BiTurbo228

Also, here's some acceleration graphs using the latest expected figures (as usual, vs KPR's starlet). I've also assumed the 6500rpm spike is an anomaly and split the difference either side, but it could well not be. 4.3 diff: 5.3 diff: I think the 5.3's a winner.

Just catching up after a couple of months away. Great seeing the progress man! Probably feels a bit painful, but it looks like a lot from where I'm standing. Couldn't agree more with your thoughts on an analogue dash. I've always had a bit of a visceral reaction to digidashes, but never really articulated it properly. Adding that to the wizardry with ECU GPS inputs and my first thought was 'I really want to see an analogue lap timer split gauge'. I'm imagining something dead simple from a physical perspective, like a little gauge with a red half and a green half, and a little pointer that tells you how you're doing compared to your PB (or previous lap).

I did! I can thoroughly recommend it. Excellent car (though is currently off the road with ABS problems). I probably wouldn't do it exactly the same way unless you don't mind a car that's a bit rough around the edges (which is unusual in Jag ownership). I used a solid flywheel so it could take ~400whp (it's currently at about 325whp and is decently quick already), but if you're happy with 250hp and a boatload of torque then a dual mass would make for a much more civilised driving experience. I think you can probably go a bit higher on later manuals, or ones from an E60, but I don't know all that much about those. Or an auto is always an option. The oodles of torque really does suit the Jag driving experience, and it even sounds alright (which is surprising given it's a diesel). The overall engine is definitely smaller than an AJ6 so is probably easier to fit, but the integrated air intake in the cam cover caused clearance issues with the XJ40 bay. I replaced it with one from an E60 535d which gives a lot more space. I'm somewhat sceptical of the quoted weights there. Only because I've weighed the AJ6 (fully dressed, incl oil and whatever coolant was left in the block, plus a getrag 290) that I just pulled out of my Jag at 325kg. Not that the ~195kg is incorrect, but you have to be really careful with engine weights to make sure folks are comparing apples-to-apples. I've got the Getrag 290 down as 49.9kg, which would put all the rest of it at ~275kg. That suggests to me that the 195kg figure is probably a bare block figure (including missing stuff like the flywheel). The crank alone of the 4.0l weighs 39kg (again, seen a picture of one on a scale). The whole engine's a bit of a monster (though if folks like Gareth Thomas are to be believed...which is a question in itself...they have a lot of potential). Because I'm very nearly as much of a geek as @Roman I've started a database of engine weights I've found from a trawl of the interwebs, making sure to only include weights that are actually verified with a picture (rather than 'my mate's mum's dog said XYZ), what was actually on the engine at the time the picture was taken, and a link to the forum I found it on for people to verify (though sod's law loads of the links will be dead now because Photobucket and Facebook have done a pretty good job so far of killing the internet). I don't have a weight for a Ford SOHC 6, but if anyone has one I'd be happy to add it. You and me both! I've got a Getrag 290 for mine, but they're £££ now and quite rare, so if it goes up the tubes I'd like to know potential replacements! Don't forget that that bit the bellhousing bolts to also unbolts from the block. If you need to shimmy around where the input shaft/crankshaft/starter/clutch end up then you can get something machined/laser cut to either change the depth or adapt to a different pattern. Definitely more expensive than just adapting the bellhousing to a different gearbox, but it's a good backup to have.

The tricky thing with using all of the VW gear will be getting the VW flywheel to play nicely with the X1/9 crank. Watching with interest though as I've got just that conundrum with an MX5 gearbox and my Triumph to work through. Currently thinking that a custom-made flywheel is probably the best option (though is £££), but I know someone on the Triumph forums has got it to work through turning down the OD of a GT6 flywheel to fit an MX5 ring gear.

Joy. Did the internet actually mean 'you can run the guts from an Alfa gearbox in the casing from a Mk2 Uno Turbo/Punto GT gearbox'? But the internet read that years ago, and has just remembered it as 'yeah they totally fit mate'. Even then I'm not 100% sure on the Mk1 Uno Turbo 'box... Also, for reference this is why Chat GPT is complete junk for any actual research. It's literally trained on the interwebs, which as we know is full of idiots at the wrong point of the Dunning-Kruger curve. For stuff that's so simple these idiots are right it's ok, but for anything of any complexity it's a crapshoot as to whether it's pulled the information from an SAE paper or VW Vortex.

Thanks for the offer, but I've got one sitting in my garage myself I can check the measurements against. Just trying to be lazy and see if anyone else has done it already!

Intriguing. Ratios would probably be better for NA. Let me know if the bellhousing bolts up as that would make some of my plans a bit easier. There's a chance it does as the T-spark engine is built on the old Fiat twincam block, which means it might share a pattern with the SOHC (not sure if it does or not). The 146 'boxes have the better synchros too. Oh, and if you're using an intermediate shaft it's the ones from a Punto GT or Mk2 Uno Turbo that fit.

The X1/9 short shaft fits just fine. I'm not sure if the long shaft fits (ooerr), but there's an intermediate shaft that comes with the Punto GT. You can use a second X1/9 short shaft on the end of that, spaced out with a gutted CV outer and some longer bolts. That puts it in the right location. The starter's in the same place as standard, but you need to use the Punto starter as the teeth don't mesh properly with the X1/9 starter and Punto ring gear. Luckily it's a nice gear-reduction lightweight one as standard. As far as I'm aware the year doesn't matter, but I don't know if there's other differences beyond the Punto GT as that's the one I picked up. I know the later HGT was NA 16v, but not sure on their gearbox arrangment.

Not that you've bought and 3d-scanned a gearbox already, but I've got a C510 5-speed in my X1/9. Came out of a Punto GT so the bellhousing and flywheel/clutch bolted straight up. I'm not sure which other Fiat SOHCs they came with as the Punto GTs aren't the most common, but you can find them in all sorts of different Fiat group cars with all sorts of ratios. The synchros in the Punto box were an enormous improvement on mine compared to the previous ones, though I did manage to screw them with a clutch leak so I'll need to sort that. Apparently the Alfa twinspark gearboxes had a redesigned synchro that's even better. Only issue with them is they're top change so I had to fab up my own cable gear change mechanism which was a bit crude but mostly worked. Oh, and to fit them you do notch the bodywork a little. Commonly done thing. I eun through it on page 3 of my thread if you're interested: https://forum.retro-rides.org/thread/217672

Ah gotcha. I was wondering because I found an old thread from back in the glory days/wild west internet of a chap who had stuck his MX5 gearbox on a faro arm, but the link to the file is dead. Was wondering if someone had squirreled that file away somewhere and it had resurfaced here. I'll check the measurements though. Better safe than sorry!

@Spencer Can you remember how you got those MX5 bellhousing measurements? I'm drawing up a Triumph I6 to MX5 gearbox plate and I've got another set of measurements from that bellhousing gasket thing they have, and was wondering which was more likely to be accurate. No worries if it's too long ago to remember.

Ah managed to misread it as 0.25mm rather than 0.025mm! Makes more sense!

Huh, had no idea you could mix and match bearing shells. The more you know!

Right, hear me out. 12 of these (or slightly smaller strommys), one set on short runners and another set on long ones. RPM-actuated butterfly to swap the inlet tracts to get the pulse tuning right. You really want to hammer that rpm-transition bog as each cylinder is briefly fed by both carbs...

To be fair, 5.3 diff for a super-short 1-5 and then a long 0.606 top for cruising would probably do the 'fairly nice all-rounder' thing very well indeed. Bit of a jump to get into 6th which might be a bit annoying, but probably made up by better cruising when you're there. 2800rpm at 60mph which is perfectly fine as well. 80whp-ish so plenty of go at that point. Even at 50mph in top it's fine with 2350rpm. Even the 4.77 diff also works out quite nicely for that. 2500rpm at 60mph and 2100rpm at 50mph. All fine. And saved the money on a new CWP. If it'll pull ok from 1500rpm then you might be able to start in 2nd, accelerate to 35mph, shift into 6th and just leave it there