Mapping out the 4.2 XK problems with an ECU, I hope this isn't heresy

That would be very interesting to see. I remember seeing a D type with a very early single turbo fitted high up and a fair way from the manifold though apparently it still gave an impressive performance increase.

Dear Rod,
the graphs are from a v12 HE engine, for what it’s worth. You can generate these from any datalog you take. I always run with the laptop connected and datalogging. It serves as a second (digital) dashboard, showing air:fuel ratios in the four downpipes, the EGTs on each exhaust port, the water flow rate through the thermostats vs the bypasses, the pre and post radiator temperatures, rpm, speed, mpg, you name it - it’s there! You can look at this in real-time or afterwards, tune in real time or afterwards.

Importantly for everyone else, an engine is still just an engine, whether it is fueled by carburettors or injection, so much of this data can be applied back to the standard cars to understand them better and debunk myths so often quoted. I posted those graphs because the early v12s had a vacuum retard factory fitted to their distributors and many users have reported the vast improvement of replacing it with an advance capsule, but then arguing about whether ported vacuum or full manifold vacuum is better, without being able to quantify why. This way, you can see how much vacuum is being applied and when in each case. Ported always, by definition, applies less or equal vacuum than full manifold vacuum, but the cut-in from no vacuum to some vacuum is clearly sharper. (Not plotted is another variable, the rate of change of vacuum advance.)

Another interesting area of study is how to start a car. It’s already datalogging how fast the crank is turning on the starter, when the fuel is injected and how well the car starts at different temperatures. From that, I’d deduce most starting problems are getting the right amount of fuel into the cylinders, as most injected cars start right on the button, whilst our carburettored cousins crank away and then start muttering about fuel pumps, or maybe lack of spark, or jet height… In my case, I run a dual fuel lpg and petrol setup, so I can even learn a bit about fuel atomisation at low temperatures - it starts fantastically well on lpg at low temperatures, better than on petrol. Doing the maths, sometimes it is on the third cylinder to be sparked - that’s just just half a crank rotation and the revs have taken off. It’s all in the datalogs and without them, you’ll always be needing to ask someone else what the answer is.

kind regards
Marek

EDIT: compare that to the limited experimentation available without a datalogging feature - see Vacuum Regulator Advance Experimenting

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My god you must have sensors everywhere, I don’t think I’d dare tackle an engine like the V12 (though I believe people have had over 1000BHP out of them). I’m completely in awe of your abilities! The starting information is particularly good though if you are starting with a gas it’s bound to make things easier, I’m going to try to study the data-log on my startup now you have inspired me.

The v12 is just two 6 cylinder engines firing 60 crank degrees apart.

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Indeed: you should have seen the rat’s nest of the PIII Rolls’ ignition system: 2, 12-cylinder distributors, firing dual plugs!

There’s always one of these:

https://e-torque.com/jaguar-cylinder-heads/#

That’s impressive though probably beyond my budget these days. An extra 100HP with the same carbs shows what can be achieved though!

Hi Rod. Just came across your post because I am trying to a similar solution to the manifold EFI dilema. But I was wondering what year your Supra transmission came from and how you mazed it to the engine? I would have throught with an adaptor plate but in your picture it didn’t loor like it.

Interesting: a year later… no more cylinder heads!

They’re still there - they just changed the URL.

https://www.e-torque.com/cylinder-heads

Dave

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Thanks!

That would be some eye candy on the JeeType, and I’m sure I’d cause some local hemorhagging when I parked a set of Strongbirds on it…:stuck_out_tongue_closed_eyes:

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First dual plug heads I was aware of were developed by Bill Terry and Gary Hagopian. The modification was not for the faint of heart. Or someone shocked by a 4 $figure price tag. Big time cut/mill/weld/repeat process.

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@Flyingfugu. Sorry for the delay, I was away last week. It was a long time ago and I can’t remember which exact model of Supra it came from, it’s possible they all use the same one. I guess the 2.5 turbo might be different from the 3ltr. There is a guy in Australia called Jeff Dello(w) who trades as Delow Auto with a sand casting setup. If you send him all the details of what you need he will make a bell-housing to connect just about any engine to any gearbox. When I had mine made it wasn’t too costly either. I managed to use the standard Jag spring plate with a toyota friction plate though making the release work was a lot of messing about. If I did it again I would use an in-line doughnut style slave cylinder.

The Supra box usually used for these conversions is a W58, which was primarily used in the late 80’s Supra 3.0 non-turbo. I think it may have also been used in Lexus 300’s. It’s geting to be a pretty rare box, while this generation of Supra’s had become quite collectable. Sources:

https://dellowconversions.com.au/

http://www.conversioncomp.co.nz/

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Thanks for the info. I’ll contact Jeff and see what he can come up with. But yes, gast and furious certainly played a rome jn the popularity of the supra, any supra.