bolts and torque
6) fit engine mount arms to engine
7) lift car off the ground on ramsp and axle stands, drop engine into car, onto engine mounts
go under car with trolley jack, lift gearbox and fit transmission subframe and mounts
9) put car back on ground

..i don't recommend it!

Engine is sitting on some standard BMW mounts but from an older car (think e24, can't completely remember). These are solid rubber and about 50% bigger than the standard mounts but bolt right in. These give quite a bit stiffness upgrade vs. the old fluid filled ones
I'd like to get some fancy vibratechnics ones in there, but that can wait for another time when I have more spare cash for shiny-bits
Transmission mounts are from rogue engineering in the US - they're pretty solid too (around 95 shore I think)

All this stiffness in the drivetrain meant time for a better gearshift!
Normal BMW shifters are mounted on a "bridge" between the body and the gearbox to damp vibration, however this fairly quickly leads to a wooly shift feel. To get around that a lot of the race cars have transmission tunnel mounted shifters that lift the pivot point and shorten the throw, as well as slickening (if thats a word) the whole thing up. They don't play nice with stock engine/trans mounts because of the movement but i think my arrangement will be ample stiff enough to give a good precice shift
BUYING one was never an option - they're a couple of hundred quid, soooo..
Roughed out a plate with mounting holes to suit the tunnel



Got started on the lathe







Then visited my local knife maker (told you he'd pop up again! Check his work out - Reeve Handmade Knives - its amazing stuff!) to use his metal working kit to shape and finish it.. After a couple of beers in the garden with various grades of wet and dry sanding the top surface, it all started to look pretty good







I also made a "shift link" - this is the piece which goes from the gear lever to the gearbox.. On a standard car its a piece of tube about 10mm dia, squashed at each end with a short pin welded into it. This acts for push-pull, and "twist". Over time the twist bit (across the gate) gets sloppy because it relies on the fit of the pin in the hole on the components at either end - given the pin is like 8mm dia or thereabouts there's not much room for slack!
Several companies sell "double shear selector rods" (DSSR) but they're 100 plus quid plus post and import duty, so again i set about making one - only have one pic of this, and its here..



..obviously very early in the process
this turned out to be a PITA hence i think i lost my mind and didn't take any pics
Basically it works on the two sides of the components either end, effectively clamping them, hence very little slack in twist. you're still subject to the tolerance of the pin back and forth but this has a lot less effect (translates to a lot less lever movement)

Little video of the whole thing installed and working BEFORE I installed the "DSSR" - you can just about tell the slack across the gate vs. fore-aft

Note: I've since turned down the delrin handle and installed my old "cue-ball" gear knob - i much prefer the feel of it. This sits directly above where the aluminium stops / delrin handle starts in the picture, so about 3" lower overall in the car

Gear stick video

[911hillclimber]

Nice work!
I went through a similar trip on my 370 bhp hill climb Impreza.
Solid rubber WRC type front engine mounts and near solid/zero movement gearbox mount and metal-to-metal shift linkage with light nylon knob (from Hewland), remarkably better gear change and no loose knob movement with throttle on-off action during the heat of the run. This is made better by the Impreza change being mounted on the back of the box but with stock mounts it bounced everywhere, easy 20mm n/s/e/w.
The 'white' knob is always in the corner of your eye making it almost instinctive to drop onto.

[johnM]

What a great thread. And to see you doing so much engineering is brill. Keep the updates coming.

Kind regards.

[smallspeed]

I used to be an engineer (MEng / CEng), but got bored with designing and engineering small things no one ever saw or thought about, so I changed jobs. It's nice to be able to get my hands dirty and do some "engineering" again and I'm actually enjoying engineering on my terms, and doing a job I find challenging that pays for these hobbies!

You're right about the shift - far more direct. After a while the BMW shift gets very sloppy.. I like the round white gear knob too - super comfortable in the hand and it does show up really well inside the car! Mine is literally an eBay job that has been made from a cue ball!

Glad people are enjoying reading the thread - I was in a bit of a slump car wise for the last month and actually its been quite positive writing all this out.. Reminds me how much I've learned, done, and has given me a bit of a shove to get on and do some more work this weekend

[911hillclimber]

I find starting a thread to an open-minded audience (like DDK) will make a project MUCH more satisfying.
I've had 4 monster threads, one still running after 8 years and 370K hits/1800 posts on my hill climb car. It adds another dimension and if it interests others just so much the better.

I got bored with being a Design Director and after 46 years of NPD took early retirement.
I now get dirty hands, have a lathe etc, make designs by pen and paper and bring them to life by racing the things I do.

So much more real than emails and spread sheets.

Old School Rules.

[smallspeed]

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!

[Darren65]

Great thread, thanks for sharing

[smallspeed]

Thanks, glad people are enjoying it! kind of wish I'd posted as I went along, but lesson learned..
Engine back in, started work on a few fiddly bits, including starting to think about my least favourite thing - wiring..

I cut the dash and mounted it to the tabs I'd added to the roll cage before painting. I also fitted the worlds biggest rear view mirror from a golf buggy!





This was a heart in mouth exercise, even with a £30 dashboard, god knows what its like doing it with a £1000 carbon dash, or an unobtainable dash from an old car!

I decided I could base the whole wiring around a mini cooper s (r53) engine fuse-box, and so purchased one complete with wiring and fuses/relays from ebay for the princely sum of £15
I then spent about a week figuring out how it works



I ordered some "offcuts" from an architectual structures company on ebay.. one pack of stainless, one of aluminium - total price was about £25 delivered which was a bargain! This is the stainless..



..each of those pieces is about 3ft long!

Don't really have any inprocess pics, but I made up a cardboard template and from that this little tray which screws in where the glovebox lived previously



With fusebox fitted..



Then bent-up a cover and painted them both black using some textured black paint, covered with another coat of matt black



Fitted #1



Fitted #2



Fitted #3



And stickered! This sticker is actually from 1992 - I kept it since I was a kid at the final (and EPIC) race of the 1992 season and some how resisted sticking it on anything!





Around then, THIS happened THis is the same Pi Research System 2 dash used in the works race cars, although they had a "BMW Version" that incorporated a few of the options as standard - back light, BMW ///M stickering, and an amplifier module that can read wheel speed direct from the two rear ABS wheel speed sensors rather than the single diff pick-up (copes better apparetly)
Back in 1991/2 this was about the same price as a granada scorpio ghia x, now a days its worth about the same as a granada scorpio ghia x
In all seriousness though, this was the reserve of the elite back in the day (along with the ridiculous Bosch Motorsport ABS system with a pump the size of a henry-hoover). People used to ask how Vic Lee's M-Team Shell / Listerine race team could afford such things in BTCC - I think we know now!
I will do a post at some point and cover some of the history of the cars, the team and THAT RACE



So to mount this, I brought a set of dead clocks from ebay for a few quid, destroyed them, and then fitted out the back of the binacle with a piece of carbon fibre sheet
This was painted matt black, and then mounted up with the dash gauges, and plonked in the dash - perfect fit!



I also made a small panel to cover the middle vent/radio area of the dash





And thats about it for now!

[911hillclimber]

Nice and simple, the best way and will be reliable too!

[mrk]

Superb level of detail, and being a bit of a BMW and ALPINA fan, am really looking forward to seeing this finished

[C3s]

An awesome thread Ben, loving every post.