[Zed.]

had a looksee into fitting a Mazda / Mx5 gearbox to a Vauxhall 'XE' engine...

a Mx5 gearbox bellhousing compared to an aftermarket Vauxhall to Ford bellhousing.
similar looking with startermotor position in similar position.

the Vauxhall bellhousing overlaid on the Mazda setup.
as it's similar then curiousity means theres scope for an adapter-plate....

Mazda bellhousing offered up to the Vauxhall engine.

BUT the gearbox's input-shaft is not long enough to enter the Vauxhall crankshaft's 'spiggot' bearing (actually a Ford bearing as the fwd Vauxhall never had one fitted)

the Vauxhall engine design has it's flywheel closer to the cylinderblock compared to the Mazda design - hence the distance seen in the previous photo...

on a slight tangent, this Vauxhall engine has been modified and has a 'skeleton' flywheel to fit a 184mm multiplate clutch.

so. I've a problem here, I could cut & weld a Vauxhall bellhousing 'lip' onto a Mazda gearbox, could go for a hybrid gearbox using the 6/5 speed I already have for the tailhousing (fit the Mx5's ppf & gearstick hole in bodyshell) and an Rx8 6 speed gearbox as theres adapter-plates available to connect various engines...

more thinking to come....

Rich.

 

[Zed.]

I'm desperately tryin to NOT work on this conversion BUT just removed the camcover & this is what I found...

was expecting it to be corroded after ~15 years in a wet garage...

big camshafts, very non-standard, lots of duration & 11.5 lift (exhaust) 12.5mm lift (inlet)

Rich.

 

[Zed.]

recording engine dimensions...

Mazda B6 1.6L cylinderbock length 372mm.

Vauxhall XE 2.0 cylinderblock length 420mm.

in the garage I've a few engines, heres another 2 XE's 😉

did some Google-fu and identified the cams in the XE...

Catcams 4600864 profiles in both inlet & exhaust so not mild by any means (OK I knew the engine was modified but after I'd bought it time ,circumstances & priorities changed so it's been almost forgotten - much like it's spec!)

I now have timing details so can lift the head off the block, hope it's just going to be a case of evicting spiders

can see some corrosion on the port floor - why I'm lifting the head...


I'm going to remove the Mazda engine & drop the Vauxhall in to assess its fitment, hopefully will not clash with any Mx5 steering or suspension components.

more waffle to follow

Rich.

 

[Zed.]

curiosity got me so....

dug up my Mazda & Ford clutch-alignment / input shafts as these are easier than using google to get their dimensions (spiggot both ~15mm diameter according to my dodgy el-cheapo digital vernier caliper)

the Vauxhall XE engine is a fwd unit so has no spiggot-bearing fitted as standard, in rwd conversions a Ford 'crossflow' needle-roller spiggot bearing is used and one of these had been fitted.
luckily the Mazda input shaft is of compatable diameter to fit.

this now points towards esier adaption of the Mazda / Asin 6 speed gearbox but this will involve cutting the face off & welding a Vauxhall friendly face on....

this way will allow retaining the ppf & origonal gearstick position and the 6speeds close-ratio gearkit (as the dogleg'd 5 speed)

more thinking & measuring to follow - now looking for a dead 6 speed to canabilise the bellhousing as a test gineapig.

Rich.

 

[Zed.]

as if by magic, some thinking & measuring happened...

needed some dimensions to plot the bellhousing cut&shut.

these are the Mazda gearbox input / first-motion shaft distances from the bellhousing's engine-face. (10mm & 31mm respectively) - not needed to fabricate the 'hybrid' but usefull to have as will show how much further rearwards the Vauxhall engine's rear face will be compared to the Mazda engine underbonnet.

next, the Mazda gearbox...
mk1 5speed top & mk2.5 6speed lower

the 'bellhousing' area, both are somewhat different but share identical dimensions @ engine face.

the Vauxhall / Ford bellhousing compared to the Mazda 6speed.

one of the considerations, the clutch slave-cylinder mounts to the Mazda bellhousing, this will be in the section to be removed and those drillings will be in the area taken-up by the Vauxhall engine - some thinking to follow....

comparing a Vauxhall 2.0L 'XE' flywheel (right) with a Mazda 1.6L B6 (left) the standard Vauxhall is ~ the same wieght as a lightened 1.6L Mazda flywheel! (Vauxhall flywheel can be lightened and skeliton steel flywheels are available to 3.5 / 4 kg and less!)

Vauxhall flywheel.

thought I'd check if it fitted in a Mazda bellhousing 😮

luckily it does!

project is slightly eaier now but still take some engineering / fabrication / welding & luck!

this shows the bellhousing / rear face of a Vauxhall cylinderblock, also shows the crankshaft centreline is inside the block - slightly stiffer than the Mazda setup...

the previous photo was taken as reference to setup this one, as a guesstemate of the Vauxhall crankshaft centre compared to the Mazda (Vauxhall fitting aftermarket conversion bellhousing & Mazda engine - gearbox baffle-plate)

from gearbox side. can see the different bolt-pattern and size with the Mazda being slimmer!

Vauxhall being shorter than Mazda.

drivers / clutch-fork side.

lower edge, the aftermarket Vauxjhall / Ford bellhousings have a 'window' and do not seem to have strength issues - also handy as can be lazy with clutch-alignment & tighten clutch bolts after fitting the gearbox

Rich.

 

[Zed.]

more measurements...

I have a Ford type 9 / Quaife 5 speed gearbox to rebuild for a friend so fitted the Vauxhall XE conversion bellhousing to get some 'working' measurements.

the Vauxhall engine differs from the Mazda as the crankshaft & flywheel protrudes into the bellhousing by ~21mm more than the Vauxhall.

this is the dimension I'll work around, the engine side of the clutch splines.

inside the gearbox, first thing I saw was the selector's 'rollpin' is missing so that is either in the bottom of the gearbox on it's magnet OR it has gone through the mesh and spread around inside

now to draw a basic cutting-list.

more to follow....

Rich.

 

[Zed.]

another (slight) tangent again....

engine-mounts.

I've been rummaging about for engine-mount parts...

I have stuff....

the bushings are Ford Escort Mk1 or Mk2 (cannot remember, they're slightly different widths), and have for over 50 years been the mainstay of countless race & rallycars on it infamous 'Worldcup' crossmember fitted to mk1&2 Escorts.
the tubes are machined to suit the bushes and the saddles origonally were intended to be Mk2 Astra drivers side / front engine-mounts - leftovers from ~15 years ago. I have several other design saddles and also brackets that can be welded to chassis-sections.

theres several heavy-duty and competition spec mounts available for the 5, I had intended to fabricate some to suit the 1.6L engine nut as I'm now looking towards the Vauxhall engine I really need to make something so my stash has yet again helped

I'll be looking more into mounts once the bellhousing situation is finalised and I can actually get the engine into the car.

Rich.

 

[Zed.]

@dadbifWhat size are the bike TB’s you got for the Mazda engine, won’t they be a bit small for the XE?

I had 45 Dellortos on mine before switching to 45 ITB’s.

I have a few sets of the GSXR1300 Hayabusa tb's, these have 45mm butterflies.

the 'common' aftermarket used throttle size on XE engines is 45mm, commonly with Weber or Dellorto carbs (these have choke-tube areas and venturi's to help with fuel atomisation / flow BUT this reduces airflow slightly compared with an 'open' bore of a throttlebody)

the GSXR1300 Hayabusa tb's have 45mm butterflies BUT are taper-throttle bodies unlike Jenvey's 'DCOE' style design - will it make a difference?

at worst, the 45mm tb will be equil to the Weber 45DCOE carbs previously fitted, at best there'll be a few more hp & torque added


I'll be selling the DCOE manifold and buying one of https://www.sbdmotorsport.co.uk/INL-MAN3-VX-2.0-2-0L-XE-Inlet-Manifold-(same-angle-as-head).html
angled types to keep a straight inlet-tract and making another set of DCOE-tb adapter-flanges.

to replicate simmilar tract lengths copying https://www.sbdmotorsport.co.uk/app/uploads/2021/01/TP-VX-2-0L-K3-TP-VX-2.0L-K4-Dimensions.pdf SBD's development

interestingly, Jenvey make the manifolds (& probably the tb's?) that SBD sell

VX/Opel XE - DCOE 0° Manifold

and Jenvey have manifold dimensions in their pdf drawings...

^^Same price as from SBD

VX/Opel XE - SF Manifold

and again Jenvey have manifold dimensions in their pdf drawings...

sorta shorter version of SBD's long taper-throttle manifold...





Rich.

Quoted the above to keep info & train-of-thought in the same place....

the head's port is ~47mm @ widest.
Jenvey's drawings suggest 44mm so manifold can be easily opened to match.

and ~26 1/2 high.
again Jenvey suggest ~26mm so blendable.

out of interest, I measured the BHR Manifold (believed made by Titan and the same pattern as that sold by SBD)

~43 1/2mm.

~23 1/2mm.

this photo shows the manifolds 'port', this is machined during manifacture - both the engine & throttle faces are bored / machined and theres actually a 'step' into the manifold, this goes against conventional porting / airflow theory......  if I remember, this is something I read ~30 years ago in CCC magazine and it's SBD's design....

as an aside,

tried the Subaru Justy Denso alternator on the Vauxhall engine.

shows the positive terminal on the top of the alternator it's close to the carburettors / throttlebodies if used with this inlet manifold - more reason to go with a 'straight' manifold for a better tract & alternator clearance.

Rich.

 

[Zed.]

decided to strip the bellhousing from the 6 speed (5 speed) gearbox to measure & hopefully cut to make a hybrid to fit the Vauxhall engine.

bellhousing off.

the offending item.

the Mazda bellhousing and a Vauxhall - Ford conversion bellhousing.

unfortunately the Mazda gearbox has a shorter input-shaft than the Ford type9 so I cannot trim the Mazda bellhousing to bolt the conversion on in place.

the Mazda over the Vauxhall. I should have photographed the 'overlap' from the side...

the gear cluster, the input / first-motion shaft has 5th gear with reverse 4th / 3rd etc. heading backwards and 6th in the tailhousing (as an overdrive gear - 5th being direct drive 1:1).

5th * reverse, can see the (smaller) reverse idler gear trying to fall out of the case.

6 speed gearboxes have their oil filler & drain plugs are located on the exhaust side, there is a relay-lever that selects 5th gear located on the inlet / UK drivers side and it's been known that unsuspecting people have removed it's pivot-pin to fill with oil - removing the pivot will almost definately involve stripping & rebuilding the gearbox as the relay will drop out of it's position & probably cause extreme swearing

I've not stripped one of these gearboxes so today was a learning experience, I know the rest of the cluster will need stripping to rebuild / reassemble so I might look into improving the layshaft's 'thrust-washer' as this seems to be problematic at higher power levels (& as I've got it stripped?)

I do have a pdf copy of the Mazda service manual for this transmission so that'll come in handy*


*presuming I don't turn it into expensive scrap playing with converting!


Rich.

 

[Zed.]

more faffin...

gave the Mazda bellhousing a quick sandblast earlier, not a great job and didn't clean the engine-face as it's going to be cut off & replaced.

took some measurements...

~144mm?

the Mazda design runs with the clutch splines ~31.5mm from the engine face of the bellhousing.

the Vauxhall design runs with the flywheel closer to the engine so ~11.5 / 12mm.

this means I need the new Vauxhall engine face ~21mm closer to the gear-cluster so overall measurement of ~123mm.

I'll probably cut the Mazda bellhousing @ the first web (~50mm?) and trim the Vauxhall bellhousing to suit, then making a Jig to square evrything...



measure once, cut a few times!


Rich.

 

[Zed.]

more gearbox thoughts....

the 6 speed gearbox has a possible weak-link, theres a thrust-washer on the laycluster that locates 4th gear and this can fail as it's inside diameter is too large - causing it to fracture the laygear's reverse gear teeth and 4th gear can shift with other issues.

anyway,

I removed the reverse gear idler & it's shaft from the gearcase.

closer view, can see the extra, sprung gears on the reverse idler and the laygears 5th gear.

closer view of the infamous thrust-washer, can see it's groove in the reverse-gear teeth.

also this has been turning (polished whitness-marking NOT galling or scrapes on the thrust-washer's side face) in it's groove so not under load in it's previous roadcar lifetime - nice to see...

I'll strip the rest of the cluster shortly but first priority will be to make a pattern of the bellhousing's first to assess the best places to cut for alignment & welding.

Rich.

 

[Zed.]

more thinking, the Vauxhall engine has different coolant pipework routing compared to the Mazda install. this isn't helped as I've already re-designed the cooling system & pipework for the Mazda engine so time for a rethink 😐

an overview of the Vauxhall pipe-route from...

https://www.sbdmotorsport.co.uk/wp/wp/pdf/2-0L_XE_Cooling_System_with_heater.pdf

this gives a problem if I want to keep using the Polo radiator as it's main hose connections are both on the same side due to the 'twinpass' design

on a positive note, theres no need to get caught into the reroute or not debate (rofl)

Rich.

 

[boosted]

I think your getting distracted by the vauxhall engine... make a plan and stick to it lol.

Sent from my SM-N950F using Tapatalk

 

[Zed.]

I think your getting distracted by the vauxhall engine... make a plan and stick to it lol.

Wish I could
I've been battling temptation for years re. Vauxhall engine in an Mx5, way longer than I've owned my Eunos's

although this is way cheaper than creating the 1.6L Mazda engine as I already have a few Vauxhall engines in varying degrees of completeness and tune, also standard engine with decent manifolds & throttlebodies is ~200hp and they really respond to tuning so ~250hp is easily achieved😜

but 200 is enough😳

😎

more thinking...

the Vauxhall 20XE engine has it's heater pipework fed from the rear of the cylinderhead, this (in a measured & guesstemated view) looks to be a little close to the bulkhead in the Mazda enginebay so some re-thinking for a different solution...

it's common to remove & blank the standard / Vauxhall fit heater pipe-stub, either with a coreplug or tapping & a threadded plug to seal so this is not an isue, the question is where can coolant be taken from to complete the circuit?

can see the standard coolant outlet / heater pipe-stub on rear of cylinderhead.

inlet port-face of a Vauxhall cylinderhead.

theres 2 rows of coreplugs on the inlet side, the upper row is into the oil-side (around valveguides etc.) and the lower row are into the coolant jacket. coreplug circled in red is looking a likely candidate to become the coolant outflow to heater.

plenty of room around the coreplug, now to remove one on a spare head & investigate, will it be threadded for a screwed fitting or just a 'press-fit' stub 🤨

more thinking to follow....

Rich

 

[Zed.]

been thinking & measuring the bellhousings for possible chopping / welding...

the Mazda 6speed has a probable cutline @ 72mm.

and 51mm for the Vauxhall...

through the clutch-fork hole on Mazda its ~ 285mm and similar on Vauxhall.

285-290mm give or take (it's cast so never perfect)

next to cut & hopefully not create a load of scrap 🤨

Rich.