Spidercar - MK2 4 door B6T

Hi

I'm part way through a B6T engine conversion into a 1980 MK2 4 door. The car has previously had stock 1600cc X-flow on DHLAs, Zetec on bike carbs for a bit and 1660cc high compression X-flow on bike carbs with EDIS but to date have been disappointed with the performance. Originally the concept was going to be a retro X-flow turbo on E85 but the head gasket went and I cracked the head. I realised that no matter what you spend on a Xflow its not going to touch the performance of a more up to date turbo'd engine.
Why B6t? Cheap to buy, RWD conversion parts available from the mx5 and it's one of those over engineered turbo engines with forged Pistons, massive rods, oil jets under Pistons and potential power outputs in the 250-300hp

So to start I've stripped everything out of the engine bay and started work on a brake set up that will take up less room than the original boosted setup. I've had a twin m/c balance bar pedal box before but I hated the feel and pedal effort. I've decided to go with a non-booted 120Y mc mounted on the fire wall; the alloy block is drilled and tapped to suit the m/c and the original bolt holes which fix the pedal box to the firewall. The pushrod is the original item shortened and held in place by a tube but welded to a bit of flat bar which picks up the same bolt holes as the block (Prototype #1)

Then I got thinking about the clutch; I looked at doing a cable clutch conversion on the mx5 box but it looked too tricky as the hydraulic setup is all designed to push rather than pull like a cable so any mounting points you could use are on the wrong side of the lever, plus there would be the unknown of pedal effort etc. I've decided to use the original master and slave cylinder. So this calls for a larger piece of aluminium. I'm part way through this so I'll post some pics when it's finished (Prototype #2)

Engine wise I've stripped all the fwd components (sold them off which covered the purchase price of the engine) and have fitted the mx5 alloy sump and oil pick-up; rear bowl setup as per the standard escort. Added an mx5 flywheel which came with an Exedy HD clutch. After that I dangled it in the engine bay, used wooden blocks to position it off the crossmember and firewall and then took measurements for some engine mounts. The mounts are a bit agricultural, just RHS and steel plate; I'll probably look at upgrading these but for the time being they will do.

Gearbox wise it is a much longer beast than the standard escort box so to get the shifter into a better position I followed this guide with some success: http://the-mite.com/mite18.htm If anyone is thinking of doing this then let me know as I think I have some useful tips which will save you some of the headaches I had. Overall I'm pretty pleased with the result

Reading back I love how casual it all sounds but I'm a bit time poor and realistically I've been at it for 6 months. The car has been off the road for 12 and has a healthy redback population living in the chassis holes and wheel arches; my kids have started calling it Spidercar

Next job is to fumigate and trial fit the engine and gearbox

Thanks for the link, it just about sums up what I thought already that the mx5 boxes aren't much good but they are fairly cheap so ill see how long it lasts

Some progress on the weekend. The hydraulic clutch master is mounted up, I just need to finish the linkage and make it look a bit nicer. Seems pretty compact though.

Yes, any braking mods legally require an engineer to certify them in NSW

Thanks for the info Mish. How much of the rear mounts did you chop off the box to fit it in?

I'm doing a simple steampipe manifold for the turbo; there's lots of information and pictures around as quite a few mx5 guys have done it before. The general consensus on the mass produced manifolds is that they are all rubbish and I'm going to need something a little different to clear the blower...
Look what the postie dropped off today; should spice up the low to mid range power delivery..

I had a productive day today, I stripped out the engine bay, removed the crossmember, cut it level with the chassis rails and welded on the 5mm plates that came courtesy of the xflow engine mounts (complete with captive nut tacked on the back) and then put it back together. The engine is in for a trial fit and I'm pretty happy with it; good clearance all around and the gear stick pops up in roughly the same spot as the type-9 box I had in it for a while (a little further back than standard but without the shifter shortened it would be right in the middle of the handbrake). I'll need to cut a bit more transmission tunnel out to get the back of the gearbox higher and level the engine a little.

For the moment though the little twin-cam looks quite at home there

Some bits and pieces of progress of late:

I've fabricated a new gearbox crossmember to suit the mx5 box. The idea is to tack two pieces of angle to the under-side of the car in the area there is some transmission tunnel reinforcement and then bolt up the crossmember. I've used a spare 35mm engine mount as the vibration dampener and I'm pretty happy with how it turned out. It's in etch primer at the moment and will get a top coat once it's had a trial fit.

Also I had some flanges laser cut for the supercharger and the second throttle body (for noise reduction on the inlet side of the charger) to blank off the idle bypass controller

I've picked up an old Haltech E6x with brand new plug components for not a lot of money and so I've started building the loom for it. The plan is to run multipoint injection and coil on plug wasted spark, 3 bar map sensor is en-route and I'm saving for some 550cc injectors out of the US. Trigger wheel is set up on the crank pulley but I forgot to take a photo, maybe next time.

Good reading. After a warm summer, must be time to evict the spiders again.
What car is the b6t from ?

So after a bit of a hiatus I'm back into it. There was no way the clutch master cylinder was going to work on the firewall as it landed too close to the inlet manifold. After much deliberation I've gone with a budget remote reservoir master cylinder setup copied from the many balance bar boxes out there. Pretty happy with the result, everything looks nice in gloss black 😉 Just made from scrap I had in the garage and a fleabay mc total cost $30 and a bit of time