Have rebuilt my 1983 XJS engine and made major modifications to virtually all stock systems and would like to share what I have learned in the process with those interested. Have many pictures of the results. Thank you.
Love to see these photos and write up
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Well you’ve done a very tidy job of it!
I don’t agree with some of your choices, but I look forward to your explanations. Perhaps you will change my mind.
interesting project, nice seats do you intend doing any light track work?
I like your copper tubing scheme !
Looks cool too.
Aristides
I’m a bit concerned about your copper cooling system piping, for two reasons:
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There doesn’t seem to be any capacity for flex between engine and rad inlet. Hence, as the engine moves on its rubber mounts, I’d expect the piping to eventually crack the inlet fitting on the rad and rip it off.
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It looks really small. While I expect it’d work OK at low power levels, I’d be worried it wouldn’t flow enough coolant at WOT and would eventually lead to overheating.
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I’d be very concerned about that, too.
No thermostat? Wow they were thirsty engines when they ran at the correct temperature, how will you maintain the correct operating temperature.
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Welcome to Jag (minutiae) Lovers: posts mods like this, and debate will occur!!
That said, if it works…good onya!!!
My first thought was those air filters are way too small. Then I went to the vinyl (?) stranded hoses. Seems an odd choice visually and for durability. Perhaps they are some other material.
Picky bar steward I.
Personally I like it. Clean that engine bay right out! I’m planning a similar house cleaning under there. Electronics relocation is also on my list.
I think there are two problems with your logic here. First, you are feeding 100% of the flow into the top left port on the rad, and that port is only supposed to see 50% of the flow. It flows only the top 1/3 of the radiator. Flow into the top right port should flow twice as much, as it flows through the bottom 2/3 of the core.
Second, you’re claiming that if a garden hose flows enough, it’s big enough – but a garden hose has at least 30psi of pressure behind it, while the pressure differential generated by the water pump can be tiny in comparison.
OK, my first point about the restrictiveness of the flow in the upper 1/3 of the rad clearly went over your head. And my point about the engine moving on its mounts also clearly went over your head. So, one last attempt to get through: How hard have you driven the car with these mods?
Do what you want, but I have no doubts as to Kirbert being correct here, or him being incorrect at all concerning anything about the XJS, or having a comprehension problem. I think you do not comprehend that he wants to tell you that the radiator inlet will fatigue and crack so you’d be better off fitting a more flexible rubber hose.
And from what I understand he knows what he’s saying. If I were you I’d rather say okay, thank you, I’ll look into it instead of attempting big boy language. However what can go wrong in terms of overheating if both heads have gauges? Worst case, they get warm, you notice and let them cool off!
The engine bay looks very nice though. But, know your limitations.
Well Frank,
Not planning to start WW3 over modifications to an XJ-S.
Are you a plumber ? Interesting use of copper tube and looks very professional.
I would agree with Kirbert about the chances flexing of the engine will crack the connection to the radiator.
However, having such a small bore cooling system is likely to be fine. It will not take long in hot weather to check that out. I modified the coupe to have an electric fan and electric pump.
That allowed me to control the cooling and calculate that a standard radiator can keep the V12 at 80deg C up to an ambient of 45deg C.
I suspect the limiting fator in cooling is the exchange of heat from coolant to air in the radiator.
That is more of a problem than the exchange of heat from engine to coolant.
More air flow is more important than more coolant flow - or is there evidence to the contrary ?
Lighten up Frank, there is an old saying - " the proof of the pudding is in the eating ".
So a year from now report back the radiator is intact, engine cooling is excellent and we all eat humble pie.
I am pretty sure reading evidence from your previous posts that we better get ready for baking it in May 2019.
If you got rid of 18 hoses ( are there really so many ? ) that would be a step in the right direction.
Looks like there is plenty of room to put in an electric pump. That has some good points versus a mechanical pump but too late to mess around now.
I am all in favour of modifications if they have a benefit.
On another topic you raised, I originally had fitted an aftermarket EFI system to the coupe with the controller in the passenger footwell. That took up a bit of room with a lot of wiring going thru the firewall. Later I changed the wiring so the controller plus ignition amp are in front of the radiator where there is plenty of room. From previous temperature logging that proves to be the only cool spot anywhere forward of the firewall.
Has nothing to do with state of tune. It has to do with torque developed in low gear.
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Frank, do not assume that just because a person does not currently own a certain car that they know nothing about a marque. People here post questions and comments to learn and or help people.
I personally think what you have done is impressive, wise? Not so sure.
I have had a radiator neck shear off, not due to the engine moving but from the radiator itself. Unbeknownst to me the cotton reels locating the radiator in the rad support had disintegrated/disappeared over the years.
As has been suggested come back in a year with a good number of miles/kilometres being run and report back.
I read that you do not wish to invite debate regarding the lack of thermostats in your car and also not being aware of a ‘correct’ running temperature, I remember a much more leaned person than I once postulate that if car manufactures can save a penny on a car they do. If a thermostat isn’t required why does every car manufacturer insist on placing them in the coolant circuit?
Regards.
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Deleting thermostats is a novelty.
I am amazed you get reasonable coolant temperatures.
However, if you do, and you are happy, so be it.
Deleting the aircon system is a brave move.
That is one you will never convince me to emulate.
I like my comfort.
Meanwhile take it easy and lower the blood pressure Frank.
You live in Florida, laid back land of eternal sunshine and occasional hurricane.
You have already won the lottery.
This forum is not the same as the political arena where insults fly thick and fast.
Like the political arena we do have " robust debate ".but are expected to be civilised and restrained.
Everybody, including me, crosses swords with Kirbert from time to time. That is part of the fun, if you have a way with words you can undermine and confound him while appearing to be as innocent as the driven snow.
Practice the art.
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Caution, Frank, you might anger the great OZ…just keep reporting on your progress and let us know how temps, etc. experiencing…looks like some great experimental data may be realized from your modifications. Best, JW
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